From 6a61bb1a866a85ee99103088100a801a693efe2a Mon Sep 17 00:00:00 2001
From: Louis <spalax@gresille.org>
Date: Wed, 12 Mar 2014 16:01:20 +0100
Subject: [PATCH] =?UTF-8?q?Am=C3=A9liorations=20du=20moteur=20de=20templat?=
 =?UTF-8?q?e=20(#9)?=
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- résolution d'un bug si le template choisi n'est pas dans datadir.
- création d'une classe templateRenderer
- correction de l'ordre de séléction des template (d'abord datadir, puis
  par défaut)
- chargement d'un langage par défaut pour que la compilation ne plante
  pas, même avec un carnet de chants vide
---
 songbook_core/build.py     | 16 ++++----
 songbook_core/songs.py     |  6 ++-
 songbook_core/templates.py | 80 ++++++++++++++++++++++----------------
 3 files changed, 60 insertions(+), 42 deletions(-)

diff --git a/songbook_core/build.py b/songbook_core/build.py
index 03f0f557..e16703af 100755
--- a/songbook_core/build.py
+++ b/songbook_core/build.py
@@ -16,7 +16,7 @@ from songbook_core import errors
 from songbook_core.files import recursive_find
 from songbook_core.index import process_sxd
 from songbook_core.songs import Song, SongsList
-from songbook_core.templates import render_tex
+from songbook_core.templates import TexRenderer
 
 EOL = "\n"
 DEFAULT_AUTHWORDS = {
@@ -129,17 +129,19 @@ class Songbook(object):
         Arguments:
         - output: a file object, in which the file will be written.
         """
-        context = parse_template(os.path.join(
-                            self.config['datadir'],
-                            'templates',
-                            self.config['template']
-                            ))
+        renderer = TexRenderer(
+                self.config['template'],
+                self.config['datadir'],
+                )
+
+        context = parse_template(renderer.file_template())
 
         context.update(self.config)
         context['titleprefixkeys'] = ["after", "sep", "ignore"]
         context['songlist'] = self.songslist
         context['filename'] = output.name[:-4]
-        render_tex(output, context, self.config['datadir'])
+
+        renderer.render_tex(output, context)
 
 
 def clean(basename):
diff --git a/songbook_core/songs.py b/songbook_core/songs.py
index f0c8811b..ed047e8c 100644
--- a/songbook_core/songs.py
+++ b/songbook_core/songs.py
@@ -128,4 +128,8 @@ class SongsList(object):
 
     def languages(self):
         """Renvoie la liste des langues utilisées par les chansons"""
-        return set().union(*[set(song.languages) for song in self.songs])
+        languages = set().union(*[set(song.languages) for song in self.songs])
+        if languages:
+            return languages
+        else:
+            return set(['english'])
diff --git a/songbook_core/templates.py b/songbook_core/templates.py
index 0af2afc2..94107cb1 100644
--- a/songbook_core/templates.py
+++ b/songbook_core/templates.py
@@ -23,38 +23,50 @@ def _escape_tex(value):
         newval = pattern.sub(replacement, newval)
     return newval
 
+class TexRenderer(object):
+    """Render a template to a LaTeX file."""
 
-def _init_tex_env(datadir=''):
-    '''Start a new jinja2 environment for .tex creation'''
-    loader = ChoiceLoader([
-                    PackageLoader('songbook_core', 'data/templates'),
-                    FileSystemLoader(os.path.join(datadir, 'templates')),
-                           ])
-    texenv = Environment(loader=loader)
-    texenv.block_start_string = '(*'
-    texenv.block_end_string = '*)'
-    texenv.variable_start_string = '(('
-    texenv.variable_end_string = '))'
-    texenv.comment_start_string = '(% comment %)'
-    texenv.comment_end_string = '(% endcomment %)'
-    texenv.filters['escape_tex'] = _escape_tex
-    texenv.trim_blocks = True
-    texenv.lstrip_blocks = True
-    return texenv
-
-
-def render_tex(output, context, datadir=''):
-    '''Render a template into a .tex file
-
-    Arguments:
-    - output: a file object to write the result
-    - context: all the data to populate the template
-    - datadir: location of the user-defined templates
-    '''
-    env = _init_tex_env(datadir=datadir)
-    template = env.get_template(context['template'])
-
-    content = template.render(**context) #pylint: disable=star-args
-    output.write(content)
-
-    return None
+    def __init__(self, template, datadir=''):
+        '''Start a new jinja2 environment for .tex creation.
+
+        Arguments:
+        - datadir: location of the user-defined templates
+        '''
+        self.template = template
+
+        self.texenv = Environment(
+                loader=ChoiceLoader([
+                    FileSystemLoader(
+                        os.path.join(datadir, 'templates')
+                        ),
+                    PackageLoader(
+                        'songbook_core', os.path.join('data', 'templates')
+                        ),
+                    ])
+                )
+        self.texenv.block_start_string = '(*'
+        self.texenv.block_end_string = '*)'
+        self.texenv.variable_start_string = '(('
+        self.texenv.variable_end_string = '))'
+        self.texenv.comment_start_string = '(% comment %)'
+        self.texenv.comment_end_string = '(% endcomment %)'
+        self.texenv.filters['escape_tex'] = _escape_tex
+        self.texenv.trim_blocks = True
+        self.texenv.lstrip_blocks = True
+
+    def file_template(self):
+        """Return the filename of the selected template."""
+        return self.texenv.get_template(self.template).filename
+
+    def render_tex(self, output, context):
+        '''Render a template into a .tex file
+
+        Arguments:
+        - output: a file object to write the result
+        - context: all the data to populate the template
+        '''
+
+        #pylint: disable=star-args
+        output.write(
+                self.texenv.get_template(self.template).render(**context)
+                )