Port string.startswith() to native code

src/base/string.lua

@@ -61,12 +61,3 @@
 		end
 		return n
 	end
-
-
---
--- Returns true if `haystack` starts with the sequence `needle`.
---
-
-	function string.startswith(haystack, needle)
-		return (haystack:find(needle, 1, true) == 1)
-	end

src/host/premake.c

@@ -69,6 +69,7 @@ static const luaL_Reg os_functions[] = {
 static const luaL_Reg string_functions[] = {
 	{ "endswith",  string_endswith },
 	{ "hash", string_hash },
+	{ "startswith", string_startswith },
 	{ NULL, NULL }
 };
 

src/host/premake.h

@@ -85,6 +85,7 @@ int os_stat(lua_State* L);
 int os_uuid(lua_State* L);
 int string_endswith(lua_State* L);
 int string_hash(lua_State* L);
+int string_startswith(lua_State* L);
 
 /* Engine interface */
 int premake_init(lua_State* L);

src/host/string_startswith.c

@@ -0,0 +1,24 @@
+/**
+ * \file   string_startswith.c
+ * \brief  Determines if a string starts with the given sequence.
+ * \author Copyright (c) 2013 Jason Perkins and the Premake project
+ */
+
+#include "premake.h"
+#include <string.h>
+
+
+int string_startswith(lua_State* L)
+{
+	const char* haystack = luaL_optstring(L, 1, NULL);
+	const char* needle   = luaL_optstring(L, 2, NULL);
+
+	if (haystack && needle)
+	{
+		int nlen = strlen(needle);
+		lua_pushboolean(L, strncmp(haystack, needle, nlen) == 0);
+		return 1;
+	}
+
+	return 0;
+}