1 files changed, 475 insertions, 0 deletions

diff --git a/range-diff.c b/range-diff.c
new file mode 100644
index 0000000..60edb2f
--- /dev/null
+++ b/range-diff.c
@@ -0,0 +1,475 @@
+#include "cache.h"
+#include "range-diff.h"
+#include "string-list.h"
+#include "run-command.h"
+#include "argv-array.h"
+#include "hashmap.h"
+#include "xdiff-interface.h"
+#include "linear-assignment.h"
+#include "diffcore.h"
+#include "commit.h"
+#include "pretty.h"
+#include "userdiff.h"
+
+struct patch_util {
+	/* For the search for an exact match */
+	struct hashmap_entry e;
+	const char *diff, *patch;
+
+	int i, shown;
+	int diffsize;
+	size_t diff_offset;
+	/* the index of the matching item in the other branch, or -1 */
+	int matching;
+	struct object_id oid;
+};
+
+/*
+ * Reads the patches into a string list, with the `util` field being populated
+ * as struct object_id (will need to be free()d).
+ */
+static int read_patches(const char *range, struct string_list *list)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	FILE *in;
+	struct strbuf buf = STRBUF_INIT, line = STRBUF_INIT;
+	struct patch_util *util = NULL;
+	int in_header = 1;
+
+	argv_array_pushl(&cp.args, "log", "--no-color", "-p", "--no-merges",
+			"--reverse", "--date-order", "--decorate=no",
+			/*
+			 * Choose indicators that are not used anywhere
+			 * else in diffs, but still look reasonable
+			 * (e.g. will not be confusing when debugging)
+			 */
+			"--output-indicator-new=>",
+			"--output-indicator-old=<",
+			"--output-indicator-context=#",
+			"--no-abbrev-commit", range,
+			NULL);
+	cp.out = -1;
+	cp.no_stdin = 1;
+	cp.git_cmd = 1;
+
+	if (start_command(&cp))
+		return error_errno(_("could not start `log`"));
+	in = fdopen(cp.out, "r");
+	if (!in) {
+		error_errno(_("could not read `log` output"));
+		finish_command(&cp);
+		return -1;
+	}
+
+	while (strbuf_getline(&line, in) != EOF) {
+		const char *p;
+
+		if (skip_prefix(line.buf, "commit ", &p)) {
+			if (util) {
+				string_list_append(list, buf.buf)->util = util;
+				strbuf_reset(&buf);
+			}
+			util = xcalloc(sizeof(*util), 1);
+			if (get_oid(p, &util->oid)) {
+				error(_("could not parse commit '%s'"), p);
+				free(util);
+				string_list_clear(list, 1);
+				strbuf_release(&buf);
+				strbuf_release(&line);
+				fclose(in);
+				finish_command(&cp);
+				return -1;
+			}
+			util->matching = -1;
+			in_header = 1;
+			continue;
+		}
+
+		if (starts_with(line.buf, "diff --git")) {
+			in_header = 0;
+			strbuf_addch(&buf, '\n');
+			if (!util->diff_offset)
+				util->diff_offset = buf.len;
+			strbuf_addch(&buf, ' ');
+			strbuf_addbuf(&buf, &line);
+		} else if (in_header) {
+			if (starts_with(line.buf, "Author: ")) {
+				strbuf_addbuf(&buf, &line);
+				strbuf_addstr(&buf, "\n\n");
+			} else if (starts_with(line.buf, "    ")) {
+				strbuf_rtrim(&line);
+				strbuf_addbuf(&buf, &line);
+				strbuf_addch(&buf, '\n');
+			}
+			continue;
+		} else if (starts_with(line.buf, "@@ "))
+			strbuf_addstr(&buf, "@@");
+		else if (!line.buf[0] || starts_with(line.buf, "index "))
+			/*
+			 * A completely blank (not ' \n', which is context)
+			 * line is not valid in a diff.  We skip it
+			 * silently, because this neatly handles the blank
+			 * separator line between commits in git-log
+			 * output.
+			 *
+			 * We also want to ignore the diff's `index` lines
+			 * because they contain exact blob hashes in which
+			 * we are not interested.
