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* [PATCH] Add a new VCSToChangeLog script
@ 2019-01-27 16:09 Siddhesh Poyarekar
  0 siblings, 0 replies; 4+ messages in thread
From: Siddhesh Poyarekar @ 2019-01-27 16:09 UTC (permalink / raw)
  To: bug-gnulib; +Cc: carlos, Siddhesh Poyarekar, joseph

From: Siddhesh Poyarekar <siddhesh@gotplt.org>

Build a more general script that parses changes in a VCS and then
prints it in a ChangeLog format.  Currently this set of scripts has
been tested on glibc and will need a vcstocl_quirks.py for gnulib.
The scripts need to be in to make sure that they're usable for glibc
once 2.29 is released.  A quirks file for gnulib will be developed and
added as a separate patch.

The script currently has a git repo backend and C frontend support.
The gitlog-to-changelog script has been moved into vcs-to-changelog as
a fallback.

Plan for the next 6 months:

- Test on gnulib and build a quirks file
- Add glibc Versions file support
- Add assembly file support
- Mentor volunteers who might want to add more frontends or repo
  backends.

	* build-aux/gitlog-to-changelog: Move to...
	* build-aux/vcs-to-changelog/gitlog-to-changelog: ... here.
	* build-aux/vcs-to-changelog/frontend_c.py: New file.
	* build-aux/vcs-to-changelog/misc_util.py: likewise.
	* build-aux/vcs-to-changelog/vcs_git.py: Likewise.
	* build-aux/vcs-to-changelog/vcs_to_changelog.py: Likewise.
---
 build-aux/vcs-to-changelog/frontend_c.py      | 829 ++++++++++++++++++
 .../gitlog-to-changelog                       |   0
 build-aux/vcs-to-changelog/misc_util.py       |  54 ++
 build-aux/vcs-to-changelog/vcs_git.py         | 155 ++++
 .../vcs-to-changelog/vcs_to_changelog.py      | 139 +++
 5 files changed, 1177 insertions(+)
 create mode 100644 build-aux/vcs-to-changelog/frontend_c.py
 rename build-aux/{ => vcs-to-changelog}/gitlog-to-changelog (100%)
 create mode 100644 build-aux/vcs-to-changelog/misc_util.py
 create mode 100644 build-aux/vcs-to-changelog/vcs_git.py
 create mode 100755 build-aux/vcs-to-changelog/vcs_to_changelog.py

