fix empty heredoc templates

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 0.3.0 - not yet released
+
+fix:
+* correct expression for identifiers
+* allow empty template interpolations
+* allow empty templates
+
 ## 0.2.0 - 2021-06-26
 
 feature:

src/scanner.cc

@@ -129,7 +129,7 @@ public:
         advance(lexer);
       }
       context_stack.push_back({ .type = HEREDOC_TEMPLATE, .heredoc_identifier = identifier });
-      return accept_and_advance(lexer, HEREDOC_IDENTIFIER);
+      return accept_inplace(lexer, HEREDOC_IDENTIFIER);
     }
     if (valid_symbols[HEREDOC_IDENTIFIER] && in_heredoc_context() && has_leading_whitespace_with_newline) {
       string expected_identifier = context_stack.back().heredoc_identifier;
@@ -138,7 +138,7 @@ public:
         if (lexer->lookahead == *it) {
           advance(lexer);
         } else {
-          return accept_and_advance(lexer, TEMPLATE_LITERAL_CHUNK);
+          return accept_inplace(lexer, TEMPLATE_LITERAL_CHUNK);
         }
       }
       // check if the identifier is on a line of its own
@@ -148,7 +148,7 @@ public:
       }
       if (lexer->lookahead == '\n') {
         context_stack.pop_back();
-        return accept_and_advance(lexer, HEREDOC_IDENTIFIER);
+        return accept_inplace(lexer, HEREDOC_IDENTIFIER);
       } else {
         advance(lexer);
         lexer->mark_end(lexer);

test/corpus/templates.txt

@@ -21,7 +21,7 @@ foo = "${ var.bar }"
                   (identifier))))))))))
 
 ================================================================================
-empty template
+empty template interpolation
 ================================================================================
 
 foo = "${}"
@@ -37,6 +37,48 @@ foo = "${}"
           (quoted_template
             (template_interpolation)))))))
 
+================================================================================
+empty heredoc template
+================================================================================
+
+foo = <<END
+END
+
+--------------------------------------------------------------------------------
+
+(config_file
+  (body
+    (attribute
+      (identifier)
+      (expression
+        (template_expr
+          (heredoc_template
+            (heredoc_start)
+            (heredoc_identifier)
+            (heredoc_identifier)))))))
+
+================================================================================
+heredoc with fake ending
+================================================================================
+
+foo = <<END
+  END    not!
+END
+
+--------------------------------------------------------------------------------
+
+(config_file
+  (body
+    (attribute
+      (identifier)
+      (expression
+        (template_expr
+          (heredoc_template
+            (heredoc_start)
+            (heredoc_identifier)
+            (template_literal)
+            (heredoc_identifier)))))))
+
 ================================================================================
 quoted template expression with escaped strings and fake strip marker
 ================================================================================