From 237066ccfc3155ec951d99a781ff4e00ff3d34cd Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Wed, 22 Jun 2011 20:30:50 -0400
Subject: [PATCH] Add initial command parser.

---
 src/cdecl99.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 5 deletions(-)

diff --git a/src/cdecl99.c b/src/cdecl99.c
index 76e64bc..6e15712 100644
--- a/src/cdecl99.c
+++ b/src/cdecl99.c
@@ -1,6 +1,7 @@
 #include <config.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <getopt.h>
 #include "readline.h"
 #include "cdecl.h"
@@ -33,17 +34,82 @@ static void print_help(void)
 	puts("Detailed help coming soon.");
 }
 
-static int repl(void)
+static int cmd_explain(char *cmd, char *arg)
 {
 	struct cdecl *decl;
+
+	decl = cdecl_parse_decl(arg);
+	cdecl_free(decl);
+
+	return 1;
+}
+
+static int cmd_quit(char *cmd, char *arg)
+{
+	return 0;
+}
+
+static int cmd_help(char *cmd, char *arg);
+
+static const struct command {
+	char name[16];
+	int (*func)(char *cmd, char *arg);
+	const char *blurb;
+} commands[] = {
+	{ "explain", cmd_explain, "Explain a C declaration." },
+	{ "help",    cmd_help,    "Print this list of commands." },
+	{ "quit",    cmd_quit,    "Quit the program." },
+	{ "exit",    cmd_quit,    NULL }
+};
+static const size_t ncommands = sizeof commands / sizeof commands[0];
+
+static int cmd_help(char *cmd, char *arg)
+{
+	for (size_t i = 0; i < ncommands; i++) {
+		if (!commands[i].blurb)
+			continue;
+
+		printf("%s -- %s\n", commands[i].name, commands[i].blurb);
+	}
+
+	return 1;
+}
+
+static int repl(void)
+{
+	char *line;
+	int ret;
+
 	print_version();
 
-	for (char *line; (line = readline("> ")); free(line)) {
-		decl = cdecl_parse_decl(line);
-		cdecl_free(decl);
+	for (; (line = readline("> ")); free(line)) {
+		char *cmd = line + strspn(line, " \t");
+		char *arg = cmd  + strcspn(cmd, " \t");
+
+		if (cmd[0] == '\0')
+			continue;
+		if (arg[0] != '\0')
+			*arg++ = '\0';
+
+		for (size_t i = 0; i < ncommands; i++) {
+			if (strcmp(cmd, commands[i].name) != 0)
+				continue;
+
+			ret = commands[i].func(cmd, arg);
+			if (ret <= 0)
+				goto out;
+			goto next;
+		}
+
+		fprintf(stderr, "Undefined command: %s\n", cmd);
+	next:
+		;
 	}
 
-	return 0;
+	ret = 0;
+out:
+	free(line);
+	return ret;
 }
 
 int main(int argc, char **argv)
-- 
2.43.2