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Diffstat (limited to 'freebase/rison.py')
| -rwxr-xr-x | freebase/rison.py | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/freebase/rison.py b/freebase/rison.py new file mode 100755 index 0000000..2f4eebc --- /dev/null +++ b/freebase/rison.py @@ -0,0 +1,308 @@ +# +# rison for python (parser only so far) +# see http://mjtemplate.org/examples/rison.html for more info +# + +###################################################################### +# +# the rison parser is based on javascript openlaszlo-json: +# Author: Oliver Steele +# Copyright: Copyright 2006 Oliver Steele. All rights reserved. +# Homepage: http:#osteele.com/sources/openlaszlo/json +# License: MIT License. +# Version: 1.0 +# + +# hacked by nix for use in uris +# ported to python by nix +# +# TODO +# +# switch to unicode +# fall through to simplejson if first char is not in '!(' - +# this allows code to use just one parser +# + + +import os, sys, re +#import simplejson +simplejson = None + +class ParserException(Exception): + pass + +class Parser(object): + WHITESPACE = '' + #WHITESPACE = " \t\n\r\f" + + # we divide the uri-safe glyphs into three sets + # <rison> and <reserved> classes are illegal in ids. + # <rison> - used by rison (possibly later) + # <reserved> - not common in strings, reserved + #not_idchar = "'!=:(),*@$;&"; + + idchar_punctuation = '_-./~' + not_idchar = ''.join([c for c in (chr(i) for i in range(127)) + if not (c.isalnum() + or c in idchar_punctuation)]) + + # additionally, we need to distinguish ids and numbers by first char + not_idstart = "-0123456789"; + + # regexp string matching a valid id + idrx = ('[^' + not_idstart + not_idchar + + '][^' + not_idchar + ']*') + + # regexp to check for valid rison ids + id_ok_re = re.compile('^' + idrx + '$', re.M) + + # regexp to find the end of an id when parsing + next_id_re = re.compile(idrx, re.M) + + def parse_json(self, str): + if len(str) > 0 and str[0] not in '!(': + return simplejson.loads(str) + return self.parse(str) + + def parse(self, str): + self.string = str + self.index = 0 + + value = self.readValue() + if self.next(): + raise ParserException("unable to parse rison string %r" % (str,)) + return value + + def readValue(self): + c = self.next() + + if c == '!': + return self.parse_bang() + if c == '(': + return self.parse_open_paren() + if c == "'": + return self.parse_single_quote() + if c in '-0123456789': + return self.parse_number() + + # fell through table, parse as an id + s = self.string + i = self.index-1 + + m = self.next_id_re.match(s, i) + if m: + id = m.group(0) + self.index = i + len(id) + return id # a string + + if c: + raise ParserException("invalid character: '" + c + "'") + raise ParserException("empty expression") + + def parse_array(self): + ar = [] + while 1: + c = self.next() + if c == ')': + return ar + + if c is None: + raise ParserException("unmatched '!('") + + if len(ar): + if c != ',': + raise ParserException("missing ','") + elif c == ',': + raise ParserException("extra ','") + else: + self.index -= 1 + n = self.readValue() + ar.append(n) + + return ar + + def parse_bang (self): + s = self.string + c = s[self.index] + self.index += 1 + if c is None: + raise ParserException('"!" at end of input') + if c not in self.bangs: + raise ParserException('unknown literal: "!' + c + '"') + x = self.bangs[c] + if callable(x): + return x(self) + + return x + + + def parse_open_paren (self): + count = 0 + o = {} + + while 1: + c = self.next() + if c == ')': + return o + if count: + if c != ',': + raise ParserException("missing ','") + elif c == ',': + raise ParserException("extra ','") + else: + self.index -= 1 + k = self.readValue() + + if self.next() != ':': + raise ParserException("missing ':'") + v = self.readValue() + + o[k] = v + count += 1 + + + def parse_single_quote(self): + s = self.string + i = self.index + start = i + segments = [] + + while 1: + if i >= len(s): + raise ParserException('unmatched "\'"') + + c = s[i] + i += 1 + if c == "'": + break + + if c == '!': + if start < i-1: + segments.append(s[start:i-1]) + c = s[i] + i += 1 + if c in "!'": + segments.append(c) + else: + raise ParserException('invalid string escape: "!'+c+'"') + + start = i + + + if start < i-1: + segments.append(s[start:i-1]) + self.index = i + return ''.join(segments) + + + # Also any number start (digit or '-') + def parse_number(self): + s = self.string + i = self.index + start = i-1 + state = 'int' + permittedSigns = '-' + transitions = { + 'int+.': 'frac', + 'int+e': 'exp', + 'frac+e': 'exp' + } + + while 1: + if i >= len(s): + i += 1 + break + + c = s[i] + i += 1 + + if '0' <= c and c <= '9': + continue + + if permittedSigns.find(c) >= 0: + permittedSigns = '' + continue + + state = transitions.get(state + '+' + c.lower(), None) + if state is None: + break + if state == 'exp': + permittedSigns = '-' + + self.index = i - 1 + s = s[start:self.index] + if s == '-': + raise ParserException("invalid number") + if re.search('[.e]', s): + return float(s) + return int(s) + + # return the next non-whitespace character, or undefined + def next(self): + l = len(self.string) + s = self.string + i = self.index + + while 1: + if i == len(s): + return None + c = s[i] + i += 1 + if c not in self.WHITESPACE: + break + + self.index = i + return c + + + bangs = { + 't': True, + 'f': False, + 'n': None, + '(': parse_array + } + + +def loads(s): + return Parser().parse(s) + +if __name__ == '__main__': + p = Parser() + + rison_examples = [ + "(a:0,b:1)", + "(a:0,b:foo,c:'23skidoo')", + "!t", + "!f", + "!n", + "''", + "0", + "1.5", + "-3", + "1e30", + "1e-30", + "G.", + "a", + "'0a'", + "'abc def'", + "()", + "(a:0)", + "(id:!n,type:/common/document)", + "!()", + "!(!t,!f,!n,'')", + "'-h'", + "a-z", + "'wow!!'", + "domain.com", + "'user@domain.com'", + "'US $10'", + "'can!'t'", + ]; + + for s in rison_examples: + print + print '*'*70 + print + print s + + print '%r' % (p.parse(s),) |