diff --git a/build-aux/vcs-to-changelog/frontend_c.py b/build-aux/vcs-to-changelog/frontend_c.py
new file mode 100644
index 000000000..c3c40ae30
--- /dev/null
+++ b/build-aux/vcs-to-changelog/frontend_c.py
@@ -0,0 +1,829 @@
+#!/usr/bin/python3
+# The C Parser.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+from enum import Enum
+import re
+from misc_util import *
+
+class block_flags(Enum):
+    ''' Flags for the code block.
+    '''
+    else_block = 1
+    macro_defined = 2
+    macro_redefined = 3
+
+
+class block_type(Enum):
+    ''' Type of code block.
+    '''
+    file = 1
+    macro_cond = 2
+    macro_def = 3
+    macro_undef = 4
+    macro_include = 5
+    macro_info = 6
+    decl = 7
+    func = 8
+    composite = 9
+    macrocall = 10
+    fndecl = 11
+    assign = 12
+    struct = 13
+    union = 14
+    enum = 15
+
+# A dictionary describing what each action (add, modify, delete) show up as in
+# the ChangeLog output.
+actions = {0:{'new': 'New', 'mod': 'Modified', 'del': 'Remove'},
+           block_type.file:{'new': 'New file', 'mod': 'Modified file',
+                            'del': 'Remove file'},
+           block_type.macro_cond:{'new': 'New', 'mod': 'Modified',
+                                  'del': 'Remove'},
+           block_type.macro_def:{'new': 'New', 'mod': 'Modified',
+                                 'del': 'Remove'},
+           block_type.macro_include:{'new': 'Include file', 'mod': 'Modified',
+                                     'del': 'Remove include'},
+           block_type.macro_info:{'new': 'New preprocessor message',
+                                  'mod': 'Modified', 'del': 'Remove'},
+           block_type.decl:{'new': 'New', 'mod': 'Modified', 'del': 'Remove'},
+           block_type.func:{'new': 'New function', 'mod': 'Modified function',
+                 'del': 'Remove function'},
+           block_type.composite:{'new': 'New', 'mod': 'Modified',
+                                 'del': 'Remove'},
+           block_type.struct:{'new': 'New struct', 'mod': 'Modified struct',
+                                 'del': 'Remove struct'},
+           block_type.union:{'new': 'New union', 'mod': 'Modified union',
+                                 'del': 'Remove union'},
+           block_type.enum:{'new': 'New enum', 'mod': 'Modified enum',
+                                 'del': 'Remove enum'},
+           block_type.macrocall:{'new': 'New', 'mod': 'Modified',
+                                 'del': 'Remove'},
+           block_type.fndecl:{'new': 'New function', 'mod': 'Modified',
+                              'del': 'Remove'},
+           block_type.assign:{'new': 'New', 'mod': 'Modified', 'del': 'Remove'}}
+
+def new_block(name, type, contents, parent, flags = 0):
+    '''  Create a new code block with the parent as PARENT.
+
+    The code block is a basic structure around which the tree representation of
+    the source code is built.  It has the following attributes:
+
+    - name: A name to refer it by in the ChangeLog
+    - type: Any one of the following types in BLOCK_TYPE.
+    - contents: The contents of the block.  For a block of types file or
+      macro_cond, this would be a list of blocks that it nests.  For other types
+      it is a list with a single string specifying its contents.
+    - parent: This is the parent of the current block, useful in setting up
+      #elif or #else blocks in the tree.
+    - flags: A special field to indicate some properties of the block. See
+      BLOCK_FLAGS for values.
+    '''
+    block = {}
+    block['matched'] = False
+    block['name'] = name
+    block['type'] = type
+    block['contents'] = contents
+    block['parent'] = parent
+    if parent:
+        parent['contents'].append(block)
+
+    block['flags'] = flags
+    block['actions'] = actions[type]
+
+    return block
+
+
+class ExprParser:
+    ''' Parent class of all of the C expression parsers.
+
+    It is necessary that the children override the parse_line() method.
+    '''
+    ATTRIBUTE = r'(((__attribute__\s*\(\([^;]+\)\))|(asm\s*\([?)]+\)))\s*)*'
+
+    def __init__(self, project_quirks, debug):
+        self.project_quirks = project_quirks
+        self.debug = debug
+
+    def fast_forward_scope(self, cur, op, loc):
+        ''' Consume lines in a code block.
+
+        Consume all lines of a block of code such as a composite type declaration or
+        a function declaration.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+
+        - Returns: The next location to be read in the array as well as the updated
+          value of CUR, which will now have the body of the function or composite
+          type.
+        '''
+        nesting = cur.count('{') - cur.count('}')
+        while nesting > 0 and loc < len(op):
+            cur = cur + ' ' + op[loc]
+
+            nesting = nesting + op[loc].count('{')
+            nesting = nesting - op[loc].count('}')
+            loc = loc + 1
+
+        return (cur, loc)
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' The parse method should always be overridden by the child.
+        '''
+        raise
+
+
+class FuncParser(ExprParser):
+    REGEX = re.compile(ExprParser.ATTRIBUTE + r'\s*(\w+)\s*\([^(][^{]+\)\s*{')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a function.
+
+        Match a function definition.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        name = found.group(5)
+        self.debug.print('FOUND FUNC: %s' % name)
+
+        # Consume everything up to the ending brace of the function.
+        (cur, loc) = self.fast_forward_scope(cur, op, loc)
+
+        new_block(name, block_type.func, [cur], code)
+
+        return '', loc
+
+
+class CompositeParser(ExprParser):
+    # Composite types such as structs and unions.
+    REGEX = re.compile(r'(struct|union|enum)\s*(\w*)\s*{')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a composite type.
+
+        Match declaration of a composite type such as a sruct or a union..
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        # Lap up all of the struct definition.
+        (cur, loc) = self.fast_forward_scope(cur, op, loc)
+
+        name = found.group(2)
+
+        if not name:
+            if 'typedef' in cur:
+                name = re.sub(r'.*}\s*(\w+);$', r'\1', cur)
+            else:
+                name= '<anoymous>'
+
+        ctype = found.group(1)
+
+        if ctype == 'struct':
+            blocktype = block_type.struct
+        if ctype == 'enum':
+            blocktype = block_type.enum
+        if ctype == 'union':
+            blocktype = block_type.union
+
+        new_block(name, block_type.composite, [cur], code)
+
+        return '', loc
+
+
+class AssignParser(ExprParser):
+    # Static assignments.
+    REGEX = re.compile(r'(\w+)\s*(\[[^\]]*\])*\s*([^\s]*attribute[\s\w()]+)?\s*=')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse an assignment statement.
+
+        This includes array assignments.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        name = found.group(1)
+        self.debug.print('FOUND ASSIGN: %s' % name)
+        # Lap up everything up to semicolon.
+        while ';' not in cur and loc < len(op):
+            cur = op[loc]
+            loc = loc + 1
+
+        new_block(name, block_type.assign, [cur], code)
+
+        return '', loc
+
+
+class DeclParser(ExprParser):
+    # Function pointer typedefs.
+    TYPEDEF_FN_RE = re.compile(r'\(\*(\w+)\)\s*\([^)]+\);')
+
+    # Simple decls.
+    DECL_RE = re.compile(r'(\w+)(\[\w*\])*\s*' + ExprParser.ATTRIBUTE + ';')
+
+    # __typeof decls.
+    TYPEOF_RE = re.compile(r'__typeof\s*\([\w\s]+\)\s*(\w+)\s*' + \
+                           ExprParser.ATTRIBUTE + ';')
+
+    # Function Declarations.
+    FNDECL_RE = re.compile(r'\s*(\w+)\s*\([^\(][^;]*\)\s*' +
+                           ExprParser.ATTRIBUTE + ';')
+
+    def __init__(self, regex, blocktype, project_quirks, debug):
+        # The regex for the current instance.
+        self.REGEX = regex
+        self.blocktype = blocktype
+        super().__init__(project_quirks, debug)
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a top level declaration.
+
+        All types of declarations except function declarations.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this function
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        # The name is the first group for all of the above regexes.  This is a
+        # coincidence, so care must be taken if regexes are added or changed to
+        # ensure that this is true.
+        name = found.group(1)
+
+        self.debug.print('FOUND DECL: %s' % name)
+        new_block(name, self.blocktype, [cur], code)
+
+        return '', loc
+
+
+class MacroParser(ExprParser):
+    # The macrocall_re peeks into the next line to ensure that it doesn't
+    # eat up a FUNC by accident.  The func_re regex is also quite crude and
+    # only intends to ensure that the function name gets picked up
+    # correctly.
+    MACROCALL_RE = re.compile(r'(\w+)\s*(\(.*\))*$')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a macro call.
+
+        Match a symbol hack macro calls that get added without semicolons.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+        - MACROS is the regex match object.
+
+        - Returns: The next location to be read in the array.
+        '''
+
+        # First we have the macros for symbol hacks and all macros we identified so
+        # far.
+        if cur.count('(') != cur.count(')'):
+            return cur, loc
+        if loc < len(op) and '{' in op[loc]:
+            return cur, loc
+
+        found = re.search(self.MACROCALL_RE, cur)
+        if found:
+            sym = found.group(1)
+            name = found.group(2)
+            if sym in macros or self.project_quirks and \
+                    sym in self.project_quirks.C_MACROS:
+                self.debug.print('FOUND MACROCALL: %s (%s)' % (sym, name))
+                new_block(sym, block_type.macrocall, [cur], code)
+                return '', loc
+
+        # Next, there could be macros that get called right inside their #ifdef, but
+        # without the semi-colon.
+        if cur.strip() == code['name'].strip():
+            self.debug.print('FOUND MACROCALL (without brackets): %s' % (cur))
+            new_block(cur, block_type.macrocall, [cur], code)
+            return '',loc
+
+        return cur, loc
+
+
+class Frontend:
+    ''' The C Frontend implementation.
+    '''
+    KNOWN_MACROS = []
+
+    def __init__(self, project_quirks, debug):
+        self.op = []
+        self.debug = debug
+        self.project_quirks = project_quirks
+
+        self.c_expr_parsers = [
+                CompositeParser(project_quirks, debug),
+                AssignParser(project_quirks, debug),
+                DeclParser(DeclParser.TYPEOF_RE, block_type.decl,
+                           project_quirks, debug),
+                DeclParser(DeclParser.TYPEDEF_FN_RE, block_type.decl,
+                           project_quirks, debug),
+                DeclParser(DeclParser.FNDECL_RE, block_type.fndecl,
+                           project_quirks, debug),
+                FuncParser(project_quirks, debug),
+                DeclParser(DeclParser.DECL_RE, block_type.decl, project_quirks,
+                           debug),
+                MacroParser(project_quirks, debug)]
+
+
+    def remove_extern_c(self):
+        ''' Process extern "C"/"C++" block nesting.
+
+        The extern "C" nesting does not add much value so it's safe to almost always
+        drop it.  Also drop extern "C++"
+        '''
+        new_op = []
+        nesting = 0
+        extern_nesting = 0
+        for l in self.op:
+            if '{' in l:
+                nesting = nesting + 1
+            if re.match(r'extern\s*"C"\s*{', l):
+                extern_nesting = nesting
+                continue
+            if '}' in l:
+                nesting = nesting - 1
+                if nesting < extern_nesting:
+                    extern_nesting = 0
+                    continue
+            new_op.append(l)
+
+        # Now drop all extern C++ blocks.
+        self.op = new_op
+        new_op = []
+        nesting = 0
+        extern_nesting = 0
+        in_cpp = False
+        for l in self.op:
+            if re.match(r'extern\s*"C\+\+"\s*{', l):
+                nesting = nesting + 1
+                in_cpp = True
+
+            if in_cpp:
+                if '{' in l:
+                    nesting = nesting + 1
+                if '}' in l:
+                    nesting = nesting - 1
+            if nesting == 0:
+                new_op.append(l)
+
+        self.op = new_op
+
+
+    def remove_comments(self, op):
+        ''' Remove comments.
+
+        Return OP by removing all comments from it.
+        '''
+        self.debug.print('REMOVE COMMENTS')
+
+        sep='\n'
+        opstr = sep.join(op)
+        opstr = re.sub(r'/\*.*?\*/', r'', opstr, flags=re.MULTILINE | re.DOTALL)
+        opstr = re.sub(r'\\\n', r' ', opstr, flags=re.MULTILINE | re.DOTALL)
+        new_op = list(filter(None, opstr.split(sep)))
+
+        return new_op
+
+
+    def normalize_condition(self, name):
+        ''' Make some minor transformations on macro conditions to make them more
+        readable.
+        '''
+        # Negation with a redundant bracket.
+        name = re.sub(r'!\s*\(\s*(\w+)\s*\)', r'! \1', name)
+        # Pull in negation of equality.
+        name = re.sub(r'!\s*\(\s*(\w+)\s*==\s*(\w+)\)', r'\1 != \2', name)
+        # Pull in negation of inequality.
+        name = re.sub(r'!\s*\(\s*(\w+)\s*!=\s*(\w+)\)', r'\1 == \2', name)
+        # Fix simple double negation.
+        name = re.sub(r'!\s*\(\s*!\s*(\w+)\s*\)', r'\1', name)
+        # Similar, but nesting a complex expression.  Because of the greedy match,
+        # this matches only the outermost brackets.
+        name = re.sub(r'!\s*\(\s*!\s*\((.*)\)\s*\)$', r'\1', name)
+        return name
+
+
+    def parse_preprocessor(self, loc, code, start = ''):
+        ''' Parse a preprocessor directive.
+
+        In case a preprocessor condition (i.e. if/elif/else), create a new code
+        block to nest code into and in other cases, identify and add entities suchas
+        include files, defines, etc.
+
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this function
+        - START is the string that should continue to be expanded in case we step
+          into a new macro scope.
+
+        - Returns: The next location to be read in the array.
+        '''
+        cur = self.op[loc]
+        loc = loc + 1
+        endblock = False
+
+        self.debug.print('PARSE_MACRO: %s' % cur)
+
+        # Remove the # and strip spaces again.
+        cur = cur[1:].strip()
+
+        # Include file.
+        if cur.find('include') == 0:
+            m = re.search(r'include\s*["<]?([^">]+)[">]?', cur)
+            new_block(m.group(1), block_type.macro_include, [cur], code)
+
+        # Macro definition.
+        if cur.find('define') == 0:
+            m = re.search(r'define\s+([a-zA-Z0-9_]+)', cur)
+            name = m.group(1)
+            exists = False
+            # Find out if this is a redefinition.
+            for c in code['contents']:
+                if c['name'] == name and c['type'] == block_type.macro_def:
+                    c['flags'] = block_flags.macro_redefined
+                    exists = True
+                    break
+            if not exists:
+                new_block(m.group(1), block_type.macro_def, [cur], code,
+                          block_flags.macro_defined)
+                # Add macros as we encounter them.
+                self.KNOWN_MACROS.append(m.group(1))
+
+        # Macro undef.
+        if cur.find('undef') == 0:
+            m = re.search(r'undef\s+([a-zA-Z0-9_]+)', cur)
+            new_block(m.group(1), block_type.macro_def, [cur], code)
+
+        # #error and #warning macros.
+        if cur.find('error') == 0 or cur.find('warning') == 0:
+            m = re.search(r'(error|warning)\s+"?(.*)"?', cur)
+            if m:
+                name = m.group(2)
+            else:
+                name = '<blank>'
+            new_block(name, block_type.macro_info, [cur], code)
+
+        # Start of an #if or #ifdef block.
+        elif cur.find('if') == 0:
+            rem = re.sub(r'ifndef', r'!', cur).strip()
+            rem = re.sub(r'(ifdef|defined|if)', r'', rem).strip()
+            rem = self.normalize_condition(rem)
+            ifdef = new_block(rem, block_type.macro_cond, [], code)
+            ifdef['headcond'] = ifdef
+            ifdef['start'] = start
+            loc = self.parse_line(loc, ifdef, start)
+
+        # End the previous #if/#elif and begin a new block.
+        elif cur.find('elif') == 0 and code['parent']:
+            rem = self.normalize_condition(re.sub(r'(elif|defined)', r'', cur).strip())
+            # The #else and #elif blocks should go into the current block's parent.
+            ifdef = new_block(rem, block_type.macro_cond, [], code['parent'])
+            ifdef['headcond'] = code['headcond']
+            loc = self.parse_line(loc, ifdef, code['headcond']['start'])
+            endblock = True
+
+        # End the previous #if/#elif and begin a new block.
+        elif cur.find('else') == 0 and code['parent']:
+            name = self.normalize_condition('!(' + code['name'] + ')')
+            ifdef = new_block(name, block_type.macro_cond, [], code['parent'],
+                              block_flags.else_block)
+            ifdef['headcond'] = code['headcond']
+            loc = self.parse_line(loc, ifdef, code['headcond']['start'])
+            endblock = True
+
+        elif cur.find('endif') == 0 and code['parent']:
+            # Insert an empty else block if there isn't one.
+            if code['flags'] != block_flags.else_block:
+                name = self.normalize_condition('!(' + code['name'] + ')')
+                ifdef = new_block(name, block_type.macro_cond, [], code['parent'],
+                                  block_flags.else_block)
+                ifdef['headcond'] = code['headcond']
+                loc = self.parse_line(loc - 1, ifdef, code['headcond']['start'])
+            endblock = True
+
+        return (loc, endblock)
+
+
+    def parse_c_expr(self, cur, loc, code):
+        ''' Parse a C expression.
+
+        CUR is the string to be parsed, which continues to grow until a match is
+        found.  OP is the string array and LOC is the first unread location in the
+        string array.  CODE is the block in which any identified expressions should
+        be added.
+        '''
+        self.debug.print('PARSING: %s' % cur)
+
+        for p in self.c_expr_parsers:
+            cur, loc = p.parse_line(cur, self.op, loc, code, self.KNOWN_MACROS)
+            if not cur:
+                break
+
+        return cur, loc
+
+
+    def expand_problematic_macros(self, cur):
+        ''' Replace problem macros with their substitutes in CUR.
+        '''
+        for p in self.project_quirks.MACRO_QUIRKS:
+            cur = re.sub(p['orig'], p['sub'], cur)
+
+        return cur
+
+
+    def parse_line(self, loc, code, start = ''):
+        '''
+        Parse the file line by line.  The function assumes a mostly GNU coding
+        standard compliant input so it might barf with anything that is eligible for
+        the Obfuscated C code contest.
+
+        The basic idea of the parser is to identify macro conditional scopes and
+        definitions, includes, etc. and then parse the remaining C code in the
+        context of those macro scopes.  The parser does not try to understand the
+        semantics of the code or even validate its syntax.  It only records high
+        level symbols in the source and makes a tree structure to indicate the
+        declaration/definition of those symbols and their scope in the macro
+        definitions.
+
+        OP is the string array.
+        LOC is the first unparsed line.
+        CODE is the block scope within which the parsing is currently going on.
+        START is the string with which this parsing should start.
