[WIP] Content errors are now gathered

* Rename `patacrep.content.Content` to `patacrep.content.ContentItem`
* Create pseudo-list `patacrep.content.ContentList`, which has an
  `errors` attribute.
* Songs that cannot be parsed at all no longer produce an empty song.

This is highly work in progress: most of the `patacrep.content.*`
packages are broken.

patacrep/content/__init__.py

@@ -3,8 +3,8 @@
 Content that can be included in a songbook is controlled by plugins. From the
 user (or .sb file) point of view, each piece of content is introduced by a
 keyword. This keywold is associated with a plugin (a submodule of this very
-module), which parses the content, and return a list of instances of the
-Content class.
+module), which parses the content, and return a ContentList object, which is
+little more than a list of instances of the ContentItem class.
 
 # Plugin definition
 
@@ -27,8 +27,8 @@ A parser is a function which takes as arguments:
     - config: the configuration object of the current songbook. Plugins can
       change it.
 
-A parser returns a list of instances of the Content class, defined in
-this module (or of subclasses of this class).
+A parser returns a ContentList object (a list of instances of the ContentItem
+class), defined in this module (or of subclasses of this class).
 
 Example: When the following piece of content is met
 
@@ -55,13 +55,13 @@ surrounded by parenthesis. It is up to the plugin to parse this argument. For
 intance, keyword "foo()(( bar()" is a perfectly valid keyword, and the parser
 associated to "foo" will get as argument the string ")(( bar(".
 
-# Content class
+# ContentItem class
 
-The content classes are subclasses of class Content defined in this module.
-Content is a perfectly valid class, but instances of it will not generate
+The content classes are subclasses of class ContentItem defined in this module.
+ContentItem is a perfectly valid class, but instances of it will not generate
 anything in the resulting .tex.
 
-More documentation in the docstring of Content.
+More documentation in the docstring of ContentItem.
 
 """
 
@@ -79,7 +79,7 @@ LOGGER = logging.getLogger(__name__)
 EOL = '\n'
 
 #pylint: disable=no-self-use
-class Content:
+class ContentItem:
     """Content item. Will render to something in the .tex file.
 
     The current jinja2.runtime.Context is passed to all function defined
@@ -100,8 +100,8 @@ class Content:
 
         # Arguments
 
-        - __previous: the songbook.content.Content object of the previous item.
-        - __context: see Content() documentation.
+        - __previous: the songbook.content.ContentItem object of the previous item.
+        - __context: see ContentItem() documentation.
 
         # Return
 
@@ -122,13 +122,37 @@ class Content:
 
 class ContentError(SongbookError):
     """Error in a content plugin."""
-    def __init__(self, keyword, message):
+    def __init__(self, keyword=None, message=None):
         super(ContentError, self).__init__()
         self.keyword = keyword
         self.message = message
 
     def __str__(self):
-        return "Content: {}: {}".format(self.keyword, self.message)
+        text = "Content"
+        if self.keyword is not None:
+            text += ": " + self.keyword
+        if self.message is not None:
+            text += ": " + self.message
+        return text
+
+class ContentList:
+    """List of content items"""
+
+    def __init__(self, *args, **kwargs):
+        self._content = list(*args, **kwargs)
+        self.errors = []
+
+    def __iter__(self):
+        yield from self._content
+
+    def extend(self, iterator):
+        return self._content.extend(iterator)
+
+    def append(self, item):
+        return self._content.append(item)
+
+    def __len__(self):
+        return len(self._content)
 
 @jinja2.contextfunction
 def render(context, content):
@@ -137,14 +161,14 @@ def render(context, content):
     Arguments:
     - context: the jinja2.runtime.context of the current template
       compilation.
-    - content: a list of Content() instances, as the one that was returned by
+    - content: a list of ContentItem() instances, as the one that was returned by
       process_content().
     """
     rendered = ""
     previous = None
     last = None
     for elem in content:
-        if not isinstance(elem, Content):
+        if not isinstance(elem, ContentItem):
             LOGGER.warning("Ignoring bad content item '{}'.".format(elem))
             continue
 
@@ -156,23 +180,23 @@ def render(context, content):
         rendered += elem.render(context) + EOL
         previous = elem
 
-    if isinstance(last, Content):
+    if isinstance(last, ContentItem):
         rendered += last.end_block(context) + EOL
 
     return rendered
 
 def process_content(content, config=None):
-    """Process content, and return a list of Content() objects.
+    """Process content, and return a list of ContentItem() objects.
 
     Arguments are:
     - content: the content field of the .sb file, which should be a list, and
       describe what is to be included in the songbook;
     - config: the configuration dictionary of the current songbook.
 
-    Return: a list of Content objects, corresponding to the content to be
+    Return: a list of ContentItem objects, corresponding to the content to be
     included in the .tex file.
     """
-    contentlist = []
+    contentlist = ContentList()
     plugins = config.get('_content_plugins', {})
     keyword_re = re.compile(r'^ *(?P<keyword>\w*) *(\((?P<argument>.*)\))? *$')
     if not content:
@@ -185,10 +209,12 @@ def process_content(content, config=None):
         try:
             match = keyword_re.match(elem[0]).groupdict()
         except AttributeError:
-            raise ContentError(elem[0], "Cannot parse content type.")
+            contentlist.errors.append(ContentError(elem[0], "Cannot parse content type."))
+            continue
         (keyword, argument) = (match['keyword'], match['argument'])
         if keyword not in plugins:
-            raise ContentError(keyword, "Unknown content type.")
+            contentlist.errors.append(ContentError(keyword, "Unknown content type."))
+            continue
         contentlist.extend(plugins[keyword](
             keyword,
             argument=argument,

patacrep/content/section.py

@@ -1,6 +1,6 @@
 """Allow LaTeX sections (starred or not) as content of a songbook."""
 
