| """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") |
