From ad54ee1182b1549880eddc8b1969d3992d9f7f1d Mon Sep 17 00:00:00 2001
From: Carlos Maniero <carlos@maniero.me>
Date: Tue, 9 May 2023 16:18:18 -0300
Subject: parser: parses an if statement no code generation

This commit parses a if statement following the grammar bellow:

  if boolean_expression {
    n_epressions;
  }

No else neither code generation was implemented.

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 src/parser.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

(limited to 'src/parser.c')

diff --git a/src/parser.c b/src/parser.c
index 848bb4a..9167f1e 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -30,6 +30,9 @@
 static bool
 parser_expression_matches_the_expected_type(parser_t *parser, ast_node_t *expression, type_t type, token_t token);
 
+static ast_node_t *
+parser_parse_block_declarations(parser_t *parser, type_t result_type);
+
 void
 parser_init(parser_t *parser, lexer_t *lexer, scope_t *scope)
 {
@@ -463,6 +466,35 @@ parser_parse_variable_declaration(parser_t *parser)
   return node;
 }
 
+static ast_node_t *
+parser_parse_if_stmt(parser_t *parser, type_t result_type)
+{
+  token_t if_token;
+  if (!expected_token(&if_token, parser, TOKEN_KEYWORD_IF)) {
+    return NULL;
+  }
+
+  ast_node_t *condition = parser_parse_expression(parser);
+
+  if (condition == NULL) {
+    return NULL;
+  }
+
+  if (!parser_expression_matches_the_expected_type(parser, condition, TYPE_BOOL, if_token)) {
+    ast_node_destroy(condition);
+    return NULL;
+  }
+
+  ast_node_t *body = parser_parse_block_declarations(parser, result_type);
+
+  if (body == NULL) {
+    ast_node_destroy(condition);
+    return NULL;
+  }
+
+  return ast_node_new_if_stmt(condition, body);
+}
+
 static bool
 is_next_statement_a_variable_declaration(parser_t *parser)
 {
@@ -487,6 +519,15 @@ is_next_statement_a_variable_assignement(parser_t *parser)
   return token.kind == TOKEN_ASSIGN;
 }
 
+static bool
+is_next_statement_a_if_stmt(parser_t *parser)
+{
+  token_t token;
+  lexer_peek_next_token(parser->lexer, &token);
+
+  return token.kind == TOKEN_KEYWORD_IF;
+}
+
 static bool
 is_next_statement_return(parser_t *parser)
 {
@@ -563,6 +604,19 @@ parser_parse_block_declarations(parser_t *parser, type_t result_type)
       continue;
     }
 
+    if (is_next_statement_a_if_stmt(parser)) {
+      ast_node_t *if_stmt = parser_parse_if_stmt(parser, result_type);
+
+      if (if_stmt == NULL) {
+        scope_leave(parser->scope);
+        ast_node_destroy_vector(body);
+        return NULL;
+      }
+
+      vector_push_back(body, if_stmt);
+      continue;
+    }
+
     if (is_next_statement_a_variable_declaration(parser)) {
       ast_node_t *variable_node = parser_parse_variable_declaration(parser);
 
-- 
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