-from patacrep.content import Content, ContentError
+from patacrep.content import ContentItem, ContentError
 
 KEYWORDS = [
     "part",
@@ -13,7 +13,7 @@ KEYWORDS = [
     ]
 FULL_KEYWORDS = KEYWORDS + ["{}*".format(word) for word in KEYWORDS]
 
-class Section(Content):
+class Section(ContentItem):
     """A LaTeX section."""
     # pylint: disable=too-few-public-methods
 
@@ -48,7 +48,7 @@ def parse(keyword, argument, contentlist, config):
             )
     if (len(contentlist) not in [1, 2]):
         raise ContentError(keyword, "Section can have one or two arguments.")
-    return [Section(keyword, *contentlist)]
+    return ContentList(Section(keyword, *contentlist))
 
 
 CONTENT_PLUGINS = dict([

patacrep/content/song.py

@@ -6,12 +6,13 @@ import logging
 import os
 import textwrap
 
-from patacrep.content import process_content, ContentError, Content
+from patacrep.content import process_content
+from patacrep.content import ContentError, ContentItem, ContentList
 from patacrep import files, errors
 
 LOGGER = logging.getLogger(__name__)
 
-class SongRenderer(Content):
+class SongRenderer(ContentItem):
     """Render a song in as a tex code."""
 
     def __init__(self, song):
@@ -71,7 +72,7 @@ def parse(keyword, argument, contentlist, config):
     plugins = config['_song_plugins']
     if '_langs' not in config:
         config['_langs'] = set()
-    songlist = []
+    songlist = ContentList()
     for songdir in config['_songdir']:
         if contentlist:
             break
@@ -95,11 +96,16 @@ def parse(keyword, argument, contentlist, config):
                                 ", ".join(["'.{}'".format(key) for key in plugins.keys()]),
                                 ))
                         continue
-                    renderer = SongRenderer(plugins[extension](
-                        filename,
-                        config,
-                        datadir=songdir.datadir,
-                        ))
+                    try:
+                        renderer = SongRenderer(plugins[extension](
+                            filename,
+                            config,
+                            datadir=songdir.datadir,
+                            ))
+                    except ContentError as error:
+                        # TODO
+                        songlist.errors.append(error)
+                        continue
                     songlist.append(renderer)
                     config["_langs"].add(renderer.song.lang)
             if len(songlist) > before:

patacrep/content/songsection.py

@@ -1,13 +1,13 @@
 """Allow 'songchapter' and 'songsection' as content of a songbook."""
 
-from patacrep.content import Content, ContentError
+from patacrep.content import ContentItem, ContentError
 
 KEYWORDS = [
     "songchapter",
     "songsection",
     ]
 
-class SongSection(Content):
+class SongSection(ContentItem):
     """A songsection or songchapter."""
     # pylint: disable=too-few-public-methods
 
@@ -34,7 +34,7 @@ def parse(keyword, argument, contentlist, config):
             keyword,
             "Starred section names must have exactly one argument.",
             )
-    return [SongSection(keyword, contentlist[0])]
+    return ContentList(SongSection(keyword, contentlist[0]))
 
 
 CONTENT_PLUGINS = dict([

patacrep/content/tex.py

@@ -5,11 +5,11 @@ import logging
 import os
 
 from patacrep import files, errors
-from patacrep.content import Content
+from patacrep.content import ContentItem, ContentList
 
 LOGGER = logging.getLogger(__name__)
 
-class LaTeX(Content):
+class LaTeX(ContentItem):
     """Inclusion of LaTeX code"""
 
     def __init__(self, filename):
@@ -35,7 +35,7 @@ def parse(keyword, argument, contentlist, config):
         LOGGER.warning(
             "Useless 'tex' content: list of files to include is empty."
             )
-    filelist = []
+    filelist = ContentList
     basefolders = itertools.chain(
         (path.fullpath for path in config['_songdir']),
         files.iter_datadirs(config['datadir']),

patacrep/songs/chordpro/syntax.py

@@ -5,6 +5,7 @@ import logging
 import ply.yacc as yacc
 import re
 
+from patacrep.content import ContentError
 from patacrep.songs import errors
 from patacrep.songs.chordpro import ast
 from patacrep.songs.chordpro.lexer import tokens, ChordProLexer
@@ -329,13 +330,5 @@ def parse_song(content, filename=None):
         lexer=ChordProLexer(filename=filename).lexer,
         )
     if parsed_content is None:
-        return ast.Song(
-            filename,
-            [],
-            errors=[functools.partial(
-                errors.SongSyntaxError,
-                line=parser._errors[-1].keywords['line'],
-                message='Fatal error during song parsing.',
-                )]
-            )
+        raise ContentError(message='Fatal error during song parsing.')
     return parsed_content