+        '''
+        cur = start
+        endblock = False
+        saved_cur = ''
+        saved_loc = 0
+        endblock_loc = loc
+
+        while loc < len(self.op):
+            nextline = self.op[loc]
+
+            # Macros.
+            if nextline[0] == '#':
+                (loc, endblock) = self.parse_preprocessor(loc, code, cur)
+                if endblock:
+                    endblock_loc = loc
+            # Rest of C Code.
+            else:
+                cur = cur + ' ' + nextline
+                cur = self.expand_problematic_macros(cur).strip()
+                cur, loc = self.parse_c_expr(cur, loc + 1, code)
+
+            if endblock and not cur:
+                # If we are returning from the first #if block, we want to proceed
+                # beyond the current block, not repeat it for any preceding blocks.
+                if code['headcond'] == code:
+                    return loc
+                else:
+                    return endblock_loc
+
+        return loc
+
+    def drop_empty_blocks(self, tree):
+        ''' Drop empty macro conditional blocks.
+        '''
+        newcontents = []
+
+        for x in tree['contents']:
+            if x['type'] != block_type.macro_cond or len(x['contents']) > 0:
+                newcontents.append(x)
+
+        for t in newcontents:
+            if t['type'] == block_type.macro_cond:
+                self.drop_empty_blocks(t)
+
+        tree['contents'] = newcontents
+
+
+    def consolidate_tree_blocks(self, tree):
+        ''' Consolidate common macro conditional blocks.
+
+        Get macro conditional blocks at the same level but scatterred across the
+        file together into a single common block to allow for better comparison.
+        '''
+        # Nothing to do for non-nesting blocks.
+        if tree['type'] != block_type.macro_cond \
+                and tree['type'] != block_type.file:
+            return
+
+        # Now for nesting blocks, get the list of unique condition names and
+        # consolidate code under them.  The result also bunches up all the
+        # conditions at the top.
+        newcontents = []
+
+        macros = [x for x in tree['contents'] \
+                  if x['type'] == block_type.macro_cond]
+        macro_names = sorted(set([x['name'] for x in macros]))
+        for m in macro_names:
+            nc = [x['contents'] for x in tree['contents'] if x['name'] == m \
+                    and x['type'] == block_type.macro_cond]
+            b = new_block(m, block_type.macro_cond, sum(nc, []), tree)
+            self.consolidate_tree_blocks(b)
+            newcontents.append(b)
+
+        newcontents.extend([x for x in tree['contents'] \
+                            if x['type'] != block_type.macro_cond])
+
+        tree['contents'] = newcontents
+
+
+    def compact_tree(self, tree):
+        ''' Try to reduce the tree to its minimal form.
+
+        A source code tree in its simplest form may have a lot of duplicated
+        information that may be difficult to compare and come up with a minimal
+        difference.
+        '''
+
+        # First, drop all empty blocks.
+        self.drop_empty_blocks(tree)
+
+        # Macro conditions that nest the entire file aren't very interesting.  This
+        # should take care of the header guards.
+        if tree['type'] == block_type.file \
+                and len(tree['contents']) == 1 \
+                and tree['contents'][0]['type'] == block_type.macro_cond:
+            tree['contents'] = tree['contents'][0]['contents']
+
+        # Finally consolidate all macro conditional blocks.
+        self.consolidate_tree_blocks(tree)
+
+
+    def parse(self, op):
+        ''' File parser.
+
+        Parse the input array of lines OP and generate a tree structure to
+        represent the file.  This tree structure is then used for comparison between
+        the old and new file.
+        '''
+        self.KNOWN_MACROS = []
+        tree = new_block('', block_type.file, [], None)
+        self.op = self.remove_comments(op)
+        self.remove_extern_c()
+        self.op = [re.sub(r'#\s+', '#', x) for x in self.op]
+        self.parse_line(0, tree)
+        self.compact_tree(tree)
+        self.dump_tree(tree, 0)
+
+        return tree
+
+
+    def print_change(self, tree, action, prologue = ''):
+        ''' Print the nature of the differences found in the tree compared to the
+        other tree.  TREE is the tree that changed, action is what the change was
+        (Added, Removed, Modified) and prologue specifies the macro scope the change
+        is in.  The function calls itself recursively for all macro condition tree
+        nodes.
+        '''
+
+        if tree['type'] != block_type.macro_cond:
+            print('\t%s(%s): %s.' % (prologue, tree['name'], action))
+            return
+
+        prologue = '%s[%s]' % (prologue, tree['name'])
+        for t in tree['contents']:
+            if t['type'] == block_type.macro_cond:
+                self.print_change(t, action, prologue)
+            else:
+                print('\t%s(%s): %s.' % (prologue, t['name'], action))
+
+
+    def compare_trees(self, left, right, prologue = ''):
+        ''' Compare two trees and print the difference.
+
+        This routine is the entry point to compare two trees and print out their
+        differences.  LEFT and RIGHT will always have the same name and type,
+        starting with block_type.file and '' at the top level.
+        '''
+
+        if left['type'] == block_type.macro_cond or left['type'] == block_type.file:
+
+            if left['type'] == block_type.macro_cond:
+                prologue = '%s[%s]' % (prologue, left['name'])
+
+            # Make sure that everything in the left tree exists in the right tree.
+            for cl in left['contents']:
+                found = False
+                for cr in right['contents']:
+                    if not cl['matched'] and not cr['matched'] and \
+                            cl['name'] == cr['name'] and cl['type'] == cr['type']:
+                        cl['matched'] = cr['matched'] = True
+                        self.compare_trees(cl, cr, prologue)
+                        found = True
+                        break
+                if not found:
+                    self.print_change(cl, cl['actions']['del'], prologue)
+
+            # ... and vice versa.  This time we only need to look at unmatched
+            # contents.
+            for cr in right['contents']:
+                if not cr['matched']:
+                    self.print_change(cr, cr['actions']['new'], prologue)
+        else:
+            if left['contents'] != right['contents']:
+                self.print_change(left, left['actions']['mod'], prologue)
+
+
+    def dump_tree(self, tree, indent):
+        ''' Print the entire tree.
+        '''
+        if not self.debug.debug:
+            return
+
+        if tree['type'] == block_type.macro_cond or tree['type'] == block_type.file:
+            print('%sScope: %s' % (' ' * indent, tree['name']))
+            for c in tree['contents']:
+                self.dump_tree(c, indent + 4)
+            print('%sEndScope: %s' % (' ' * indent, tree['name']))
+        else:
+            if tree['type'] == block_type.func:
+                print('%sFUNC: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.composite:
+                print('%sCOMPOSITE: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.assign:
+                print('%sASSIGN: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.fndecl:
+                print('%sFNDECL: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.decl:
+                print('%sDECL: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macrocall:
+                print('%sMACROCALL: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macro_def:
+                print('%sDEFINE: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macro_include:
+                print('%sINCLUDE: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macro_undef:
+                print('%sUNDEF: %s' % (' ' * indent, tree['name']))
+            else:
+                print('%sMACRO LEAF: %s' % (' ' * indent, tree['name']))
+
+
+    def compare(self, oldfile, newfile):
+        ''' Entry point for the C backend.
+
+        Parse the two files into trees and compare them.  Print the result of the
+        comparison in the ChangeLog-like format.
+        '''
+        self.debug.print('LEFT TREE')
+        self.debug.print('-' * 80)
+        left = self.parse(oldfile)
+
+        self.debug.print('RIGHT TREE')
+        self.debug.print('-' * 80)
+        right = self.parse(newfile)
+
+        self.compare_trees(left, right)
diff --git a/build-aux/gitlog-to-changelog b/build-aux/vcs-to-changelog/gitlog-to-changelog
similarity index 100%
rename from build-aux/gitlog-to-changelog
rename to build-aux/vcs-to-changelog/gitlog-to-changelog
diff --git a/build-aux/vcs-to-changelog/misc_util.py b/build-aux/vcs-to-changelog/misc_util.py
new file mode 100644
index 000000000..50a1346ce
--- /dev/null
+++ b/build-aux/vcs-to-changelog/misc_util.py
@@ -0,0 +1,54 @@
+# General Utility functions.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+import sys
+
+class DebugUtil:
+    debug = False
+    def __init__(self, debug):
+        self.debug = debug
+
+    def eprint(self, *args, **kwargs):
+        ''' Print to stderr.
+        '''
+        print(*args, file=sys.stderr, **kwargs)
+
+
+    def print(self, *args, **kwargs):
+        ''' Convenience function to print diagnostic information in the program.
+        '''
+        if self.debug:
+            self.eprint(*args, **kwargs)
+
+
+def decode(string):
+    ''' Attempt to decode a string.
+
+    Decode a string read from the source file.  The multiple attempts are needed
+    due to the presence of the page break characters and some tests in locales.
+    '''
+    codecs = ['utf8', 'latin1', 'cp1252']
+
+    for i in codecs:
+        try:
+            return string.decode(i)
+        except UnicodeDecodeError:
+            pass
+
+    DebugUtil.eprint('Failed to decode: %s' % string)
+
diff --git a/build-aux/vcs-to-changelog/vcs_git.py b/build-aux/vcs-to-changelog/vcs_git.py
new file mode 100644
index 000000000..02fcd8a46
--- /dev/null
+++ b/build-aux/vcs-to-changelog/vcs_git.py
@@ -0,0 +1,155 @@
+# Git repo support.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+from vcs_to_changelog import analyze_diff
+import subprocess
+import re
+from misc_util import *
+
+class GitRepo:
+    def __init__(self, ignore_list, debug):
+        self.ignore_list = ignore_list
+        self.debug = debug
+
+
+    def exec_git_cmd(self, args):
+        ''' Execute a git command and return its result as a list of strings.
+        '''
+        args.insert(0, 'git')
+        self.debug.print(args)
+        proc = subprocess.Popen(args, stdout=subprocess.PIPE)
+
+        # Clean up the output by removing trailing spaces, newlines and dropping
+        # blank lines.
+        op = [decode(x[:-1]).strip() for x in proc.stdout]
+        op = [re.sub(r'[\s\f]+', ' ', x) for x in op]
+        op = [x for x in op if x]
+        return op
+
+
+    def list_changes(self, commit, frontends):
+        ''' List changes in a single commit.
+
+        For the input commit id COMMIT, identify the files that have changed and the
+        nature of their changes.  Print commit information in the ChangeLog format,
+        calling into helper functions as necessary.
+        '''
+
+        op = self.exec_git_cmd(['show', '--date=short', '--raw', commit])
+        authors = []
+        date = ''
+        merge = False
+        copyright_exempt=''
+
+        for l in op:
+            if l.lower().find('copyright-paperwork-exempt:') == 0 \
+                    and 'yes' in l.lower():
+                copyright_exempt=' (tiny change)'
+            elif l.lower().find('co-authored-by:') == 0 or \
+                    l.find('Author:') == 0:
+                author = l.split(':')[1]
+                author = re.sub(r'(.*)\s*(<.*)', r'\1  \2', author)
+                authors.append(author)
+            elif l.find('Date:') == 0:
+                date=l[5:].strip()
+            elif l.find('Merge:') == 0:
+                merge = True
+
+        # Find raw commit information for all non-ChangeLog files.
+        op = [x[1:] for x in op if len(x) > 0 and re.match(r'^:[0-9]+', x)]
+
+        # Skip all ignored files.
+        for ign in self.ignore_list:
+            op = [x for x in op if ign not in x]
+
+        # It was only the ChangeLog, ignore.
+        if len(op) == 0:
+            return
+
+        print('%s  %s' % (date, authors[0]))
+
+        if (len(authors) > 1):
+            authors = authors[1:]
+            for author in authors:
+                print('            %s' % author)
+
+        print()
+
+        if merge:
+           print('\t MERGE COMMIT: %s\n' % commit)
+           return
+
+        print('\tCOMMIT%s: %s\n' % (copyright_exempt, commit))
+
+        # Each of these lines has a space separated format like so:
+        # :<OLD MODE> <NEW MODE> <OLD REF> <NEW REF> <OPERATION> <FILE1> <FILE2>
+        #
+        # where OPERATION can be one of the following:
+        # A: File added
+        # D: File removed
+        # M[0-9]{3}: File modified
+        # R[0-9]{3}: File renamed, with the 3 digit number following it indicating
+        # what percentage of the file is intact.
+        # C[0-9]{3}: File copied.  Same semantics as R.
+        # T: The permission bits of the file changed
+        # U: Unmerged.  We should not encounter this, so we ignore it/
+        # X, or anything else: Most likely a bug.  Report it.
+        #
+        # FILE2 is set only when OPERATION is R or C, to indicate the new file name.
+        #
+        # Also note that merge commits have a different format here, with three
+        # entries each for the modes and refs, but we don't bother with it for now.
+        #
+        # For more details: https://git-scm.com/docs/diff-format
+        for f in op:
+            data = f.split()
+            if data[4] == 'A':
+                print('\t* %s: New file.' % data[5])
+            elif data[4] == 'D':
+                print('\t* %s: Delete file.' % data[5])
+            elif data[4] == 'T':
+                print('\t* %s: Changed file permission bits from %s to %s' % \
+                        (data[5], data[0], data[1]))
+            elif data[4][0] == 'M':
+                print('\t* %s: Modified.' % data[5])
+                analyze_diff(data[5],
+                             self.exec_git_cmd(['show', data[2]]),
+                             self.exec_git_cmd(['show', data[3]]), frontends)
+            elif data[4][0] == 'R' or data[4][0] == 'C':
+                change = int(data[4][1:])
+                print('\t* %s: Move to...' % data[5])
+                print('\t* %s: ... here.' % data[6])
+                if change < 100:
+                    analyze_diff(data[6],
+                                 self.exec_git_cmd(['show', data[2]]),
+                                 self.exec_git_cmd(['show', data[3]]), frontends)
+            # We should never encounter this, so ignore for now.
+            elif data[4] == 'U':
+                pass
+            else:
+                eprint('%s: Unknown line format %s' % (commit, data[4]))
+                sys.exit(42)
+
+        print('')
+
+
+    def list_commits(self, revs):
+        ''' List commit IDs between the two revs in the REVS list.
+        '''
+        ref = revs[0] + '..' + revs[1]
+        return self.exec_git_cmd(['log', '--pretty=%H', ref])
diff --git a/build-aux/vcs-to-changelog/vcs_to_changelog.py b/build-aux/vcs-to-changelog/vcs_to_changelog.py
new file mode 100755
index 000000000..a106ebd74
--- /dev/null
+++ b/build-aux/vcs-to-changelog/vcs_to_changelog.py
@@ -0,0 +1,139 @@
+#!/usr/bin/python3
+# Main VCSToChangeLog script.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+''' Generate a ChangeLog style output based on a VCS log.
+
+This script takes two revisions as input and generates a ChangeLog style output
+for all revisions between the two revisions.
+
+This script is intended to be executed from the project parent directory, where
+a script called vcstocl_quirks.py is assumed to be present.  The script must
+define a function called get_project_quirks that returns a object of class type
+ProjectQuirks or a subclass of the same.  The definition of the ProjectQuirks
+class is below and it specifies the properties that the project must set to
+ensure correct parsing of its contents.
+
+Among other things, ProjectQurks specifies the VCS to read from; the default is
+assumed to be git.  The script then studies the VCS log and for each change,
+list out the nature of changes in the constituent files.
+
+Each file type may have parser frontends that can read files and construct
+objects that may be compared to determine the minimal changes that occured in
+each revision.  For files that do not have parsers, we may only know the nature
+of changes at the top level depending on the information that the VCS stores.
+
+The parser frontend must have a compare() method that takes the old and new
+files as arrays of strings and prints the output in ChangeLog format.
+
+Currently implemented VCS:
+
+    git
+
+Currently implemented frontends:
+
+    C
+'''
+import sys
+import os
+import re
+import argparse
+from misc_util import *
+import frontend_c
+from vcs_git import *
+
+debug = DebugUtil(False)
+
+class ProjectQuirks:
+    # This is a list of regex substitutions for C/C++ macros that are known to
+    # break parsing of the C programs.  Each member of this list is a dict with
+    # the key 'orig' having the regex and 'sub' having the substitution of the
+    # regex.
+    MACRO_QUIRKS = []
+
+    # This is a list of macro definitions that are extensively used and are
+    # known to break parsing due to some characteristic, mainly the lack of a
+    # semicolon at the end.
+    C_MACROS = []
+
+    # The repo type, defaults to git.
+    repo = 'git'
+
+    # List of files to ignore either because they are not needed (such as the
+    # ChangeLog) or because they are non-parseable.  For example, glibc has a
+    # header file that is only assembly code, which breaks the C parser.
+    IGNORE_LIST = ['ChangeLog']
+
+
+# Load quirks from the current project if they exist.
+sys.path.append(os.getcwd())
+try:
+    from vcstocl_quirks import *
+    project_quirks = get_project_quirks(debug)
+except:
+    project_quirks = ProjectQuirks()
+
+def analyze_diff(filename, oldfile, newfile, frontends):
+    ''' Parse the output of the old and new files and print the difference.
+
+    For input files OLDFILE and NEWFILE with name FILENAME, generate reduced
+    trees for them and compare them.  We limit our comparison to only C source
+    files.
+    '''
+    name, ext = os.path.splitext(filename)
+
+    if not ext in frontends.keys():
+        return None
+    else:
+        frontend = frontends[ext]
+        frontend.compare(oldfile, newfile)
+
+
+def main(repo, frontends, refs):
+    ''' ChangeLog Generator Entry Point.
+    '''
+    commits = repo.list_commits(args.refs)
+    for commit in commits:
+        repo.list_changes(commit, frontends)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('refs', metavar='ref', type=str, nargs=2,
+                     help='Refs to print ChangeLog entries between')
+
+    parser.add_argument('-d', '--debug', required=False, action='store_true',
+                     help='Run the file parser debugger.')
+
+    args = parser.parse_args()
+
+    debug.debug = args.debug
+    print('debug is ', debug.debug)
+
+    if len(args.refs) < 2:
+        debug.eprint('Two refs needed to get a ChangeLog.')
+        sys.exit(os.EX_USAGE)
+
+    REPO = {'git': GitRepo(project_quirks.IGNORE_LIST, debug)}
+
+    fe_c = frontend_c.Frontend(project_quirks, debug)
+    FRONTENDS = {'.c': fe_c,
+                 '.h': fe_c}
+
+    main(REPO[project_quirks.repo], FRONTENDS, args.refs)
-- 
2.19.2



