parser: Use peek and drop token when parsing expressions

3 files changed, 12 insertions, 13 deletions

diff --git a/src/lexer.c b/src/lexer.c
index f937170..b60fbb5 100644
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -232,11 +232,10 @@ lexer_peek_next_token(lexer_t *lexer, token_t *token)
 }
 
 void
-lexer_step_back_to(lexer_t *lexer, token_t *token)
+lexer_drop_next_token(lexer_t *lexer)
 {
-  lexer->cur = token->bol + token->col;
-  lexer->row = token->row;
-  lexer->bol = token->bol;
+  token_t token;
+  lexer_next_token(lexer, &token);
 }
 
 void
diff --git a/src/lexer.h b/src/lexer.h
index 0b9f2ad..abee53a 100644
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -83,7 +83,7 @@ void
 lexer_drop_char(lexer_t *lexer);
 
 void
-lexer_step_back_to(lexer_t *lexer, token_t *token);
+lexer_drop_next_token(lexer_t *lexer);
 
 void
 lexer_peek_next_token(lexer_t *lexer, token_t *token);
diff --git a/src/parser.c b/src/parser.c
index 662449b..af372fb 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -167,9 +167,11 @@ parser_parse_term(parser_t *parser, ast_node_t *node)
     return false;
 
   token_t token;
-  lexer_next_token(parser->lexer, &token);
+  lexer_peek_next_token(parser->lexer, &token);
 
   while (token.kind == TOKEN_STAR || token.kind == TOKEN_SLASH) {
+    lexer_drop_next_token(parser->lexer);
+
     ast_node_t *left = ast_node_new();
     *left = *node;
 
@@ -179,11 +181,9 @@ parser_parse_term(parser_t *parser, ast_node_t *node)
 
     ast_node_init_binary_operation(node, token_to_binary_operation_kind(&token), left, right);
 
-    lexer_next_token(parser->lexer, &token);
+    lexer_peek_next_token(parser->lexer, &token);
   }
 
-  lexer_step_back_to(parser->lexer, &token);
-
   return true;
 }
 
@@ -201,9 +201,11 @@ parser_parse_expression(parser_t *parser, ast_node_t *node)
     return false;
 
   token_t token;
-  lexer_next_token(parser->lexer, &token);
+  lexer_peek_next_token(parser->lexer, &token);
 
   while (token.kind == TOKEN_PLUS || token.kind == TOKEN_MINUS) {
+    lexer_drop_next_token(parser->lexer);
+
     ast_node_t *left = ast_node_new();
     *left = *node;
 
@@ -213,11 +215,9 @@ parser_parse_expression(parser_t *parser, ast_node_t *node)
 
     ast_node_init_binary_operation(node, token_to_binary_operation_kind(&token), left, right);
 
-    lexer_next_token(parser->lexer, &token);
+    lexer_peek_next_token(parser->lexer, &token);
   }
 
-  lexer_step_back_to(parser->lexer, &token);
-
   return true;
 }