Improve command matching

* src/eclat.c (name_matches): New function.
(find_command_name): Use it.
(main): Handle --match-commands.
* src/cmdline.opt: New option: --match-commands.
* doc/eclat.1: Document new command matching algorithm.

2 files changed, 61 insertions, 7 deletions

diff --git a/src/cmdline.opt b/src/cmdline.opt
index 7726416..84b495f 100644
--- a/src/cmdline.opt
+++ b/src/cmdline.opt
@@ -57,6 +57,12 @@ BEGIN
 	preprocess_only = 1;
 END
 
+OPTION(match-command,m,,
+       [<find matching command names>])
+BEGIN
+	match_command_mode = 1;
+END	
+
 GROUP(Modifiers)
 
 OPTION(config-file,c,FILE,
diff --git a/src/eclat.c b/src/eclat.c
index 6af9eb5..a0a7be0 100644
--- a/src/eclat.c
+++ b/src/eclat.c
@@ -19,6 +19,7 @@
 char *conffile = SYSCONFDIR "/eclat.conf" ;
 int lint_mode;
 int dry_run_mode;
+int match_command_mode;
 int preprocess_only = 0;
 
 char *endpoint = "ec2.amazonaws.com";
@@ -263,25 +264,55 @@ listcmd()
 	putchar('\n');
 }
 
+#define NO_MATCH      0
+#define EXACT_MATCH   1
+#define PARTIAL_MATCH 2
+
+static int
+name_matches(const char *p, const char *q)
+{
+	int match = EXACT_MATCH;
+	
+	for (;; p++, q++) {
+		if (*p == 0)
+			return *q == 0 ? match : NO_MATCH;
+		else if (*q == 0)
+			return PARTIAL_MATCH;
+		else if (*p == *q)
+			continue;
+		else if (*q == '-') {
+			for (; *p != '-'; p++)
+				if (!*p)
+					return NO_MATCH;
+			match = PARTIAL_MATCH;
+		} else
+			break;
+	}
+	return NO_MATCH;
+}	
+
 struct command *
 find_command_name(const char *name)
 {
 	struct command *cp, *match = NULL;
-	size_t namelen = strlen(name);
 	
 	for (cp = cmdtab; cp < cmdtab + cmdcnt; cp++) {
-		if (!strncmp(cp->ident, name, namelen)) {
-			if (strlen(cp->ident) == namelen)
-				return cp;
-			else if (!match)
+		switch (name_matches(cp->ident, name)) {
+		case NO_MATCH:
+			break;
+		case EXACT_MATCH:
+			return cp;
+		case PARTIAL_MATCH:
+			if (!match)
 				match = cp;
 			else {
 				/* Second match */
-				err("ambiguous command %s:");
+				err("ambiguous command %s:", name);
 				err("  %s", match->ident);
 				err("  %s", cp->ident);
 				while (++cp < cmdtab + cmdcnt)
-					if (!strncmp(cp->ident, name, namelen))
+					if (name_matches(cp->ident, name) !=
+					    NO_MATCH)
 						err("  %s", cp->ident);
 				exit(EX_USAGE);
 			}
@@ -290,6 +321,16 @@ find_command_name(const char *name)
 	return match;
 }
 
+static void
+print_matching_commands(const char *pat)
+{
+	struct command *cp;
+	
+	for (cp = cmdtab; cp < cmdtab + cmdcnt; cp++)
+		if (name_matches(cp->ident, pat) != NO_MATCH)
+			printf("%s\n", cp->ident);
+}
+
 struct command *
 find_command_tag(const char *tag)
 {
@@ -549,6 +590,13 @@ main(int argc, char **argv)
 	argc -= index;
 	argv += index;
 
+	if (match_command_mode) {
+		if (argc != 1)
+			die(EX_USAGE, "wrong number of arguments");
+		print_matching_commands(argv[0]);
+		return 0;
+	}
+	
 	if (argc) {
 		command = find_command_name(argv[0]);
 		if (!command)