1 files changed, 118 insertions, 23 deletions

diff --git a/ui-ssdiff.c b/ui-ssdiff.c
index 5673642..408e620 100644
--- a/ui-ssdiff.c
+++ b/ui-ssdiff.c
@@ -1,274 +1,369 @@
 #include "cgit.h"
 #include "html.h"
 #include "ui-shared.h"
 
 extern int use_ssdiff;
 
 static int current_old_line, current_new_line;
 
 struct deferred_lines {
 	int line_no;
 	char *line;
 	struct deferred_lines *next;
 };
 
 static struct deferred_lines *deferred_old, *deferred_old_last;
 static struct deferred_lines *deferred_new, *deferred_new_last;
 
+static char *longest_common_subsequence(char *A, char *B)
+{
+	int i, j, ri;
+	int m = strlen(A);
+	int n = strlen(B);
+	int L[m + 1][n + 1];
+	int tmp1, tmp2;
+	int lcs_length;
+	char *result;
+
+	for (i = m; i >= 0; i--) {
+		for (j = n; j >= 0; j--) {
+			if (A[i] == '\0' || B[j] == '\0') {
+				L[i][j] = 0;
+			} else if (A[i] == B[j]) {
+				L[i][j] = 1 + L[i + 1][j + 1];
+			} else {
+				tmp1 = L[i + 1][j];
+				tmp2 = L[i][j + 1];
+				L[i][j] = (tmp1 > tmp2 ? tmp1 : tmp2);
+			}
+		}
+	}
+
+	lcs_length = L[0][0];
+	result = xmalloc(lcs_length + 2);
+	memset(result, 0, sizeof(*result) * (lcs_length + 2));
+
+	ri = 0;
+	i = 0;
+	j = 0;
+	while (i < m && j < n) {
+		if (A[i] == B[j]) {
+			result[ri] = A[i];
+			ri += 1;
+			i += 1;
+			j += 1;
+		} else if (L[i + 1][j] >= L[i][j + 1]) {
+			i += 1;
+		} else {
+			j += 1;
+		}
+	}
+	return result;
+}
+
 static int line_from_hunk(char *line, char type)
 {
 	char *buf1, *buf2;
 	int len;
 
 	buf1 = strchr(line, type);
 	if (buf1 == NULL)
 		return 0;
 	buf1 += 1;
 	buf2 = strchr(buf1, ',');
 	if (buf2 == NULL)
 		return 0;
 	len = buf2 - buf1;
 	buf2 = xmalloc(len + 1);
 	strncpy(buf2, buf1, len);
 	buf2[len] = '\0';
 	int res = atoi(buf2);
 	free(buf2);
 	return res;
 }
 
 static char *replace_tabs(char *line)
 {
 	char *prev_buf = line;
 	char *cur_buf;
 	int linelen = strlen(line);
 	int n_tabs = 0;
 	int i;
 	char *result;
 	char *spaces = "        ";
 
 	if (linelen == 0) {
 		result = xmalloc(1);
 		result[0] = '\0';
 		return result;
 	}
 
 	for (i = 0; i < linelen; i++)
 		if (line[i] == '\t')
 			n_tabs += 1;
 	result = xmalloc(linelen + n_tabs * 8 + 1);
 	result[0] = '\0';
 
 	while (1) {
 		cur_buf = strchr(prev_buf, '\t');
 		if (!cur_buf) {
 			strcat(result, prev_buf);
 			break;
 		} else {
 			strcat(result, " ");
 			strncat(result, spaces, 8 - (strlen(result) % 8));
 			strncat(result, prev_buf, cur_buf - prev_buf);
 		}
 		prev_buf = cur_buf + 1;
 	}
 	return result;
 }
 
