Merge early parts of branch 'js/diff'

diff --combined diff.c
index fb1411c52d1cce9c51ad33272624e4d027debc2e,bc32a4aa29171af6ca268a54cde881934079de83..22b643cc2520664416ceac9998d401a6585f07bf
--- 1/diff.c
--- 2/diff.c
+++ b/diff.c
@@@ -25,6 -25,20 +25,20 @@@ int git_diff_config(const char *var, co
        return git_default_config(var, value);
  }
  
+ enum color_diff {
+       DIFF_PLAIN = 0,
+       DIFF_METAINFO = 1,
+       DIFF_FILE_OLD = 2,
+       DIFF_FILE_NEW = 3,
+ };
+ 
+ static const char *diff_colors[] = {
+       "\033[0;0m",
+       "\033[1;35m",
+       "\033[1;31m",
+       "\033[1;34m",
+ };
+ 
  static char *quote_one(const char *str)
  {
        int needlen;
@@@ -177,23 -191,54 +191,54 @@@ static int fill_mmfile(mmfile_t *mf, st
  }
  
  struct emit_callback {
+       struct xdiff_emit_state xm;
+       int nparents, color_diff;
        const char **label_path;
  };
  
- static int fn_out(void *priv, mmbuffer_t *mb, int nbuf)
+ static inline void color_diff(int diff_use_color, enum color_diff ix)
+ {
+       if (diff_use_color)
+               fputs(diff_colors[ix], stdout);
+ }
+ 
+ static void fn_out_consume(void *priv, char *line, unsigned long len)
  {
        int i;
        struct emit_callback *ecbdata = priv;
  
        if (ecbdata->label_path[0]) {
+               color_diff(ecbdata->color_diff, DIFF_METAINFO);
                printf("--- %s\n", ecbdata->label_path[0]);
+               color_diff(ecbdata->color_diff, DIFF_METAINFO);
                printf("+++ %s\n", ecbdata->label_path[1]);
                ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
        }
-       for (i = 0; i < nbuf; i++)
-               if (!fwrite(mb[i].ptr, mb[i].size, 1, stdout))
-                       return -1;
-       return 0;
+ 
+       /* This is not really necessary for now because
+        * this codepath only deals with two-way diffs.
+        */
+       for (i = 0; i < len && line[i] == '@'; i++)
+               ;
+       if (2 <= i && i < len && line[i] == ' ') {
+               ecbdata->nparents = i - 1;
+               color_diff(ecbdata->color_diff, DIFF_METAINFO);
+       }
+       else if (len < ecbdata->nparents)
+               color_diff(ecbdata->color_diff, DIFF_PLAIN);
+       else {
+               int nparents = ecbdata->nparents;
+               int color = DIFF_PLAIN;
+               for (i = 0; i < nparents && len; i++) {
+                       if (line[i] == '-')
+                               color = DIFF_FILE_OLD;
+                       else if (line[i] == '+')
+                               color = DIFF_FILE_NEW;
+               }
+               color_diff(ecbdata->color_diff, color);
+       }
+       fwrite(line, len, 1, stdout);
+       color_diff(ecbdata->color_diff, DIFF_PLAIN);
  }
  
  static char *pprint_rename(const char *a, const char *b)
@@@ -515,7 -560,7 +560,7 @@@ static void emit_binary_diff(mmfile_t *
                else
                        line[0] = bytes - 26 + 'a' - 1;
                encode_85(line + 1, cp, bytes);
 -              cp += bytes;
 +              cp = (char *) cp + bytes;
                puts(line);
        }
        printf("\n");
@@@ -549,25 -594,35 +594,35 @@@ static void builtin_diff(const char *na
        b_two = quote_two("b/", name_b);
        lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
        lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
+       color_diff(o->color_diff, DIFF_METAINFO);
        printf("diff --git %s %s\n", a_one, b_two);
        if (lbl[0][0] == '/') {
                /* /dev/null */
+               color_diff(o->color_diff, DIFF_METAINFO);
                printf("new file mode %06o\n", two->mode);
-               if (xfrm_msg && xfrm_msg[0])
+               if (xfrm_msg && xfrm_msg[0]) {
+                       color_diff(o->color_diff, DIFF_METAINFO);
                        puts(xfrm_msg);
+               }
        }
        else if (lbl[1][0] == '/') {
                printf("deleted file mode %06o\n", one->mode);
-               if (xfrm_msg && xfrm_msg[0])
+               if (xfrm_msg && xfrm_msg[0]) {
+                       color_diff(o->color_diff, DIFF_METAINFO);
                        puts(xfrm_msg);
+               }
        }
        else {
                if (one->mode != two->mode) {
+                       color_diff(o->color_diff, DIFF_METAINFO);
                        printf("old mode %06o\n", one->mode);
+                       color_diff(o->color_diff, DIFF_METAINFO);
                        printf("new mode %06o\n", two->mode);
                }
-               if (xfrm_msg && xfrm_msg[0])
+               if (xfrm_msg && xfrm_msg[0]) {
+                       color_diff(o->color_diff, DIFF_METAINFO);
                        puts(xfrm_msg);
+               }
                /*
                 * we do not run diff between different kind
                 * of objects.
@@@ -575,6 -630,7 +630,7 @@@
                if ((one->mode ^ two->mode) & S_IFMT)
                        goto free_ab_and_return;
                if (complete_rewrite) {
+                       color_diff(o->color_diff, DIFF_PLAIN);
                        emit_rewrite_diff(name_a, name_b, one, two);
                        goto free_ab_and_return;
                }
@@@ -602,7 -658,9 +658,9 @@@
                xdemitcb_t ecb;
                struct emit_callback ecbdata;
  
+               memset(&ecbdata, 0, sizeof(ecbdata));
                ecbdata.label_path = lbl;
+               ecbdata.color_diff = o->color_diff;
                xpp.flags = XDF_NEED_MINIMAL;
                xecfg.ctxlen = o->context;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
@@@ -612,8 -670,9 +670,9 @@@
                        xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
                else if (!strncmp(diffopts, "-u", 2))
                        xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
-               ecb.outf = fn_out;
+               ecb.outf = xdiff_outf;
                ecb.priv = &ecbdata;
+               ecbdata.xm.consume = fn_out_consume;
                xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
        }
  
@@@ -1456,6 -1515,8 +1515,8 @@@ int diff_opt_parse(struct diff_options 
                else if (40 < options->abbrev)
                        options->abbrev = 40;
        }
+       else if (!strcmp(arg, "--color"))
+               options->color_diff = 1;
        else
                return 0;
        return 1;