| # |
| # Licensed to the Apache Software Foundation (ASF) under one |
| # or more contributor license agreements. See the NOTICE file |
| # distributed with this work for additional information |
| # regarding copyright ownership. The ASF licenses this file |
| # to you under the Apache License, Version 2.0 (the |
| # "License"); you may not use this file except in compliance |
| # with the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, |
| # software distributed under the License is distributed on an |
| # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| # KIND, either express or implied. See the License for the |
| # specific language governing permissions and limitations |
| # under the License. |
| # |
| |
| class Parser: |
| |
| def __init__(self, **kwargs): |
| self.output = "" |
| self.environ = {"out": self.parse} |
| for k, v in kwargs.items(): |
| self.environ[k] = v |
| self.text = "" |
| self.level = 0 |
| self.line = None |
| |
| def action(self, actor): |
| text = self.text |
| self.text = "" |
| actor(text) |
| |
| def out(self, text): |
| self.output += text |
| |
| def prefix_lines(self, text): |
| return "%s%s" % ("\n"*(self.line - 1 - text.count("\n")), text) |
| |
| def evaluate(self, text): |
| self.out(str(eval(self.prefix_lines(text), self.environ, self.environ))) |
| |
| def execute(self, text): |
| exec self.prefix_lines(text) in self.environ, self.environ |
| |
| def parse(self, input): |
| old_line = self.line |
| try: |
| state = self.start |
| self.line = 1 |
| for ch in input: |
| state = state(ch) |
| if ch == "\n": |
| self.line += 1 |
| if state == self.start: |
| self.action(self.out) |
| elif state == self.alnum: |
| self.action(self.evaluate) |
| else: |
| raise ParseError() |
| finally: |
| self.line = old_line |
| |
| def start(self, ch): |
| if ch == "$": |
| return self.dollar |
| else: |
| self.text += ch |
| return self.start |
| |
| def dollar(self, ch): |
| if ch == "$": |
| self.text += "$" |
| return self.start |
| elif ch == "(": |
| self.action(self.out) |
| return self.expression |
| elif ch == "{": |
| self.action(self.out) |
| return self.block |
| else: |
| self.action(self.out) |
| self.text += ch |
| return self.alnum |
| |
| def alnum(self, ch): |
| if ch.isalnum(): |
| self.text += ch |
| return self.alnum |
| else: |
| self.action(self.evaluate) |
| self.text += ch |
| return self.start |
| |
| def match(self, ch, start, end): |
| if ch == start: |
| self.level += 1 |
| if ch == end: |
| self.level -= 1 |
| |
| def block(self, ch): |
| if not self.level and ch == "}": |
| self.action(self.execute) |
| return self.start |
| else: |
| self.match(ch, "{", "}") |
| self.text += ch |
| return self.block |
| |
| def expression(self, ch): |
| if not self.level and ch == ")": |
| self.action(self.evaluate) |
| return self.start |
| else: |
| self.match(ch, "(", ")") |
| self.text += ch |
| return self.expression |