+			 */
+			continue;
+		else if (line.buf[0] == '>') {
+			strbuf_addch(&buf, '+');
+			strbuf_add(&buf, line.buf + 1, line.len - 1);
+		} else if (line.buf[0] == '<') {
+			strbuf_addch(&buf, '-');
+			strbuf_add(&buf, line.buf + 1, line.len - 1);
+		} else if (line.buf[0] == '#') {
+			strbuf_addch(&buf, ' ');
+			strbuf_add(&buf, line.buf + 1, line.len - 1);
+		} else {
+			strbuf_addch(&buf, ' ');
+			strbuf_addbuf(&buf, &line);
+		}
+
+		strbuf_addch(&buf, '\n');
+		util->diffsize++;
+	}
+	fclose(in);
+	strbuf_release(&line);
+
+	if (util)
+		string_list_append(list, buf.buf)->util = util;
+	strbuf_release(&buf);
+
+	if (finish_command(&cp))
+		return -1;
+
+	return 0;
+}
+
+static int patch_util_cmp(const void *dummy, const struct patch_util *a,
+		     const struct patch_util *b, const char *keydata)
+{
+	return strcmp(a->diff, keydata ? keydata : b->diff);
+}
+
+static void find_exact_matches(struct string_list *a, struct string_list *b)
+{
+	struct hashmap map;
+	int i;
+
+	hashmap_init(&map, (hashmap_cmp_fn)patch_util_cmp, NULL, 0);
+
+	/* First, add the patches of a to a hash map */
+	for (i = 0; i < a->nr; i++) {
+		struct patch_util *util = a->items[i].util;
+
+		util->i = i;
+		util->patch = a->items[i].string;
+		util->diff = util->patch + util->diff_offset;
+		hashmap_entry_init(util, strhash(util->diff));
+		hashmap_add(&map, util);
+	}
+
+	/* Now try to find exact matches in b */
+	for (i = 0; i < b->nr; i++) {
+		struct patch_util *util = b->items[i].util, *other;
+
+		util->i = i;
+		util->patch = b->items[i].string;
+		util->diff = util->patch + util->diff_offset;
+		hashmap_entry_init(util, strhash(util->diff));
+		other = hashmap_remove(&map, util, NULL);
+		if (other) {
+			if (other->matching >= 0)
+				BUG("already assigned!");
+
+			other->matching = i;
+			util->matching = other->i;
+		}
+	}
+
+	hashmap_free(&map, 0);
+}
+
+static void diffsize_consume(void *data, char *line, unsigned long len)
+{
+	(*(int *)data)++;
+}
+
+static int diffsize(const char *a, const char *b)
+{
+	xpparam_t pp = { 0 };
+	xdemitconf_t cfg = { 0 };
+	mmfile_t mf1, mf2;
+	int count = 0;
+
+	mf1.ptr = (char *)a;
+	mf1.size = strlen(a);
+	mf2.ptr = (char *)b;
+	mf2.size = strlen(b);
+
+	cfg.ctxlen = 3;
+	if (!xdi_diff_outf(&mf1, &mf2, diffsize_consume, &count, &pp, &cfg))
+		return count;
+
+	error(_("failed to generate diff"));
+	return COST_MAX;
+}
+
+static void get_correspondences(struct string_list *a, struct string_list *b,
+				int creation_factor)
+{
+	int n = a->nr + b->nr;
+	int *cost, c, *a2b, *b2a;
+	int i, j;
+
+	ALLOC_ARRAY(cost, st_mult(n, n));
+	ALLOC_ARRAY(a2b, n);
+	ALLOC_ARRAY(b2a, n);
+
+	for (i = 0; i < a->nr; i++) {
+		struct patch_util *a_util = a->items[i].util;
+
+		for (j = 0; j < b->nr; j++) {
+			struct patch_util *b_util = b->items[j].util;
+
+			if (a_util->matching == j)
+				c = 0;
+			else if (a_util->matching < 0 && b_util->matching < 0)
+				c = diffsize(a_util->diff, b_util->diff);
+			else
+				c = COST_MAX;
+			cost[i + n * j] = c;
+		}
+
+		c = a_util->matching < 0 ?
