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