^ permalink raw reply related	[flat|nested] 4+ messages in thread

* [PATCH] Add a new VCSToChangeLog script
@ 2019-01-27 16:34 Siddhesh Poyarekar
  2019-01-27 18:38 ` Bruno Haible
  0 siblings, 1 reply; 4+ messages in thread
From: Siddhesh Poyarekar @ 2019-01-27 16:34 UTC (permalink / raw)
  To: bug-gnulib; +Cc: Siddhesh Poyarekar

Build a more general script that parses changes in a VCS and then
prints it in a ChangeLog format.  Currently this set of scripts has
been tested on glibc and will need a vcstocl_quirks.py for gnulib.
The scripts need to be in to make sure that they're usable for glibc
once 2.29 is released.  A quirks file for gnulib will be developed and
added as a separate patch.

The script currently has a git repo backend and C frontend support.
The gitlog-to-changelog script has been moved into vcs-to-changelog as
a fallback.

Plan for the next 6 months:

- Test on gnulib and build a quirks file
- Add glibc Versions file support
- Add assembly file support
- Mentor volunteers who might want to add more frontends or repo
  backends.

	* build-aux/gitlog-to-changelog: Move to...
	* build-aux/vcs-to-changelog/gitlog-to-changelog: ... here.
	* build-aux/vcs-to-changelog/frontend_c.py: New file.
	* build-aux/vcs-to-changelog/misc_util.py: likewise.
	* build-aux/vcs-to-changelog/vcs_git.py: Likewise.
	* build-aux/vcs-to-changelog/vcs_to_changelog.py: Likewise.
---
 build-aux/vcs-to-changelog/frontend_c.py      | 829 ++++++++++++++++++
 .../gitlog-to-changelog                       |   0
 build-aux/vcs-to-changelog/misc_util.py       |  54 ++
 build-aux/vcs-to-changelog/vcs_git.py         | 155 ++++
 .../vcs-to-changelog/vcs_to_changelog.py      | 139 +++
 5 files changed, 1177 insertions(+)
 create mode 100644 build-aux/vcs-to-changelog/frontend_c.py
 rename build-aux/{ => vcs-to-changelog}/gitlog-to-changelog (100%)
 create mode 100644 build-aux/vcs-to-changelog/misc_util.py
 create mode 100644 build-aux/vcs-to-changelog/vcs_git.py
 create mode 100755 build-aux/vcs-to-changelog/vcs_to_changelog.py

