lang: replace stack-based parser with a recursive parser

lang/parse/keyword.c

@@ -0,0 +1,31 @@
+#include "ctx.h"
+
+bool peek_keyword(struct ivy_parser *parser, enum ivy_keyword kw)
+{
+	struct ivy_token *tok = peek_token(parser);
+	if (!tok || tok->t_type != IVY_TOK_KEYWORD) {
+		return false;
+	}
+
+	if (tok->t_keyword != kw) {
+		return false;
+	}
+
+	return true;
+}
+
+bool parse_keyword(struct ivy_parser *parser, enum ivy_keyword kw)
+{
+	struct ivy_token *tok = peek_token(parser);
+	if (!tok || tok->t_type != IVY_TOK_KEYWORD) {
+		return false;
+	}
+
+	if (tok->t_keyword != kw) {
+		return false;
+	}
+
+	parse_token(parser);
+	ivy_token_destroy(tok);
+	return true;
+}