mirror of https://github.com/patacrep/patacrep.git
Engine for LaTeX songbooks
http://www.patacrep.com
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239 lines
8.4 KiB
239 lines
8.4 KiB
"""Template for .tex generation settings and utilities"""
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from jinja2 import Environment, FileSystemLoader, ChoiceLoader, \
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TemplateNotFound, nodes
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from jinja2.ext import Extension
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from jinja2.meta import find_referenced_templates as find_templates
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import os
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import re
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import json
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from patacrep import errors, files
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from patacrep.latex import lang2babel
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import patacrep.encoding
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_LATEX_SUBS = (
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(re.compile(r'\\'), r'\\textbackslash'),
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(re.compile(r'([{}_#%&$])'), r'\\\1'),
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(re.compile(r'~'), r'\~{}'),
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(re.compile(r'\^'), r'\^{}'),
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(re.compile(r'"'), r"''"),
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(re.compile(r'\.\.\.+'), r'\\ldots'),
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)
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_VARIABLE_REGEXP = re.compile(
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r"""
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\(\*-?\ *variables\ *\*\) # Match (* variables *) or (*- variables *)
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( # Match and capture the following:
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(?: # Start of non-capturing group, used to match a single character
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(?! # only if it's impossible to match the following:
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\(\*-?\ * # - a literal (* or (*-
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(?: # Inner non-capturing group, used for the following alternation:
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variables # - Either match the word variables
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| # or
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endvariables # - the word endvariables
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) # End of inner non-capturing group
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\ *-?\*\) # - a literal *) or -*)
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) # End of negative lookahead assertion
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. # Match any single character
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)* # Repeat as often as possible
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) # End of capturing group 1
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\(\*\ *endvariables\ *-?\*\) # until (* endvariables *) or (* endvariables -*) is matched.
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""",
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re.VERBOSE|re.DOTALL)
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class VariablesExtension(Extension):
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"""Extension to jinja2 to silently ignore variable block.
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Instead, they are parsed by this module.
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"""
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# pylint: disable=too-few-public-methods
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tags = set(['variables'])
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def parse(self, parser):
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next(parser.stream)
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parser.parse_statements(
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end_tokens=['name:endvariables'],
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drop_needle=True,
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)
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return nodes.Const("") # pylint: disable=no-value-for-parameter
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def _escape_tex(value):
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'''Escape TeX special characters'''
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newval = value
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for pattern, replacement in _LATEX_SUBS:
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newval = pattern.sub(replacement, newval)
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return newval
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class Renderer:
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"""Render a template to a LaTeX file."""
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# pylint: disable=too-few-public-methods
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def __init__(self, template, jinjaenv, encoding=None):
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self.encoding = encoding
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self.jinjaenv = jinjaenv
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self.jinjaenv.block_start_string = '(*'
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self.jinjaenv.block_end_string = '*)'
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self.jinjaenv.variable_start_string = '(('
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self.jinjaenv.variable_end_string = '))'
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self.jinjaenv.comment_start_string = '(% comment %)'
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self.jinjaenv.comment_end_string = '(% endcomment %)'
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self.jinjaenv.line_comment_prefix = '%!'
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self.jinjaenv.filters['escape_tex'] = _escape_tex
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self.jinjaenv.trim_blocks = True
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self.jinjaenv.lstrip_blocks = True
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self.jinjaenv.globals["path2posix"] = files.path2posix
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self.jinjaenv.globals["lang2babel"] = lang2babel
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self.template = self.jinjaenv.get_template(template)
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class TexBookRenderer(Renderer):
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"""Tex renderer for the whole songbook"""
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def __init__(self, template, datadirs, lang, encoding=None):
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'''Start a new jinja2 environment for .tex creation.
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Arguments:
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- template: name of the template to use.
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- datadirs: list of locations of the data directory
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(which may contain file <datadir>/templates/<template>).
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- lang: main language of songbook.
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- encoding: if set, encoding of the template.
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'''
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self.lang = lang
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# Load templates in filesystem ...
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loaders = [
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FileSystemLoader(os.path.join(datadir, 'templates'))
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for datadir in datadirs
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]
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jinjaenv = Environment(
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loader=ChoiceLoader(loaders),
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extensions=[VariablesExtension],
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)
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try:
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super().__init__(template, jinjaenv, encoding)
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except TemplateNotFound as exception:
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# Only works if all loaders are FileSystemLoader().
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paths = [
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item
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for loader in self.jinjaenv.loader.loaders
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for item in loader.searchpath
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]
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raise errors.TemplateError(
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exception,
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errors.notfound(
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exception.name,
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paths,
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message='Template "{name}" not found in {paths}.'
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),
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)
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def get_variables(self):
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'''Get and return a dictionary with the default values
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for all the variables
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'''
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data = self.get_template_variables(self.template)
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variables = dict()
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for name, param in data.items():
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variables[name] = self._get_default(param)
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return variables
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def _get_default(self, parameter):
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'''Get the default value for the parameter, according to the language.
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'''
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default = None
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try:
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default = parameter['default']
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except KeyError:
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return None
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if self.lang in default:
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variable = default[self.lang]
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elif "default" in default:
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variable = default["default"]
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elif "en" in default:
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variable = default["en"]
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elif len(default):
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variable = default.popitem()[1]
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else:
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variable = None
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return variable
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def get_template_variables(self, template, skip=None):
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"""Parse the template to extract the variables as a dictionary.
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If the template includes or extends other templates, load them as well.
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Arguments:
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- template: the name of the template, as a string.
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- skip: a list of templates (as strings) to skip: if they are included
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in 'template' (or one of its subtemplates), it is not parsed.
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"""
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if not skip:
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skip = []
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variables = {}
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(current, templates) = self.parse_template(template)
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for subtemplate in templates:
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if subtemplate in skip:
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continue
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variables.update(
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self.get_template_variables(
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subtemplate,
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skip + templates
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)
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)
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variables.update(current)
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return variables
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def parse_template(self, template):
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"""Return (variables, templates).
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Argument:
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- template: name of the template to parse.
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Return values:
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- variables: a dictionary of variables contained in 'template', NOT
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recursively (included templates are not parsed).
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- templates: list of included temlates, NOT recursively.
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"""
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subvariables = {}
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templatename = self.jinjaenv.get_template(template).filename
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with patacrep.encoding.open_read(
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templatename,
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encoding=self.encoding
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) as template_file:
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content = template_file.read()
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subtemplates = list(find_templates(self.jinjaenv.parse(content)))
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match = re.findall(_VARIABLE_REGEXP, content)
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if match:
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for var in match:
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try:
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subvariables.update(json.loads(var))
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except ValueError as exception:
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raise errors.TemplateError(
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exception,
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(
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"Error while parsing json in file "
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"{filename}. The json string was:"
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"\n'''\n{jsonstring}\n'''"
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).format(
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filename=templatename,
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jsonstring=var,
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)
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)
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return (subvariables, subtemplates)
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def render_tex(self, output, context):
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'''Render a template into a .tex file
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Arguments:
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- output: a file object to write the result
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- context: a dict of all the data to populate the template
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'''
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output.write(self.template.render(context))
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