diff --git a/build-aux/vcs-to-changelog/frontend_c.py b/build-aux/vcs-to-changelog/frontend_c.py
new file mode 100644
index 000000000..c3c40ae30
--- /dev/null
+++ b/build-aux/vcs-to-changelog/frontend_c.py
@@ -0,0 +1,829 @@
+#!/usr/bin/python3
+# The C Parser.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+from enum import Enum
+import re
+from misc_util import *
+
+class block_flags(Enum):
+    ''' Flags for the code block.
+    '''
+    else_block = 1
+    macro_defined = 2
+    macro_redefined = 3
+
+
+class block_type(Enum):
+    ''' Type of code block.
+    '''
+    file = 1
+    macro_cond = 2
+    macro_def = 3
+    macro_undef = 4
+    macro_include = 5
+    macro_info = 6
+    decl = 7
+    func = 8
+    composite = 9
+    macrocall = 10
+    fndecl = 11
+    assign = 12
+    struct = 13
+    union = 14
+    enum = 15
+
+# A dictionary describing what each action (add, modify, delete) show up as in
+# the ChangeLog output.
+actions = {0:{'new': 'New', 'mod': 'Modified', 'del': 'Remove'},
+           block_type.file:{'new': 'New file', 'mod': 'Modified file',
+                            'del': 'Remove file'},
+           block_type.macro_cond:{'new': 'New', 'mod': 'Modified',
+                                  'del': 'Remove'},
+           block_type.macro_def:{'new': 'New', 'mod': 'Modified',
+                                 'del': 'Remove'},
+           block_type.macro_include:{'new': 'Include file', 'mod': 'Modified',
+                                     'del': 'Remove include'},
+           block_type.macro_info:{'new': 'New preprocessor message',
+                                  'mod': 'Modified', 'del': 'Remove'},
+           block_type.decl:{'new': 'New', 'mod': 'Modified', 'del': 'Remove'},
+           block_type.func:{'new': 'New function', 'mod': 'Modified function',
+                 'del': 'Remove function'},
+           block_type.composite:{'new': 'New', 'mod': 'Modified',
+                                 'del': 'Remove'},
+           block_type.struct:{'new': 'New struct', 'mod': 'Modified struct',
+                                 'del': 'Remove struct'},
+           block_type.union:{'new': 'New union', 'mod': 'Modified union',
+                                 'del': 'Remove union'},
+           block_type.enum:{'new': 'New enum', 'mod': 'Modified enum',
+                                 'del': 'Remove enum'},
+           block_type.macrocall:{'new': 'New', 'mod': 'Modified',
+                                 'del': 'Remove'},
+           block_type.fndecl:{'new': 'New function', 'mod': 'Modified',
+                              'del': 'Remove'},
+           block_type.assign:{'new': 'New', 'mod': 'Modified', 'del': 'Remove'}}
+
+def new_block(name, type, contents, parent, flags = 0):
+    '''  Create a new code block with the parent as PARENT.
+
+    The code block is a basic structure around which the tree representation of
+    the source code is built.  It has the following attributes:
+
+    - name: A name to refer it by in the ChangeLog
+    - type: Any one of the following types in BLOCK_TYPE.
+    - contents: The contents of the block.  For a block of types file or
+      macro_cond, this would be a list of blocks that it nests.  For other types
+      it is a list with a single string specifying its contents.
+    - parent: This is the parent of the current block, useful in setting up
+      #elif or #else blocks in the tree.
+    - flags: A special field to indicate some properties of the block. See
+      BLOCK_FLAGS for values.
+    '''
+    block = {}
+    block['matched'] = False
+    block['name'] = name
+    block['type'] = type
+    block['contents'] = contents
+    block['parent'] = parent
+    if parent:
+        parent['contents'].append(block)
+
+    block['flags'] = flags
+    block['actions'] = actions[type]
+
+    return block
+
+
+class ExprParser:
+    ''' Parent class of all of the C expression parsers.
+
+    It is necessary that the children override the parse_line() method.
+    '''
+    ATTRIBUTE = r'(((__attribute__\s*\(\([^;]+\)\))|(asm\s*\([?)]+\)))\s*)*'
+
+    def __init__(self, project_quirks, debug):
+        self.project_quirks = project_quirks
+        self.debug = debug
+
+    def fast_forward_scope(self, cur, op, loc):
+        ''' Consume lines in a code block.
+
+        Consume all lines of a block of code such as a composite type declaration or
+        a function declaration.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+
+        - Returns: The next location to be read in the array as well as the updated
+          value of CUR, which will now have the body of the function or composite
+          type.
+        '''
+        nesting = cur.count('{') - cur.count('}')
+        while nesting > 0 and loc < len(op):
+            cur = cur + ' ' + op[loc]
+
+            nesting = nesting + op[loc].count('{')
+            nesting = nesting - op[loc].count('}')
+            loc = loc + 1
+
+        return (cur, loc)
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' The parse method should always be overridden by the child.
+        '''
+        raise
+
+
+class FuncParser(ExprParser):
+    REGEX = re.compile(ExprParser.ATTRIBUTE + r'\s*(\w+)\s*\([^(][^{]+\)\s*{')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a function.
+
+        Match a function definition.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        name = found.group(5)
+        self.debug.print('FOUND FUNC: %s' % name)
+
+        # Consume everything up to the ending brace of the function.
+        (cur, loc) = self.fast_forward_scope(cur, op, loc)
+
+        new_block(name, block_type.func, [cur], code)
+
+        return '', loc
+
+
+class CompositeParser(ExprParser):
+    # Composite types such as structs and unions.
+    REGEX = re.compile(r'(struct|union|enum)\s*(\w*)\s*{')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a composite type.
+
+        Match declaration of a composite type such as a sruct or a union..
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        # Lap up all of the struct definition.
+        (cur, loc) = self.fast_forward_scope(cur, op, loc)
+
+        name = found.group(2)
+
+        if not name:
+            if 'typedef' in cur:
+                name = re.sub(r'.*}\s*(\w+);$', r'\1', cur)
+            else:
+                name= '<anoymous>'
+
+        ctype = found.group(1)
+
+        if ctype == 'struct':
+            blocktype = block_type.struct
+        if ctype == 'enum':
+            blocktype = block_type.enum
+        if ctype == 'union':
+            blocktype = block_type.union
+
+        new_block(name, block_type.composite, [cur], code)
+
+        return '', loc
+
+
+class AssignParser(ExprParser):
+    # Static assignments.
+    REGEX = re.compile(r'(\w+)\s*(\[[^\]]*\])*\s*([^\s]*attribute[\s\w()]+)?\s*=')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse an assignment statement.
+
+        This includes array assignments.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        name = found.group(1)
+        self.debug.print('FOUND ASSIGN: %s' % name)
+        # Lap up everything up to semicolon.
+        while ';' not in cur and loc < len(op):
+            cur = op[loc]
+            loc = loc + 1
+
+        new_block(name, block_type.assign, [cur], code)
+
+        return '', loc
+
+
+class DeclParser(ExprParser):
+    # Function pointer typedefs.
+    TYPEDEF_FN_RE = re.compile(r'\(\*(\w+)\)\s*\([^)]+\);')
+
+    # Simple decls.
+    DECL_RE = re.compile(r'(\w+)(\[\w*\])*\s*' + ExprParser.ATTRIBUTE + ';')
+
+    # __typeof decls.
+    TYPEOF_RE = re.compile(r'__typeof\s*\([\w\s]+\)\s*(\w+)\s*' + \
+                           ExprParser.ATTRIBUTE + ';')
+
+    # Function Declarations.
+    FNDECL_RE = re.compile(r'\s*(\w+)\s*\([^\(][^;]*\)\s*' +
+                           ExprParser.ATTRIBUTE + ';')
+
+    def __init__(self, regex, blocktype, project_quirks, debug):
+        # The regex for the current instance.
+        self.REGEX = regex
+        self.blocktype = blocktype
+        super().__init__(project_quirks, debug)
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a top level declaration.
+
+        All types of declarations except function declarations.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this function
+
+        - Returns: The next location to be read in the array.
+        '''
+        found = re.search(self.REGEX, cur)
+        if not found:
+            return cur, loc
+
+        # The name is the first group for all of the above regexes.  This is a
+        # coincidence, so care must be taken if regexes are added or changed to
+        # ensure that this is true.
+        name = found.group(1)
+
+        self.debug.print('FOUND DECL: %s' % name)
+        new_block(name, self.blocktype, [cur], code)
+
+        return '', loc
+
+
+class MacroParser(ExprParser):
+    # The macrocall_re peeks into the next line to ensure that it doesn't
+    # eat up a FUNC by accident.  The func_re regex is also quite crude and
+    # only intends to ensure that the function name gets picked up
+    # correctly.
+    MACROCALL_RE = re.compile(r'(\w+)\s*(\(.*\))*$')
+
+    def parse_line(self, cur, op, loc, code, macros):
+        ''' Parse a macro call.
+
+        Match a symbol hack macro calls that get added without semicolons.
+
+        - CUR is the string to consume this expression from
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this
+        - MACROS is the regex match object.
+
+        - Returns: The next location to be read in the array.
+        '''
+
+        # First we have the macros for symbol hacks and all macros we identified so
+        # far.
+        if cur.count('(') != cur.count(')'):
+            return cur, loc
+        if loc < len(op) and '{' in op[loc]:
+            return cur, loc
+
+        found = re.search(self.MACROCALL_RE, cur)
+        if found:
+            sym = found.group(1)
+            name = found.group(2)
+            if sym in macros or self.project_quirks and \
+                    sym in self.project_quirks.C_MACROS:
+                self.debug.print('FOUND MACROCALL: %s (%s)' % (sym, name))
+                new_block(sym, block_type.macrocall, [cur], code)
+                return '', loc
+
+        # Next, there could be macros that get called right inside their #ifdef, but
+        # without the semi-colon.
+        if cur.strip() == code['name'].strip():
+            self.debug.print('FOUND MACROCALL (without brackets): %s' % (cur))
+            new_block(cur, block_type.macrocall, [cur], code)
+            return '',loc
+
+        return cur, loc
+
+
+class Frontend:
+    ''' The C Frontend implementation.
+    '''
+    KNOWN_MACROS = []
+
+    def __init__(self, project_quirks, debug):
+        self.op = []
+        self.debug = debug
+        self.project_quirks = project_quirks
+
+        self.c_expr_parsers = [
+                CompositeParser(project_quirks, debug),
+                AssignParser(project_quirks, debug),
+                DeclParser(DeclParser.TYPEOF_RE, block_type.decl,
+                           project_quirks, debug),
+                DeclParser(DeclParser.TYPEDEF_FN_RE, block_type.decl,
+                           project_quirks, debug),
+                DeclParser(DeclParser.FNDECL_RE, block_type.fndecl,
+                           project_quirks, debug),
+                FuncParser(project_quirks, debug),
+                DeclParser(DeclParser.DECL_RE, block_type.decl, project_quirks,
+                           debug),
+                MacroParser(project_quirks, debug)]
+
+
+    def remove_extern_c(self):
+        ''' Process extern "C"/"C++" block nesting.
+
+        The extern "C" nesting does not add much value so it's safe to almost always
+        drop it.  Also drop extern "C++"
+        '''
+        new_op = []
+        nesting = 0
+        extern_nesting = 0
+        for l in self.op:
+            if '{' in l:
+                nesting = nesting + 1
+            if re.match(r'extern\s*"C"\s*{', l):
+                extern_nesting = nesting
+                continue
+            if '}' in l:
+                nesting = nesting - 1
+                if nesting < extern_nesting:
+                    extern_nesting = 0
+                    continue
+            new_op.append(l)
+
+        # Now drop all extern C++ blocks.
+        self.op = new_op
+        new_op = []
+        nesting = 0
+        extern_nesting = 0
+        in_cpp = False
+        for l in self.op:
+            if re.match(r'extern\s*"C\+\+"\s*{', l):
+                nesting = nesting + 1
+                in_cpp = True
+
+            if in_cpp:
+                if '{' in l:
+                    nesting = nesting + 1
+                if '}' in l:
+                    nesting = nesting - 1
+            if nesting == 0:
+                new_op.append(l)
+
+        self.op = new_op
+
+
+    def remove_comments(self, op):
+        ''' Remove comments.
+
+        Return OP by removing all comments from it.
+        '''
+        self.debug.print('REMOVE COMMENTS')
+
+        sep='\n'
+        opstr = sep.join(op)
+        opstr = re.sub(r'/\*.*?\*/', r'', opstr, flags=re.MULTILINE | re.DOTALL)
+        opstr = re.sub(r'\\\n', r' ', opstr, flags=re.MULTILINE | re.DOTALL)
+        new_op = list(filter(None, opstr.split(sep)))
+
+        return new_op
+
+
+    def normalize_condition(self, name):
+        ''' Make some minor transformations on macro conditions to make them more
+        readable.
+        '''
+        # Negation with a redundant bracket.
