wikiextractor/WikiExtractor.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
#
# =============================================================================
#  Version: 2.19 (Apr 16, 2015)
#  Author: Giuseppe Attardi (attardi@di.unipi.it), University of Pisa
#	   Antonio Fuschetto (fuschett@di.unipi.it), University of Pisa
#
#  Contributors:
#	Leonardo Souza (lsouza@amtera.com.br)
#	Juan Manuel Caicedo (juan@cavorite.com)
#	Humberto Pereira (begini@gmail.com)
#	Siegfried-A. Gevatter (siegfried@gevatter.com)
#	Pedro Assis (pedroh2306@gmail.com)
#	Wim Muskee (wimmuskee@gmail.com)
#	Radics Geza (radicsge@gmail.com)
#
# =============================================================================
#  Copyright (c) 2009. Giuseppe Attardi (attardi@di.unipi.it).
# =============================================================================
#  This file is part of Tanl.
#
#  Tanl is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License, version 3,
#  as published by the Free Software Foundation.
#
#  Tanl is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <http://www.gnu.org/licenses/>.
# =============================================================================

"""Wikipedia Extractor:
Extracts and cleans text from a Wikipedia database dump and stores output in a
number of files of similar size in a given directory.
Each file will contain several documents in the format:

	<doc id="" url="" title="">
        ...
        </doc>

This version performs template expansion by preprocesssng the whole dump and
collecting template definitions.
"""

import sys, os.path
import re, random
import argparse
from itertools import izip
import logging, traceback
import urllib
import bz2
import codecs
from htmlentitydefs import name2codepoint
import urllib
import Queue, threading, multiprocessing

#===========================================================================

# Program version
version = '2.18'

### PARAMS ####################################################################

##
# Defined in <siteinfo>
# We include as default Template, when loading external template file.
knownNamespaces = set(['Template'])

##
# Whether to preserve links in output
#
keepLinks = False

##
# Whether to transform sections into HTML
#
keepSections = False

##
# The namespace used for template definitions
templateNamespace = 'Template'

##
# Recognize only these namespaces
# w: Internal links to the Wikipedia
# wiktionary: Wiki dictionary
# wikt: shortcut for Wiktionary
#
acceptedNamespaces = ['w', 'wiktionary', 'wikt']

##
# Drop these elements from article text
#
discardElements = [
        'gallery', 'timeline', 'noinclude', 'pre',
        'table', 'tr', 'td', 'th', 'caption',
        'form', 'input', 'select', 'option', 'textarea',
        'ul', 'li', 'ol', 'dl', 'dt', 'dd', 'menu', 'dir',
        'ref', 'references', 'img', 'imagemap', 'source', 'small'
        ]

# This is obtained from <siteinfo>
urlbase = None

def get_url(id):
    global urlbase
    return "%s?curid=%s" % (urlbase, id)

#=========================================================================
#
# MediaWiki Markup Grammar
# https://www.mediawiki.org/wiki/Preprocessor_ABNF

# xml-char = %x9 / %xA / %xD / %x20-D7FF / %xE000-FFFD / %x10000-10FFFF
# sptab = SP / HTAB

# ; everything except ">" (%x3E)
# attr-char = %x9 / %xA / %xD / %x20-3D / %x3F-D7FF / %xE000-FFFD / %x10000-10FFFF

# literal         = *xml-char
# title           = wikitext-L3
# part-name       = wikitext-L3
# part-value      = wikitext-L3
# part            = ( part-name "=" part-value ) / ( part-value )
# parts           = [ title *( "|" part ) ]
# tplarg          = "{{{" parts "}}}"
# template        = "{{" parts "}}"
# link            = "[[" wikitext-L3 "]]"

# comment         = "<!--" literal "-->"
# unclosed-comment = "<!--" literal END
# ; the + in the line-eating-comment rule was absent between MW 1.12 and MW 1.22
# line-eating-comment = LF LINE-START *SP +( comment *SP ) LINE-END

# attr            = *attr-char
# nowiki-element  = "<nowiki" attr ( "/>" / ( ">" literal ( "</nowiki>" / END ) ) )

# wikitext-L2     = heading / wikitext-L3 / *wikitext-L2
# wikitext-L3     = literal / template / tplarg / link / comment /
#                   line-eating-comment / unclosed-comment / xmlish-element /
#                   *wikitext-L3

#------------------------------------------------------------------------------

selfClosingTags = [ 'br', 'hr', 'nobr', 'ref', 'references', 'nowiki' ]

# These tags are dropped, keeping their content.
# handle 'a' separately, depending on keepLinks
ignoredTags = [
    'b', 'big', 'blockquote', 'center', 'cite', 'div', 'em',
    'font', 'h1', 'h2', 'h3', 'h4', 'hiero', 'i', 'kbd', 'nowiki',
    'p', 'plaintext', 's', 'span', 'strike', 'strong',
    'sub', 'sup', 'tt', 'u', 'var'
]

placeholder_tags = {'math':'formula', 'code':'codice'}

def normalizeTitle(title):
    """Normalize title"""
    # remove leading/trailing whitespace and underscores
    title = title.strip(' _')
    # replace sequences of whitespace and underscore chars with a single space
    title = re.sub(r'[\s_]+', ' ', title)

    m = re.match(r'([^:]*):(\s*)(\S(?:.*))', title)
    if m:
        prefix = m.group(1)
        if m.group(2):
            optionalWhitespace = ' '
        else:
            optionalWhitespace = ''
        rest = m.group(3)

        ns = normalizeNamespace(prefix)
        if ns in knownNamespaces:
            # If the prefix designates a known namespace, then it might be
            # followed by optional whitespace that should be removed to get
            # the canonical page name
            # (e.g., "Category:  Births" should become "Category:Births").
            title = ns + ":" + ucfirst(rest)
        else:
            # No namespace, just capitalize first letter.
            # If the part before the colon is not a known namespace, then we
            # must not remove the space after the colon (if any), e.g.,
            # "3001: The_Final_Odyssey" != "3001:The_Final_Odyssey".
            # However, to get the canonical page name we must contract multiple
            # spaces into one, because
            # "3001:   The_Final_Odyssey" != "3001: The_Final_Odyssey".
            title = ucfirst(prefix) + ":" + optionalWhitespace + ucfirst(rest)
    else:
        # no namespace, just capitalize first letter
        title = ucfirst(title)
    return title

##
# Removes HTML or XML character references and entities from a text string.
#
# @param text The HTML (or XML) source text.
# @return The plain text, as a Unicode string, if necessary.

def unescape(text):
    def fixup(m):
        text = m.group(0)
        code = m.group(1)
        try:
            if text[1] == "#":  # character reference
                if text[2] == "x":
                    return unichr(int(code[1:], 16))
                else:
                    return unichr(int(code))
            else:               # named entity
                return unichr(name2codepoint[code])
        except:
            return text # leave as is

    return re.sub("&#?(\w+);", fixup, text)

# Match HTML comments
# The buggy template {{Template:T}} has a comment terminating with just "->"
comment = re.compile(r'<!--.*?-->', re.DOTALL)

# Match elements to ignore
discard_element_patterns = [re.compile(r'<\s*%s\b[^>/]*>.*?<\s*/\s*%s>' % (tag, tag), re.DOTALL | re.IGNORECASE) for tag in discardElements]

# Match ignored tags
ignored_tag_patterns = []
def ignoreTag(tag):
    left = re.compile(r'<%s\b[^>/]*>' % tag, re.IGNORECASE) # both <ref> and <reference>
    right = re.compile(r'</\s*%s>' % tag, re.IGNORECASE)
    ignored_tag_patterns.append((left, right))

for tag in ignoredTags:
    ignoreTag(tag)

