jupyter_nbconvert/exporters/pdf.py

"""Export to PDF via latex"""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

import subprocess
import os
import sys

from IPython.utils.py3compat import which
from IPython.utils.traitlets import Integer, List, Bool, Instance
from IPython.utils.tempdir import TemporaryWorkingDirectory
from .latex import LatexExporter


class PDFExporter(LatexExporter):
    """Writer designed to write to PDF files"""

    latex_count = Integer(3, config=True,
        help="How many times latex will be called."
    )

    latex_command = List([u"pdflatex", u"{filename}"], config=True, 
        help="Shell command used to compile latex."
    )

    bib_command = List([u"bibtex", u"{filename}"], config=True,
        help="Shell command used to run bibtex."
    )

    verbose = Bool(False, config=True,
        help="Whether to display the output of latex commands."
    )

    temp_file_exts = List(['.aux', '.bbl', '.blg', '.idx', '.log', '.out'], config=True,
        help="File extensions of temp files to remove after running."
    )
    
    writer = Instance("jupyter_nbconvert.writers.FilesWriter", args=())

    def run_command(self, command_list, filename, count, log_function):
        """Run command_list count times.
        
        Parameters
        ----------
        command_list : list
            A list of args to provide to Popen. Each element of this
            list will be interpolated with the filename to convert.
        filename : unicode
            The name of the file to convert.
        count : int
            How many times to run the command.
        
        Returns
        -------
        success : bool
            A boolean indicating if the command was successful (True)
            or failed (False).
        """
        command = [c.format(filename=filename) for c in command_list]

        # On windows with python 2.x there is a bug in subprocess.Popen and
        # unicode commands are not supported
        if sys.platform == 'win32' and sys.version_info < (3,0):
            #We must use cp1252 encoding for calling subprocess.Popen
            #Note that sys.stdin.encoding and encoding.DEFAULT_ENCODING
            # could be different (cp437 in case of dos console)
            command = [c.encode('cp1252') for c in command]

        # This will throw a clearer error if the command is not found
        cmd = which(command_list[0])
        if cmd is None:
            raise OSError("%s not found on PATH" % command_list[0])
        
        times = 'time' if count == 1 else 'times'
        self.log.info("Running %s %i %s: %s", command_list[0], count, times, command)
        with open(os.devnull, 'rb') as null:
            stdout = subprocess.PIPE if not self.verbose else None
            for index in range(count):
                p = subprocess.Popen(command, stdout=stdout, stdin=null)
                out, err = p.communicate()
                if p.returncode:
                    if self.verbose:
                        # verbose means I didn't capture stdout with PIPE,
                        # so it's already been displayed and `out` is None.
                        out = u''
                    else:
                        out = out.decode('utf-8', 'replace')
                    log_function(command, out)
                    return False # failure
        return True # success

    def run_latex(self, filename):
        """Run pdflatex self.latex_count times."""

        def log_error(command, out):
            self.log.critical(u"%s failed: %s\n%s", command[0], command, out)

        return self.run_command(self.latex_command, filename, 
            self.latex_count, log_error)

    def run_bib(self, filename):
        """Run bibtex self.latex_count times."""
        filename = os.path.splitext(filename)[0]

        def log_error(command, out):
            self.log.warn('%s had problems, most likely because there were no citations',
                command[0])
            self.log.debug(u"%s output: %s\n%s", command[0], command, out)

        return self.run_command(self.bib_command, filename, 1, log_error)

    def clean_temp_files(self, filename):
        """Remove temporary files created by pdflatex/bibtex."""
        self.log.info("Removing temporary LaTeX files")
        filename = os.path.splitext(filename)[0]
        for ext in self.temp_file_exts:
            try:
                os.remove(filename+ext)
            except OSError:
                pass

    def from_notebook_node(self, nb, resources=None, **kw):
        latex, resources = super(PDFExporter, self).from_notebook_node(
            nb, resources=resources, **kw
        )
        with TemporaryWorkingDirectory() as td:
            notebook_name = "notebook"
            tex_file = self.writer.write(latex, resources, notebook_name=notebook_name)
            self.log.info("Building PDF")
            rc = self.run_latex(tex_file)
            if not rc:
                rc = self.run_bib(tex_file)
            if not rc:
                rc = self.run_latex(tex_file)
            
            pdf_file = notebook_name + '.pdf'
            if not os.path.isfile(pdf_file):
                raise RuntimeError("PDF creating failed")
            self.log.info('PDF successfully created')
            with open(pdf_file, 'rb') as f:
                pdf_data = f.read()
        
        # convert output extension to pdf
        # the writer above required it to be tex
        resources['output_extension'] = '.pdf'
        
        return pdf_data, resources