+        name = re.sub(r'!\s*\(\s*(\w+)\s*\)', r'! \1', name)
+        # Pull in negation of equality.
+        name = re.sub(r'!\s*\(\s*(\w+)\s*==\s*(\w+)\)', r'\1 != \2', name)
+        # Pull in negation of inequality.
+        name = re.sub(r'!\s*\(\s*(\w+)\s*!=\s*(\w+)\)', r'\1 == \2', name)
+        # Fix simple double negation.
+        name = re.sub(r'!\s*\(\s*!\s*(\w+)\s*\)', r'\1', name)
+        # Similar, but nesting a complex expression.  Because of the greedy match,
+        # this matches only the outermost brackets.
+        name = re.sub(r'!\s*\(\s*!\s*\((.*)\)\s*\)$', r'\1', name)
+        return name
+
+
+    def parse_preprocessor(self, loc, code, start = ''):
+        ''' Parse a preprocessor directive.
+
+        In case a preprocessor condition (i.e. if/elif/else), create a new code
+        block to nest code into and in other cases, identify and add entities suchas
+        include files, defines, etc.
+
+        - OP is the string array for the file
+        - LOC is the first unread location in CUR
+        - CODE is the block to which we add this function
+        - START is the string that should continue to be expanded in case we step
+          into a new macro scope.
+
+        - Returns: The next location to be read in the array.
+        '''
+        cur = self.op[loc]
+        loc = loc + 1
+        endblock = False
+
+        self.debug.print('PARSE_MACRO: %s' % cur)
+
+        # Remove the # and strip spaces again.
+        cur = cur[1:].strip()
+
+        # Include file.
+        if cur.find('include') == 0:
+            m = re.search(r'include\s*["<]?([^">]+)[">]?', cur)
+            new_block(m.group(1), block_type.macro_include, [cur], code)
+
+        # Macro definition.
+        if cur.find('define') == 0:
+            m = re.search(r'define\s+([a-zA-Z0-9_]+)', cur)
+            name = m.group(1)
+            exists = False
+            # Find out if this is a redefinition.
+            for c in code['contents']:
+                if c['name'] == name and c['type'] == block_type.macro_def:
+                    c['flags'] = block_flags.macro_redefined
+                    exists = True
+                    break
+            if not exists:
+                new_block(m.group(1), block_type.macro_def, [cur], code,
+                          block_flags.macro_defined)
+                # Add macros as we encounter them.
+                self.KNOWN_MACROS.append(m.group(1))
+
+        # Macro undef.
+        if cur.find('undef') == 0:
+            m = re.search(r'undef\s+([a-zA-Z0-9_]+)', cur)
+            new_block(m.group(1), block_type.macro_def, [cur], code)
+
+        # #error and #warning macros.
+        if cur.find('error') == 0 or cur.find('warning') == 0:
+            m = re.search(r'(error|warning)\s+"?(.*)"?', cur)
+            if m:
+                name = m.group(2)
+            else:
+                name = '<blank>'
+            new_block(name, block_type.macro_info, [cur], code)
+
+        # Start of an #if or #ifdef block.
+        elif cur.find('if') == 0:
+            rem = re.sub(r'ifndef', r'!', cur).strip()
+            rem = re.sub(r'(ifdef|defined|if)', r'', rem).strip()
+            rem = self.normalize_condition(rem)
+            ifdef = new_block(rem, block_type.macro_cond, [], code)
+            ifdef['headcond'] = ifdef
+            ifdef['start'] = start
+            loc = self.parse_line(loc, ifdef, start)
+
+        # End the previous #if/#elif and begin a new block.
+        elif cur.find('elif') == 0 and code['parent']:
+            rem = self.normalize_condition(re.sub(r'(elif|defined)', r'', cur).strip())
+            # The #else and #elif blocks should go into the current block's parent.
+            ifdef = new_block(rem, block_type.macro_cond, [], code['parent'])
+            ifdef['headcond'] = code['headcond']
+            loc = self.parse_line(loc, ifdef, code['headcond']['start'])
+            endblock = True
+
+        # End the previous #if/#elif and begin a new block.
+        elif cur.find('else') == 0 and code['parent']:
+            name = self.normalize_condition('!(' + code['name'] + ')')
+            ifdef = new_block(name, block_type.macro_cond, [], code['parent'],
+                              block_flags.else_block)
+            ifdef['headcond'] = code['headcond']
+            loc = self.parse_line(loc, ifdef, code['headcond']['start'])
+            endblock = True
+
+        elif cur.find('endif') == 0 and code['parent']:
+            # Insert an empty else block if there isn't one.
+            if code['flags'] != block_flags.else_block:
+                name = self.normalize_condition('!(' + code['name'] + ')')
+                ifdef = new_block(name, block_type.macro_cond, [], code['parent'],
+                                  block_flags.else_block)
+                ifdef['headcond'] = code['headcond']
+                loc = self.parse_line(loc - 1, ifdef, code['headcond']['start'])
+            endblock = True
+
+        return (loc, endblock)
+
+
+    def parse_c_expr(self, cur, loc, code):
+        ''' Parse a C expression.
+
+        CUR is the string to be parsed, which continues to grow until a match is
+        found.  OP is the string array and LOC is the first unread location in the
+        string array.  CODE is the block in which any identified expressions should
+        be added.
+        '''
+        self.debug.print('PARSING: %s' % cur)
+
+        for p in self.c_expr_parsers:
+            cur, loc = p.parse_line(cur, self.op, loc, code, self.KNOWN_MACROS)
+            if not cur:
+                break
+
+        return cur, loc
+
+
+    def expand_problematic_macros(self, cur):
+        ''' Replace problem macros with their substitutes in CUR.
+        '''
+        for p in self.project_quirks.MACRO_QUIRKS:
+            cur = re.sub(p['orig'], p['sub'], cur)
+
+        return cur
+
+
+    def parse_line(self, loc, code, start = ''):
+        '''
+        Parse the file line by line.  The function assumes a mostly GNU coding
+        standard compliant input so it might barf with anything that is eligible for
+        the Obfuscated C code contest.
+
+        The basic idea of the parser is to identify macro conditional scopes and
+        definitions, includes, etc. and then parse the remaining C code in the
+        context of those macro scopes.  The parser does not try to understand the
+        semantics of the code or even validate its syntax.  It only records high
+        level symbols in the source and makes a tree structure to indicate the
+        declaration/definition of those symbols and their scope in the macro
+        definitions.
+
+        OP is the string array.
+        LOC is the first unparsed line.
+        CODE is the block scope within which the parsing is currently going on.
+        START is the string with which this parsing should start.
+        '''
+        cur = start
+        endblock = False
+        saved_cur = ''
+        saved_loc = 0
+        endblock_loc = loc
+
+        while loc < len(self.op):
+            nextline = self.op[loc]
+
+            # Macros.
+            if nextline[0] == '#':
+                (loc, endblock) = self.parse_preprocessor(loc, code, cur)
+                if endblock:
+                    endblock_loc = loc
+            # Rest of C Code.
+            else:
+                cur = cur + ' ' + nextline
+                cur = self.expand_problematic_macros(cur).strip()
+                cur, loc = self.parse_c_expr(cur, loc + 1, code)
+
+            if endblock and not cur:
+                # If we are returning from the first #if block, we want to proceed
+                # beyond the current block, not repeat it for any preceding blocks.
+                if code['headcond'] == code:
+                    return loc
+                else:
+                    return endblock_loc
+
+        return loc
+
+    def drop_empty_blocks(self, tree):
+        ''' Drop empty macro conditional blocks.
+        '''
+        newcontents = []
+
+        for x in tree['contents']:
+            if x['type'] != block_type.macro_cond or len(x['contents']) > 0:
+                newcontents.append(x)
+
+        for t in newcontents:
+            if t['type'] == block_type.macro_cond:
+                self.drop_empty_blocks(t)
+
+        tree['contents'] = newcontents
+
+
+    def consolidate_tree_blocks(self, tree):
+        ''' Consolidate common macro conditional blocks.
+
+        Get macro conditional blocks at the same level but scatterred across the
+        file together into a single common block to allow for better comparison.
+        '''
+        # Nothing to do for non-nesting blocks.
+        if tree['type'] != block_type.macro_cond \
+                and tree['type'] != block_type.file:
+            return
+
+        # Now for nesting blocks, get the list of unique condition names and
+        # consolidate code under them.  The result also bunches up all the
+        # conditions at the top.
+        newcontents = []
+
+        macros = [x for x in tree['contents'] \
+                  if x['type'] == block_type.macro_cond]
+        macro_names = sorted(set([x['name'] for x in macros]))
+        for m in macro_names:
+            nc = [x['contents'] for x in tree['contents'] if x['name'] == m \
+                    and x['type'] == block_type.macro_cond]
+            b = new_block(m, block_type.macro_cond, sum(nc, []), tree)
+            self.consolidate_tree_blocks(b)
+            newcontents.append(b)
+
+        newcontents.extend([x for x in tree['contents'] \
+                            if x['type'] != block_type.macro_cond])
+
+        tree['contents'] = newcontents
+
+
+    def compact_tree(self, tree):
+        ''' Try to reduce the tree to its minimal form.
+
+        A source code tree in its simplest form may have a lot of duplicated
+        information that may be difficult to compare and come up with a minimal
+        difference.
+        '''
+
+        # First, drop all empty blocks.
+        self.drop_empty_blocks(tree)
+
+        # Macro conditions that nest the entire file aren't very interesting.  This
+        # should take care of the header guards.
+        if tree['type'] == block_type.file \
+                and len(tree['contents']) == 1 \
+                and tree['contents'][0]['type'] == block_type.macro_cond:
+            tree['contents'] = tree['contents'][0]['contents']
+
+        # Finally consolidate all macro conditional blocks.
+        self.consolidate_tree_blocks(tree)
+
+
+    def parse(self, op):
+        ''' File parser.
+
+        Parse the input array of lines OP and generate a tree structure to
+        represent the file.  This tree structure is then used for comparison between
+        the old and new file.
+        '''
+        self.KNOWN_MACROS = []
+        tree = new_block('', block_type.file, [], None)
+        self.op = self.remove_comments(op)
+        self.remove_extern_c()
+        self.op = [re.sub(r'#\s+', '#', x) for x in self.op]
+        self.parse_line(0, tree)
+        self.compact_tree(tree)
+        self.dump_tree(tree, 0)
+
+        return tree
+
+
+    def print_change(self, tree, action, prologue = ''):
+        ''' Print the nature of the differences found in the tree compared to the
+        other tree.  TREE is the tree that changed, action is what the change was
+        (Added, Removed, Modified) and prologue specifies the macro scope the change
+        is in.  The function calls itself recursively for all macro condition tree
+        nodes.
+        '''
+
+        if tree['type'] != block_type.macro_cond:
+            print('\t%s(%s): %s.' % (prologue, tree['name'], action))
+            return
+
+        prologue = '%s[%s]' % (prologue, tree['name'])
+        for t in tree['contents']:
+            if t['type'] == block_type.macro_cond:
+                self.print_change(t, action, prologue)
+            else:
+                print('\t%s(%s): %s.' % (prologue, t['name'], action))
+
+
+    def compare_trees(self, left, right, prologue = ''):
+        ''' Compare two trees and print the difference.
+
+        This routine is the entry point to compare two trees and print out their
+        differences.  LEFT and RIGHT will always have the same name and type,
+        starting with block_type.file and '' at the top level.
+        '''
+
+        if left['type'] == block_type.macro_cond or left['type'] == block_type.file:
+
+            if left['type'] == block_type.macro_cond:
+                prologue = '%s[%s]' % (prologue, left['name'])
+
+            # Make sure that everything in the left tree exists in the right tree.
+            for cl in left['contents']:
+                found = False
+                for cr in right['contents']:
+                    if not cl['matched'] and not cr['matched'] and \
+                            cl['name'] == cr['name'] and cl['type'] == cr['type']:
+                        cl['matched'] = cr['matched'] = True
+                        self.compare_trees(cl, cr, prologue)
+                        found = True
+                        break
+                if not found:
+                    self.print_change(cl, cl['actions']['del'], prologue)
+
+            # ... and vice versa.  This time we only need to look at unmatched
+            # contents.
+            for cr in right['contents']:
+                if not cr['matched']:
+                    self.print_change(cr, cr['actions']['new'], prologue)
+        else:
