xref: /external/chromium_org/third_party/markdown/__init__.py

# markdown is released under the BSD license
# Copyright 2007, 2008 The Python Markdown Project (v. 1.7 and later)
# Copyright 2004, 2005, 2006 Yuri Takhteyev (v. 0.2-1.6b)
# Copyright 2004 Manfred Stienstra (the original version)
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# *   Redistributions of source code must retain the above copyright
#     notice, this list of conditions and the following disclaimer.
# *   Redistributions in binary form must reproduce the above copyright
#     notice, this list of conditions and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
# *   Neither the name of the <organization> nor the
#     names of its contributors may be used to endorse or promote products
#     derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE PYTHON MARKDOWN PROJECT ''AS IS'' AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL ANY CONTRIBUTORS TO THE PYTHON MARKDOWN PROJECT
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.


"""
Python Markdown
===============

Python Markdown converts Markdown to HTML and can be used as a library or
called from the command line.

## Basic usage as a module:

    import markdown
    html = markdown.markdown(your_text_string)

See <http://packages.python.org/Markdown/> for more
information and instructions on how to extend the functionality of
Python Markdown.  Read that before you try modifying this file.

## Authors and License

Started by [Manfred Stienstra](http://www.dwerg.net/).  Continued and
maintained  by [Yuri Takhteyev](http://www.freewisdom.org), [Waylan
Limberg](http://achinghead.com/) and [Artem Yunusov](http://blog.splyer.com).

Contact: markdown@freewisdom.org

Copyright 2007-2013 The Python Markdown Project (v. 1.7 and later)
Copyright 200? Django Software Foundation (OrderedDict implementation)
Copyright 2004, 2005, 2006 Yuri Takhteyev (v. 0.2-1.6b)
Copyright 2004 Manfred Stienstra (the original version)

License: BSD (see LICENSE for details).
"""

from __future__ import absolute_import
from __future__ import unicode_literals
from .__version__ import version, version_info
import re
import codecs
import sys
import logging
from . import util
from .preprocessors import build_preprocessors
from .blockprocessors import build_block_parser
from .treeprocessors import build_treeprocessors
from .inlinepatterns import build_inlinepatterns
from .postprocessors import build_postprocessors
from .extensions import Extension
from .serializers import to_html_string, to_xhtml_string

__all__ = ['Markdown', 'markdown', 'markdownFromFile']

logger = logging.getLogger('MARKDOWN')


class Markdown(object):
    """Convert Markdown to HTML."""

    doc_tag = "div"     # Element used to wrap document - later removed

    option_defaults = {
        'html_replacement_text' : '[HTML_REMOVED]',
        'tab_length'            : 4,
        'enable_attributes'     : True,
        'smart_emphasis'        : True,
        'lazy_ol'               : True,
    }

    output_formats = {
        'html'  : to_html_string,
        'html4' : to_html_string,
        'html5' : to_html_string,
        'xhtml' : to_xhtml_string,
        'xhtml1': to_xhtml_string,
        'xhtml5': to_xhtml_string,
    }

    ESCAPED_CHARS = ['\\', '`', '*', '_', '{', '}', '[', ']',
                    '(', ')', '>', '#', '+', '-', '.', '!']

    def __init__(self, *args, **kwargs):
        """
        Creates a new Markdown instance.

        Keyword arguments:

        * extensions: A list of extensions.
           If they are of type string, the module mdx_name.py will be loaded.
           If they are a subclass of markdown.Extension, they will be used
           as-is.
        * extension_configs: Configuration settingis for extensions.
        * output_format: Format of output. Supported formats are:
            * "xhtml1": Outputs XHTML 1.x. Default.
            * "xhtml5": Outputs XHTML style tags of HTML 5
            * "xhtml": Outputs latest supported version of XHTML (currently XHTML 1.1).
            * "html4": Outputs HTML 4
            * "html5": Outputs HTML style tags of HTML 5
            * "html": Outputs latest supported version of HTML (currently HTML 4).
            Note that it is suggested that the more specific formats ("xhtml1"
            and "html4") be used as "xhtml" or "html" may change in the future
            if it makes sense at that time.
        * safe_mode: Disallow raw html. One of "remove", "replace" or "escape".
        * html_replacement_text: Text used when safe_mode is set to "replace".
        * tab_length: Length of tabs in the source. Default: 4
        * enable_attributes: Enable the conversion of attributes. Default: True
        * smart_emphasis: Treat `_connected_words_` intelegently Default: True
        * lazy_ol: Ignore number of first item of ordered lists. Default: True

        """

        # For backward compatibility, loop through old positional args
        pos = ['extensions', 'extension_configs', 'safe_mode', 'output_format']
        c = 0
        for arg in args:
            if pos[c] not in kwargs:
                kwargs[pos[c]] = arg
            c += 1
            if c == len(pos):
                # ignore any additional args
                break