# Match selfClosing HTML tags
selfClosing_tag_patterns = [
    re.compile(r'<\s*%s\b[^>]*/\s*>' % tag, re.DOTALL | re.IGNORECASE) for tag in selfClosingTags
]

# Match HTML placeholder tags
placeholder_tag_patterns = [
    (re.compile(r'<\s*%s(\s*| [^>]+?)>.*?<\s*/\s*%s\s*>' % (tag, tag), re.DOTALL | re.IGNORECASE),
     repl) for tag, repl in placeholder_tags.items()
]

# Match preformatted lines
preformatted = re.compile(r'^ .*?$')

# Match external links (space separates second optional parameter)
externalLink = re.compile(r'\[\w+[^ ]*? (.*?)]')
externalLinkNoAnchor = re.compile(r'\[\w+[&\]]*\]')

# Matches bold/italic
bold_italic = re.compile(r"'''''(.*?)'''''")
bold = re.compile(r"'''(.*?)'''")
italic_quote = re.compile(r"''\"([^\"]*?)\"''")
italic = re.compile(r"''(.*?)''")
quote_quote = re.compile(r'""([^"]*?)""')

# Matches space
spaces = re.compile(r' {2,}')

# Matches dots
dots = re.compile(r'\.{4,}')

#======================================================================

substWords = 'subst:|safesubst:'

class Extractor(object):
    """
    An extraction task on a article.
    """

    def __init__(self, id, title, page):
        """
        :param page: a list of lines.
        """
        self.id = id
        self.title = title
        self.page = page
        self.magicWords = MagicWords()
        self.frame = []

    def extract(self, out=sys.stdout):
        logging.info("%s\t%s" % (self.id, self.title))
        text = ''.join(self.page)
        url = get_url(self.id)
        header = '<doc id="%s" url="%s" title="%s">\n' % (self.id, url, self.title)
        # Separate header from text with a newline.
        header += self.title + '\n\n'
        header = header.encode('utf-8')
        self.magicWords['pagename'] = self.title
        self.magicWords['fullpagename'] = fullyQualifiedTemplateTitle(self.title)
        text = clean(self, text)
        footer = "\n</doc>\n"
        if out != sys.stdout:
            out.reserve(len(header) + len(text) + len(footer))
        out.write(header)
        for line in compact(text):
            out.write(line.encode('utf-8'))
            out.write('\n')
        out.write(footer)

    #----------------------------------------------------------------------
    # Expand templates

    maxTemplateRecursionLevels = 30
    maxParameterRecursionLevels = 10

    # check for template beginning
    reOpen = re.compile('(?<!{){{(?!{)', re.DOTALL)

    def expandTemplates(self, wikitext):
        """
        :param wikitext: the text to be expanded.

        Templates are frequently nested. Occasionally, parsing mistakes may
        cause template insertion to enter an infinite loop, for instance when
        trying to instantiate Template:Country

        {{country_{{{1}}}|{{{2}}}|{{{2}}}|size={{{size|}}}|name={{{name|}}}}}

        which is repeatedly trying to insert template 'country_', which is
        again resolved to Template:Country. The straightforward solution of
        keeping track of templates that were already inserted for the current
        article would not work, because the same template may legally be used
        more than once, with different parameters in different parts of the
        article.  Therefore, we limit the number of iterations of nested
        template inclusion.

        """

        res = ''
        if len(self.frame) >= self.maxTemplateRecursionLevels:
            logging.warn('Max template recursion exceeded!')
            return res

        #logging.debug('<expandTemplates ' + str(len(self.frame)))

        cur = 0
        # look for matching {{...}}
        for s,e in findMatchingBraces(wikitext, 2):
            res += wikitext[cur:s] + self.expandTemplate(wikitext[s+2:e-2])
            cur = e
        # leftover
        res += wikitext[cur:]
        logging.debug('   expandTemplates> ' + str(len(self.frame)) + ' ' + res)
        return res

    def templateParams(self, parameters):
        """
        Build a dictionary with positional or name key to expanded parameters.
        :param parameters: the parts[1:] of a template, i.e. all except the title.
        :param depth: recusion depth.
        """
        templateParams = {}

        if not parameters:
            return templateParams
        logging.debug('<templateParams: ' + str(len(self.frame)) + ' ' + '|'.join(parameters))

        # evaluate parameters, since they may contain templates, including the
        # symbol "=".
        # {{#ifexpr: {{{1}}} = 1 }}
        parameters = [self.expandTemplates(p) for p in parameters]

        # Parameters can be either named or unnamed. In the latter case, their
        # name is defined by their ordinal position (1, 2, 3, ...).

        unnamedParameterCounter = 0

        # It's legal for unnamed parameters to be skipped, in which case they
        # will get default values (if available) during actual instantiation.
        # That is {{template_name|a||c}} means parameter 1 gets
        # the value 'a', parameter 2 value is not defined, and parameter 3 gets
        # the value 'c'.  This case is correctly handled by function 'split',
        # and does not require any special handling.
        for param in parameters:
            # Spaces before or after a parameter value are normally ignored,
            # UNLESS the parameter contains a link (to prevent possible gluing
            # the link to the following text after template substitution)

            # Parameter values may contain "=" symbols, hence the parameter
            # name extends up to the first such symbol.

            # It is legal for a parameter to be specified several times, in
            # which case the last assignment takes precedence. Example:
            # "{{t|a|b|c|2=B}}" is equivalent to "{{t|a|B|c}}".
            # Therefore, we don't check if the parameter has been assigned a
            # value before, because anyway the last assignment should override
            # any previous ones.
            # FIXME: Don't use DOTALL here since parameters may be tags with
            # attributes, e.g. <div class="templatequotecite">
            # Parameters may span several lines, like:
            # {{Reflist|colwidth=30em|refs=
            # &lt;ref name=&quot;Goode&quot;&gt;Title&lt;/ref&gt;

            # The '=' might occurr within an HTML attribute: "&lt;ref name=value".
            m = re.match(' *([^= ]*?) *=(.*)', param, re.DOTALL)
            if m:
                # This is a named parameter.  This case also handles parameter
                # assignments like "2=xxx", where the number of an unnamed
                # parameter ("2") is specified explicitly - this is handled
                # transparently.

                parameterName = m.group(1).strip()
                parameterValue = m.group(2)

                if ']]' not in parameterValue: # if the value does not contain a link, trim whitespace
                    parameterValue = parameterValue.strip()
                templateParams[parameterName] = parameterValue
            else:
                # this is an unnamed parameter
                unnamedParameterCounter += 1

                if ']]' not in param: # if the value does not contain a link, trim whitespace
                    param = param.strip()
                templateParams[str(unnamedParameterCounter)] = param
        logging.debug('   templateParams> ' + str(len(self.frame)) + ' ' + '|'.join(templateParams.values()))
        return templateParams

    def expandTemplate(self, body):
        """Expands template invocation.
        :param body: the parts of a template.

        :see http://meta.wikimedia.org/wiki/Help:Expansion for an explanation
        of the process.

        See in particular: Expansion of names and values
        http://meta.wikimedia.org/wiki/Help:Expansion#Expansion_of_names_and_values

        For most parser functions all names and values are expanded,
        regardless of what is relevant for the result. The branching functions
        (#if, #ifeq, #iferror, #ifexist, #ifexpr, #switch) are exceptions.

        All names in a template call are expanded, and the titles of the
        tplargs in the template body, after which it is determined which
        values must be expanded, and for which tplargs in the template body
        the first part (default).