+            if left['contents'] != right['contents']:
+                self.print_change(left, left['actions']['mod'], prologue)
+
+
+    def dump_tree(self, tree, indent):
+        ''' Print the entire tree.
+        '''
+        if not self.debug.debug:
+            return
+
+        if tree['type'] == block_type.macro_cond or tree['type'] == block_type.file:
+            print('%sScope: %s' % (' ' * indent, tree['name']))
+            for c in tree['contents']:
+                self.dump_tree(c, indent + 4)
+            print('%sEndScope: %s' % (' ' * indent, tree['name']))
+        else:
+            if tree['type'] == block_type.func:
+                print('%sFUNC: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.composite:
+                print('%sCOMPOSITE: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.assign:
+                print('%sASSIGN: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.fndecl:
+                print('%sFNDECL: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.decl:
+                print('%sDECL: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macrocall:
+                print('%sMACROCALL: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macro_def:
+                print('%sDEFINE: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macro_include:
+                print('%sINCLUDE: %s' % (' ' * indent, tree['name']))
+            elif tree['type'] == block_type.macro_undef:
+                print('%sUNDEF: %s' % (' ' * indent, tree['name']))
+            else:
+                print('%sMACRO LEAF: %s' % (' ' * indent, tree['name']))
+
+
+    def compare(self, oldfile, newfile):
+        ''' Entry point for the C backend.
+
+        Parse the two files into trees and compare them.  Print the result of the
+        comparison in the ChangeLog-like format.
+        '''
+        self.debug.print('LEFT TREE')
+        self.debug.print('-' * 80)
+        left = self.parse(oldfile)
+
+        self.debug.print('RIGHT TREE')
+        self.debug.print('-' * 80)
+        right = self.parse(newfile)
+
+        self.compare_trees(left, right)
diff --git a/build-aux/gitlog-to-changelog b/build-aux/vcs-to-changelog/gitlog-to-changelog
similarity index 100%
rename from build-aux/gitlog-to-changelog
rename to build-aux/vcs-to-changelog/gitlog-to-changelog
diff --git a/build-aux/vcs-to-changelog/misc_util.py b/build-aux/vcs-to-changelog/misc_util.py
new file mode 100644
index 000000000..50a1346ce
--- /dev/null
+++ b/build-aux/vcs-to-changelog/misc_util.py
@@ -0,0 +1,54 @@
+# General Utility functions.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+import sys
+
+class DebugUtil:
+    debug = False
+    def __init__(self, debug):
+        self.debug = debug
+
+    def eprint(self, *args, **kwargs):
+        ''' Print to stderr.
+        '''
+        print(*args, file=sys.stderr, **kwargs)
+
+
+    def print(self, *args, **kwargs):
+        ''' Convenience function to print diagnostic information in the program.
+        '''
+        if self.debug:
+            self.eprint(*args, **kwargs)
+
+
+def decode(string):
+    ''' Attempt to decode a string.
+
+    Decode a string read from the source file.  The multiple attempts are needed
+    due to the presence of the page break characters and some tests in locales.
+    '''
+    codecs = ['utf8', 'latin1', 'cp1252']
+
+    for i in codecs:
+        try:
+            return string.decode(i)
+        except UnicodeDecodeError:
+            pass
+
+    DebugUtil.eprint('Failed to decode: %s' % string)
+
diff --git a/build-aux/vcs-to-changelog/vcs_git.py b/build-aux/vcs-to-changelog/vcs_git.py
new file mode 100644
index 000000000..02fcd8a46
--- /dev/null
+++ b/build-aux/vcs-to-changelog/vcs_git.py
@@ -0,0 +1,155 @@
+# Git repo support.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+from vcs_to_changelog import analyze_diff
+import subprocess
+import re
+from misc_util import *
+
+class GitRepo:
+    def __init__(self, ignore_list, debug):
+        self.ignore_list = ignore_list
+        self.debug = debug
+
+
+    def exec_git_cmd(self, args):
+        ''' Execute a git command and return its result as a list of strings.
+        '''
+        args.insert(0, 'git')
+        self.debug.print(args)
+        proc = subprocess.Popen(args, stdout=subprocess.PIPE)
+
+        # Clean up the output by removing trailing spaces, newlines and dropping
+        # blank lines.
+        op = [decode(x[:-1]).strip() for x in proc.stdout]
+        op = [re.sub(r'[\s\f]+', ' ', x) for x in op]
+        op = [x for x in op if x]
+        return op
+
+
+    def list_changes(self, commit, frontends):
+        ''' List changes in a single commit.
+
+        For the input commit id COMMIT, identify the files that have changed and the
+        nature of their changes.  Print commit information in the ChangeLog format,
+        calling into helper functions as necessary.
+        '''
+
+        op = self.exec_git_cmd(['show', '--date=short', '--raw', commit])
+        authors = []
+        date = ''
+        merge = False
+        copyright_exempt=''
+
+        for l in op:
+            if l.lower().find('copyright-paperwork-exempt:') == 0 \
+                    and 'yes' in l.lower():
+                copyright_exempt=' (tiny change)'
+            elif l.lower().find('co-authored-by:') == 0 or \
+                    l.find('Author:') == 0:
+                author = l.split(':')[1]
+                author = re.sub(r'(.*)\s*(<.*)', r'\1  \2', author)
+                authors.append(author)
+            elif l.find('Date:') == 0:
+                date=l[5:].strip()
+            elif l.find('Merge:') == 0:
+                merge = True
+
+        # Find raw commit information for all non-ChangeLog files.
+        op = [x[1:] for x in op if len(x) > 0 and re.match(r'^:[0-9]+', x)]
+
+        # Skip all ignored files.
+        for ign in self.ignore_list:
+            op = [x for x in op if ign not in x]
+
+        # It was only the ChangeLog, ignore.
+        if len(op) == 0:
+            return
+
+        print('%s  %s' % (date, authors[0]))
+
+        if (len(authors) > 1):
+            authors = authors[1:]
+            for author in authors:
+                print('            %s' % author)
+
+        print()
+
+        if merge:
+           print('\t MERGE COMMIT: %s\n' % commit)
+           return
+
+        print('\tCOMMIT%s: %s\n' % (copyright_exempt, commit))
+
+        # Each of these lines has a space separated format like so:
+        # :<OLD MODE> <NEW MODE> <OLD REF> <NEW REF> <OPERATION> <FILE1> <FILE2>
+        #
+        # where OPERATION can be one of the following:
+        # A: File added
+        # D: File removed
+        # M[0-9]{3}: File modified
+        # R[0-9]{3}: File renamed, with the 3 digit number following it indicating
+        # what percentage of the file is intact.
+        # C[0-9]{3}: File copied.  Same semantics as R.
+        # T: The permission bits of the file changed
+        # U: Unmerged.  We should not encounter this, so we ignore it/
+        # X, or anything else: Most likely a bug.  Report it.
+        #
+        # FILE2 is set only when OPERATION is R or C, to indicate the new file name.
+        #
+        # Also note that merge commits have a different format here, with three
+        # entries each for the modes and refs, but we don't bother with it for now.
+        #
+        # For more details: https://git-scm.com/docs/diff-format
+        for f in op:
+            data = f.split()
+            if data[4] == 'A':
+                print('\t* %s: New file.' % data[5])
+            elif data[4] == 'D':
+                print('\t* %s: Delete file.' % data[5])
+            elif data[4] == 'T':
+                print('\t* %s: Changed file permission bits from %s to %s' % \
+                        (data[5], data[0], data[1]))
+            elif data[4][0] == 'M':
+                print('\t* %s: Modified.' % data[5])
+                analyze_diff(data[5],
+                             self.exec_git_cmd(['show', data[2]]),
+                             self.exec_git_cmd(['show', data[3]]), frontends)
+            elif data[4][0] == 'R' or data[4][0] == 'C':
+                change = int(data[4][1:])
+                print('\t* %s: Move to...' % data[5])
+                print('\t* %s: ... here.' % data[6])
+                if change < 100:
+                    analyze_diff(data[6],
+                                 self.exec_git_cmd(['show', data[2]]),
+                                 self.exec_git_cmd(['show', data[3]]), frontends)
+            # We should never encounter this, so ignore for now.
+            elif data[4] == 'U':
+                pass
+            else:
+                eprint('%s: Unknown line format %s' % (commit, data[4]))
+                sys.exit(42)
+
+        print('')
+
+
+    def list_commits(self, revs):
+        ''' List commit IDs between the two revs in the REVS list.
+        '''
+        ref = revs[0] + '..' + revs[1]
+        return self.exec_git_cmd(['log', '--pretty=%H', ref])
diff --git a/build-aux/vcs-to-changelog/vcs_to_changelog.py b/build-aux/vcs-to-changelog/vcs_to_changelog.py
new file mode 100755
index 000000000..a106ebd74
--- /dev/null
+++ b/build-aux/vcs-to-changelog/vcs_to_changelog.py
@@ -0,0 +1,139 @@
+#!/usr/bin/python3
+# Main VCSToChangeLog script.
+# Copyright (C) 2019 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+# Written by Siddhesh Poyarekar
+
+''' Generate a ChangeLog style output based on a VCS log.
+
+This script takes two revisions as input and generates a ChangeLog style output
+for all revisions between the two revisions.
+
+This script is intended to be executed from the project parent directory, where
+a script called vcstocl_quirks.py is assumed to be present.  The script must
+define a function called get_project_quirks that returns a object of class type
+ProjectQuirks or a subclass of the same.  The definition of the ProjectQuirks
+class is below and it specifies the properties that the project must set to
+ensure correct parsing of its contents.
+
+Among other things, ProjectQurks specifies the VCS to read from; the default is
+assumed to be git.  The script then studies the VCS log and for each change,
+list out the nature of changes in the constituent files.
+
+Each file type may have parser frontends that can read files and construct
+objects that may be compared to determine the minimal changes that occured in
+each revision.  For files that do not have parsers, we may only know the nature
+of changes at the top level depending on the information that the VCS stores.
+
+The parser frontend must have a compare() method that takes the old and new
+files as arrays of strings and prints the output in ChangeLog format.
+
+Currently implemented VCS:
+
+    git
+
+Currently implemented frontends:
+
+    C
+'''
+import sys
+import os
+import re
+import argparse
+from misc_util import *
+import frontend_c
+from vcs_git import *
+
+debug = DebugUtil(False)
+
+class ProjectQuirks:
+    # This is a list of regex substitutions for C/C++ macros that are known to
+    # break parsing of the C programs.  Each member of this list is a dict with
+    # the key 'orig' having the regex and 'sub' having the substitution of the
+    # regex.
+    MACRO_QUIRKS = []
+
+    # This is a list of macro definitions that are extensively used and are
+    # known to break parsing due to some characteristic, mainly the lack of a
+    # semicolon at the end.
+    C_MACROS = []
+
+    # The repo type, defaults to git.
+    repo = 'git'
+
+    # List of files to ignore either because they are not needed (such as the
+    # ChangeLog) or because they are non-parseable.  For example, glibc has a
+    # header file that is only assembly code, which breaks the C parser.
+    IGNORE_LIST = ['ChangeLog']
+
+
+# Load quirks from the current project if they exist.
+sys.path.append(os.getcwd())
+try:
+    from vcstocl_quirks import *
+    project_quirks = get_project_quirks(debug)
+except:
+    project_quirks = ProjectQuirks()
+
+def analyze_diff(filename, oldfile, newfile, frontends):
+    ''' Parse the output of the old and new files and print the difference.
+
+    For input files OLDFILE and NEWFILE with name FILENAME, generate reduced
+    trees for them and compare them.  We limit our comparison to only C source
+    files.
+    '''
+    name, ext = os.path.splitext(filename)
+
+    if not ext in frontends.keys():
+        return None
+    else:
+        frontend = frontends[ext]
+        frontend.compare(oldfile, newfile)
+
+
+def main(repo, frontends, refs):
+    ''' ChangeLog Generator Entry Point.
+    '''
+    commits = repo.list_commits(args.refs)
+    for commit in commits:
+        repo.list_changes(commit, frontends)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('refs', metavar='ref', type=str, nargs=2,
+                     help='Refs to print ChangeLog entries between')
+
+    parser.add_argument('-d', '--debug', required=False, action='store_true',
+                     help='Run the file parser debugger.')
+
+    args = parser.parse_args()
+
+    debug.debug = args.debug
+    print('debug is ', debug.debug)
+
+    if len(args.refs) < 2:
+        debug.eprint('Two refs needed to get a ChangeLog.')
+        sys.exit(os.EX_USAGE)
+
+    REPO = {'git': GitRepo(project_quirks.IGNORE_LIST, debug)}
+
+    fe_c = frontend_c.Frontend(project_quirks, debug)
+    FRONTENDS = {'.c': fe_c,
+                 '.h': fe_c}
+
+    main(REPO[project_quirks.repo], FRONTENDS, args.refs)
-- 
2.19.2



