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# -*- test-case-name: twisted.words.test.test_xpath -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
# pylint: disable=W9401,W9402
# DO NOT EDIT xpathparser.py!
#
# It is generated from xpathparser.g using Yapps. Make needed changes there.
# This also means that the generated Python may not conform to Twisted's coding
# standards, so it is wrapped in exec to prevent automated checkers from
# complaining.
# HOWTO Generate me:
#
# 1.) Grab a copy of yapps2:
# https://github.com/smurfix/yapps
#
# Note: Do NOT use the package in debian/ubuntu as it has incompatible
# modifications. The original at http://theory.stanford.edu/~amitp/yapps/
# hasn't been touched since 2003 and has not been updated to work with
# Python 3.
#
# 2.) Generate the grammar:
#
# yapps2 xpathparser.g xpathparser.py.proto
#
# 3.) Edit the output to depend on the embedded runtime, and remove extraneous
# imports:
#
# sed -e '/^# Begin/,${/^[^ ].*mport/d}' -e 's/runtime\.//g' \
# -e "s/^\(from __future\)/exec(r'''\n\1/" -e"\$a''')"
# xpathparser.py.proto > xpathparser.py
"""
XPath Parser.
Besides the parser code produced by Yapps, this module also defines the
parse-time exception classes, a scanner class, a base class for parsers
produced by Yapps, and a context class that keeps track of the parse stack.
These have been copied from the Yapps runtime module.
"""
from __future__ import print_function
import sys, re
MIN_WINDOW=4096
# File lookup window
class SyntaxError(Exception):
"""When we run into an unexpected token, this is the exception to use"""
def __init__(self, pos=None, msg="Bad Token", context=None):
Exception.__init__(self)
self.pos = pos
self.msg = msg
self.context = context
def __str__(self):
if not self.pos: return 'SyntaxError'
else: return 'SyntaxError@%s(%s)' % (repr(self.pos), self.msg)
class NoMoreTokens(Exception):
"""Another exception object, for when we run out of tokens"""
pass
class Token:
"""Yapps token.
This is a container for a scanned token.
"""
def __init__(self, type,value, pos=None):
"""Initialize a token."""
self.type = type
self.value = value
self.pos = pos
def __repr__(self):
output = '<%s: %s' % (self.type, repr(self.value))
if self.pos:
output += " @ "
if self.pos[0]:
output += "%s:" % self.pos[0]
if self.pos[1]:
output += "%d" % self.pos[1]
if self.pos[2] is not None:
output += ".%d" % self.pos[2]
output += ">"
return output
in_name=0
class Scanner:
"""Yapps scanner.
The Yapps scanner can work in context sensitive or context
insensitive modes. The token(i) method is used to retrieve the
i-th token. It takes a restrict set that limits the set of tokens
it is allowed to return. In context sensitive mode, this restrict
set guides the scanner. In context insensitive mode, there is no
restriction (the set is always the full set of tokens).
"""
def __init__(self, patterns, ignore, input="",
file=None,filename=None,stacked=False):
"""Initialize the scanner.
Parameters:
patterns : [(terminal, uncompiled regex), ...] or None
ignore : {terminal:None, ...}
input : string
If patterns is None, we assume that the subclass has
defined self.patterns : [(terminal, compiled regex), ...].
Note that the patterns parameter expects uncompiled regexes,
whereas the self.patterns field expects compiled regexes.
The 'ignore' value is either None or a callable, which is called
with the scanner and the to-be-ignored match object; this can
be used for include file or comment handling.
"""
if not filename:
global in_name
filename="<f.%d>" % in_name
in_name += 1
self.input = input
self.ignore = ignore
self.file = file
self.filename = filename
self.pos = 0
self.del_pos = 0 # skipped
self.line = 1
self.del_line = 0 # skipped
self.col = 0
self.tokens = []
self.stack = None
self.stacked = stacked
self.last_read_token = None
self.last_token = None
self.last_types = None
if patterns is not None:
# Compile the regex strings into regex objects
self.patterns = []
for terminal, regex in patterns:
self.patterns.append( (terminal, re.compile(regex)) )
def stack_input(self, input="", file=None, filename=None):
"""Temporarily parse from a second file."""
# Already reading from somewhere else: Go on top of that, please.
if self.stack:
# autogenerate a recursion-level-identifying filename
if not filename:
filename = 1
else:
try:
filename += 1
except TypeError:
pass
# now pass off to the include file
self.stack.stack_input(input,file,filename)
else:
try:
filename += 0
except TypeError:
pass
else:
filename = "<str_%d>" % filename
# self.stack = object.__new__(self.__class__)
# Scanner.__init__(self.stack,self.patterns,self.ignore,input,file,filename, stacked=True)
# Note that the pattern+ignore are added by the generated
# scanner code
self.stack = self.__class__(input,file,filename, stacked=True)
def get_pos(self):
"""Return a file/line/char tuple."""
