- DHParser/parse.py MetaParser, OneOrMore, ZeroOrMore: multiple infinite loop...

- DHParser/parse.py MetaParser, OneOrMore, ZeroOrMore: multiple infinite loop error messages at the same location will be avoided.

DHParser/error.py

@@ -88,6 +88,7 @@ class Error:
     MALFORMED_ERROR_STRING                   = ErrorCode(1060)
     AMBIGUOUS_ERROR_HANDLING                 = ErrorCode(1070)
     REDEFINED_DIRECTIVE                      = ErrorCode(1080)
+    INFINITE_LOOP                            = ErrorCode(1090)
 
     def __init__(self, message: str, pos, code: ErrorCode = ERROR,
                  orig_pos: int = -1, line: int = -1, column: int = -1) -> None:

DHParser/parse.py

@@ -1266,8 +1266,8 @@ class DropWhitespace(Whitespace):
 class MetaParser(Parser):
     def _return_value(self, node: Optional[Node]) -> Node:
         """
-        Generate a return node if a single node has been returned from
-        any descendant parsers. Empty nodes will be dropped silently.
+        Generates a return node if a single node has been returned from
+        any descendant parsers. Anonymous empty nodes will be dropped.
         If `self` is an unnamed parser, a non-empty descendant node
         will be passed through. If the descendant node is anonymous,
         it will be dropped and only its result will be kept.
@@ -1288,9 +1288,14 @@ class MetaParser(Parser):
             return EMPTY_NODE  # avoid creation of a node object for anonymous empty nodes
         return Node(self.tag_name, node or ())  # unoptimized code
 
-
     @cython.locals(N=cython.int)
     def _return_values(self, results: Tuple[Node, ...]) -> Node:
+        """
+        Generates a return node from a tuple of returned nodes from
+        descendant parsers. Anonymous empty nodes will be removed from
+        the tuple. Anonymous child nodes will be flattened if
+        `grammar.flatten_tree__` is True.
+        """
         assert isinstance(results, tuple)
         N = len(results)
         if N > 1:
@@ -1311,6 +1316,21 @@ class MetaParser(Parser):
             return EMPTY_NODE  # avoid creation of a node object for anonymous empty nodes
         return Node(self.tag_name, results)  # unoptimized code
 
+    def add_infinite_loop_error(self, node):
+        """
+        Add an "infitnite loop detected" error to the given node, unless an infinite
+        loop detection error has already been notified at the same location. (As a
+        consequence, only the innermost parser where an infinite loop is detected
+        will be set the error message, which is prefereble to a stack of error
+        messages from failed as well as its calling parsers.)
+        """
+        if (not node.pos in
+            (err.pos for err in
+             filter(lambda e: e.code == Error.INFINITE_LOOP, self.grammar.tree__.errors))):
+            self.grammar.tree__.add_error(
+                node, Error(dsl_error_msg(self, 'Infinite Loop encountered.'),
+                            node.pos, Error.INFINITE_LOOP))
+
 
 class UnaryParser(MetaParser):
     """
@@ -1447,8 +1467,7 @@ class ZeroOrMore(Option):
             if not node:
                 break
             if len(text) == n:
-                self.grammar.tree__.add_error(
-                    node, Error(dsl_error_msg(self, 'Infinite Loop encountered.'), node.pos))
+                self.add_infinite_loop_error(node)
             results += (node,)
         nd = self._return_values(results)  # type: Node
         return nd, text
@@ -1494,8 +1513,7 @@ class OneOrMore(UnaryParser):
             if not node:
                 break
             if len(text_) == n:
-                self.grammar.tree__.add_error(
-                    node, Error(dsl_error_msg(self, 'Infinite Loop encountered.'), node.pos))
+                self.add_infinite_loop_error(node)
             results += (node,)
         if results == ():
             return None, text

examples/BibTeX/BibTeXCompiler.py

@@ -57,10 +57,10 @@ class BibTeXGrammar(Grammar):
     r"""Parser for a BibTeX source file.
     """
     text = Forward()
-    source_hash__ = "4e4011722001b0019b7b980a02559de1"
+    source_hash__ = "d9a1a1b431a3185dab127be165a37719"
     parser_initialization__ = ["upon instantiation"]
     resume_rules__ = {}
-    COMMENT__ = r'(?i)%%.*\n'
+    COMMENT__ = r'//'
     WHITESPACE__ = r'\s*'
     WSP_RE__ = mixin_comment(whitespace=WHITESPACE__, comment=COMMENT__)
     wsp__ = Whitespace(WSP_RE__)

examples/BibTeX/grammar_tests/REPORT/01_test_entry.md

@@ -68,14 +68,8 @@ Match test "entry" for parser "entry" failed:
 	  organization = {Wikipedia}
 	}
 
-	6:68: Error (1000): DSL parser specification error: Infinite Loop encountered. Caught by parser "CONTENT_STRING = {/(?i)[^{}%]+/ | /(?i)(?=%)/ ~}+". 
+	6:68: Error (1090): DSL parser specification error: Infinite Loop encountered. Caught by parser "CONTENT_STRING = {/(?i)[^{}%]+/ | /(?i)(?=%)/ ~}+". 
 		Call stack: entry->:ZeroOrMore->:Series->content->:Series->text->:Alternative->CONTENT_STRING->:Alternative->:Series->:Whitespace
-	6:68: Error (1000): DSL parser specification error: Infinite Loop encountered. Caught by parser "CONTENT_STRING = {/(?i)[^{}%]+/ | /(?i)(?=%)/ ~}+". 
-		Call stack: entry->:ZeroOrMore->:Series->content->:Series->text->:Alternative->CONTENT_STRING->:Alternative->:Series->:Whitespace
-	6:68: Error (1000): DSL parser specification error: Infinite Loop encountered. Caught by parser "text = {CONTENT_STRING | '{' ~ text '}' ~}". 
-		Call stack: entry->:ZeroOrMore->:Series->content->:Series->text->:Alternative->CONTENT_STRING
-	6:68: Error (1000): DSL parser specification error: Infinite Loop encountered. Caught by parser "COMMA_TERMINATED_STRING = {/(?i)[^,%]+/ | /(?i)(?=%)/ ~}". 
-		Call stack: entry->:ZeroOrMore->:Series->content->plain_content->COMMA_TERMINATED_STRING->:Alternative
 	6:68: Error (1010): '}' ~ expected, "%E2\%80\%9" found!
 	6:69: Error (1040): Parser stopped before end! trying to recover but stopping history recording at this point.
 	7:1: Error (1020): Parser did not match!