1############################################################################### 2# 3# Copyright (c) 2011 Ruslan Spivak 4# 5# Permission is hereby granted, free of charge, to any person obtaining a copy 6# of this software and associated documentation files (the "Software"), to deal 7# in the Software without restriction, including without limitation the rights 8# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9# copies of the Software, and to permit persons to whom the Software is 10# furnished to do so, subject to the following conditions: 11# 12# The above copyright notice and this permission notice shall be included in 13# all copies or substantial portions of the Software. 14# 15# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 21# THE SOFTWARE. 22# 23############################################################################### 24 25__author__ = 'Ruslan Spivak <ruslan.spivak@gmail.com>' 26 27 28class ASTVisitor(object): 29 """Base class for custom AST node visitors. 30 31 Example: 32 33 >>> from slimit.parser import Parser 34 >>> from slimit.visitors.nodevisitor import ASTVisitor 35 >>> 36 >>> text = ''' 37 ... var x = { 38 ... "key1": "value1", 39 ... "key2": "value2" 40 ... }; 41 ... ''' 42 >>> 43 >>> class MyVisitor(ASTVisitor): 44 ... def visit_Object(self, node): 45 ... '''Visit object literal.''' 46 ... for prop in node: 47 ... left, right = prop.left, prop.right 48 ... print 'Property value: %s' % right.value 49 ... # visit all children in turn 50 ... self.visit(prop) 51 ... 52 >>> 53 >>> parser = Parser() 54 >>> tree = parser.parse(text) 55 >>> visitor = MyVisitor() 56 >>> visitor.visit(tree) 57 Property value: "value1" 58 Property value: "value2" 59 60 """ 61 62 def visit(self, node): 63 method = 'visit_%s' % node.__class__.__name__ 64 return getattr(self, method, self.generic_visit)(node) 65 66 def generic_visit(self, node): 67 for child in node: 68 self.visit(child) 69 70 71class NodeVisitor(object): 72 """Simple node visitor.""" 73 74 def visit(self, node): 75 """Returns a generator that walks all children recursively.""" 76 for child in node: 77 yield child 78 for subchild in self.visit(child): 79 yield subchild 80 81 82def visit(node): 83 visitor = NodeVisitor() 84 for child in visitor.visit(node): 85 yield child 86