^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: [PATCH] Add a new VCSToChangeLog script
  2019-01-27 16:34 Siddhesh Poyarekar
@ 2019-01-27 18:38 ` Bruno Haible
  2019-01-28  3:57   ` Siddhesh Poyarekar
  0 siblings, 1 reply; 4+ messages in thread
From: Bruno Haible @ 2019-01-27 18:38 UTC (permalink / raw)
  To: Siddhesh Poyarekar; +Cc: bug-gnulib

Hi Siddhesh,

> Build a more general script that parses changes in a VCS and then
> prints it in a ChangeLog format.

Can you please give some more context?
  * Is it a tool meant to operate on the history and produce a (large)
    ChangeLog file, like gitlog-to-changelog?
    Or is it a tool meant to help the developer prepare a git commit
    message and ChangeLog entry, like 'vc-dwim' from Jim Meyering?
  * In the first case, why is it useful for the program to understand
    the syntax of specific files? Can you show an example? And how
    would you combine the machine-generated parts with the human-written
    parts? I mean, an entry without human-written parts, like
      * foo.c (func1, func2, func3): Modified.
      * bar.c (func4, func5, func6): Modified.
    is not particularly useful to look at.

If the goal is that the tool operates with several version control
systems, do you also have an adapter 'vcs_svn.py'?

Also, since this is a significant contribution, do you already have
started copyright assignments to the FSF for your Gnulib contributions?

> +    codecs = ['utf8', 'latin1', 'cp1252']

1. Can you please use the standardized name 'utf-8'? Use of nonstandardized
   charset identifiers causes interoperability problems.
2. Since latin1 is a subset of cp1252, you can omit 'latin1' here.

Bruno



^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] Add a new VCSToChangeLog script
  2019-01-27 18:38 ` Bruno Haible
@ 2019-01-28  3:57   ` Siddhesh Poyarekar
  0 siblings, 0 replies; 4+ messages in thread
From: Siddhesh Poyarekar @ 2019-01-28  3:57 UTC (permalink / raw)
  To: Bruno Haible; +Cc: bug-gnulib

On 28/01/19 12:08 AM, Bruno Haible wrote:

> Hi Siddhesh,
>
>> Build a more general script that parses changes in a VCS and then
>> prints it in a ChangeLog format.
> Can you please give some more context?


Sorry about that, there was a pretty extensive conversation on other
lists[1][2][3] and in my hurry to get this out before the glibc 2.29
release I overlooked the fact that everyone on this list may not have
that context.  I've described the intent in response to your questions
below.


>   * Is it a tool meant to operate on the history and produce a (large)
>     ChangeLog file, like gitlog-to-changelog?
>     Or is it a tool meant to help the developer prepare a git commit
>     message and ChangeLog entry, like 'vc-dwim' from Jim Meyering?


The general consensus from those discussions above was that it would be
acceptable to have ChangeLog entries auto-generated to approximate a
ChangeLog entry from the git history, but not just its commit log like
gitlog-to-changelog does but by parsing the contents of the difference
to determine what changed and prepare a ChangeLog entry based on that. 
The result is this script, which is unlike gitlog-to-changelog.  For
projects that need a precise ChangeLog (in the glibc project we have
general agreement on having decent approximations) they can continue
using the gitlog-to-changelog script until vcs-to-changelog.py gets to
the point of being acceptable for them.

I wasn't aware of vc-dwim (or more specifically, vc-chlog) and from the
description it looks like there is overlap.  I'll study that project;
maybe all my work is unnecessary and we can just use vc-chlog...


>   * In the first case, why is it useful for the program to understand
>     the syntax of specific files? Can you show an example? And how
>     would you combine the machine-generated parts with the human-written
>     parts? I mean, an entry without human-written parts, like
>       * foo.c (func1, func2, func3): Modified.
>       * bar.c (func4, func5, func6): Modified.
>     is not particularly useful to look at.

The output is not intended to be human-edited.  The point of the script
is to not have to write or maintain ChangeLog entries at all.  If one
needs to see a ChangeLog-like output (i.e. what changed as opposed to
why and doesn't want to grok the diff), they can use the script with the
relevant refs and get the output.  That's why it is useful for the
script to understand the syntax of specific files.  The script currently
does not look inside functions or structs because it was initially
agreed that only high level changes need to be listed (hence the
'approximation' of a ChangeLog).  The parser can be enhanced to look
further inside in future, and it's on my list to do.  The list is quite
long, so if gnulib or glibc participates in GSoC I'll be happy to mentor
students who express interest in doing this too.


> If the goal is that the tool operates with several version control
> systems, do you also have an adapter 'vcs_svn.py'?

I wrote this for glibc to begin with, but during discussions it was
apparent that other projects would be interested in this as well, which
is why I split out the repo backend to make it easier to add other VCS
backends.  I don't intend to write a vcs_svn.py but if a project is
interested in it, it should be pretty straightforward to write one and
plug it in.  Or they could convince me to write one, but that will be
queued up behind glibc support bits such as the Versions file parser. 
Again, <insert GSoC pitch here>.


> Also, since this is a significant contribution, do you already have
> started copyright assignments to the FSF for your Gnulib contributions?


I should be covered under Linaro's assignment.


>> +    codecs = ['utf8', 'latin1', 'cp1252']
> 1. Can you please use the standardized name 'utf-8'? Use of nonstandardized
>    charset identifiers causes interoperability problems.

I believe that's defined by python, but I'll test if 'utf-8' works and
use that instead.


> 2. Since latin1 is a subset of cp1252, you can omit 'latin1' here.

OK, I'll change this.


Siddhesh

[1] https://lists.gnu.org/archive/html/bug-standards/2018-05/msg00010.html

[2] https://lists.gnu.org/archive/html/bug-standards/2018-11/msg00000.html

[3] https://sourceware.org/ml/libc-alpha/2018-12/msg00855.html




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2019-01-27 16:34 Siddhesh Poyarekar
2019-01-27 18:38 ` Bruno Haible
2019-01-28  3:57   ` Siddhesh Poyarekar

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