bindings/python/codegen/scmexpr.py

   1 #!/usr/bin/env python
   2 # -*- Mode: Python; py-indent-offset: 4 -*-
   3 from __future__ import generators
   4
   5 import string
   6 import types
   7 from cStringIO import StringIO
   8
   9 class error(Exception):
  10     def __init__(self, filename, lineno, msg):
  11         Exception.__init__(self, msg)
  12         self.filename = filename
  13         self.lineno = lineno
  14         self.msg = msg
  15     def __str__(self):
  16         return '%s:%d: error: %s' % (self.filename, self.lineno, self.msg)
  17
  18 trans = [' '] * 256
  19 for i in range(256):
  20     if chr(i) in string.letters + string.digits + '_':
  21         trans[i] = chr(i)
  22     else:
  23         trans[i] = '_'
  24 trans = string.join(trans, '')
  25
  26 def parse(filename):
  27     if isinstance(filename, str):
  28         fp = open(filename, 'r')
  29     else: # if not string, assume it is some kind of iterator
  30         fp = filename
  31         filename = getattr(fp, 'name', '<unknown>')
  32     whitespace = ' \t\n\r\x0b\x0c'
  33     nonsymbol = whitespace + '();\'"'
  34     stack = []
  35     openlines = []
  36     lineno = 0
  37     for line in fp:
  38         pos = 0
  39         lineno += 1
  40         while pos < len(line):
  41             if line[pos] in whitespace: # ignore whitespace
  42                 pass
  43             elif line[pos] == ';': # comment
  44                 break
  45             elif line[pos:pos+2] == "'(":
  46                 pass # the open parenthesis will be handled next iteration
  47             elif line[pos] == '(':
  48                 stack.append(())
  49                 openlines.append(lineno)
  50             elif line[pos] == ')':
  51                 if len(stack) == 0:
  52                     raise error(filename, lineno, 'close parenthesis found when none open')
  53                 closed = stack[-1]
  54                 del stack[-1]
  55                 del openlines[-1]
  56                 if stack:
  57                     stack[-1] += (closed,)
  58                 else:
  59                     yield closed
  60             elif line[pos] == '"': # quoted string
  61                 if not stack:
  62                     raise error(filename, lineno,
  63                                 'string found outside of s-expression')
  64                 endpos = pos + 1
  65                 chars = []
  66                 while endpos < len(line):
  67                     if endpos+1 < len(line) and line[endpos] == '\\':
  68                         endpos += 1
  69                         if line[endpos] == 'n':
  70                             chars.append('\n')
  71                         elif line[endpos] == 'r':
  72                             chars.append('\r')
  73                         elif line[endpos] == 't':
  74                             chars.append('\t')
  75                         else:
  76                             chars.append('\\')
  77                             chars.append(line[endpos])
  78                     elif line[endpos] == '"':
  79                         break
  80                     else:
  81                         chars.append(line[endpos])
  82                     endpos += 1
  83                 if endpos >= len(line):
  84                     raise error(filename, lineno, "unclosed quoted string")
  85                 pos = endpos
  86                 stack[-1] += (''.join(chars),)
  87             else: # symbol/number
  88                 if not stack:
  89                     raise error(filename, lineno,
  90                                 'identifier found outside of s-expression')
  91                 endpos = pos
  92                 while endpos < len(line) and line[endpos] not in nonsymbol:
  93                     endpos += 1
  94                 symbol = line[pos:endpos]
  95                 pos = max(pos, endpos-1)
  96                 try: symbol = int(symbol)
  97                 except ValueError:
  98                     try: symbol = float(symbol)
  99                     except ValueError: pass
 100                 stack[-1] += (symbol,)
 101             pos += 1
 102     if len(stack) != 0:
 103         msg = '%d unclosed parentheses found at end of ' \
 104               'file (opened on line(s) %s)' % (len(stack),
 105                                                ', '.join(map(str, openlines)))
 106         raise error(filename, lineno, msg)
 107
 108 class Parser:
 109     def __init__(self, filename):
 110         """Argument is either a string, a parse tree, or file object"""
 111         self.filename = filename
 112     def startParsing(self, filename=None):
 113         statements = parse(filename or self.filename)
 114         for statement in statements:
 115             self.handle(statement)
 116     def handle(self, tup):
 117         cmd = string.translate(tup[0], trans)
 118         if hasattr(self, cmd):
 119             getattr(self, cmd)(*tup[1:])
 120         else:
 121             self.unknown(tup)
 122     def unknown(self, tup):
 123         pass
 124
 125 _testString = """; a scheme file
 126 (define-func gdk_font_load    ; a comment at end of line
 127   GdkFont
 128   ((string name)))
 129
 130 (define-boxed GdkEvent
 131   gdk_event_copy
 132   gdk_event_free
 133   "sizeof(GdkEvent)")
 134 """
 135
 136 if __name__ == '__main__':
 137     import sys
 138     if sys.argv[1:]:
 139         fp = open(sys.argv[1])
 140     else:
 141         fp = StringIO(_testString)
 142     statements = parse(fp)
 143     for s in statements:
 144         print `s`