[6s] Break out builtin commands into a list of structs

The 6s builtin commands are now in a separate file, with a list of name,
description, and function pointers.

src/user/6s/6s.module

@@ -5,5 +5,6 @@ module("6s",
     deps = [ "libc", "edit" ],
     description = "j6 shell",
     sources = [
+        "commands.cpp",
         "main.cpp",
     ])

src/user/6s/commands.cpp

@@ -0,0 +1,35 @@
+#include <edit/line.h>
+#include <util/format.h>
+#include "commands.h"
+
+static void
+help(edit::source &s)
+{
+    for (unsigned i = 0; i < g_builtins_count; ++i) {
+        char line[100];
+        util::counted<char> output { line, sizeof(line) };
+
+        builtin &cmd = g_builtins[i];
+
+        size_t len = util::format(output, "%20s - %s\r\n", cmd.name(), cmd.description());
+        s.write(line, len);
+    }
+}
+
+static void
+version(edit::source &s)
+{
+    static const char *gv = GIT_VERSION;
+
+    char line[100];
+    util::counted<char> output { line, sizeof(line) };
+
+    size_t len = util::format(output, "jsix version %s\r\n", gv);
+    s.write(line, len);
+}
+
+builtin g_builtins[] = {
+    { "help",       "list availble commands",               help },
+    { "version",    "print current jsix version",           version },
+};
+size_t g_builtins_count = sizeof(g_builtins) / sizeof(g_builtins[0]);

src/user/6s/commands.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <stddef.h>
+
+namespace edit {
+    class source;
+}
+
+
+class builtin
+{
+public:
+    using runf = void (*)(edit::source &);
+
+    builtin(const char *name, const char *desc, runf func) :
+        m_name {name}, m_desc {desc}, m_func {func} {}
+
+    const char * name() const { return m_name; }
+    const char * description() const { return m_desc; }
+
+    void run(edit::source &s) { m_func(s); }
+
+private:
+    const char *m_name;
+    const char *m_desc;
+    runf m_func;
+};
+
+
+extern builtin g_builtins[];
+extern size_t  g_builtins_count;

src/user/6s/main.cpp

@@ -11,6 +11,8 @@
 #include <j6/types.h>
 #include <edit/line.h>
 
+#include "commands.h"
+
 extern "C" {
     int main(int, const char **);
 }
@@ -111,14 +113,14 @@ handle_command(edit::source &s, const char *command, size_t len)
     if (len == 0)
         return;
 
-    if (strncmp(command, "help", len) == 0) {
+    for (unsigned i = 0; i < g_builtins_count; ++i) {
-        s.write("help", 4);
+        builtin &cmd = g_builtins[i];
-        s.write("\r\n", 2);
+        if (strncmp(command, cmd.name(), len) == 0) {
-        s.write("version", 7);
+            cmd.run(s);
-        s.write("\r\n", 2);
+            return;
-    } else if (!strncmp(command, "version", len)) {
-        static const char *version = GIT_VERSION;
-        s.write(version, strlen(version));
-        s.write("\r\n", 2);
         }
     }
+
+    static const char unknown[] = "\x1b[1;33mUnknown command.\x1b[0m\r\n";
+    s.write(unknown, sizeof(unknown)-1);
+}