        In the case of a tplarg, any parts beyond the first are never
        expanded.  The possible name and the value of the first part is
        expanded if the title does not match a name in the template call.

        :see code for braceSubstitution at
        https://doc.wikimedia.org/mediawiki-core/master/php/html/Parser_8php_source.html#3397:

        """

        # template        = "{{" parts "}}"

        # Templates and tplargs are decomposed in the same way, with pipes as
        # separator, even though eventually any parts in a tplarg after the first
        # (the parameter default) are ignored, and an equals sign in the first
        # part is treated as plain text.
        # Pipes inside inner templates and tplargs, or inside double rectangular
        # brackets within the template or tplargs are not taken into account in
        # this decomposition.
        # The first part is called title, the other parts are simply called parts.

        # If a part has one or more equals signs in it, the first equals sign
        # determines the division into name = value. Equals signs inside inner
        # templates and tplargs, or inside double rectangular brackets within the
        # part are not taken into account in this decomposition. Parts without
        # equals sign are indexed 1, 2, .., given as attribute in the <name> tag.

        if len(self.frame) >= self.maxTemplateRecursionLevels:
            logging.warn('Reached max template recursion: %d' %
                         self.maxTemplateRecursionLevels)
            logging.debug('   INVOCATION> ' + str(len(self.frame)) + ' ' + body)
            return ''

        logging.debug('INVOCATION ' + str(len(self.frame)) + ' ' + body)

        parts = splitParameters(body)
        # title is the portion before the first |
        logging.debug('TITLE ' + parts[0].strip())
        title = self.expandTemplates(parts[0].strip())

        # SUBST
        if re.match(substWords, title):
            if title.startswith('subst'):
                return body
            title = re.sub(substWords, '', title)

        if title.lower() in self.magicWords.values:
            return self.magicWords[title.lower()]

        # Parser functions
        # The first argument is everything after the first colon.
        colon = title.find(':')
        if colon > 1:
            funct = title[:colon]
            parts[0] = title[colon+1:].strip() # side-effect (parts[0] not used later)
            # arguments after first are not evaluated
            ret = callParserFunction(funct, parts, self.frame)
            return self.expandTemplates(ret)

        title = fullyQualifiedTemplateTitle(title)

        redirected = redirects.get(title)
        if redirected:
            title = redirected

        if title not in templates:
            # The page being included could not be identified
            return ''

        # get the template
        template = templates[title]
        logging.debug('TEMPLATE %s: %s' % (title, template))

        # tplarg          = "{{{" parts "}}}"
        # parts           = [ title *( "|" part ) ]
        # part            = ( part-name "=" part-value ) / ( part-value )
        # part-name       = wikitext-L3
        # part-value      = wikitext-L3
        # wikitext-L3     = literal / template / tplarg / link / comment /
        #                   line-eating-comment / unclosed-comment /
        #		    xmlish-element / *wikitext-L3

        # A tplarg may contain other parameters as well as templates, e.g.:
        #   {{{text|{{{quote|{{{1|{{error|Error: No text given}}}}}}}}}}}
        # hence no simple RE like this would work:
        #   '{{{((?:(?!{{{).)*?)}}}'
        # We must use full CF parsing.

        # the parameter name itself might be computed, e.g.:
        #   {{{appointe{{#if:{{{appointer14|}}}|r|d}}14|}}}

        # Because of the multiple uses of double-brace and triple-brace
        # syntax, expressions can sometimes be ambiguous.
        # Precedence rules specifed here:
        # http://www.mediawiki.org/wiki/Preprocessor_ABNF#Ideal_precedence
        # resolve ambiguities like this:
        #   {{{{ }}}} -> { {{{ }}} }
        #   {{{{{ }}}}} -> {{ {{{ }}} }}
        #
        # :see: https://en.wikipedia.org/wiki/Help:Template#Handling_parameters

        # Evaluate parameters.
        # build a dict of name-values for the parameter values
        params = self.templateParams(parts[1:])

        # Perform parameter substitution
        instantiated = self.substParameters(template, params)
        #logging.debug('instantiated ' + str(len(self.frame)) + ' ' + template)
        self.frame.append((title, params))
        value = self.expandTemplates(instantiated)
        self.frame.pop()
        logging.debug('   INVOCATION> ' + str(len(self.frame)) + ' ' + value)
        return value

    def substParameters(self, body, params, subst_depth=0):
        """
        :param body: the body of a template.
        :param params: dict of name-values template parameters.
        :param subst_depth: depth of recursive parameter substitutions.
        """
        # We perform parameter substitutions recursively.
        # We also limit the maximum number of iterations to avoid too long or
        # even endless loops (in case of malformed input).

        # :see: http://meta.wikimedia.org/wiki/Help:Expansion#Distinction_between_variables.2C_parser_functions.2C_and_templates
        #
        # Parameter values are assigned to parameters in two (?) passes.
        # Therefore a parameter name in a template can depend on the value of
        # another parameter of the same template, regardless of the order in
        # which they are specified in the template call, for example, using
        # Template:ppp containing "{{{{{{p}}}}}}", {{ppp|p=q|q=r}} and even
        # {{ppp|q=r|p=q}} gives r, but using Template:tvvv containing
        # "{{{{{{{{{p}}}}}}}}}", {{tvvv|p=q|q=r|r=s}} gives s.

        logging.debug('substParameters (%d, %d) %s' % (len(self.frame), subst_depth, body))

        result = ''
        if subst_depth > self.maxParameterRecursionLevels:
            logging.warn('Reachead maximum parameter recursions: %d' %
                     self.maxParameterRecursionLevels)
            return result

        start = 0
        # we must handle nesting, s.a.
        # {{{1|{{PAGENAME}}}
        # {{{italics|{{{italic|}}}
        # {{#if:{{{{{#if:{{{nominee|}}}|nominee|candidate}}|}}}|
        #

        for s,e in findMatchingBraces(body, 3):
            # invoke substParameter on outer {{{}}}
            result += body[start:s] + self.substParameter(body[s+3:e-3],
                                                          params, subst_depth+1)
            start = e
        result += body[start:]                     # leftover
        return result

    def substParameter(self, parameter, params, subst_depth):
        """
        :param parameter: the parts of a tplarg.
        :param params: dict of name-values of template parameters.
        """
        # the parameter name itself might contain templates, e.g.:
        # appointe{{#if:{{{appointer14|}}}|r|d}}14|

        # any parts in a tplarg after the first (the parameter default) are
        # ignored, and an equals sign in the first part is treated as plain text.
        #logging.debug(' subst ' + parameter + ' ' + str(params))

        parts = splitParameters(parameter)
        if len(parts) > 1:
            # This parameter has a default value
            paramName = self.expandTemplates(self.substParameters(parts[0], params, subst_depth))
            defaultValue = parts[1]

            if paramName in params:
                return params[paramName]  # use parameter value specified in template invocation
            else: # use the default value
                defaultValue = self.substParameters(defaultValue, params, subst_depth)
                return self.expandTemplates(defaultValue)
        # parameter without a default value
        parameter = self.substParameters(parameter, params, subst_depth)
        parameter = self.expandTemplates(parameter)
        if parameter in params:
            return params[parameter]  # use parameter value specified in template invocation
        # Parameter not specified in template invocation and without
        # a default value.
        # The Wiki rules for templates
        # (see http://meta.wikimedia.org/wiki/Help:Template)
        # would require to keep the parameter in 3 braces, but we just drop them.
        return ''
        # Surplus parameters - i.e., those assigned values in template
        # invocation but not used in the template body - are simply ignored.

