path: root/scripts/debug_lexer.py

#!/usr/bin/python
"""
    Lexing error finder
    ~~~~~~~~~~~~~~~~~~~

    For the source files given on the command line, display
    the text where Error tokens are being generated, along
    with some context.

    :copyright: Copyright 2006-2022 by the Pygments team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""

import os
import sys
import struct

# always prefer Pygments from source if exists
srcpath = os.path.join(os.path.dirname(__file__), '..')
if os.path.isdir(os.path.join(srcpath, 'pygments')):
    sys.path.insert(0, srcpath)


from pygments.lexer import RegexLexer, ExtendedRegexLexer, LexerContext, \
    ProfilingRegexLexer, ProfilingRegexLexerMeta
from pygments.lexers import get_lexer_by_name, find_lexer_class, \
    find_lexer_class_for_filename, guess_lexer
from pygments.token import Error, Text, _TokenType
from pygments.cmdline import _parse_options


class DebuggingRegexLexer(ExtendedRegexLexer):
    """Make the state stack, position and current match instance attributes."""

    def get_tokens_unprocessed(self, text, stack=('root',)):
        """
        Split ``text`` into (tokentype, text) pairs.

        ``stack`` is the initial stack (default: ``['root']``)
        """
        tokendefs = self._tokens
        self.ctx = ctx = LexerContext(text, 0)
        ctx.stack = list(stack)
        statetokens = tokendefs[ctx.stack[-1]]
        while 1:
            for rexmatch, action, new_state in statetokens:
                self.m = m = rexmatch(text, ctx.pos, ctx.end)
                if m:
                    if action is not None:
                        if type(action) is _TokenType:
                            yield ctx.pos, action, m.group()
                            ctx.pos = m.end()
                        else:
                            if not isinstance(self, ExtendedRegexLexer):
                                yield from action(self, m)
                                ctx.pos = m.end()
                            else:
                                yield from action(self, m, ctx)
                                if not new_state:
                                    # altered the state stack?
                                    statetokens = tokendefs[ctx.stack[-1]]
                    if new_state is not None:
                        # state transition
                        if isinstance(new_state, tuple):
                            for state in new_state:
                                if state == '#pop':
                                    ctx.stack.pop()
                                elif state == '#push':
                                    ctx.stack.append(ctx.stack[-1])
                                else:
                                    ctx.stack.append(state)
                        elif isinstance(new_state, int):
                            # pop
                            del ctx.stack[new_state:]
                        elif new_state == '#push':
                            ctx.stack.append(ctx.stack[-1])
                        else:
                            assert False, 'wrong state def: %r' % new_state
                        statetokens = tokendefs[ctx.stack[-1]]
                    break
            else:
                try:
                    if ctx.pos >= ctx.end:
                        break
                    if text[ctx.pos] == '\n':
                        # at EOL, reset state to 'root'
                        ctx.stack = ['root']
                        statetokens = tokendefs['root']
                        yield ctx.pos, Text, '\n'
                        ctx.pos += 1
                        continue
                    yield ctx.pos, Error, text[ctx.pos]
                    ctx.pos += 1
                except IndexError:
                    break


def decode_atheris(bstr):
    """Decode a byte string into a Unicode string using the algorithm
    of Google's Atheris fuzzer library, which aims to produce a wide
    range of possible Unicode inputs.

    Corresponds to ConsumeUnicodeImpl() with filter_surrogates=false in
    https://github.com/google/atheris/blob/master/fuzzed_data_provider.cc
    """
    if len(bstr) < 2:
        return ''
    # The first byte only selects if the rest is decoded as ascii, "utf-16" or "utf-32"
    spec, bstr = bstr[0], bstr[1:]
    if spec & 1:  # pure ASCII
        return ''.join(chr(ch & 0x7f) for ch in bstr)
    elif spec & 2:  # UTF-16
        bstr = bstr if len(bstr) % 2 == 0 else bstr[:-1]
        return bstr.decode('utf16')

    # else UTF-32
    def valid_codepoint(ch):
        ch &= 0x1fffff
        if ch & 0x100000:
            ch &= ~0x0f0000
        return chr(ch)

    chars = struct.unpack('%dI%dx' % divmod(len(bstr), 4), bstr)
    return ''.join(map(valid_codepoint), chars)


def main(fn, lexer=None, options={}):
    if fn == '-':
        text = sys.stdin.read()
    else:
        with open(fn, 'rb') as fp:
            text = fp.read()
        if decode_strategy == 'latin1':
            try:
                text = text.decode('utf8')
            except UnicodeError:
                print('Warning: non-UTF8 input, using latin1')
                text = text.decode('latin1')
        elif decode_strategy == 'utf8-ignore':
            try:
                text = text.decode('utf8')
            except UnicodeError:
                print('Warning: ignoring non-UTF8 bytes in input')
                text = text.decode('utf8', 'ignore')
        elif decode_strategy == 'atheris':
            text = decode_atheris(text)

    text = text.strip('\n') + '\n'

