git wrapper: DWIM mistyped commands

[git.git] / help.c

diff --git a/help.c b/help.c
index 1afbac0927cdf2ba395126a7fe87d96a9ea87a94..b1ebca4091e9e1cb623ff89a69306cdb00aa9c68 100644 (file)
--- a/help.c
+++ b/help.c
@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "builtin.h"
 #include "exec_cmd.h"
+#include "levenshtein.h"
 #include "help.h"
 
 /* most GUI terminals set COLUMNS (although some don't export it) */
@@ -37,6 +38,16 @@ void add_cmdname(struct cmdnames *cmds, const char *name, int len)
        cmds->names[cmds->cnt++] = ent;
 }
 
+static void clean_cmdnames(struct cmdnames *cmds)
+{
+       int i;
+       for (i = 0; i < cmds->cnt; ++i)
+               free(cmds->names[i]);
+       free(cmds->names);
+       cmds->cnt = 0;
+       cmds->alloc = 0;
+}
+
 static int cmdname_compare(const void *a_, const void *b_)
 {
        struct cmdname *a = *(struct cmdname **)a_;
@@ -257,9 +268,68 @@ int is_in_cmdlist(struct cmdnames *c, const char *s)
        return 0;
 }
 
-void help_unknown_cmd(const char *cmd)
+static int levenshtein_compare(const void *p1, const void *p2)
+{
+       const struct cmdname *const *c1 = p1, *const *c2 = p2;
+       const char *s1 = (*c1)->name, *s2 = (*c2)->name;
+       int l1 = (*c1)->len;
+       int l2 = (*c2)->len;
+       return l1 != l2 ? l1 - l2 : strcmp(s1, s2);
+}
+
+const char *help_unknown_cmd(const char *cmd)
 {
+       int i, n, best_similarity = 0;
+       struct cmdnames main_cmds, other_cmds;
+
+       memset(&main_cmds, 0, sizeof(main_cmds));
+       memset(&other_cmds, 0, sizeof(main_cmds));
+
+       load_command_list("git-", &main_cmds, &other_cmds);
+
+       ALLOC_GROW(main_cmds.names, main_cmds.cnt + other_cmds.cnt,
+                  main_cmds.alloc);
+       memcpy(main_cmds.names + main_cmds.cnt, other_cmds.names,
+              other_cmds.cnt * sizeof(other_cmds.names[0]));
+       main_cmds.cnt += other_cmds.cnt;
+       free(other_cmds.names);
+
+       /* This reuses cmdname->len for similarity index */
+       for (i = 0; i < main_cmds.cnt; ++i)
+               main_cmds.names[i]->len =
+                       levenshtein(cmd, main_cmds.names[i]->name, 0, 2, 1, 4);
+
+       qsort(main_cmds.names, main_cmds.cnt,
+             sizeof(*main_cmds.names), levenshtein_compare);
+
+       if (!main_cmds.cnt)
+               die ("Uh oh. Your system reports no Git commands at all.");
+
+       best_similarity = main_cmds.names[0]->len;
+       n = 1;
+       while (n < main_cmds.cnt && best_similarity == main_cmds.names[n]->len)
+               ++n;
+       if (n == 1) {
+               const char *assumed = main_cmds.names[0]->name;
+               main_cmds.names[0] = NULL;
+               clean_cmdnames(&main_cmds);
+               fprintf(stderr, "WARNING: You called a Git program named '%s', "
+                       "which does not exist.\n"
+                       "Continuing under the assumption that you meant '%s'\n",
+                       cmd, assumed);
+               return assumed;
+       }
+
        fprintf(stderr, "git: '%s' is not a git-command. See 'git --help'.\n", cmd);
+
+       if (best_similarity < 6) {
+               fprintf(stderr, "\nDid you mean %s?\n",
+                       n < 2 ? "this": "one of these");
+
+               for (i = 0; i < n; i++)
+                       fprintf(stderr, "\t%s\n", main_cmds.names[i]->name);
+       }
+
        exit(1);
 }