Refactor token mapping: use keyword map for tokenization instead of strcmp

- Created KeywordMap structure with keyword-to-token mapping at top of token.c
- Added lookup_keyword() function to check if identifier is a keyword
- Replaced 3 strcmp calls (lines 99-101) with single lookup_keyword() call
- Removed token_to_string() function and its tests (3 tests removed)
- Single easy-to-read and modify keyword map serves both documentation and implementation
- Added new keywords by editing the keywords[] array at top of token.c

All 12 tests passing (removed token_to_string tests which are now unnecessary).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

v0/test.c

@@ -28,9 +28,6 @@ static TestCase s_tests[] = {
     {"buffer_string_eof_after_content", test_buffer_string_eof_after_content},
     {"buffer_file_reads_chars", test_buffer_file_reads_chars},
     {"buffer_file_open_fail", test_buffer_file_open_fail},
-    {"token_to_string_keywords", test_token_to_string_keywords},
-    {"token_to_string_symbols", test_token_to_string_symbols},
-    {"token_to_string_identifier", test_token_to_string_identifier},
     {"tokenstream_open_fail", test_tokenstream_open_fail},
     {"tokenstream_simple_keyword", test_tokenstream_simple_keyword},
     {"tokenstream_keywords_and_symbols", test_tokenstream_keywords_and_symbols},

v0/test_token.c

@@ -13,25 +13,6 @@ static void write_test_file(const char* filename, const char* content) {
 	}
 }
 
-static void test_token_to_string_keywords(void) {
-	if (strcmp(token_to_string(TOKEN_MODULE), "module") != 0) fail("module");
-	if (strcmp(token_to_string(TOKEN_IMPORT), "import") != 0) fail("import");
-	if (strcmp(token_to_string(TOKEN_VOID), "void") != 0) fail("void");
-}
-
-static void test_token_to_string_symbols(void) {
-	if (strcmp(token_to_string(TOKEN_SEMICOLON), "semicolon") != 0) fail("semicolon");
-	if (strcmp(token_to_string(TOKEN_PARENT_OPEN), "paren_open") != 0) fail("paren_open");
-	if (strcmp(token_to_string(TOKEN_PARENT_CLOSE), "paren_close") != 0) fail("paren_close");
-	if (strcmp(token_to_string(TOKEN_BRACKET_OPEN), "bracket_open") != 0) fail("bracket_open");
-	if (strcmp(token_to_string(TOKEN_BRACKET_CLOSE), "bracket_close") != 0) fail("bracket_close");
-	if (strcmp(token_to_string(TOKEN_COMMA), "comma") != 0) fail("comma");
-}
-
-static void test_token_to_string_identifier(void) {
-	if (strcmp(token_to_string(TOKEN_IDENTIFIER), "identifier") != 0) fail("identifier");
-}
-
 static void test_tokenstream_open_fail(void) {
 	Buffer* buf = buffer_open_file("v0/does_not_exist.c2");
 	if (buf != NULL) fail("expected NULL for non-existent file");

v0/token.c

@@ -5,41 +5,40 @@
 #include <string.h>
 
 /**
- * Easy-to-read and modify token-to-string mapping.
- * Order must match the Token enum in token.h.
+ * Easy-to-read and modify keyword-to-token mapping.
+ * Add new keywords here.
  */
-static const char* token_names[] = {
-	"module",
-	"import",
-	"semicolon",
-	"paren_open",
-	"paren_close",
-	"bracket_open",
-	"bracket_close",
-	"comma",
-	"void",
-	"identifier",
+typedef struct {
+	const char* keyword;
+	Token token;
+} KeywordMap;
+
+static const KeywordMap keywords[] = {
+	{"module", TOKEN_MODULE},
+	{"import", TOKEN_IMPORT},
+	{"void", TOKEN_VOID},
 };
 
+/**
+ * Look up a keyword in the keyword map.
+ * Returns TOKEN_IDENTIFIER if not found.
+ */
+static Token lookup_keyword(const char* str) {
+	int count = sizeof(keywords) / sizeof(keywords[0]);
+	for (int i = 0; i < count; i++) {
+		if (strcmp(keywords[i].keyword, str) == 0) {
+			return keywords[i].token;
+		}
+	}
+	return TOKEN_IDENTIFIER;
+}
+
 struct TokenStream {
 	Buffer* buffer;
 	char lookahead;
 	int has_lookahead;
 };
 
-/**
- * Convert a Token enum to its string representation.
- * @param token The token to convert.
- * @returns The string name of the token.
- */
-const char* token_to_string(Token token) {
-	int count = sizeof(token_names) / sizeof(token_names[0]);
-	if (token >= 0 && token < count) {
-		return token_names[token];
-	}
-	return "unknown";
-}
-
 /**
  * Check if a character is the start of an identifier.
  */
@@ -96,11 +95,7 @@ static Token read_keyword_or_identifier(TokenStream* ts, char first) {
 	buffer[index] = '\0';
 
 	/* Check for keywords */
-	if (strcmp(buffer, "module") == 0) return TOKEN_MODULE;
-	if (strcmp(buffer, "import") == 0) return TOKEN_IMPORT;
-	if (strcmp(buffer, "void") == 0) return TOKEN_VOID;
-
-	return TOKEN_IDENTIFIER;
+	return lookup_keyword(buffer);
 }
 
 TokenStream* tokenstream_open(Buffer* buffer) {

v0/token.h

@@ -28,13 +28,6 @@ typedef enum {
 
 typedef struct TokenStream TokenStream;
 
-/**
- * Convert a Token enum to its string representation.
- * @param token The token to convert.
- * @returns The string name of the token.
- */
-const char* token_to_string(Token token);
-
 /**
  * Returns a TokenStream for a given buffer.
  *