[PATCH olang] parser: conform block line feeds with the spec

[Carlos Maniero <carlos@maniero.me>]

The line feeds has been handled by the statement parser functions when
the olang spec describe this grammar rule as a block responsibility.

There was also a FIXME related to allowing line feeds in between the
if/else statement and the block start that was also addressed.

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 src/parser.c                            | 47 ++++++++++++++-----------
 tests/olc/0031_else_extra_line_feeds.ol | 30 ++++++++++++++++
 2 files changed, 57 insertions(+), 20 deletions(-)
 create mode 100644 tests/olc/0031_else_extra_line_feeds.ol

diff --git a/src/parser.c b/src/parser.c
index d16b79d..2096129 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -70,6 +70,9 @@ parser_parse_factor(parser_t *parser);
 static void
 skip_line_feeds(lexer_t *lexer);
 
+static void
+peek_next_non_lf_token(lexer_t *lexer, token_t *token);
+
 void
 parser_init(parser_t *parser, lexer_t *lexer, arena_t *arena)
 {
@@ -493,6 +496,12 @@ StartLoop:
         return NULL;
     }
 
+    if (!skip_expected_token(parser, TOKEN_LF)) {
+        return NULL;
+    }
+
+    skip_line_feeds(parser->lexer);
+
     list_append(node_block->as_block.nodes, node);
 
     goto StartLoop;
@@ -522,11 +531,6 @@ parser_parse_return_stmt(parser_t *parser)
     ast_node_t *node_return_stmt = ast_new_node_return_stmt(parser->arena, token_ret.loc, expr);
     assert(node_return_stmt);
 
-    if (!skip_expected_token(parser, TOKEN_LF)) {
-        return NULL;
-    }
-    skip_line_feeds(parser->lexer);
-
     return node_return_stmt;
 }
 
@@ -544,6 +548,8 @@ parser_parse_if_stmt(parser_t *parser)
         return NULL;
     }
 
+    skip_line_feeds(parser->lexer);
+
     ast_node_t *then = parser_parse_block(parser);
 
     if (then == NULL) {
@@ -553,29 +559,25 @@ parser_parse_if_stmt(parser_t *parser)
     ast_node_t *_else = NULL;
 
     token_t next_token;
-    lexer_next_token(parser->lexer, &next_token);
-
-    // FIXME: We are not allowing line feed right after if block statement when
-    //        the else branch is present.  We also noticed that if has the same
-    //        problem which will be addressed later.
+    peek_next_non_lf_token(parser->lexer, &next_token);
 
     if (next_token.kind == TOKEN_ELSE) {
+        skip_line_feeds(parser->lexer);
+        lexer_next_token(parser->lexer, &next_token);
+        skip_line_feeds(parser->lexer);
+
         _else = parser_parse_block(parser);
 
         if (_else == NULL) {
             return NULL;
         }
 
-    } else if (!expected_token(&next_token, TOKEN_LF)) {
-        return NULL;
     }
 
     ast_node_t *node_if_stmt = ast_new_node_if_stmt(parser->arena, token_if.loc, cond, then, _else);
 
     assert(node_if_stmt);
 
-    skip_line_feeds(parser->lexer);
-
     return node_if_stmt;
 }
 
@@ -608,8 +610,6 @@ parser_parse_var_def(parser_t *parser)
 
     ast_node_t *var_node = ast_new_node_var_def(parser->arena, token_id.loc, token_id.value, var_type, expr);
 
-    skip_line_feeds(parser->lexer);
-
     return var_node;
 }
 
@@ -631,10 +631,6 @@ parser_parse_var_assign_stmt(parser_t *parser)
     ast_node_t *ref = ast_new_node_ref(parser->arena, token_id.loc, token_id.value);
     ast_node_t *expr = parser_parse_expr(parser);
 
-    // FIXME: The expected line feed should be parsed from parent call
-    //        according to the grammar rules
-    skip_line_feeds(parser->lexer);
-
     return ast_new_node_var_assign_stmt(parser->arena, token_eq.loc, ref, expr);
 }
 
@@ -683,3 +679,14 @@ skip_line_feeds(lexer_t *lexer)
         lexer_peek_next(lexer, &token);
     }
 }
+
+static void
+peek_next_non_lf_token(lexer_t *lexer, token_t *token)
+{
+    lexer_cursor_t cur = lexer->cur;
+
+    skip_line_feeds(lexer);
+    lexer_peek_next(lexer, token);
+
+    lexer->cur = cur;
+}
diff --git a/tests/olc/0031_else_extra_line_feeds.ol b/tests/olc/0031_else_extra_line_feeds.ol
new file mode 100644
index 0000000..bc44ccd
--- /dev/null
+++ b/tests/olc/0031_else_extra_line_feeds.ol
@@ -0,0 +1,30 @@
+# Copyright (C) 2024 olang mantainers
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+fn main(): u32
+{
+  if 0 != 0
+  {
+    return 1
+  }
+  else
+  {
+    return 0
+  }
+}
+
+# TEST test_compile(exit_code=0)
+
+# TEST test_run_binary(exit_code=0)

base-commit: 3c8975ba27c87d084187eefe622cbd783e289c99
-- 
2.46.0