if self.stack: return self.stack.get_pos()
return (self.filename, self.line+self.del_line, self.col)
# def __repr__(self):
# """Print the last few tokens that have been scanned in"""
# output = ''
# for t in self.tokens:
# output += '%s\n' % (repr(t),)
# return output
def print_line_with_pointer(self, pos, length=0, out=sys.stderr):
"""Print the line of 'text' that includes position 'p',
along with a second line with a single caret (^) at position p"""
file,line,p = pos
if file != self.filename:
if self.stack: return self.stack.print_line_with_pointer(pos,length=length,out=out)
print >>out, "(%s: not in input buffer)" % file
return
text = self.input
p += length-1 # starts at pos 1
origline=line
line -= self.del_line
spos=0
if line > 0:
while 1:
line = line - 1
try:
cr = text.index("\n",spos)
except ValueError:
if line:
text = ""
break
if line == 0:
text = text[spos:cr]
break
spos = cr+1
else:
print >>out, "(%s:%d not in input buffer)" % (file,origline)
return
# Now try printing part of the line
text = text[max(p-80, 0):p+80]
p = p - max(p-80, 0)
# Strip to the left
i = text[:p].rfind('\n')
j = text[:p].rfind('\r')
if i < 0 or (0 <= j < i): i = j
if 0 <= i < p:
p = p - i - 1
text = text[i+1:]
# Strip to the right
i = text.find('\n', p)
j = text.find('\r', p)
if i < 0 or (0 <= j < i): i = j
if i >= 0:
text = text[:i]
# Now shorten the text
while len(text) > 70 and p > 60:
# Cut off 10 chars
text = "..." + text[10:]
p = p - 7
# Now print the string, along with an indicator
print >>out, '> ',text
print >>out, '> ',' '*p + '^'
def grab_input(self):
"""Get more input if possible."""
if not self.file: return
if len(self.input) - self.pos >= MIN_WINDOW: return
data = self.file.read(MIN_WINDOW)
if data is None or data == "":
self.file = None
# Drop bytes from the start, if necessary.
if self.pos > 2*MIN_WINDOW:
self.del_pos += MIN_WINDOW
self.del_line += self.input[:MIN_WINDOW].count("\n")
self.pos -= MIN_WINDOW
self.input = self.input[MIN_WINDOW:] + data
else:
self.input = self.input + data
def getchar(self):
"""Return the next character."""
self.grab_input()
c = self.input[self.pos]
self.pos += 1
return c
def token(self, restrict, context=None):
"""Scan for another token."""
while 1:
if self.stack:
try:
return self.stack.token(restrict, context)
except StopIteration:
self.stack = None
# Keep looking for a token, ignoring any in self.ignore
self.grab_input()
# special handling for end-of-file
if self.stacked and self.pos==len(self.input):
raise StopIteration
# Search the patterns for the longest match, with earlier
# tokens in the list having preference
best_match = -1
best_pat = '(error)'
best_m = None
for p, regexp in self.patterns:
# First check to see if we're ignoring this token
if restrict and p not in restrict and p not in self.ignore:
continue
m = regexp.match(self.input, self.pos)
if m and m.end()-m.start() > best_match:
# We got a match that's better than the previous one
best_pat = p
best_match = m.end()-m.start()
best_m = m
# If we didn't find anything, raise an error
if best_pat == '(error)' and best_match < 0:
msg = 'Bad Token'
if restrict:
msg = 'Trying to find one of '+', '.join(restrict)
raise SyntaxError(self.get_pos(), msg, context=context)
ignore = best_pat in self.ignore
value = self.input[self.pos:self.pos+best_match]
if not ignore:
tok=Token(type=best_pat, value=value, pos=self.get_pos())
self.pos += best_match
npos = value.rfind("\n")
if npos > -1:
self.col = best_match-npos
self.line += value.count("\n")
else:
self.col += best_match
# If we found something that isn't to be ignored, return it
if not ignore:
if len(self.tokens) >= 10:
del self.tokens[0]
self.tokens.append(tok)
self.last_read_token = tok
# print repr(tok)
return tok
else:
ignore = self.ignore[best_pat]
if ignore:
ignore(self, best_m)
def peek(self, *types, **kw):
"""Returns the token type for lookahead; if there are any args
then the list of args is the set of token types to allow"""
context = kw.get("context",None)
if self.last_token is None:
self.last_types = types
self.last_token = self.token(types,context)
elif self.last_types:
for t in types:
if t not in self.last_types:
raise NotImplementedError("Unimplemented: restriction set changed")
return self.last_token.type
def scan(self, type, **kw):
"""Returns the matched text, and moves to the next token"""
context = kw.get("context",None)
if self.last_token is None:
tok = self.token([type],context)
else:
if self.last_types and type not in self.last_types:
raise NotImplementedError("Unimplemented: restriction set changed")
tok = self.last_token
self.last_token = None
if tok.type != type:
if not self.last_types: self.last_types=[]
raise SyntaxError(tok.pos, 'Trying to find '+type+': '+ ', '.join(self.last_types)+", got "+tok.type, context=context)
return tok.value
class Parser:
"""Base class for Yapps-generated parsers.
