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#
# 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
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