[PATCH v5 03/10] add-interactive.c: implement list_modified

["Slavica Djukic via GitGitGadget" <gitgitgadget@gmail.com>]

From: Slavica Djukic <slawica92@hotmail.com>

Implement list_modified from Perl, which will be used
by most of the *_cmd functions, including status in the
following commit.

It lists a numstat comparing changed files between a) the worktree and
the index; b) the index and the HEAD.

To do so, we use run_diff_index() and run_diff_files() to get changed
files, use the diffstat API on them to get the numstat and use a
combination of a hashmap and qsort() to print the result in
O(n) + O(n lg n) complexity.

Add new file: add-interactive.c which will be used for implementing
"application logic" of git add -i (alongside with add-interactive.h,
added in later commit), whereas add--helper.c will be used mostly
for parsing the command line.

Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Original-patch-by: Daniel Ferreira <bnmvco@gmail.com>
Signed-off-by: Slavica Djukic <slawica92@hotmail.com>
---
 Makefile          |   1 +
 add-interactive.c | 188 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 189 insertions(+)
 create mode 100644 add-interactive.c

diff --git a/Makefile b/Makefile
index e64e202deb..1b3c06b633 100644
--- a/Makefile
+++ b/Makefile
@@ -847,6 +847,7 @@ LIB_H = $(shell $(FIND) . \
 	-name '*.h' -print)
 
 LIB_OBJS += abspath.o
+LIB_OBJS += add-interactive.o
 LIB_OBJS += advice.o
 LIB_OBJS += alias.o
 LIB_OBJS += alloc.o
diff --git a/add-interactive.c b/add-interactive.c
new file mode 100644
index 0000000000..7d096207d4
--- /dev/null
+++ b/add-interactive.c
@@ -0,0 +1,188 @@
+#include "cache.h"
+#include "commit.h"
+#include "color.h"
+#include "config.h"
+#include "diffcore.h"
+#include "revision.h"
+
+enum collection_phase {
+	WORKTREE,
+	INDEX
+};
+
+struct file_stat {
+	struct hashmap_entry ent;
+	struct {
+		uintmax_t added, deleted;
+	} index, worktree;
+	char name[FLEX_ARRAY];
+};
+
+struct collection_status {
+	enum collection_phase phase;
+
+	const char *reference;
+	struct pathspec pathspec;
+
+	struct hashmap file_map;
+};
+
+static int hash_cmp(const void *unused_cmp_data, const void *entry,
+		    const void *entry_or_key, const void *keydata)
+{
+	const struct file_stat *e1 = entry, *e2 = entry_or_key;
+	const char *name = keydata ? keydata : e2->name;
+
+	return strcmp(e1->name, name);
+}
+
+static int alphabetical_cmp(const void *a, const void *b)
+{
+	struct file_stat *f1 = *((struct file_stat **)a);
+	struct file_stat *f2 = *((struct file_stat **)b);
+
+	return strcmp(f1->name, f2->name);
+}
+
+static void collect_changes_cb(struct diff_queue_struct *q,
+			       struct diff_options *options,
+			       void *data)
+{
+	struct collection_status *s = data;
+	struct diffstat_t stat = { 0 };
+	int i;
+
+	if (!q->nr)
+		return;
+
+	compute_diffstat(options, &stat);
+
+	for (i = 0; i < stat.nr; i++) {
+		struct file_stat *entry;
+		const char *name = stat.files[i]->name;
+		unsigned int hash = strhash(name);
+
+		entry = hashmap_get_from_hash(&s->file_map, hash, name);
+		if (!entry) {
+			FLEX_ALLOC_STR(entry, name, name);
+			hashmap_entry_init(entry, hash);
+			hashmap_add(&s->file_map, entry);
+		}
+
+		if (s->phase == WORKTREE) {
+			entry->worktree.added = stat.files[i]->added;
+			entry->worktree.deleted = stat.files[i]->deleted;
+		} else if (s->phase == INDEX) {
+			entry->index.added = stat.files[i]->added;
+			entry->index.deleted = stat.files[i]->deleted;
+		}
+	}
+}
+
+static void collect_changes_worktree(struct collection_status *s)
+{
+	struct rev_info rev;
+
+	s->phase = WORKTREE;
+
+	init_revisions(&rev, NULL);
+	setup_revisions(0, NULL, &rev, NULL);
+
+	rev.max_count = 0;
+
+	rev.diffopt.flags.ignore_dirty_submodules = 1;
+	rev.diffopt.output_format = DIFF_FORMAT_CALLBACK;
+	rev.diffopt.format_callback = collect_changes_cb;
+	rev.diffopt.format_callback_data = s;
+
+	run_diff_files(&rev, 0);
+}
+
+static void collect_changes_index(struct collection_status *s)
+{
+	struct rev_info rev;
+	struct setup_revision_opt opt = { 0 };
+
+	s->phase = INDEX;
+
+	init_revisions(&rev, NULL);
+	opt.def = s->reference;
+	setup_revisions(0, NULL, &rev, &opt);
+
+	rev.diffopt.output_format = DIFF_FORMAT_CALLBACK;
+	rev.diffopt.format_callback = collect_changes_cb;
+	rev.diffopt.format_callback_data = s;
+
+	run_diff_index(&rev, 1);
+}
+
+static int is_inital_commit(void)
+{
+	struct object_id sha1;
+	if (get_oid("HEAD", &sha1))
+		return 1;
+	return 0;
+}
+
+static const char *get_diff_reference(void)
+{
+	if(is_inital_commit())
+		return empty_tree_oid_hex();
+	return "HEAD";
+}
+
+static void filter_files(const char *filter, struct hashmap *file_map,
+			 struct file_stat **files)
+{
+
+	for (int i = 0; i < hashmap_get_size(file_map); i++) {
+		struct file_stat *f = files[i];
+
+		if ((!(f->worktree.added || f->worktree.deleted)) &&
+		   (!strcmp(filter, "file-only")))
+				hashmap_remove(file_map, f, NULL);
+
+		if ((!(f->index.added || f->index.deleted)) &&
+		   (!strcmp(filter, "index-only")))
+				hashmap_remove(file_map, f, NULL);
+	}
+}
+
+static struct collection_status *list_modified(struct repository *r, const char *filter)
+{
+	int i = 0;
+	struct collection_status *s = xcalloc(1, sizeof(*s));
+	struct hashmap_iter iter;
+	struct file_stat **files;
+	struct file_stat *entry;
+
+	if (repo_read_index(r) < 0) {
+		printf("\n");
+		return NULL;
+	}
+
+	s->reference = get_diff_reference();
+	hashmap_init(&s->file_map, hash_cmp, NULL, 0);
+
+	collect_changes_worktree(s);
+	collect_changes_index(s);
+
+	if (hashmap_get_size(&s->file_map) < 1) {
+		printf("\n");
+		return NULL;
+	}
+
+	hashmap_iter_init(&s->file_map, &iter);
+
+	files = xcalloc(hashmap_get_size(&s->file_map), sizeof(struct file_stat *));
+	while ((entry = hashmap_iter_next(&iter))) {
+		files[i++] = entry;
+	}
+	QSORT(files, hashmap_get_size(&s->file_map), alphabetical_cmp);
+
+	if (filter)
+		filter_files(filter, &s->file_map, files);
+
+	free(files);
+	return s;
+}
-- 
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