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#!/usr/bin/env python
# -*- Mode: Python; py-indent-offset: 4 -*-
from __future__ import generators
import string
from cStringIO import StringIO
class error(Exception):
def __init__(self, filename, lineno, msg):
Exception.__init__(self, msg)
self.filename = filename
self.lineno = lineno
self.msg = msg
def __str__(self):
return '%s:%d: error: %s' % (self.filename, self.lineno, self.msg)
trans = [' '] * 256
for i in range(256):
if chr(i) in string.letters + string.digits + '_':
trans[i] = chr(i)
else:
trans[i] = '_'
trans = string.join(trans, '')
def parse(filename):
if isinstance(filename, str):
fp = open(filename, 'r')
else: # if not string, assume it is some kind of iterator
fp = filename
filename = getattr(fp, 'name', '<unknown>')
whitespace = ' \t\n\r\x0b\x0c'
nonsymbol = whitespace + '();\'"'
stack = []
openlines = []
lineno = 0
for line in fp:
pos = 0
lineno += 1
while pos < len(line):
if line[pos] in whitespace: # ignore whitespace
pass
elif line[pos] == ';': # comment
break
elif line[pos:pos+2] == "'(":
pass # the open parenthesis will be handled next iteration
elif line[pos] == '(':
stack.append(())
openlines.append(lineno)
elif line[pos] == ')':
if len(stack) == 0:
raise error(filename, lineno, 'close parenthesis found when none open')
closed = stack[-1]
del stack[-1]
del openlines[-1]
if stack:
stack[-1] += (closed,)
else:
yield closed
elif line[pos] == '"': # quoted string
if not stack:
raise error(filename, lineno,
'string found outside of s-expression')
endpos = pos + 1
chars = []
while endpos < len(line):
if endpos+1 < len(line) and line[endpos] == '\\':
endpos += 1
if line[endpos] == 'n':
chars.append('\n')
elif line[endpos] == 'r':
chars.append('\r')
elif line[endpos] == 't':
chars.append('\t')
else:
chars.append('\\')
chars.append(line[endpos])
elif line[endpos] == '"':
break
else:
chars.append(line[endpos])
endpos += 1
if endpos >= len(line):
raise error(filename, lineno, "unclosed quoted string")
pos = endpos
stack[-1] += (''.join(chars),)
else: # symbol/number
if not stack:
raise error(filename, lineno,
'identifier found outside of s-expression')
endpos = pos
while endpos < len(line) and line[endpos] not in nonsymbol:
endpos += 1
symbol = line[pos:endpos]
pos = max(pos, endpos-1)
try: symbol = int(symbol)
except ValueError:
try: symbol = float(symbol)
except ValueError: pass
stack[-1] += (symbol,)
pos += 1
if len(stack) != 0:
msg = '%d unclosed parentheses found at end of ' \
'file (opened on line(s) %s)' % (len(stack),
', '.join(map(str, openlines)))
raise error(filename, lineno, msg)
class Parser:
def __init__(self, filename):
"""Argument is either a string, a parse tree, or file object"""
self.filename = filename
def startParsing(self, filename=None):
statements = parse(filename or self.filename)
for statement in statements:
self.handle(statement)
def handle(self, tup):
cmd = string.translate(tup[0], trans)
if hasattr(self, cmd):
getattr(self, cmd)(*tup[1:])
else:
self.unknown(tup)
def unknown(self, tup):
pass
_testString = """; a scheme file
(define-func gdk_font_load ; a comment at end of line
GdkFont
((string name)))
(define-boxed GdkEvent
gdk_event_copy
gdk_event_free
"sizeof(GdkEvent)")
"""
if __name__ == '__main__':
import sys
if sys.argv[1:]:
fp = open(sys.argv[1])
else:
fp = StringIO(_testString)
statements = parse(fp)
for s in statements:
print `s`
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