# ----------------------------------------------------------------------
# parameter handling

def splitParameters(paramsList, sep='|'):
    """
    :param paramList: the parts of a template or tplarg.

    Split template parameters at the separator :param sep:, which defaults to
    "|". The fuction can be used also to split also key-value pairs at the
    separator "=".

    Template parameters often contain URLs, internal links, text or even
    template expressions, since we evaluate templates outside in.
    This is required for cases like:
      {{#if: {{{1}}} | {{lc:{{{1}}} | "parameter missing"}}
    Parameters are separated by "|" symbols. However, we
    cannot simply split the string on "|" symbols, since these
    also appear inside templates and internal links, e.g.

     {{if:|
      |{{#if:the president|
           |{{#if:|
               [[Category:Hatnote templates|A{{PAGENAME}}]]
            }}
       }}
     }}

    We split parameters at the "|" symbols that are not inside any pair
    {{{...}}}, {{...}}, [[...]], {|...|}.
    """

    # Must handle:
    # #ifeq: ped|article|[http://emedicine.medscape.com/article/180-overview|[http://www.emedicine.com/ped/topic180.htm#{{#if: |section~}}

    parameters = []
    cur = 0
    for s,e in findBalanced(paramsList,
                            ['{{{', '{{', '[[', '{|'],
                            ['}}}', '}}', ']]', '|}']):
        par = paramsList[cur:s].split(sep)
        if par:
            if parameters:
                # portion before | belongs to previous parameter
                parameters[-1] += par[0]
                if len(par) > 1:
                    # rest are new parameters
                    parameters.extend(par[1:])
            else:
                parameters = par
        elif not parameters:
            parameters = ['']   # create first param
        # add span to last previous parameter
        parameters[-1] += paramsList[s:e]
        cur = e
    # leftover
    par = paramsList[cur:].split(sep)
    if par:
        if parameters:
            # portion before | belongs to previous parameter
            parameters[-1] += par[0]
            if len(par) > 1:
                # rest are new parameters
                parameters.extend(par[1:])
        else:
            parameters = par

    #logging.debug('splitParameters ' + sep + ' ' + paramsList + '\ndict:  ' + str(parameters))
    return parameters

def findMatchingBraces(text, ldelim):
    """
    :param ldelim: number of braces to match.
    """
    # Parsing is done with respect to pairs of double braces {{..}} delimiting
    # a template, and pairs of triple braces {{{..}}} delimiting a tplarg.
    # If double opening braces are followed by triple closing braces or
    # conversely, this is taken as delimiting a template, with one left-over
    # brace outside it, taken as plain text. For any pattern of braces this
    # defines a set of templates and tplargs such that any two are either
    # separate or nested (not overlapping).

    # Unmatched double rectangular closing brackets can be in a template or
    # tplarg, but unmatched double rectangular opening brackets
    # cannot. Unmatched double or triple closing braces inside a pair of
    # double rectangular brackets are treated as plain text.
    # Other formulation: in ambiguity between template or tplarg on one hand,
    # and a link on the other hand, the structure with the rightmost opening
    # takes precedence, even if this is the opening of a link without any
    # closing, so not producing an actual link.

    # In the case of more than three opening braces the last three are assumed
    # to belong to a tplarg, unless there is no matching triple of closing
    # braces, in which case the last two opening braces are are assumed to
    # belong to a template.

    # We must skip individual { like in: {{#ifeq: {{padleft:|1|}} | { | | &nbsp;}}
    # We must resolve ambiguities like this:
    #   {{{{ }}}} -> { {{{ }}} }
    #   {{{{{ }}}}} -> {{ {{{ }}} }}
    #   {{#if:{{{{{#if:{{{nominee|}}}|nominee|candidate}}|}}}|...}}

    # Handle:
    # {{{{{|safesubst:}}}#Invoke:String|replace|{{{1|{{{{{|safesubst:}}}PAGENAME}}}}}|%s+%([^%(]-%)$||plain=false}}

    reOpen = re.compile('{' * ldelim) # inner
    reClose = re.compile('([{]{2,})|(}{2,})')       # at least 2
    cur = 0
    # scan text after {*ldelim looking for matching }*ldelim
    while True:
        m1 = reOpen.search(text, cur)
        if not m1:
            return
        npar = ldelim
        end = m1.end()
        while True:
            m2 = reClose.search(text, end)
            if not m2:
                return      # unbalanced
            end = m2.end()
            if m2.lastindex == 1:
                npar += len(m2.group(1))
            else:
                close = len(m2.group(2))
                if close < npar:
                    npar -= close
                    if npar < ldelim:
                        # spurious {
                        if close == ldelim and all([text[i]=='{' for i in range(m1.start(),m1.start()+npar)]):
                            # we got a proper closing though
                            yield m1.start()+npar, end
                        cur = end
                        break
                    else:
                        cur = end
                else:
                    # resolve ambiguities
                    if ldelim == 3:
                        if close > 3 and all([text[i]=='{' for i in range(m1.start()+3,m1.start()+close)]):
                            yield m1.start()+close-3, end-close+3
                        elif text[m1.start()+3] == '{' and  text[m1.start()+4] != '{':
                            # spurious {
                            yield m1.start()+1, end
                        else:   # close >= npar
                            yield m1.start(), end-close+npar
                    else:    # ldelim == 2
                        yield m1.start(), end-close+npar
                    cur = end
                    break

def findBalanced(text, openDelim, closeDelim, openPatterns=None,
                 startDelim=None):
    """
    Assuming that text contains a properly balanced expression using
    :param openDelim: as opening delimiters and
    :param closeDelim: as closing delimiters.
    :param openPatterns: use these regex patterns for matching open delimiters.
      Sometimes patterns are ambiguous, hence specifying '{{{(?!{)' avoids
      matching '{{{{' for '{{{'.
    :param startDelim: start searching for this delimiter.
    :return: an iterator producing pairs (start, end) of start and end
    positions in text containing a balanced expression.
    """
    if openPatterns:
        openPat = '|'.join(openPatterns)
    else:
        openPat = '|'.join([re.escape(x) for x in openDelim])
    # patter for delimiters expected after each opening delimiter
    afterPat = { o:re.compile(openPat+'|'+c, re.DOTALL) for o,c in izip(openDelim, closeDelim)}
    stack = []
    start = 0
    cur = 0
    end = len(text)
    startSet = False
    if startDelim is not None:
        if openPatterns:
            startPat = re.compile(openPatterns[startDelim])
        else:
            startPat = re.compile(openDelim[startDelim])
    else:
        startPat = re.compile(openPat)
    nextPat = startPat
    while True:
        next = nextPat.search(text, cur)
        if not next:
            return
        if not startSet:
            start = next.start()
            startSet = True
        delim = next.group(0)
        if delim in openDelim:
            stack.append(delim)
            nextPat = afterPat[delim]
        else:
            opening = stack.pop()
            # assert opening == openDelim[closeDelim.index(next.group(0))]
            if stack:
                nextPat = afterPat[stack[-1]]
            else:
                yield start, next.end()
                nextPat = startPat
                start = next.end()
                startSet = False
        cur = next.end()

# ----------------------------------------------------------------------
# Modules

# Only minimal support
# FIXME: import Lua modules.

modules = {
    'convert' : {
        'convert': lambda x, u, *rest: x+' '+u, # no conversion
    }
}

# ----------------------------------------------------------------------
# variables

class MagicWords(object):
    """
    One copy in each Extractor.

