Added parsing of songs \[ macros [#15](/patacrep/songbook-web/issues/15)

songbook_core/plastex.py

@@ -59,6 +59,7 @@ class SongParser(object):
         tex.ownerDocument.context.loadBaseMacros()
         sys.path.append(os.path.dirname(__file__))
         tex.ownerDocument.context.loadPackage(tex, "plastex_patchedbabel")
+        tex.ownerDocument.context.loadPackage(tex, "plastex_chord")
         tex.ownerDocument.context.loadPackage(tex, "plastex_songs")
         sys.path.pop()
         return tex

songbook_core/plastex_chord.py

@@ -0,0 +1,110 @@
+# -*- coding: utf-8 -*-
+
+r"""PlasTeX module to deal with chords commands of the songs LaTeX package
+
+Chords are set using commands like \[C]. This package parses those commands.
+"""
+
+from plasTeX import Command, Environment, Macro
+from plasTeX.Base.LaTeX.Math import BeginDisplayMath
+
+# Count the number of levels of 'verse' environment: IN_VERSE==1 means that we
+# are in a 'verse' environment; IN_VERSE==2 means that we are in two included
+# 'verse' environment, and so on.
+IN_VERSE = 0
+
+def wrap_displaymath(cls):
+    """Decorator to store the depth of 'verse' environment
+
+    In the invoke() method classes, global variable IN_VERSE indicates the
+    number of 'verse' (or 'chorus' or 'verse*') environment we are in.
+    """
+
+    # pylint: disable=no-init,too-few-public-methods
+    class DisplayMath(cls):
+        """Wrapper to LaTeX environment updating IN_VERSE"""
+        blockType = True
+        # pylint: disable=super-on-old-class,global-statement,no-member
+        def invoke(self, tex):
+            """Wrapper to invoke() to update global variable IN_VERSE."""
+            global IN_VERSE
+            if self.macroMode == Macro.MODE_BEGIN:
+                IN_VERSE += 1
+            else:
+                IN_VERSE -= 1
+            super(DisplayMath, self).invoke(tex)
+    return DisplayMath
+
+# pylint: disable=too-many-public-methods
+@wrap_displaymath
+class Verse(Environment):
+    """LaTeX 'verse' environment"""
+    macroName = 'verse'
+
+# pylint: disable=too-many-public-methods
+@wrap_displaymath
+class VerseStar(Environment):
+    """LaTeX 'verse*' environment"""
+    macroName = 'verse*'
+
+# pylint: disable=too-many-public-methods
+@wrap_displaymath
+class Chorus(Environment):
+    """LaTeX 'chorus' environment"""
+    macroName = 'chorus'
+
+
+
+class BeginChord(Command):
+    """Beginning of a chord notation"""
+    macroName = 'chord'
+    macroMode = Command.MODE_BEGIN
+
+    @property
+    def source(self):
+        """Return chord LaTeX code."""
+        return r'\[{}]'.format(''.join([str(item) for item in self.childNodes]))
+
+class EndChord(Command):
+    """End of a chord notation"""
+    macroMode = Command.MODE_END
+
+class BeginChordOrDisplayMath(BeginDisplayMath):
+    r"""Wrapper to BeginDisplayMath
+
+    In a 'verse' (or 'verse*' or 'chorus') environment, the '\[' macro
+    displays a chord. Otherwise, it corresponds to the usual LaTeX math mode.
+    This class calls the right method, depending on the inclusion of this
+    macro in a verse environment.
+    """
+    macroName = '['
+
+    def digest(self, tokens):
+        """Consume the tokens corresponding to the arguments of this macro"""
+        if IN_VERSE:
+            for item in tokens:
+                if item.nodeType == item.TEXT_NODE and item.nodeValue == ']':
+                    break
+                self.appendChild(item)
+        else:
+            return super(BeginChordOrDisplayMath, self).digest(tokens)
+
+    def invoke(self, tex):
+        """Process this macro"""
+        if IN_VERSE:
+            begin = BeginChord()
+            self.ownerDocument.context.push(begin) # pylint: disable=no-member
+            self.parse(tex)
+
+            for token in tex:
+                if token.nodeType == token.TEXT_NODE and token.nodeValue == ']':
+                    break
+                else:
+                    begin.appendChild(token)
+
+            end = EndChord()
+            self.ownerDocument.context.push(end) # pylint: disable=no-member
+
+            return [begin]
+        else:
+            return super(BeginChordOrDisplayMath, self).invoke(tex)