parser: Introduce statement keywords

This commit introduces a few changes in pipalang syntax. Now, both
functions and variables requires keywords to be defined.

before:

  main(): i32 {
    a: i32 = 2;
    return a;
  }

now:

  fn main(): i32 {
    let a: i32 = 2;
    return a;
  }

Signed-off-by: Carlos Maniero <carlos@maniero.me>
Reviewed-by: Johnny Richard <johnny@johnnyrichard.com>

2 files changed, 33 insertions, 17 deletions

diff --git a/test/lexer_test.c b/test/lexer_test.c
index 5326f5c..a3f644d 100644
--- a/test/lexer_test.c
+++ b/test/lexer_test.c
@@ -51,6 +51,22 @@ assert_token_at(char *source, int token_index, token_kind_t expected_kind, char
   assert_string_equal(expected, actual);
 }
 
+void
+assert_keyword(char *source, token_kind_t expected_kind)
+{
+  assert_token_at(source, 0, expected_kind, source);
+}
+
+static MunitResult
+test_tokenize_keywords(const MunitParameter params[], void *user_data_or_fixture)
+{
+  assert_keyword("return", TOKEN_KEYWORD_RETURN);
+  assert_keyword("fn", TOKEN_KEYWORD_FN);
+  assert_keyword("let", TOKEN_KEYWORD_LET);
+
+  return MUNIT_OK;
+}
+
 static MunitResult
 test_tokenize_number(const MunitParameter params[], void *user_data_or_fixture)
 {
@@ -106,6 +122,7 @@ test_peek_next_token(const MunitParameter params[], void *user_data_or_fixture)
 
 static MunitTest tests[] = {
   { "/test_tokenize_digit", test_tokenize_number, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
+  { "/test_tokenize_keywords", test_tokenize_keywords, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { "/test_tokenize_op", test_tokenize_op, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { "/test_tokenize_unknown", test_tokenize_unknown, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { "/test_peek_next_token", test_peek_next_token, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
diff --git a/test/parser_test.c b/test/parser_test.c
index 2d749da..a1614b9 100644
--- a/test/parser_test.c
+++ b/test/parser_test.c
@@ -64,7 +64,7 @@ test_parse_function(const MunitParameter params[], void *user_data_or_fixture)
   lexer_t lexer;
   scope_t *scope = scope_new();
 
-  make_lexer_from_static_src(&lexer, "main(): i32 { \nreturn 42;\n }");
+  make_lexer_from_static_src(&lexer, "fn main(): i32 { \nreturn 42;\n }");
   parser_init(&parser, &lexer, scope);
   ast_node_t *ast_function = parser_parse_function_declaration(&parser);
 
@@ -98,7 +98,7 @@ test_parse_variable_definition(const MunitParameter params[], void *user_data_or
   lexer_t lexer;
   scope_t *scope = scope_new();
 
-  make_lexer_from_static_src(&lexer, "main(): i32 { \nvariable : i32 = 42; \nreturn variable;\n }");
+  make_lexer_from_static_src(&lexer, "fn main(): i32 { \nlet variable: i32 = 42; \nreturn variable;\n }");
   parser_init(&parser, &lexer, scope);
   ast_node_t *ast_function = parser_parse_function_declaration(&parser);
 
@@ -203,31 +203,30 @@ assert_string_view_equal(char *expected, string_view_t actual)
 static MunitResult
 test_parse_basic_syntax_errors(const MunitParameter params[], void *user_data_or_fixture)
 {
-  assert_parser_error("(): i32 { return 42; }", "expected 'TOKEN_NAME' but got '('");
-  assert_parser_error("main): i32 { return 42; }", "expected '(' but got ')'");
-  assert_parser_error("main(: i32 { return 42; }", "expected ')' but got ':'");
-  assert_parser_error("main() i32 { return 42; }", "expected ':' but got 'TOKEN_NAME'");
-  assert_parser_error("main(): { return 42; }", "expected 'TOKEN_NAME' but got '{'");
-  assert_parser_error("main(): i32 return 42; }", "expected '{' but got 'return'");
-  assert_parser_error("main(): i32 { 42; }", "unexpected token 'TOKEN_NUMBER' value='42'");
-  assert_parser_error("main(): i32 { return; }", "unexpected '; (;)' token");
-  assert_parser_error("main(): i32 { return 42;", "expected '}' but got end of file");
-  assert_parser_error("main(): beff { return 42; }", "type 'beff' is not defined");
-  assert_parser_error("main(): i32 { return b; }", "identifier 'b' not defined");
-  assert_parser_error("main(): i32 { b = 1; return b; }", "trying to assign 'b' before defining it.");
+  assert_parser_error("main(): i32 { return 42; }", "expected 'fn' but got 'TOKEN_NAME'");
+  assert_parser_error("fn (): i32 { return 42; }", "expected 'TOKEN_NAME' but got '('");
+  assert_parser_error("fn main): i32 { return 42; }", "expected '(' but got ')'");
+  assert_parser_error("fn main(: i32 { return 42; }", "expected ')' but got ':'");
+  assert_parser_error("fn main() i32 { return 42; }", "expected ':' but got 'TOKEN_NAME'");
+  assert_parser_error("fn main(): { return 42; }", "expected 'TOKEN_NAME' but got '{'");
+  assert_parser_error("fn main(): i32 return 42; }", "expected '{' but got 'return'");
+  assert_parser_error("fn main(): i32 { 42; }", "unexpected token 'TOKEN_NUMBER' value='42'");
+  assert_parser_error("fn main(): i32 { return; }", "unexpected '; (;)' token");
+  assert_parser_error("fn main(): i32 { return 42;", "expected '}' but got end of file");
+  assert_parser_error("fn main(): beff { return 42; }", "type 'beff' is not defined");
+  assert_parser_error("fn main(): i32 { return b; }", "identifier 'b' not defined");
+  assert_parser_error("fn main(): i32 { b = 1; return b; }", "trying to assign 'b' before defining it.");
   // FIXME: once function calls are implemented, this error should inform that
   // neither a variable or function call was found.
-  assert_parser_error("main(): i32 { oxi 42; }", "unexpected token 'TOKEN_NAME' value='oxi'");
+  assert_parser_error("fn main(): i32 { oxi 42; }", "unexpected token 'TOKEN_NAME' value='oxi'");
 
   return MUNIT_OK;
 }
 
 static MunitTest tests[] = {
   { "/test_parse_function", test_parse_function, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
-  { "/test_parse_function", test_parse_function, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { "/test_parse_basic_syntax_errors", test_parse_basic_syntax_errors, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { "/test_parse_arithmetic_expression", test_parse_arithmetic_expression, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
-  { "/test_parse_arithmetic_expression", test_parse_arithmetic_expression, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { "/test_parse_variable_definition", test_parse_variable_definition, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL },
   { NULL, NULL, NULL, NULL, MUNIT_TEST_OPTION_NONE, NULL }
 };