    if lexer is not None:
        lxcls = get_lexer_by_name(lexer).__class__
    elif guess:
        lxcls = guess_lexer(text).__class__
        print('Using lexer: %s (%s.%s)' % (lxcls.name, lxcls.__module__,
                                           lxcls.__name__))
    else:
        lxcls = find_lexer_class_for_filename(os.path.basename(fn))
        if lxcls is None:
            name, rest = fn.split('_', 1)
            lxcls = find_lexer_class(name)
            if lxcls is None:
                raise AssertionError('no lexer found for file %r' % fn)
        print('Using lexer: %s (%s.%s)' % (lxcls.name, lxcls.__module__,
                                           lxcls.__name__))
    debug_lexer = False
    # if profile:
    #     # does not work for e.g. ExtendedRegexLexers
    #     if lxcls.__bases__ == (RegexLexer,):
    #         # yes we can!  (change the metaclass)
    #         lxcls.__class__ = ProfilingRegexLexerMeta
    #         lxcls.__bases__ = (ProfilingRegexLexer,)
    #         lxcls._prof_sort_index = profsort
    # else:
    #     if lxcls.__bases__ == (RegexLexer,):
    #         lxcls.__bases__ = (DebuggingRegexLexer,)
    #         debug_lexer = True
    #     elif lxcls.__bases__ == (DebuggingRegexLexer,):
    #         # already debugged before
    #         debug_lexer = True
    #     else:
    #         # HACK: ExtendedRegexLexer subclasses will only partially work here.
    #         lxcls.__bases__ = (DebuggingRegexLexer,)
    #         debug_lexer = True

    lx = lxcls(**options)
    lno = 1
    tokens = []
    states = []

    def show_token(tok, state):
        reprs = list(map(repr, tok))
        print('   ' + reprs[1] + ' ' + ' ' * (29-len(reprs[1])) + reprs[0], end=' ')
        if debug_lexer:
            print(' ' + ' ' * (29-len(reprs[0])) + ' : '.join(state)
                  if state else '', end=' ')
        print()

    for type, val in lx.get_tokens(text):
        lno += val.count('\n')
        if type == Error and not ignerror:
            print('Error parsing', fn, 'on line', lno)
            if not showall:
                print('Previous tokens' + (debug_lexer and ' and states' or '') + ':')
                for i in range(max(len(tokens) - num, 0), len(tokens)):
                    if debug_lexer:
                        show_token(tokens[i], states[i])
                    else:
                        show_token(tokens[i], None)
            print('Error token:')
            vlen = len(repr(val))
            print('   ' + repr(val), end=' ')
            if debug_lexer and hasattr(lx, 'ctx'):
                print(' ' * (60-vlen) + ' : '.join(lx.ctx.stack), end=' ')
            print()
            print()
            return 1
        tokens.append((type, val))
        if debug_lexer:
            if hasattr(lx, 'ctx'):
                states.append(lx.ctx.stack[:])
            else:
                states.append(None)
        if showall:
            show_token((type, val), states[-1] if debug_lexer else None)
    return 0


def print_help():
    print('''\
Pygments development helper to quickly debug lexers.

    scripts/debug_lexer.py [options] file ...

Give one or more filenames to lex them and display possible error tokens
and/or profiling info.  Files are assumed to be encoded in UTF-8.

Selecting lexer and options:

    -l NAME         use lexer named NAME (default is to guess from
                    the given filenames)
    -g              guess lexer from content
    -u              if input is non-utf8, use "ignore" handler instead
                    of using latin1 encoding
    -U              use Atheris fuzzer's method of converting
                    byte input to Unicode
    -O OPTIONSTR    use lexer options parsed from OPTIONSTR

Debugging lexing errors:

    -n N            show the last N tokens on error
    -a              always show all lexed tokens (default is only
                    to show them when an error occurs)
    -e              do not stop on error tokens

Profiling:

    -p              use the ProfilingRegexLexer to profile regexes
                    instead of the debugging lexer
    -s N            sort profiling output by column N (default is
                    column 4, the time per call)
''')


num = 10
showall = False
ignerror = False
lexer = None
options = {}
profile = False
profsort = 4
guess = False
decode_strategy = 'latin1'

if __name__ == '__main__':
    import getopt
    opts, args = getopt.getopt(sys.argv[1:], 'n:l:aepO:s:hguU')
    for opt, val in opts:
        if opt == '-n':
            num = int(val)
        elif opt == '-a':
            showall = True
        elif opt == '-e':
            ignerror = True
        elif opt == '-l':
            lexer = val
        elif opt == '-p':
            profile = True
        elif opt == '-s':
            profsort = int(val)
        elif opt == '-O':
            options = _parse_options([val])
        elif opt == '-g':
            guess = True
        elif opt == '-u':
            decode_strategy = 'utf8-ignore'
        elif opt == '-U':
            decode_strategy = 'atheris'
        elif opt == '-h':
            print_help()
            sys.exit(0)
    ret = 0
    if not args:
        print_help()
    for f in args:
        ret += main(f, lexer, options)
    sys.exit(bool(ret))