    @see https://doc.wikimedia.org/mediawiki-core/master/php/MagicWord_8php_source.html
    """
    names = [
        '!',
        'currentmonth',
        'currentmonth1',
        'currentmonthname',
        'currentmonthnamegen',
        'currentmonthabbrev',
        'currentday',
        'currentday2',
        'currentdayname',
        'currentyear',
        'currenttime',
        'currenthour',
        'localmonth',
        'localmonth1',
        'localmonthname',
        'localmonthnamegen',
        'localmonthabbrev',
        'localday',
        'localday2',
        'localdayname',
        'localyear',
        'localtime',
        'localhour',
        'numberofarticles',
        'numberoffiles',
        'numberofedits',
        'articlepath',
        'pageid',
        'sitename',
        'server',
        'servername',
        'scriptpath',
        'stylepath',
        'pagename',
        'pagenamee',
        'fullpagename',
        'fullpagenamee',
        'namespace',
        'namespacee',
        'namespacenumber',
        'currentweek',
        'currentdow',
        'localweek',
        'localdow',
        'revisionid',
        'revisionday',
        'revisionday2',
        'revisionmonth',
        'revisionmonth1',
        'revisionyear',
        'revisiontimestamp',
        'revisionuser',
        'revisionsize',
        'subpagename',
        'subpagenamee',
        'talkspace',
        'talkspacee',
        'subjectspace',
        'subjectspacee',
        'talkpagename',
        'talkpagenamee',
        'subjectpagename',
        'subjectpagenamee',
        'numberofusers',
        'numberofactiveusers',
        'numberofpages',
        'currentversion',
        'rootpagename',
        'rootpagenamee',
        'basepagename',
        'basepagenamee',
        'currenttimestamp',
        'localtimestamp',
        'directionmark',
        'contentlanguage',
        'numberofadmins',
        'cascadingsources',
    ]

    def __init__(self):
        self.values = {}
        self.values['!'] = '|'

    def __getitem__(self, name):
        return self.values.get(name)

    def __setitem__(self, name, value):
        self.values[name] = value

# ----------------------------------------------------------------------
# parser functions utilities

def ucfirst(string):
    """:return: a string with its first character uppercase"""
    if string:
        if len(string) > 1:
            return string[0].upper() + string[1:]
        else:
            return string.upper()
    else:
        return ''

def lcfirst(string):
    """:return: a string with its first character lowercase"""
    if string:
        if len(string) > 1:
            return string[0].lower() + string[1:]
        else:
            return string.lower()
    else:
        return ''

def fullyQualifiedTemplateTitle(templateTitle):
    """
    Determine the namespace of the page being included through the template
    mechanism
    """
    if templateTitle.startswith(':'):
        # Leading colon by itself implies main namespace, so strip this colon
        return ucfirst(templateTitle[1:])
    else:
        m = re.match('([^:]*)(:.*)', templateTitle)
        if m:
            # colon found but not in the first position - check if it
            # designates a known namespace
            prefix = normalizeNamespace(m.group(1))
            if prefix in knownNamespaces:
                return prefix + ucfirst(m.group(2))
    # The title of the page being included is NOT in the main namespace and
    # lacks any other explicit designation of the namespace - therefore, it
    # is resolved to the Template namespace (that's the default for the
    # template inclusion mechanism).

    # This is a defense against pages whose title only contains UTF-8 chars
    # that are reduced to an empty string. Right now I can think of one such
    # case - <C2><A0> which represents the non-breaking space.
    # In this particular case, this page is a redirect to [[Non-nreaking
    # space]], but having in the system a redirect page with an empty title
    # causes numerous problems, so we'll live happier without it.
    if templateTitle:
        return "Template:" + ucfirst(templateTitle)
    else:
        logging.warn("Skipping page with empty title")
        return ''

def normalizeNamespace(ns):
    return ucfirst(ns)

# ----------------------------------------------------------------------
# see http://www.mediawiki.org/wiki/Help:Extension:ParserFunctions
# https://github.com/Wikia/app/blob/dev/extensions/ParserFunctions/ParserFunctions_body.php

class Infix:
    """Infix operators.
    The calling sequence for the infix is:
      x |op| y
    """
    def __init__(self, function):
        self.function = function
    def __ror__(self, other):
        return Infix(lambda x, self=self, other=other: self.function(other, x))
    def __or__(self, other):
        return self.function(other)
    def __rlshift__(self, other):
        return Infix(lambda x, self=self, other=other: self.function(other, x))
    def __rshift__(self, other):
        return self.function(other)
    def __call__(self, value1, value2):
        return self.function(value1, value2)

ROUND = Infix(lambda x,y: round(x, y))

def sharp_expr(expr):
    try:
        expr = re.sub('mod', '%', expr)
        expr = re.sub('\bdiv\b', '/', expr)
        expr = re.sub('\bround\b', '|ROUND|', expr)
        return str(eval(expr))
    except:
        return ""

def sharp_if(testValue, valueIfTrue, valueIfFalse=None, *args):
    if testValue.strip():
        # The {{#if:}} function is an if-then-else construct.
        # The applied condition is: "The condition string is non-empty".
        valueIfTrue = valueIfTrue.strip()
        if valueIfTrue:
            return valueIfTrue
    elif valueIfFalse:
        return valueIfFalse.strip()
    return ""

def sharp_ifeq(lvalue, rvalue, valueIfTrue, valueIfFalse=None, *args):
    rvalue = rvalue.strip()
    if rvalue:
        # lvalue is always defined
        if lvalue.strip() == rvalue:
            # The {{#ifeq:}} function is an if-then-else construct. The
            # applied condition is "is rvalue equal to lvalue". Note that this
            # does only string comparison while MediaWiki implementation also
            # supports numerical comparissons.

            if valueIfTrue:
                return valueIfTrue.strip()
        else:
            if valueIfFalse:
                return valueIfFalse.strip()
    return ""

def sharp_iferror(test, then='', Else=None, *args):
    if re.match('<(?:strong|span|p|div)\s(?:[^\s>]*\s+)*?class="(?:[^"\s>]*\s+)*?error(?:\s[^">]*)?"', test):
        return then
    elif Else is None:
        return test.strip()
    else:
        return Else.strip()

def sharp_switch(primary, *params):
    # FIXME: we don't support numeric expressions in primary

    # {{#switch: comparison string
    #  | case1 = result1
    #  | case2
    #  | case4 = result2
    #  | #default = result3
    # }}

    primary = primary.strip()
    found = False
    default = None
    rvalue = None
    lvalue = ''
    for param in params:
        # handle cases like:
        # [http://www.perseus.tufts.edu/hopper/text?doc=Perseus...]
        pair = splitParameters(param, '=')
        lvalue = pair[0].strip()
        rvalue = None
        if len(pair) > 1:
            # got "="
            rvalue = pair[1].strip()
            if found or lvalue == primary:
                # Found a match, return now
                return rvalue
            elif lvalue == '#default':
                default = rvalue
                rvalue = None   # avoid defaulting to last case
                # else wrong case, continue
        elif lvalue == primary:
            # If the value matches, set a flag and continue
            found = True
    # Default case
    # Check if the last item had no = sign, thus specifying the default case
    if rvalue is not None:
        return lvalue
    elif default is not None:
        return default
    return ''