+static int calc_deferred_lines(struct deferred_lines *start)
+{
+	struct deferred_lines *item = start;
+	int result = 0;
+	while (item) {
+		result += 1;
+		item = item->next;
+	}
+	return result;
+}
+
 static void deferred_old_add(char *line, int line_no)
 {
 	struct deferred_lines *item = xmalloc(sizeof(struct deferred_lines));
 	item->line = xstrdup(line);
 	item->line_no = line_no;
 	item->next = NULL;
 	if (deferred_old) {
 		deferred_old_last->next = item;
 		deferred_old_last = item;
 	} else {
 		deferred_old = deferred_old_last = item;
 	}
 }
 
 static void deferred_new_add(char *line, int line_no)
 {
 	struct deferred_lines *item = xmalloc(sizeof(struct deferred_lines));
 	item->line = xstrdup(line);
 	item->line_no = line_no;
 	item->next = NULL;
 	if (deferred_new) {
 		deferred_new_last->next = item;
 		deferred_new_last = item;
 	} else {
 		deferred_new = deferred_new_last = item;
 	}
 }
 
-static void print_ssdiff_line(char *class, int old_line_no, char *old_line,
-			      int new_line_no, char *new_line)
+static void print_part_with_lcs(char *class, char *line, char *lcs)
 {
+	int line_len = strlen(line);
+	int i, j;
+	char c[2] = " ";
+	int same = 1;
+
+	j = 0;
+	for (i = 0; i < line_len; i++) {
+		c[0] = line[i];
+		if (same) {
+			if (line[i] == lcs[j])
+				j += 1;
+			else {
+				same = 0;
+				htmlf("<span class='%s'>", class);
+			}
+		} else if (line[i] == lcs[j]) {
+			same = 1;
+			htmlf("</span>");
+			j += 1;
+		}
+		html_txt(c);
+	}
+}
+
+static void print_ssdiff_line(char *class,
+			      int old_line_no,
+			      char *old_line,
+			      int new_line_no,
+			      char *new_line, int individual_chars)
+{
+	char *lcs = NULL;
+	if (old_line)
+		old_line = replace_tabs(old_line + 1);
+	if (new_line)
+		new_line = replace_tabs(new_line + 1);
+	if (individual_chars && old_line && new_line)
+		lcs = longest_common_subsequence(old_line, new_line);
 	html("<tr>");
 	if (old_line_no > 0)
 		htmlf("<td class='lineno'>%d</td><td class='%s'>",
 		      old_line_no, class);
 	else if (old_line)
 		htmlf("<td class='lineno'></td><td class='%s'>", class);
 	else
 		htmlf("<td class='lineno'></td><td class='%s_dark'>", class);
-
 	if (old_line) {
-		old_line = replace_tabs(old_line + 1);
+		if (lcs)
+			print_part_with_lcs("del", old_line, lcs);
+		else
 		html_txt(old_line);
-		free(old_line);
 	}
 
 	html("</td>");
-
 	if (new_line_no > 0)
 		htmlf("<td class='lineno'>%d</td><td class='%s'>",
 		      new_line_no, class);
 	else if (new_line)
 		htmlf("<td class='lineno'></td><td class='%s'>", class);
 	else
 		htmlf("<td class='lineno'></td><td class='%s_dark'>", class);
-
 	if (new_line) {
-		new_line = replace_tabs(new_line + 1);
+		if (lcs)
+			print_part_with_lcs("add", new_line, lcs);
+		else
 		html_txt(new_line);
-		free(new_line);
 	}
 
 	html("</td></tr>");
+	if (lcs)
+		free(lcs);
+	if (new_line)
+		free(new_line);
+	if (old_line)
+		free(old_line);
 }
 
 static void print_deferred_old_lines()
 {
 	struct deferred_lines *iter_old, *tmp;
-
 	iter_old = deferred_old;
 	while (iter_old) {
 		print_ssdiff_line("del", iter_old->line_no,
-				  iter_old->line, -1, NULL);
+				  iter_old->line, -1, NULL, 0);
 		tmp = iter_old->next;
 		free(iter_old);
 		iter_old = tmp;
 	}
 }
 
