GPM Templates: allow comments to start in any column, not just the first.

manual/template_lang.rst

@@ -293,7 +293,7 @@ Notes:
 * In a logical context, any non-empty value is ``True``
 * In a logical context, the empty value is ``False``
 * Strings and numbers can be used interchangeably. For example, ``10`` and ``'10'`` are the same thing.
-* Comments are lines starting with a '#' character. Comments beginning later in a line are not supported.
+* Comments are lines starting with blanks or tabs then a '#' character.
 
 **Operator precedence**
 

src/calibre/gui2/dialogs/template_dialog.py

@@ -348,7 +348,9 @@ class TemplateHighlighter(QSyntaxHighlighter):
 
         if not text:
             pass
-        elif text[0] == '#':
+        elif re.match(r'[ \t]*#', text):
+            # Line with only a comment possibly preceded with spaces or tabs
+            # This works in both GPM and python
             self.setFormat(0, textLength, self.Formats['comment'])
             return
 

src/calibre/utils/formatter.py

@@ -1715,7 +1715,7 @@ class TemplateFormatter(string.Formatter):
             (r'\w+',                     lambda x,t: (_Parser.LEX_ID, t)),
             (r'".*?((?<!\\)")',          lambda x,t: (_Parser.LEX_CONST, t[1:-1])),
             (r'\'.*?((?<!\\)\')',        lambda x,t: (_Parser.LEX_CONST, t[1:-1])),
-            (r'\n#.*?(?:(?=\n)|$)',      lambda x,t: _Parser.LEX_NEWLINE),
+            (r'\n[ \t]*#.*?(?:(?=\n)|$)',lambda x,t: _Parser.LEX_NEWLINE),
             (r'\s',                      lambda x,t: _Parser.LEX_NEWLINE if t == '\n' else None),
         ], flags=re.DOTALL)