Python: Copy Python extractor to codeql repo

python/extractor/lark/exceptions.py

@@ -0,0 +1,86 @@
+from .utils import STRING_TYPE
+
+class LarkError(Exception):
+    pass
+
+class GrammarError(LarkError):
+    pass
+
+class ParseError(LarkError):
+    pass
+
+class LexError(LarkError):
+    pass
+
+class UnexpectedInput(LarkError):
+    pos_in_stream = None
+
+    def get_context(self, text, span=40):
+        pos = self.pos_in_stream
+        start = max(pos - span, 0)
+        end = pos + span
+        before = text[start:pos].rsplit('\n', 1)[-1]
+        after = text[pos:end].split('\n', 1)[0]
+        return before + after + '\n' + ' ' * len(before) + '^\n'
+
+    def match_examples(self, parse_fn, examples):
+        """ Given a parser instance and a dictionary mapping some label with
+            some malformed syntax examples, it'll return the label for the
+            example that bests matches the current error.
+        """
+        assert self.state is not None, "Not supported for this exception"
+
+        candidate = None
+        for label, example in examples.items():
+            assert not isinstance(example, STRING_TYPE)
+
+            for malformed in example:
+                try:
+                    parse_fn(malformed)
+                except UnexpectedInput as ut:
+                    if ut.state == self.state:
+                        try:
+                            if ut.token == self.token:  # Try exact match first
+                                return label
+                        except AttributeError:
+                            pass
+                        if not candidate:
+                            candidate = label
+
+        return candidate
+
+
+class UnexpectedCharacters(LexError, UnexpectedInput):
+    def __init__(self, seq, lex_pos, line, column, allowed=None, considered_tokens=None, state=None):
+        message = "No terminal defined for '%s' at line %d col %d" % (seq[lex_pos], line, column)
+
+        self.line = line
+        self.column = column
+        self.allowed = allowed
+        self.considered_tokens = considered_tokens
+        self.pos_in_stream = lex_pos
+        self.state = state
+
+        message += '\n\n' + self.get_context(seq)
+        if allowed:
+            message += '\nExpecting: %s\n' % allowed
+
+        super(UnexpectedCharacters, self).__init__(message)
+
+
+
+class UnexpectedToken(ParseError, UnexpectedInput):
+    def __init__(self, token, expected, considered_rules=None, state=None):
+        self.token = token
+        self.expected = expected     # XXX str shouldn't necessary
+        self.line = getattr(token, 'line', '?')
+        self.column = getattr(token, 'column', '?')
+        self.considered_rules = considered_rules
+        self.state = state
+        self.pos_in_stream = getattr(token, 'pos_in_stream', None)
+
+        message = ("Unexpected token %r at line %s, column %s.\n"
+                   "Expected: %s\n"
+                   % (token, self.line, self.column, ', '.join(self.expected)))
+
+        super(UnexpectedToken, self).__init__(message)