def visit(self, node):
"""Walk a parse tree, transforming it into another representation.
Recursively descend a parse tree, dispatching to the method named after
the rule in the :class:`~parsimonious.grammar.Grammar` that produced
each node. If, for example, a rule was... ::
bold = '<b>'
...the ``visit_bold()`` method would be called. It is your
responsibility to subclass :class:`NodeVisitor` and implement those
methods.
"""
method = getattr(self, 'visit_' + node.expr_name, self.generic_visit)
# Call that method, and show where in the tree it failed if it blows
# up.
try:
return method(node, [self.visit(n) for n in node])
except (VisitationError, UndefinedLabel):
# Don't catch and re-wrap already-wrapped exceptions.
raise
except self.unwrapped_exceptions:
raise
except Exception:
# Catch any exception, and tack on a parse tree so it's easier to
# see where it went wrong.
exc_class, exc, tb = exc_info()
reraise(VisitationError, VisitationError(exc, exc_class, node), tb)
def visit(self, node):
"""Rewrite original method to use lower-case method, and not "generic" function."""
try:
# Get the "visit_%s" method, using the lower case version of the rule.
method = getattr(self, 'visit_%s' % node.expr_name.lower())
except AttributeError:
# If the method is not defined, we do nothing for this node.
return
# Below is untouched code from the original ``visit`` method.
# Call that method, and show where in the tree it failed if it blows up.
try:
return method(node, [self.visit(n) for n in node])
except (VisitationError, UndefinedLabel):
# Don't catch and re-wrap already-wrapped exceptions.
raise
except self.unwrapped_exceptions:
raise
except Exception:
# Catch any exception, and tack on a parse tree so it's easier to
# see where it went wrong.
exc_class, exc, trace = sys.exc_info()
raise VisitationError(exc, exc_class, node).with_traceback(trace)
def visit(self, node):
method = getattr(self, 'visit_' + node.expr_name, self.generic_visit)
# Call that method, and show where in the tree it failed if it blows
# up.
try:
return method(node, [self.visit(n) for n in node])
except (VisitationError, UndefinedLabel, RecursiveLabel):
# Don't catch and re-wrap already-wrapped exceptions.
raise
except Exception:
# Catch any exception, and tack on a parse tree so it's easier to
# see where it went wrong.
exc_class, exc, tb = sys.exc_info()
raise VisitationError(exc, exc_class, node).with_traceback(tb)
def visit(self, node):
"""
See the ``NodeVisitor`` visit method. This just changes the order in which
we visit nonterminals from right to left to left to right.
"""
method = getattr(self, 'visit_' + node.expr_name, self.generic_visit)
# Call that method, and show where in the tree it failed if it blows
# up.
try:
# Changing this to reverse here!
return method(node, [self.visit(child) for child in reversed(list(node))])
except (VisitationError, UndefinedLabel):
# Don't catch and re-wrap already-wrapped exceptions.
raise
except self.unwrapped_exceptions:
raise
except Exception: # pylint: disable=broad-except
# Catch any exception, and tack on a parse tree so it's easier to
# see where it went wrong.
exc_class, exc, traceback = exc_info()
reraise(VisitationError, VisitationError(exc, exc_class, node), traceback)