First version of side-by-side diff.

This constitutes the first prototype of a side-by-side diff. It is not
possible to switch between unidiff and side-by-side diff at all at this
stage.

Signed-off-by: Ragnar Ouchterlony <ragnar@lysator.liu.se>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 264 insertions, 0 deletions

diff --git a/ui-ssdiff.c b/ui-ssdiff.c
new file mode 100644
index 0000000..3591ab4
--- a/dev/null
+++ b/ui-ssdiff.c
@@ -0,0 +1,264 @@
+#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 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 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)
+{
+        html("<tr>");
+        if (old_line_no > 0)
+                htmlf("<td class='%s'>%d </td><td class='%s'>", class,
+                      old_line_no, class);
+        else
+                htmlf("<td class='%s_dark'>  </td><td class='%s_dark'>", class, class);
+
+        if (old_line) {
+                old_line = replace_tabs(old_line + 1);
+                html_txt(old_line);
+                free(old_line);
+        }
+
+        html("  </td>");
+
+        if (new_line_no > 0)
+                htmlf("<td class='%s'>  %d </td><td class='%s'>", class,
+                      new_line_no, class);
+        else
+                htmlf("<td class='%s_dark'>  </td><td class='%s_dark'>", class, class);
+
+        if (new_line) {
+                new_line = replace_tabs(new_line + 1);
+                html_txt(new_line);
+                free(new_line);
+        }
+
+        html("</td></tr>");
+}
+
+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);
+                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);
+                tmp = iter_new->next;
+                free(iter_new);
+                iter_new = tmp;
+        }
+}
+
+static void print_deferred_changed_lines()
+{
+        struct deferred_lines *iter_old, *iter_new, *tmp;
+
+        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);
+                else if (iter_old)
+                        print_ssdiff_line("changed", iter_old->line_no,
+                                          iter_old->line, -1, NULL);
+                else if (iter_new)
+                        print_ssdiff_line("changed", -1, NULL,
+                                          iter_new->line_no, iter_new->line);
+
+                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_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()
+{
+        current_old_line = 0;
+        current_new_line = 0;
+        html("<table class='ssdiff'>");
+}
+
+void cgit_ssdiff_footer()
+{
+        if (deferred_old || deferred_new)
+                cgit_ssdiff_print_deferred_lines();
+        html("</table>");
+}