        # Loop through kwargs and assign defaults
        for option, default in self.option_defaults.items():
            setattr(self, option, kwargs.get(option, default))

        self.safeMode = kwargs.get('safe_mode', False)
        if self.safeMode and 'enable_attributes' not in kwargs:
            # Disable attributes in safeMode when not explicitly set
            self.enable_attributes = False

        self.registeredExtensions = []
        self.docType = ""
        self.stripTopLevelTags = True

        self.build_parser()

        self.references = {}
        self.htmlStash = util.HtmlStash()
        self.set_output_format(kwargs.get('output_format', 'xhtml1'))
        self.registerExtensions(extensions=kwargs.get('extensions', []),
                                configs=kwargs.get('extension_configs', {}))
        self.reset()

    def build_parser(self):
        """ Build the parser from the various parts. """
        self.preprocessors = build_preprocessors(self)
        self.parser = build_block_parser(self)
        self.inlinePatterns = build_inlinepatterns(self)
        self.treeprocessors = build_treeprocessors(self)
        self.postprocessors = build_postprocessors(self)
        return self

    def registerExtensions(self, extensions, configs):
        """
        Register extensions with this instance of Markdown.

        Keyword arguments:

        * extensions: A list of extensions, which can either
           be strings or objects.  See the docstring on Markdown.
        * configs: A dictionary mapping module names to config options.

        """
        for ext in extensions:
            if isinstance(ext, util.string_type):
                ext = self.build_extension(ext, configs.get(ext, []))
            if isinstance(ext, Extension):
                ext.extendMarkdown(self, globals())
            elif ext is not None:
                raise TypeError(
                    'Extension "%s.%s" must be of type: "markdown.Extension"'
                    % (ext.__class__.__module__, ext.__class__.__name__))

        return self

    def build_extension(self, ext_name, configs = []):
        """Build extension by name, then return the module.

        The extension name may contain arguments as part of the string in the
        following format: "extname(key1=value1,key2=value2)"

        """

        # Parse extensions config params (ignore the order)
        configs = dict(configs)
        pos = ext_name.find("(") # find the first "("
        if pos > 0:
            ext_args = ext_name[pos+1:-1]
            ext_name = ext_name[:pos]
            pairs = [x.split("=") for x in ext_args.split(",")]
            configs.update([(x.strip(), y.strip()) for (x, y) in pairs])

        # Setup the module name
        module_name = ext_name
        if '.' not in ext_name:
            module_name = '.'.join(['third_party.markdown.extensions', ext_name])

        # Try loading the extension first from one place, then another
        try: # New style (markdown.extensons.<extension>)
            module = __import__(module_name, {}, {}, [module_name.rpartition('.')[0]])
        except ImportError:
            module_name_old_style = '_'.join(['mdx', ext_name])
            try: # Old style (mdx_<extension>)
                module = __import__(module_name_old_style)
            except ImportError as e:
                message = "Failed loading extension '%s' from '%s' or '%s'" \
                    % (ext_name, module_name, module_name_old_style)
                e.args = (message,) + e.args[1:]
                raise

        # If the module is loaded successfully, we expect it to define a
        # function called makeExtension()
        try:
            return module.makeExtension(configs.items())
        except AttributeError as e:
            message = e.args[0]
            message = "Failed to initiate extension " \
                      "'%s': %s" % (ext_name, message)
            e.args = (message,) + e.args[1:]
            raise

    def registerExtension(self, extension):
        """ This gets called by the extension """
        self.registeredExtensions.append(extension)
        return self

    def reset(self):
        """
        Resets all state variables so that we can start with a new text.
        """
        self.htmlStash.reset()
        self.references.clear()

        for extension in self.registeredExtensions:
            if hasattr(extension, 'reset'):
                extension.reset()

        return self

    def set_output_format(self, format):
        """ Set the output format for the class instance. """
        self.output_format = format.lower()
        try:
            self.serializer = self.output_formats[self.output_format]
        except KeyError as e:
            valid_formats = list(self.output_formats.keys())
            valid_formats.sort()
            message = 'Invalid Output Format: "%s". Use one of %s.' \
                       % (self.output_format,
                          '"' + '", "'.join(valid_formats) + '"')
            e.args = (message,) + e.args[1:]
            raise
        return self

    def convert(self, source):
        """
        Convert markdown to serialized XHTML or HTML.

        Keyword arguments:

        * source: Source text as a Unicode string.

        Markdown processing takes place in five steps:

        1. A bunch of "preprocessors" munge the input text.
        2. BlockParser() parses the high-level structural elements of the
           pre-processed text into an ElementTree.
        3. A bunch of "treeprocessors" are run against the ElementTree. One
           such treeprocessor runs InlinePatterns against the ElementTree,
           detecting inline markup.
        4. Some post-processors are run against the text after the ElementTree
           has been serialized into text.
        5. The output is written to a string.

