112 lines
2.6 KiB
Python
112 lines
2.6 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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import re
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class Type:
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def __init__(self, name, pattern=None):
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self.name = name
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self.pattern = pattern
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def __repr__(self):
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return self.name
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class Lexicon:
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def __init__(self):
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self.types = []
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self._eof = None
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def define(self, name, pattern):
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t = Type(name, pattern)
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self.types.append(t)
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return t
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def eof(self, name):
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t = Type(name)
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self._eof = t
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return t
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def compile(self):
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types = self.types[:]
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joined = "|".join(["(%s)" % t.pattern for t in types])
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rexp = re.compile(joined)
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return Lexer(types, self._eof, rexp)
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class Token:
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def __init__(self, type, value, input, position):
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self.type = type
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self.value = value
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self.input = input
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self.position = position
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def line_info(self):
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return line_info(self.input, self.position)
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def __repr__(self):
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if self.value is None:
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return repr(self.type)
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else:
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return "%s(%r)" % (self.type, self.value)
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class LexError(Exception):
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pass
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def line_info(st, pos):
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idx = 0
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lineno = 1
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column = 0
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line_pos = 0
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while idx < pos:
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if st[idx] == "\n":
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lineno += 1
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column = 0
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line_pos = idx
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column += 1
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idx += 1
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end = st.find("\n", line_pos)
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if end < 0:
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end = len(st)
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line = st[line_pos:end]
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return line, lineno, column
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class Lexer:
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def __init__(self, types, eof, rexp):
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self.types = types
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self.eof = eof
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self.rexp = rexp
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def lex(self, st):
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pos = 0
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while pos < len(st):
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m = self.rexp.match(st, pos)
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if m is None:
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line, ln, col = line_info(st, pos)
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raise LexError("unrecognized characters line:%s,%s: %s" % (ln, col, line))
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else:
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idx = m.lastindex
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t = Token(self.types[idx - 1], m.group(idx), st, pos)
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yield t
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pos = m.end()
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yield Token(self.eof, None, st, pos)
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