# Extension Scribuntu
def sharp_invoke(module, function, frame):
    functions = modules.get(module)
    if functions:
        funct = functions.get(function)
        if funct:
            # find parameters in frame whose title is the one of the original
            # template invocation
            templateTitle = fullyQualifiedTemplateTitle(function)
            pair = next((x for x in frame if x[0] == templateTitle), None)
            if pair:
                params = pair[1]
                # extract positional args
                params = [params.get(str(i+1)) for i in range(len(params))]
                return funct(*params)
            else:
                return funct()
    return ''

parserFunctions = {

    '#expr': sharp_expr,

    '#if': sharp_if,

    '#ifeq': sharp_ifeq,

    '#iferror': sharp_iferror,

    '#ifexpr': lambda *args: '', # not supported

    '#ifexist': lambda *args: '', # not supported

    '#rel2abs': lambda *args: '', # not supported

    '#switch': sharp_switch,

    '#language': lambda *args: '', # not supported

    '#time': lambda *args: '', # not supported

    '#timel': lambda *args: '', # not supported

    '#titleparts': lambda *args: '', # not supported

    # This function is used in some pages to construct links
    # http://meta.wikimedia.org/wiki/Help:URL
    'urlencode': lambda string, *rest: urllib.quote(string.encode('utf-8')),

    'lc': lambda string: string.lower() if string else '',

    'lcfirst': lambda string: lcfirst(string),

    'lc': lambda string: string.upper() if string else '',

    'ucfirst': lambda string: ucfirst(string),

    'int': lambda  string: string,

}

def callParserFunction(functionName, args, frame):
    """
    Parser functions have similar syntax as templates, except that
    the first argument is everything after the first colon.
    :return: the result of the invocation, None in case of failure.

    http://meta.wikimedia.org/wiki/Help:ParserFunctions
    """

    try:
       if functionName == '#invoke':
           # special handling of frame
           ret = sharp_invoke(args[0].strip(), args[1].strip(), frame)
           logging.debug('parserFunction> ' + functionName + ' ' + ret)
           return ret
       if functionName in parserFunctions:
           ret = parserFunctions[functionName](*args)
           logging.debug('parserFunction> ' + functionName + ' ' + ret)
           return ret
    except:
        return ""             # FIXME: fix errors

    return ""

# ----------------------------------------------------------------------
# Expand using WikiMedia API
# import json

# def expandTemplates(text):
#     """Expand templates invoking MediaWiki API"""
#     text = urlib.urlencodew(text.encode('utf-8'))
#     base = urlbase[:urlbase.rfind('/')]
#     url = base + "/w/api.php?action=expandtemplates&format=json&text=" + text
#     exp = json.loads(urllib.urlopen(url))
#     return exp['expandtemplates']['*']

# ----------------------------------------------------------------------
# Extract Template definition

reNoinclude = re.compile(r'<noinclude>(?:.*?)</noinclude>', re.DOTALL)
reIncludeonly = re.compile(r'<includeonly>|</includeonly>', re.DOTALL)

templates = {}
redirects = {}

def define_template(title, page):
    global templates
    global redirects

    #title = normalizeTitle(title)

    # check for redirects
    m = re.match('#REDIRECT.*?\[\[([^\]]*)]]', page[0])
    if m:
        redirects[title] = m.group(1) #normalizeTitle(m.group(1))
        return

    text = unescape(''.join(page))

    # We're storing template text for future inclusion, therefore,
    # remove all <noinclude> text and keep all <includeonly> text
    # (but eliminate <includeonly> tags per se).
    # However, if <onlyinclude> ... </onlyinclude> parts are present,
    # then only keep them and discard the rest of the template body.
    # This is because using <onlyinclude> on a text fragment is
    # equivalent to enclosing it in <includeonly> tags **AND**
    # enclosing all the rest of the template body in <noinclude> tags.

    # remove comments
    text = comment.sub('', text)

    # eliminate <noinclude> fragments
    text = reNoinclude.sub('', text)
    # eliminate unterminated <noinclude> elements
    text = re.sub(r'<noinclude\s*>.*$', '', text, flags=re.DOTALL)

    onlyincludeAccumulator = ''
    for m in re.finditer('<onlyinclude>(.*?)</onlyinclude>', text, re.DOTALL):
        onlyincludeAccumulator += m.group(1)
    if onlyincludeAccumulator:
        text = onlyincludeAccumulator
    else:
        text = reIncludeonly.sub('', text)

    if text:
        if title in templates:
            logging.warn('Redefining: ' + title)
        templates[title] = text

# ----------------------------------------------------------------------

def dropNested(text, openDelim, closeDelim):
    """
    A matching function for nested expressions, e.g. namespaces and tables.
    """
    openRE = re.compile(openDelim)
    closeRE = re.compile(closeDelim)
    # partition text in separate blocks { } { }
    spans = []                # pairs (s, e) for each partition
    nest = 0                    # nesting level
    start = openRE.search(text, 0)
    if not start:
        return text
    end = closeRE.search(text, start.end())
    next = start
    while end:
        next = openRE.search(text, next.end())
        if not next:            # termination
            while nest:         # close all pending
                nest -=1
                end0 = closeRE.search(text, end.end())
                if end0:
                    end = end0
                else:
                    break
            spans.append((start.start(), end.end()))
            break
        while end.end() < next.start():
            # { } {
            if nest:
                nest -= 1
                # try closing more
                last = end.end()
                end = closeRE.search(text, end.end())
                if not end:     # unbalanced
                    if spans:
                        span = (spans[0][0], last)
                    else:
                        span = (start.start(), last)
                    spans = [span]
                    break
            else:
                spans.append((start.start(), end.end()))
                # advance start, find next close
                start = next
                end = closeRE.search(text, next.end())
                break           # { }
        if next != start:
            # { { }
            nest += 1
    # collect text outside partitions
    return dropSpans(spans, text)

def dropSpans(spans, text):
    """
    Drop from text the blocks identified in :param spans:, possibly nested.
    """
    spans.sort()
    res = ''
    offset = 0
    for s, e in  spans:
        if offset <= s:         # handle nesting
            if offset < s:
                res += text[offset:s]
            offset = e
    res += text[offset:]
    return res

# Match interwiki links, | separates parameters.
# First parameter is displayed, also trailing concatenated text included
# in display, e.g. 's' for plural).
#
# Can be nested [[File:..|..[[..]]..|..]], [[Category:...]], etc.
# We first expand inner ones, than remove enclosing ones.
# Deal also with: [[Help:IPA for Catalan|[anˈdɔra]]]

parametrizedLink = re.compile(r'\[\[[^\]]*?]]')

# Function applied to wikiLinks
def make_anchor_tag(link, trail):
    if link[1] == '[':
        parts = splitParameters(link[2:-2])
    else:
        parts = splitParameters(link[1:-1])
    link = parts[0]
    colon = link.find(':')
    if colon > 0 and link[:colon] not in acceptedNamespaces:
        return ''
    if colon == 0:
        # drop also :File:
        colon2 = link.find(':', colon+1)
        if colon2 > 1 and link[colon+1:colon2] not in acceptedNamespaces:
            return ''
    anchor = parts[-1] if len(parts) > 1 else link
    anchor += trail
    if keepLinks:
        return '<a href="%s">%s</a>' % (urllib.quote(link.encode('utf-8')), anchor)
    else:
        return anchor

# ----------------------------------------------------------------------

# match tail after wikilink
tailRE = re.compile('\w*')

expand_templates = True

def clean(extractor, text):

    if (expand_templates):
        # expand templates
        # See: http://www.mediawiki.org/wiki/Help:Templates
        text = extractor.expandTemplates(text)
    else:
        # Drop transclusions (template, parser functions)
        text = dropNested(text, r'{{', r'}}')

    # Drop tables
    text = dropNested(text, r'{\|', r'\|}')

    # Expand links
    res = ''
    cur = 0
    # This is too slow.
    # for m in wikiLink.finditer(text):
    #     res += text[cur:m.start()] + make_anchor_tag(m)
    #     cur = m.end()
    # text = res + text[cur:]
    # Matches also: [[Help:IPA for Spanish|[a'ðoβe]]]
    for s,e in findBalanced(text, ['[[', '['], [']]', ']']):
        m = tailRE.match(text, e)
        if m:
            trail = m.group(0)
            end = m.end()
        else:
            trail = ''
            end = e
        res += text[cur:s] + make_anchor_tag(text[s:e], trail)
        cur = end
    text = res + text[cur:]