 static void print_deferred_new_lines()
 {
 	struct deferred_lines *iter_new, *tmp;
-
 	iter_new = deferred_new;
 	while (iter_new) {
-		print_ssdiff_line("add", -1, NULL, iter_new->line_no,
-				  iter_new->line);
+		print_ssdiff_line("add", -1, NULL,
+				  iter_new->line_no, iter_new->line, 0);
 		tmp = iter_new->next;
 		free(iter_new);
 		iter_new = tmp;
 	}
 }
 
 static void print_deferred_changed_lines()
 {
 	struct deferred_lines *iter_old, *iter_new, *tmp;
+	int n_old_lines = calc_deferred_lines(deferred_old);
+	int n_new_lines = calc_deferred_lines(deferred_new);
+	int individual_chars = (n_old_lines == n_new_lines ? 1 : 0);
 
 	iter_old = deferred_old;
 	iter_new = deferred_new;
 	while (iter_old || iter_new) {
 		if (iter_old && iter_new)
 			print_ssdiff_line("changed", iter_old->line_no,
 					  iter_old->line,
-					  iter_new->line_no, iter_new->line);
+					  iter_new->line_no, iter_new->line,
+					  individual_chars);
 		else if (iter_old)
 			print_ssdiff_line("changed", iter_old->line_no,
-					  iter_old->line, -1, NULL);
+					  iter_old->line, -1, NULL, 0);
 		else if (iter_new)
 			print_ssdiff_line("changed", -1, NULL,
-					  iter_new->line_no, iter_new->line);
-
+					  iter_new->line_no, iter_new->line, 0);
 		if (iter_old) {
 			tmp = iter_old->next;
 			free(iter_old);
 			iter_old = tmp;
 		}
 
 		if (iter_new) {
 			tmp = iter_new->next;
 			free(iter_new);
 			iter_new = tmp;
 		}
 	}
 }
 
 void cgit_ssdiff_print_deferred_lines()
 {
 	if (!deferred_old && !deferred_new)
 		return;
-
 	if (deferred_old && !deferred_new)
 		print_deferred_old_lines();
 	else if (!deferred_old && deferred_new)
 		print_deferred_new_lines();
 	else
 		print_deferred_changed_lines();
-
 	deferred_old = deferred_old_last = NULL;
 	deferred_new = deferred_new_last = NULL;
 }
 
 /*
  * print a single line returned from xdiff
  */
 void cgit_ssdiff_line_cb(char *line, int len)
 {
 	char c = line[len - 1];
-
 	line[len - 1] = '\0';
-
 	if (line[0] == '@') {
 		current_old_line = line_from_hunk(line, '-');
 		current_new_line = line_from_hunk(line, '+');
 	}
 
 	if (line[0] == ' ') {
 		if (deferred_old || deferred_new)
 			cgit_ssdiff_print_deferred_lines();
 		print_ssdiff_line("ctx", current_old_line, line,
-				  current_new_line, line);
+				  current_new_line, line, 0);
 		current_old_line += 1;
 		current_new_line += 1;
 	} else if (line[0] == '+') {
 		deferred_new_add(line, current_new_line);
 		current_new_line += 1;
 	} else if (line[0] == '-') {
 		deferred_old_add(line, current_old_line);
 		current_old_line += 1;
 	} else if (line[0] == '@') {
 		html("<tr><td colspan='4' class='hunk'>");
 		html_txt(line);
 		html("</td></tr>");
 	} else {
 		html("<tr><td colspan='4' class='ctx'>");
 		html_txt(line);
 		html("</td></tr>");
 	}
 	line[len - 1] = c;
 }
 
 void cgit_ssdiff_header_begin()
 {
 	current_old_line = -1;
 	current_new_line = -1;
 	html("<tr><td class='space' colspan='4'><div></div></td></tr>");
 	html("<tr><td class='head' colspan='4'>");
 }
 
 void cgit_ssdiff_header_end()
 {
 	html("</td><tr>");
 }
 
 void cgit_ssdiff_footer()
 {
 	if (deferred_old || deferred_new)
 		cgit_ssdiff_print_deferred_lines();
 	html("<tr><td class='foot' colspan='4'></td></tr>");
 }