git wrapper: DWIM mistyped commands

This patch introduces a modified Damerau-Levenshtein algorithm into
Git's code base, and uses it with the following penalties to show some
similar commands when an unknown command was encountered:

	swap = 0, insertion = 1, substitution = 2, deletion = 4

A typical output would now look like this:

	$ git sm
	git: 'sm' is not a git-command. See 'git --help'.

	Did you mean one of these?
		am
		rm

The cut-off is at similarity rating 6, which was empirically determined
to give sensible results.

As a convenience, if there is only one candidate, Git continues under
the assumption that the user mistyped it.  Example:

	$ git reabse
	WARNING: You called a Git program named 'reabse', which does
	not exist.
	Continuing under the assumption that you meant 'rebase'
	[...]

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Schindelin 2008-08-31 15:50:23 +02:00 коммит произвёл Junio C Hamano
Родитель a1184d85e8
Коммит 8af84dadb1
7 изменённых файлов: 133 добавлений и 4 удалений

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@ -358,6 +358,7 @@ LIB_H += graph.h
LIB_H += grep.h
LIB_H += hash.h
LIB_H += help.h
LIB_H += levenshtein.h
LIB_H += list-objects.h
LIB_H += ll-merge.h
LIB_H += log-tree.h
@ -433,6 +434,7 @@ LIB_OBJS += hash.o
LIB_OBJS += help.o
LIB_OBJS += ident.o
LIB_OBJS += interpolate.o
LIB_OBJS += levenshtein.o
LIB_OBJS += list-objects.o
LIB_OBJS += ll-merge.o
LIB_OBJS += lockfile.o

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@ -11,7 +11,7 @@ extern const char git_usage_string[];
extern const char git_more_info_string[];
extern void list_common_cmds_help(void);
extern void help_unknown_cmd(const char *cmd);
extern const char *help_unknown_cmd(const char *cmd);
extern void prune_packed_objects(int);
extern int read_line_with_nul(char *buf, int size, FILE *file);
extern int fmt_merge_msg(int merge_summary, struct strbuf *in,

4
git.c
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@ -499,7 +499,9 @@ int main(int argc, const char **argv)
cmd, argv[0]);
exit(1);
}
help_unknown_cmd(cmd);
argv[0] = help_unknown_cmd(cmd);
handle_internal_command(argc, argv);
execv_dashed_external(argv);
}
fprintf(stderr, "Failed to run command '%s': %s\n",

72
help.c
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@ -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);
}

2
help.h
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@ -5,7 +5,7 @@ struct cmdnames {
int alloc;
int cnt;
struct cmdname {
size_t len;
size_t len; /* also used for similarity index in help.c */
char name[FLEX_ARRAY];
} **names;
};

47
levenshtein.c Normal file
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@ -0,0 +1,47 @@
#include "cache.h"
#include "levenshtein.h"
int levenshtein(const char *string1, const char *string2,
int w, int s, int a, int d)
{
int len1 = strlen(string1), len2 = strlen(string2);
int *row0 = xmalloc(sizeof(int) * (len2 + 1));
int *row1 = xmalloc(sizeof(int) * (len2 + 1));
int *row2 = xmalloc(sizeof(int) * (len2 + 1));
int i, j;
for (j = 0; j <= len2; j++)
row1[j] = j * a;
for (i = 0; i < len1; i++) {
int *dummy;
row2[0] = (i + 1) * d;
for (j = 0; j < len2; j++) {
/* substitution */
row2[j + 1] = row1[j] + s * (string1[i] != string2[j]);
/* swap */
if (i > 0 && j > 0 && string1[i - 1] == string2[j] &&
string1[i] == string2[j - 1] &&
row2[j + 1] > row0[j - 1] + w)
row2[j + 1] = row0[j - 1] + w;
/* deletion */
if (j + 1 < len2 && row2[j + 1] > row1[j + 1] + d)
row2[j + 1] = row1[j + 1] + d;
/* insertion */
if (row2[j + 1] > row2[j] + a)
row2[j + 1] = row2[j] + a;
}
dummy = row0;
row0 = row1;
row1 = row2;
row2 = dummy;
}
i = row1[len2];
free(row0);
free(row1);
free(row2);
return i;
}

8
levenshtein.h Normal file
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@ -0,0 +1,8 @@
#ifndef LEVENSHTEIN_H
#define LEVENSHTEIN_H
int levenshtein(const char *string1, const char *string2,
int swap_penalty, int substition_penalty,
int insertion_penalty, int deletion_penalty);
#endif