"""
def __init__(self, scanner):
self._scanner = scanner
def _stack(self, input="",file=None,filename=None):
"""Temporarily read from someplace else"""
self._scanner.stack_input(input,file,filename)
self._tok = None
def _peek(self, *types, **kw):
"""Returns the token type for lookahead; if there are any args
then the list of args is the set of token types to allow"""
return self._scanner.peek(*types, **kw)
def _scan(self, type, **kw):
"""Returns the matched text, and moves to the next token"""
return self._scanner.scan(type, **kw)
class Context:
"""Class to represent the parser's call stack.
Every rule creates a Context that links to its parent rule. The
contexts can be used for debugging.
"""
def __init__(self, parent, scanner, rule, args=()):
"""Create a new context.
Args:
parent: Context object or None
scanner: Scanner object
rule: string (name of the rule)
args: tuple listing parameters to the rule
"""
self.parent = parent
self.scanner = scanner
self.rule = rule
self.args = args
while scanner.stack: scanner = scanner.stack
self.token = scanner.last_read_token
def __str__(self):
output = ''
if self.parent: output = str(self.parent) + ' > '
output += self.rule
return output
def print_error(err, scanner, max_ctx=None):
"""Print error messages, the parser stack, and the input text -- for human-readable error messages."""
# NOTE: this function assumes 80 columns :-(
# Figure out the line number
pos = err.pos
if not pos:
pos = scanner.get_pos()
file_name, line_number, column_number = pos
print('%s:%d:%d: %s' % (file_name, line_number, column_number, err.msg), file=sys.stderr)
scanner.print_line_with_pointer(pos)
context = err.context
token = None
while context:
print('while parsing %s%s:' % (context.rule, tuple(context.args)), file=sys.stderr)
if context.token:
token = context.token
if token:
scanner.print_line_with_pointer(token.pos, length=len(token.value))
context = context.parent
if max_ctx:
max_ctx = max_ctx-1
if not max_ctx:
break
def wrap_error_reporter(parser, rule, *args,**kw):
try:
return getattr(parser, rule)(*args,**kw)
except SyntaxError as e:
print_error(e, parser._scanner)
except NoMoreTokens:
print('Could not complete parsing; stopped around here:', file=sys.stderr)
print(parser._scanner, file=sys.stderr)
from twisted.words.xish.xpath import AttribValue, BooleanValue, CompareValue
from twisted.words.xish.xpath import Function, IndexValue, LiteralValue
from twisted.words.xish.xpath import _AnyLocation, _Location
%%
parser XPathParser:
ignore: "\\s+"
token INDEX: "[0-9]+"
token WILDCARD: "\*"
token IDENTIFIER: "[a-zA-Z][a-zA-Z0-9_\-]*"
token ATTRIBUTE: "\@[a-zA-Z][a-zA-Z0-9_\-]*"
token FUNCNAME: "[a-zA-Z][a-zA-Z0-9_]*"
token CMP_EQ: "\="
token CMP_NE: "\!\="
token STR_DQ: '"([^"]|(\\"))*?"'
token STR_SQ: "'([^']|(\\'))*?'"
token OP_AND: "and"
token OP_OR: "or"
token END: "$"
rule XPATH: PATH {{ result = PATH; current = result }}
( PATH {{ current.childLocation = PATH; current = current.childLocation }} ) * END
{{ return result }}
rule PATH: ("/" {{ result = _Location() }} | "//" {{ result = _AnyLocation() }} )
( IDENTIFIER {{ result.elementName = IDENTIFIER }} | WILDCARD {{ result.elementName = None }} )
( "\[" PREDICATE {{ result.predicates.append(PREDICATE) }} "\]")*
{{ return result }}
rule PREDICATE: EXPR {{ return EXPR }} |
INDEX {{ return IndexValue(INDEX) }}
rule EXPR: FACTOR {{ e = FACTOR }}
( BOOLOP FACTOR {{ e = BooleanValue(e, BOOLOP, FACTOR) }} )*
{{ return e }}
rule BOOLOP: ( OP_AND {{ return OP_AND }} | OP_OR {{ return OP_OR }} )
rule FACTOR: TERM {{ return TERM }}
| "\(" EXPR "\)" {{ return EXPR }}
rule TERM: VALUE {{ t = VALUE }}
[ CMP VALUE {{ t = CompareValue(t, CMP, VALUE) }} ]
{{ return t }}
rule VALUE: "@" IDENTIFIER {{ return AttribValue(IDENTIFIER) }} |
FUNCNAME {{ f = Function(FUNCNAME); args = [] }}
"\(" [ VALUE {{ args.append(VALUE) }}
(
"," VALUE {{ args.append(VALUE) }}
)*
] "\)" {{ f.setParams(*args); return f }} |
STR {{ return LiteralValue(STR[1:len(STR)-1]) }}
rule CMP: (CMP_EQ {{ return CMP_EQ }} | CMP_NE {{ return CMP_NE }})
rule STR: (STR_DQ {{ return STR_DQ }} | STR_SQ {{ return STR_SQ }})