        """

        # Fixup the source text
        if not source.strip():
            return ''  # a blank unicode string

        try:
            source = util.text_type(source)
        except UnicodeDecodeError as e:
            # Customise error message while maintaining original trackback
            e.reason += '. -- Note: Markdown only accepts unicode input!'
            raise

        # Split into lines and run the line preprocessors.
        self.lines = source.split("\n")
        for prep in self.preprocessors.values():
            self.lines = prep.run(self.lines)

        # Parse the high-level elements.
        root = self.parser.parseDocument(self.lines).getroot()

        # Run the tree-processors
        for treeprocessor in self.treeprocessors.values():
            newRoot = treeprocessor.run(root)
            if newRoot:
                root = newRoot

        # Serialize _properly_.  Strip top-level tags.
        output = self.serializer(root)
        if self.stripTopLevelTags:
            try:
                start = output.index('<%s>'%self.doc_tag)+len(self.doc_tag)+2
                end = output.rindex('</%s>'%self.doc_tag)
                output = output[start:end].strip()
            except ValueError:
                if output.strip().endswith('<%s />'%self.doc_tag):
                    # We have an empty document
                    output = ''
                else:
                    # We have a serious problem
                    raise ValueError('Markdown failed to strip top-level tags. Document=%r' % output.strip())

        # Run the text post-processors
        for pp in self.postprocessors.values():
            output = pp.run(output)

        return output.strip()

    def convertFile(self, input=None, output=None, encoding=None):
        """Converts a markdown file and returns the HTML as a unicode string.

        Decodes the file using the provided encoding (defaults to utf-8),
        passes the file content to markdown, and outputs the html to either
        the provided stream or the file with provided name, using the same
        encoding as the source file. The 'xmlcharrefreplace' error handler is
        used when encoding the output.

        **Note:** This is the only place that decoding and encoding of unicode
        takes place in Python-Markdown.  (All other code is unicode-in /
        unicode-out.)

        Keyword arguments:

        * input: File object or path. Reads from stdin if `None`.
        * output: File object or path. Writes to stdout if `None`.
        * encoding: Encoding of input and output files. Defaults to utf-8.

        """

        encoding = encoding or "utf-8"

        # Read the source
        if input:
            if isinstance(input, util.string_type):
                input_file = codecs.open(input, mode="r", encoding=encoding)
            else:
                input_file = codecs.getreader(encoding)(input)
            text = input_file.read()
            input_file.close()
        else:
            text = sys.stdin.read()
            if not isinstance(text, util.text_type):
                text = text.decode(encoding)

        text = text.lstrip('\ufeff') # remove the byte-order mark

        # Convert
        html = self.convert(text)

        # Write to file or stdout
        if output:
            if isinstance(output, util.string_type):
                output_file = codecs.open(output, "w",
                                          encoding=encoding,
                                          errors="xmlcharrefreplace")
                output_file.write(html)
                output_file.close()
            else:
                writer = codecs.getwriter(encoding)
                output_file = writer(output, errors="xmlcharrefreplace")
                output_file.write(html)
                # Don't close here. User may want to write more.
        else:
            # Encode manually and write bytes to stdout.
            html = html.encode(encoding, "xmlcharrefreplace")
            try:
                # Write bytes directly to buffer (Python 3).
                sys.stdout.buffer.write(html)
            except AttributeError:
                # Probably Python 2, which works with bytes by default.
                sys.stdout.write(html)

        return self


"""
EXPORTED FUNCTIONS
=============================================================================

Those are the two functions we really mean to export: markdown() and
markdownFromFile().
"""

def markdown(text, *args, **kwargs):
    """Convert a markdown string to HTML and return HTML as a unicode string.

    This is a shortcut function for `Markdown` class to cover the most
    basic use case.  It initializes an instance of Markdown, loads the
    necessary extensions and runs the parser on the given text.

    Keyword arguments:

    * text: Markdown formatted text as Unicode or ASCII string.
    * Any arguments accepted by the Markdown class.

    Returns: An HTML document as a string.

    """
    md = Markdown(*args, **kwargs)
    return md.convert(text)


def markdownFromFile(*args, **kwargs):
    """Read markdown code from a file and write it to a file or a stream.

    This is a shortcut function which initializes an instance of Markdown,
    and calls the convertFile method rather than convert.

    Keyword arguments:

    * input: a file name or readable object.
    * output: a file name or writable object.
    * encoding: Encoding of input and output.
    * Any arguments accepted by the Markdown class.

    """
    # For backward compatibility loop through positional args
    pos = ['input', 'output', 'extensions', 'encoding']
    c = 0
    for arg in args:
        if pos[c] not in kwargs:
            kwargs[pos[c]] = arg
        c += 1
        if c == len(pos):
            break

    md = Markdown(**kwargs)
    md.convertFile(kwargs.get('input', None),
                   kwargs.get('output', None),
                   kwargs.get('encoding', None))