    # Drop all remaining ones
    text = parametrizedLink.sub('', text)

    # Handle external links
    text = externalLink.sub(r'\1', text)
    text = externalLinkNoAnchor.sub('', text)

    # Handle bold/italic/quote
    text = bold_italic.sub(r'\1', text)
    text = bold.sub(r'\1', text)
    text = italic_quote.sub(r'&quot;\1&quot;', text)
    text = italic.sub(r'&quot;\1&quot;', text)
    text = quote_quote.sub(r'\1', text)
    # residuals of unbalanced quotes
    text = text.replace("'''", '').replace("''", '&quot;')

    ################ Process HTML ###############

    # turn into HTML
    text = unescape(text)
    # do it again (&amp;nbsp;)
    text = unescape(text)

    # Collect spans

    spans = []
    # Drop HTML comments
    for m in comment.finditer(text):
            spans.append((m.start(), m.end()))

    # Drop self-closing tags
    for pattern in selfClosing_tag_patterns:
        for m in pattern.finditer(text):
            spans.append((m.start(), m.end()))

    # Drop ignored tags
    for left, right in ignored_tag_patterns:
        for m in left.finditer(text):
            spans.append((m.start(), m.end()))
        for m in right.finditer(text):
            spans.append((m.start(), m.end()))

    # Bulk remove all spans
    text = dropSpans(spans, text)

    # Drop discarded elements
    spans = []
    for pattern in discard_element_patterns:
        for m in pattern.finditer(text):
            spans.append((m.start(),m.end()))
    # bulk removal
    text = dropSpans(spans, text)

    # Expand placeholders
    for pattern, placeholder in placeholder_tag_patterns:
        index = 1
        for match in pattern.finditer(text):
            text = text.replace(match.group(), '%s_%d' % (placeholder, index))
            index += 1

    text = text.replace('<<', u'«').replace('>>', u'»')

    #############################################

    # Cleanup text
    text = text.replace('\t', ' ')
    text = spaces.sub(' ', text)
    text = dots.sub('...', text)
    text = re.sub(u' (,:\.\)\]»)', r'\1', text)
    text = re.sub(u'(\[\(«) ', r'\1', text)
    text = re.sub(r'\n\W+?\n', '\n', text) # lines with only punctuations
    text = text.replace(',,', ',').replace(',.', '.')
    return text

section = re.compile(r'(==+)\s*(.*?)\s*\1')

def compact(text):
    """Deal with headers, lists, empty sections, residuals of tables"""
    page = []                   # list of paragraph
    headers = {}                # Headers for unfilled sections
    emptySection = False        # empty sections are discarded
    inList = False              # whether opened <UL>

    for line in text.split('\n'):

        if not line:
            continue
        # Handle section titles
        m = section.match(line)
        if m:
            title = m.group(2)
            lev = len(m.group(1))
            if keepSections:
                page.append("<h%d>%s</h%d>" % (lev, title, lev))
            if title and title[-1] not in '!?':
                title += '.'
            headers[lev] = title
            # drop previous headers
            for i in headers.keys():
                if i > lev:
                    del headers[i]
            emptySection = True
            continue
        # Handle page title
        if line.startswith('++'):
            title = line[2:-2]
            if title:
                if title[-1] not in '!?':
                    title += '.'
                page.append(title)
        # handle indents
        elif line[0] == ':':
            page.append(line[1:])
        # handle lists
        elif line[0] in '*#;':
            if keepSections:
                page.append("<li>%s</li>" % line[1:])
            else:
                continue

        # Drop residuals of lists
        elif line[0] in '{|' or line[-1] in '}':
            continue
        # Drop irrelevant lines
        elif (line[0] == '(' and line[-1] == ')') or line.strip('.-') == '':
            continue
        elif len(headers):
            items = headers.items()
            items.sort()
            for (i, v) in items:
                page.append(v)
            headers.clear()
            page.append(line)   # first line
            emptySection = False
        elif not emptySection:
            page.append(line)
        # dangerous
        # # Drop preformatted
        # elif line[0] == ' ':
        #     continue

    return page

def handle_unicode(entity):
    numeric_code = int(entity[2:-1])
    if numeric_code >= 0x10000: return ''
    return unichr(numeric_code)

#------------------------------------------------------------------------------
# Output

class NextFile(object):
    """
    Synchronous generation of next available file name.
    """

    filesPerDir = 100

    def __init__(self, lock, path_name):
        self.lock = lock
        self.path_name = path_name
        self.dir_index = -1
        self.file_index = -1

    def next(self):
        with self.lock:
            self.file_index = (self.file_index + 1) % NextFile.filesPerDir
            if self.file_index == 0:
                self.dir_index += 1
            dirname = self._dirname()
            if not os.path.isdir(dirname):
                os.makedirs(dirname)
            return self._filepath()

    def _dirname(self):
        char1 = self.dir_index % 26
        char2 = self.dir_index / 26 % 26
        return os.path.join(self.path_name, '%c%c' % (ord('A') + char2, ord('A') + char1))

    def _filepath(self):
        return '%s/wiki_%02d' % (self._dirname(), self.file_index)

class OutputSplitter(object):
    """
    File-like object, that splits output to multiple files of a given max size.
    """

    def __init__(self, nextFile, max_file_size=0, compress=True):
        """
        :param nextfile: a NextFile object from which to obtain filenames
            to use.
        :param max_file_size: the maximum size of each file.
        :para compress: whether to write data with bzip compression.
        """
        self.nextFile = nextFile
        self.compress = compress
        self.max_file_size = max_file_size
        self.file = self.open(self.nextFile.next())

    def reserve(self, size):
        if self.file.tell() + size > self.max_file_size:
            self.close()
            self.file = self.open(self.nextFile.next())

    def write(self, data):
        self.file.write(data)

    def close(self):
        self.file.close()

    def open(self, filename):
        if self.compress:
            return bz2.BZ2File(filename + '.bz2', 'w')
        else:
            return open(filename, 'w')

# ----------------------------------------------------------------------
# READER

tagRE = re.compile(r'(.*?)<(/?\w+)[^>]*>(?:([^<]*)(<.*?>)?)?')
#                    1     2               3      4
#tagRE = re.compile(r'(.*?)<(/?\w+)[^>]*>([^<]*)')

def load_templates(file, output_file=None):
    """
    Load templates from :param file:.
    :param output_file: file where to save templates.
    """
    templatePrefix = templateNamespace + ':'
    articles = 0
    page = []
    inText = False
    if output_file:
        output = codecs.open(output_file, 'wb', 'utf-8')
    for line in file:
        line = line.decode('utf-8')
        if '<' not in line:         # faster than doing re.search()
            if inText:
                page.append(line)
            continue
        m = tagRE.search(line)
        if not m:
            continue
        tag = m.group(2)
        if tag == 'page':
            page = []
        elif tag == 'title':
            title = m.group(3)
        elif tag == 'text':
            inText = True
            line = line[m.start(3):m.end(3)]
            page.append(line)
            if m.lastindex == 4: # open-close
                inText = False
        elif tag == '/text':
            if m.group(1):
                page.append(m.group(1))
            inText = False
        elif inText:
            page.append(line)
        elif tag == '/page':
            if title.startswith(templatePrefix):
                define_template(title, page)
                if output_file:
                    output.write('<page>\n')
                    output.write('   <title>%s</title>\n' % title)
                    output.write('   <ns>10</ns>\n')
                    output.write('   <text>')
                    for line in page:
                        output.write(line)
                    output.write('   </text>\n')
                    output.write('</page>\n')
            page = []
            articles += 1
            if articles % 10000 == 0:
                logging.info("Preprocessed: %d pages" % articles)

def process_dump(input_file, template_file, outdir, file_size, file_compress, threads):
    """
    :param input_file: name of the wikipedia dump file.
    :param template_file: optional file with template definitions.
    :param outdir: name of the directory where to store extracted files.
    :param file_size: max size of each extracted file.
    :param file_compress: whether to compress files with bzip.
    """
    global urlbase
    global knownNamespaces
    global templateNamespace
    global expand_templates

    if input_file.lower().endswith("bz2"):
        opener = bz2.BZ2File
    else:
        opener = open

    input = opener(input_file)

