astTools.py 文件源码

def occursIn(sub, super):
    """Does the first AST occur as a subtree of the second?"""
    superStatementTypes = [ ast.Module, ast.Interactive, ast.Suite,
                            ast.FunctionDef, ast.ClassDef, ast.For, 
                            ast.While, ast.If, ast.With, ast.Try, 
                            ast.ExceptHandler ]
    if (not isinstance(super, ast.AST)):
        return False
    if type(sub) == type(super) and compareASTs(sub, super, checkEquality=True) == 0:
        return True
    # we know that a statement can never occur in an expression 
    # (or in a non-statement-holding statement), so cut the search off now to save time.
    if isStatement(sub) and type(super) not in superStatementTypes:
        return False 
    for child in ast.iter_child_nodes(super):
        if occursIn(sub, child):
            return True
    return False