From 8af84dadb142f7321ff0ce8690385e99da8ede2f Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Sun, 31 Aug 2008 15:50:23 +0200 Subject: [PATCH] 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 Signed-off-by: Alex Riesen Signed-off-by: Junio C Hamano --- Makefile | 2 ++ builtin.h | 2 +- git.c | 4 ++- help.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++- help.h | 2 +- levenshtein.c | 47 +++++++++++++++++++++++++++++++++ levenshtein.h | 8 ++++++ 7 files changed, 133 insertions(+), 4 deletions(-) create mode 100644 levenshtein.c create mode 100644 levenshtein.h diff --git a/Makefile b/Makefile index bf400e64f..3daa6dcdb 100644 --- a/Makefile +++ b/Makefile @@ -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 diff --git a/builtin.h b/builtin.h index f3502d305..e67cb2090 100644 --- a/builtin.h +++ b/builtin.h @@ -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, diff --git a/git.c b/git.c index 37b1d76a0..54c5bfa69 100644 --- a/git.c +++ b/git.c @@ -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", diff --git a/help.c b/help.c index 1afbac092..b1ebca409 100644 --- 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); } diff --git a/help.h b/help.h index 3f1ae89dd..5fc789270 100644 --- a/help.h +++ b/help.h @@ -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; }; diff --git a/levenshtein.c b/levenshtein.c new file mode 100644 index 000000000..db52f2c20 --- /dev/null +++ b/levenshtein.c @@ -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; +} diff --git a/levenshtein.h b/levenshtein.h new file mode 100644 index 000000000..0173abeef --- /dev/null +++ b/levenshtein.h @@ -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 -- 2.26.2