+			a_util->diffsize * creation_factor / 100 : COST_MAX;
+		for (j = b->nr; j < n; j++)
+			cost[i + n * j] = c;
+	}
+
+	for (j = 0; j < b->nr; j++) {
+		struct patch_util *util = b->items[j].util;
+
+		c = util->matching < 0 ?
+			util->diffsize * creation_factor / 100 : COST_MAX;
+		for (i = a->nr; i < n; i++)
+			cost[i + n * j] = c;
+	}
+
+	for (i = a->nr; i < n; i++)
+		for (j = b->nr; j < n; j++)
+			cost[i + n * j] = 0;
+
+	compute_assignment(n, n, cost, a2b, b2a);
+
+	for (i = 0; i < a->nr; i++)
+		if (a2b[i] >= 0 && a2b[i] < b->nr) {
+			struct patch_util *a_util = a->items[i].util;
+			struct patch_util *b_util = b->items[a2b[i]].util;
+
+			a_util->matching = a2b[i];
+			b_util->matching = i;
+		}
+
+	free(cost);
+	free(a2b);
+	free(b2a);
+}
+
+static void output_pair_header(struct diff_options *diffopt,
+			       int patch_no_width,
+			       struct strbuf *buf,
+			       struct strbuf *dashes,
+			       struct patch_util *a_util,
+			       struct patch_util *b_util)
+{
+	struct object_id *oid = a_util ? &a_util->oid : &b_util->oid;
+	struct commit *commit;
+	char status;
+	const char *color_reset = diff_get_color_opt(diffopt, DIFF_RESET);
+	const char *color_old = diff_get_color_opt(diffopt, DIFF_FILE_OLD);
+	const char *color_new = diff_get_color_opt(diffopt, DIFF_FILE_NEW);
+	const char *color_commit = diff_get_color_opt(diffopt, DIFF_COMMIT);
+	const char *color;
+
+	if (!dashes->len)
+		strbuf_addchars(dashes, '-',
+				strlen(find_unique_abbrev(oid,
+							  DEFAULT_ABBREV)));
+
+	if (!b_util) {
+		color = color_old;
+		status = '<';
+	} else if (!a_util) {
+		color = color_new;
+		status = '>';
+	} else if (strcmp(a_util->patch, b_util->patch)) {
+		color = color_commit;
+		status = '!';
+	} else {
+		color = color_commit;
+		status = '=';
+	}
+
+	strbuf_reset(buf);
+	strbuf_addstr(buf, status == '!' ? color_old : color);
+	if (!a_util)
+		strbuf_addf(buf, "%*s:  %s ", patch_no_width, "-", dashes->buf);
+	else
+		strbuf_addf(buf, "%*d:  %s ", patch_no_width, a_util->i + 1,
+			    find_unique_abbrev(&a_util->oid, DEFAULT_ABBREV));
+
+	if (status == '!')
+		strbuf_addf(buf, "%s%s", color_reset, color);
+	strbuf_addch(buf, status);
+	if (status == '!')
+		strbuf_addf(buf, "%s%s", color_reset, color_new);
+
+	if (!b_util)
+		strbuf_addf(buf, " %*s:  %s", patch_no_width, "-", dashes->buf);
+	else
+		strbuf_addf(buf, " %*d:  %s", patch_no_width, b_util->i + 1,
+			    find_unique_abbrev(&b_util->oid, DEFAULT_ABBREV));
+
+	commit = lookup_commit_reference(the_repository, oid);
+	if (commit) {
+		if (status == '!')
