+#include "commit.h"
+#include "refs.h"
+
+static char *def = NULL;
+static int no_revs = 0;
+static int single_rev = 0;
+static int revs_only = 0;
+static int do_rev_argument = 1;
+static int output_revs = 0;
+static int flags_only = 0;
+static int no_flags = 0;
+static int output_sq = 0;
+
+#define NORMAL 0
+#define REVERSED 1
+static int show_type = NORMAL;
+
+/*
+ * Some arguments are relevant "revision" arguments,
+ * others are about output format or other details.
+ * This sorts it all out.
+ */
+static int is_rev_argument(const char *arg)
+{
+ static const char *rev_args[] = {
+ "--max-count=",
+ "--max-age=",
+ "--min-age=",
+ "--merge-order",
+ "--topo-order",
+ "--bisect",
+ "--no-merges",
+ NULL
+ };
+ const char **p = rev_args;
+
+ for (;;) {
+ const char *str = *p++;
+ int len;
+ if (!str)
+ return 0;
+ len = strlen(str);
+ if (!strncmp(arg, str, len))
+ return 1;
+ }
+}
+
+static void show(const char *arg)
+{
+ if (output_sq) {
+ int sq = '\'', ch;
+
+ putchar(sq);
+ while ((ch = *arg++)) {
+ if (ch == sq)
+ fputs("'\\'", stdout);
+ putchar(ch);
+ }
+ putchar(sq);
+ putchar(' ');
+ }
+ else
+ puts(arg);
+}
+
+static void show_rev(int type, const unsigned char *sha1)
+{
+ if (no_revs)
+ return;
+ output_revs++;
+
+ /* Hexadecimal string plus possibly a carret;
+ * this does not have to be quoted even under output_sq.
+ */
+ printf("%s%s%c", type == show_type ? "" : "^", sha1_to_hex(sha1),
+ output_sq ? ' ' : '\n');
+}
+
+static void show_rev_arg(char *rev)
+{
+ if (no_revs)
+ return;
+ show(rev);
+}
+
+static void show_norev(char *norev)
+{
+ if (flags_only)
+ return;
+ if (revs_only)
+ return;
+ show(norev);
+}
+
+static void show_arg(char *arg)
+{
+ if (no_flags)
+ return;
+ if (do_rev_argument && is_rev_argument(arg))
+ show_rev_arg(arg);
+ else
+ show_norev(arg);
+}
+
+static void show_default(void)
+{
+ char *s = def;
+
+ if (s) {
+ unsigned char sha1[20];
+
+ def = NULL;
+ if (!get_sha1(s, sha1)) {
+ show_rev(NORMAL, sha1);
+ return;
+ }
+ show_arg(s);
+ }
+}
+
+static int show_reference(const char *refname, const unsigned char *sha1)
+{
+ show_rev(NORMAL, sha1);
+ return 0;
+}