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- """Check for errs in the AST.
- The Python parser does not catch all syntax errors. Others, like
- assignments with invalid targets, are caught in the code generation
- phase.
- The compiler package catches some errors in the transformer module.
- But it seems clearer to write checkers that use the AST to detect
- errors.
- """
- from compiler import ast, walk
- def check(tree, multi=None):
- v = SyntaxErrorChecker(multi)
- walk(tree, v)
- return v.errors
- class SyntaxErrorChecker:
- """A visitor to find syntax errors in the AST."""
- def __init__(self, multi=None):
- """Create new visitor object.
- If optional argument multi is not None, then print messages
- for each error rather than raising a SyntaxError for the
- first.
- """
- self.multi = multi
- self.errors = 0
- def error(self, node, msg):
- self.errors = self.errors + 1
- if self.multi is not None:
- print "%s:%s: %s" % (node.filename, node.lineno, msg)
- else:
- raise SyntaxError, "%s (%s:%s)" % (msg, node.filename, node.lineno)
- def visitAssign(self, node):
- # the transformer module handles many of these
- pass
- ## for target in node.nodes:
- ## if isinstance(target, ast.AssList):
- ## if target.lineno is None:
- ## target.lineno = node.lineno
- ## self.error(target, "can't assign to list comprehension")
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