    # collect siteinfo
    for line in input:
        line = line.decode('utf-8')
        m = tagRE.search(line)
        if not  m:
            continue
        tag = m.group(2)
        if tag == 'base':
            # discover urlbase from the xml dump file
            # /mediawiki/siteinfo/base
            base = m.group(3)
            urlbase = base[:base.rfind("/")]
        elif tag == 'namespace':
            knownNamespaces.add(m.group(3))
            if re.search('key="10"', line):
                templateNamespace = m.group(3)
        elif tag == '/siteinfo':
            break

    if expand_templates:
        # preprocess
        logging.info("Preprocessing dump to collect template definitions: this may take some time.")
        if template_file and os.path.exists(template_file):
            input.close()
            with open(template_file) as file:
                load_templates(file)
        else:
            load_templates(input, template_file)
            input.close()
        input = opener(input_file)

    # process pages
    logging.info("Starting processing pages from %s." % input_file)

    # initialize jobs queue
    #threads = multiprocessing.cpu_count()
    logging.info("Using %d CPUs." % threads)
    queue = Queue.Queue(maxsize=2 * threads)
    lock = threading.Lock()  # for protecting shared state.

    nextFile = NextFile(lock, outdir)

    # start worker threads
    workers = []
    for _ in xrange(max(1, threads - 1)): # keep one for master
        output_splitter = OutputSplitter(nextFile, file_size, file_compress)
        extractor = ExtractorThread(queue, output_splitter)
        workers.append(extractor)

    # we collect indivual lines, since str.join() is significantly faster than
    # concatenation
    page = []
    id = None
    inText = False
    redirect = False
    for line in input:
        line = line.decode('utf-8')
        if '<' not in line:         # faster than doing re.search()
            if inText:
                page.append(line)
            continue
        m = tagRE.search(line)
        if not m:
            continue
        tag = m.group(2)
        if tag == 'page':
            page = []
            redirect = False
        elif tag == 'id' and not id:
            id = m.group(3)
        elif tag == 'title':
            title = m.group(3)
        elif tag == 'redirect':
            redirect = True
        elif tag == 'text':
            inText = True
            line = line[m.start(3):m.end(3)]
            page.append(line)
            if m.lastindex == 4: # open-close
                inText = False
        elif tag == '/text':
            if m.group(1):
                page.append(m.group(1))
            inText = False
        elif inText:
            page.append(line)
        elif tag == '/page':
            colon = title.find(':')
            if (colon < 0 or title[:colon] in acceptedNamespaces) and \
                    not redirect and not title.startswith(templateNamespace):
                queue.put(Extractor(id, title, page), True) # block if full
            id = None
            page = []

    # wait for empty queue
    queue.join()

    input.close()


#----------------------------------------------------------------------
# Multithread version

class ExtractorThread(threading.Thread):
    """
    Extractor thread.
    """
    def __init__(self, queue, splitter):
        self._queue = queue
        self._splitter = splitter
        threading.Thread.__init__(self)
        self.setDaemon(True)  # let the process die when main thread is killed
        self.start()

    def run(self):
        while True:
            job = self._queue.get()
            if job:
                job.extract(self._splitter)
                self._queue.task_done()
            else:
                break

# ----------------------------------------------------------------------

# Minimum size of output files
minFileSize = 200 * 1024

def main():
    global keepLinks, keepSections, urlbase, acceptedNamespaces
    global expand_templates

    parser = argparse.ArgumentParser(prog=os.path.basename(sys.argv[0]),
        formatter_class=argparse.RawDescriptionHelpFormatter,
                                     description=__doc__)
    parser.add_argument("input",
                        help="XML wiki dump file")
    parser.add_argument("-o", "--output", default="text",
                        help="output directory")
    parser.add_argument("-b", "--bytes", default="1M",
                        help="put specified bytes per output file (default is %(default)s)", metavar="n[KMG]")
    parser.add_argument("-B", "--base",
                        help="base URL for the Wikipedia pages")
    parser.add_argument("-c", "--compress", action="store_true",
                        help="compress output files using bzip")
    parser.add_argument("-l", "--links", action="store_true",
                        help="preserve links")
    parser.add_argument("-ns", "--namespaces", default="", metavar="ns1,ns2",
                        help="accepted namespaces")
    parser.add_argument("-q", "--quiet", action="store_true",
                        help="suppress reporting progress info")
    parser.add_argument("--debug", action="store_true",
                        help="print debug info")
    parser.add_argument("-s", "--sections", action="store_true",
                        help="preserve sections")
    parser.add_argument("-a", "--article", action="store_true",
                        help="analyze a file containing a single article (debug) option")
    # parser.add_argument("-f", "--format", choices=(PLAIN, JSON), default=PLAIN,
    #                     help="choose output format default is %(default)s")
    parser.add_argument("--templates",
                        help="use or create file containing templates")
    parser.add_argument("--no-templates", action="store_false",
                        help="Do not expand templates")
    parser.add_argument("--threads", type=int, default=2,
                        help="Number of threads to use (default 2)")
    parser.add_argument("-v", "--version", action="version",
                        version='%(prog)s ' + version,
                        help="print program version")

    args = parser.parse_args()

    keepLinks = args.links
    keepSections = args.sections
    expand_templates = args.no_templates

    if args.base:
        urlbase = args.base

    try:
        power = 'kmg'.find(args.bytes[-1].lower()) + 1
        file_size = int(args.bytes[:-1]) * 1024 ** power 
        if file_size < minFileSize: raise ValueError()
    except ValueError:
        logging.error('Insufficient or invalid size: %s' % args.bytes)
        return

    if args.namespaces:
        acceptedNamespaces = set(args.ns.split(','))

    logger = logging.getLogger()
    if not args.quiet:
        logger.setLevel(logging.INFO)
    if args.debug:
        logger.setLevel(logging.DEBUG)

    input_file = args.input

    if not keepLinks:
        ignoreTag('a')

    if args.article:
        if args.templates:
            if os.path.exists(args.templates):
                with open(args.templates) as file:
                    load_templates(file)

        with open(input_file) as file:
            page = file.read().decode('utf-8')
            m = re.search(r'<id>(.*)</id>', page)
            id = m.group(1) if m else 0
            m = re.search(r'<title>(.*)</title>', page)
            if m:
                title = m.group(1)
            Extractor(id, title, [page]).extract()
        return

    output_dir = args.output
    if not os.path.isdir(output_dir):
        try:
            os.makedirs(output_dir)
        except:
            logging.error('Could not create: %s' % output_dir)
            return

    process_dump(input_file, args.templates, output_dir, file_size,
                 args.compress, args.threads)

if __name__ == '__main__':
    main()