converters/transformers.py

"""

"""

from __future__ import print_function


from IPython.config.configurable import Configurable
from IPython.utils.traitlets import Unicode, Bool, Dict, List

class ConfigurableTransformers(Configurable):
    """ A configurable transformer """

    def __init__(self, config=None, **kw):
        super(ConfigurableTransformers, self).__init__(config=config, **kw)

    def __call__(self, nb, other):
        try :
            for worksheet in nb.worksheets :
                for index, cell in enumerate(worksheet.cells):
                    worksheet.cells[index], other = self.cell_transform(cell, other, index)
            return nb, other
        except NotImplementedError:
            raise NotImplementedError('should be implemented by subclass')

    def cell_transform(self, cell, other, index):
        """
        Overwrite if you want to apply a transformation on each cell
        """
        raise NotImplementedError('should be implemented by subclass')


class ActivatableTransformer(ConfigurableTransformers):

    enabled = Bool(False, config=True)

    def __call__(self, nb, other):
        if not self.enabled :
            return nb, other
        else :
            return super(ActivatableTransformer, self).__call__(nb, other)


def cell_preprocessor(function):
    """ wrap a function to be executed on all cells of a notebook

    wrapped function  parameters :
    cell  : the cell
    other : external resources
    index : index of the cell
    """
    def wrappedfunc(nb, other):
        for worksheet in nb.worksheets :
            for index, cell in enumerate(worksheet.cells):
                worksheet.cells[index], other = function(cell, other, index)
        return nb, other
    return wrappedfunc


@cell_preprocessor
def haspyout_transformer(cell, other, count):
    """
    Add a haspyout flag to cell that have it

    Easier for templating, where you can't know in advance
    wether to write the out prompt

    """
    cell.type = cell.cell_type
    cell.haspyout = False
    for out in cell.get('outputs', []):
        if out.output_type == 'pyout':
            cell.haspyout = True
            break
    return cell, other

@cell_preprocessor
def coalesce_streams(cell, other, count):
    """merge consecutive sequences of stream output into single stream

    to prevent extra newlines inserted at flush calls

    TODO: handle \r deletion
    """
    outputs = cell.get('outputs', [])
    if not outputs:
        return cell, other
    new_outputs = []
    last = outputs[0]
    new_outputs = [last]
    for output in outputs[1:]:
        if (output.output_type == 'stream' and
            last.output_type == 'stream' and
            last.stream == output.stream
        ):
            last.text += output.text
        else:
            new_outputs.append(output)

    cell.outputs = new_outputs
    return cell, other



class ExtractFigureTransformer(ActivatableTransformer):

    extra_ext_map =  Dict({},
            config=True,
            help="""extra map to override extension based on type.
            Usefull for latex where svg will be converted to pdf before inclusion
            """
            )
    display_data_priority = List(['html', 'pdf', 'svg', 'latex', 'png', 'jpg', 'jpeg' , 'text'],
            config=True,
              help= """
                    An ordered list of prefered output type, the first
                    encounterd will usually be used when converting discarding
                    the others.
                    """
            )

    key_format_map =  Dict({},
            config=True,
            )

    figname_format_map =  Dict({},
            config=True,
            )

    #to do change this to .format {} syntax
    default_key_tpl = Unicode('_fig_{count:02d}.{ext}', config=True)

    def _get_ext(self, ext):
        if ext in self.extra_ext_map :
            return self.extra_ext_map[ext]
        return ext

    def _new_figure(self, data, fmt, count):
        """Create a new figure file in the given format.

        """
        tplf = self.figname_format_map.get(fmt,self.default_key_tpl)
        tplk = self.key_format_map.get(fmt,self.default_key_tpl)

        # option to pass the hash as data ?
        figname = tplf.format(count=count, ext=self._get_ext(fmt))
        key     = tplk.format(count=count, ext=self._get_ext(fmt))

        # Binary files are base64-encoded, SVG is already XML
        if fmt in ('png', 'jpg', 'pdf'):
            data = data.decode('base64')

        return figname, key, data


    def cell_transform(self, cell, other, count):
        if other.get('figures', None) is None :
            other['figures'] = {}
        for out in cell.get('outputs', []):
            for out_type in self.display_data_priority:
                if out.hasattr(out_type):
                    figname, key, data = self._new_figure(out[out_type], out_type, count)
                    out['key_'+out_type] = figname
                    other['figures'][key] = data
                    count = count+1
        return cell, other

class RevealHelpTransformer(ConfigurableTransformers):

    def __call__(self, nb, other):
        try :
            for worksheet in nb.worksheets :
                for i, cell in enumerate(worksheet.cells):
                    cell.metadata.slide_type = cell.metadata.get('slideshow', {}).get('slide_type', None)
                    if cell.metadata.slide_type is None:
                        cell.metadata.slide_type = '-'
                    if cell.metadata.slide_type in ['slide']:
                        worksheet.cells[i - 1].metadata.slide_helper = 'slide_end'
                    if cell.metadata.slide_type in ['subslide']:
                        worksheet.cells[i - 1].metadata.slide_helper = 'subslide_end'
            return nb, other
        except NotImplementedError as error :
            raise NotImplementedError('should be implemented by subclass')


class CSSHtmlHeaderTransformer(ActivatableTransformer):

    def __call__(self, nb, resources):
        """Fetch and add css to the resource dict

        Fetch css from IPython adn Pygment to add at the beginning
        of the html files.

        Add this css in resources in the "inlining.css" key
        """
        resources['inlining'] = {}
        resources['inlining']['css'] = self.header
        return nb, resources

    header = []

    def __init__(self, config=None, **kw):
        super(CSSHtmlHeaderTransformer, self).__init__(config=config, **kw)
        if self.enabled :
            self.regen_header()

    def regen_header(self):
        ## lazy load asa this might not be use in many transformers
        import os
        from IPython.utils import path
        import io
        from pygments.formatters import HtmlFormatter
        header = []
        static = os.path.join(path.get_ipython_package_dir(),
            'frontend', 'html', 'notebook', 'static',
        )
        here = os.path.split(os.path.realpath(__file__))[0]
        css = os.path.join(static, 'css')
        for sheet in [
            # do we need jquery and prettify?
            # os.path.join(static, 'jquery', 'css', 'themes', 'base',
            # 'jquery-ui.min.css'),
            # os.path.join(static, 'prettify', 'prettify.css'),
            os.path.join(css, 'boilerplate.css'),
            os.path.join(css, 'fbm.css'),
            os.path.join(css, 'notebook.css'),
            os.path.join(css, 'renderedhtml.css'),
            os.path.join(css, 'style.min.css'),
            # our overrides:
            os.path.join(here, '..', 'css', 'static_html.css'),
        ]:
            try:
                with io.open(sheet, encoding='utf-8') as f:
                    s = f.read()
                    header.append(s)
            except IOError:
                # new version of ipython with style.min.css, pass
                pass

        pygments_css = HtmlFormatter().get_style_defs('.highlight')
        header.append(pygments_css)
        self.header = header