+			strbuf_addf(buf, "%s%s", color_reset, color);
+
+		strbuf_addch(buf, ' ');
+		pp_commit_easy(CMIT_FMT_ONELINE, commit, buf);
+	}
+	strbuf_addf(buf, "%s\n", color_reset);
+
+	fwrite(buf->buf, buf->len, 1, diffopt->file);
+}
+
+static struct userdiff_driver no_func_name = {
+	.funcname = { "$^", 0 }
+};
+
+static struct diff_filespec *get_filespec(const char *name, const char *p)
+{
+	struct diff_filespec *spec = alloc_filespec(name);
+
+	fill_filespec(spec, &null_oid, 0, 0644);
+	spec->data = (char *)p;
+	spec->size = strlen(p);
+	spec->should_munmap = 0;
+	spec->is_stdin = 1;
+	spec->driver = &no_func_name;
+
+	return spec;
+}
+
+static void patch_diff(const char *a, const char *b,
+			      struct diff_options *diffopt)
+{
+	diff_queue(&diff_queued_diff,
+		   get_filespec("a", a), get_filespec("b", b));
+
+	diffcore_std(diffopt);
+	diff_flush(diffopt);
+}
+
+static void output(struct string_list *a, struct string_list *b,
+		   struct diff_options *diffopt)
+{
+	struct strbuf buf = STRBUF_INIT, dashes = STRBUF_INIT;
+	int patch_no_width = decimal_width(1 + (a->nr > b->nr ? a->nr : b->nr));
+	int i = 0, j = 0;
+
+	/*
+	 * We assume the user is really more interested in the second argument
+	 * ("newer" version). To that end, we print the output in the order of
+	 * the RHS (the `b` parameter). To put the LHS (the `a` parameter)
+	 * commits that are no longer in the RHS into a good place, we place
+	 * them once we have shown all of their predecessors in the LHS.
+	 */
+
+	while (i < a->nr || j < b->nr) {
+		struct patch_util *a_util, *b_util;
+		a_util = i < a->nr ? a->items[i].util : NULL;
+		b_util = j < b->nr ? b->items[j].util : NULL;
+
+		/* Skip all the already-shown commits from the LHS. */
+		while (i < a->nr && a_util->shown)
+			a_util = ++i < a->nr ? a->items[i].util : NULL;
+
+		/* Show unmatched LHS commit whose predecessors were shown. */
+		if (i < a->nr && a_util->matching < 0) {
+			output_pair_header(diffopt, patch_no_width,
+					   &buf, &dashes, a_util, NULL);
+			i++;
+			continue;
+		}
+
+		/* Show unmatched RHS commits. */
+		while (j < b->nr && b_util->matching < 0) {
+			output_pair_header(diffopt, patch_no_width,
+					   &buf, &dashes, NULL, b_util);
+			b_util = ++j < b->nr ? b->items[j].util : NULL;
+		}
+
+		/* Show matching LHS/RHS pair. */
+		if (j < b->nr) {
+			a_util = a->items[b_util->matching].util;
+			output_pair_header(diffopt, patch_no_width,
+					   &buf, &dashes, a_util, b_util);
+			if (!(diffopt->output_format & DIFF_FORMAT_NO_OUTPUT))
+				patch_diff(a->items[b_util->matching].string,
+					   b->items[j].string, diffopt);
+			a_util->shown = 1;
+			j++;
+		}
+	}
+	strbuf_release(&buf);
+	strbuf_release(&dashes);
+}
+
+static struct strbuf *output_prefix_cb(struct diff_options *opt, void *data)
+{
+	return data;
+}
+
+int show_range_diff(const char *range1, const char *range2,
+		    int creation_factor, int dual_color,
+		    struct diff_options *diffopt)
+{
+	int res = 0;
+
+	struct string_list branch1 = STRING_LIST_INIT_DUP;
+	struct string_list branch2 = STRING_LIST_INIT_DUP;
+
+	if (read_patches(range1, &branch1))
+		res = error(_("could not parse log for '%s'"), range1);
+	if (!res && read_patches(range2, &branch2))
+		res = error(_("could not parse log for '%s'"), range2);
+
+	if (!res) {
+		struct diff_options opts;
+		struct strbuf indent = STRBUF_INIT;
+
+		memcpy(&opts, diffopt, sizeof(opts));
+		opts.output_format = DIFF_FORMAT_PATCH;
+		opts.flags.suppress_diff_headers = 1;
+		opts.flags.dual_color_diffed_diffs = dual_color;
+		opts.output_prefix = output_prefix_cb;
+		strbuf_addstr(&indent, "    ");
+		opts.output_prefix_data = &indent;
+		diff_setup_done(&opts);
+
+		find_exact_matches(&branch1, &branch2);
+		get_correspondences(&branch1, &branch2, creation_factor);
+		output(&branch1, &branch2, &opts);
+
+		strbuf_release(&indent);
+	}
+
+	string_list_clear(&branch1, 1);
+	string_list_clear(&branch2, 1);
+
+	return res;
+}