Implement custom markdown <foo.abc> to reference tune.

Also ensure filename matches are not greedy, and so work if there are
two filenames on a line.

abcfield.py

@@ -18,6 +18,7 @@
 #
 
 import optparse
+import pathlib
 import re
 import subprocess
 import sys
@@ -164,11 +165,22 @@ def convertMarkdown(t, latex):
         target = "--to=html"
     res = subprocess.check_output(['pandoc', '--from=markdown', target], input=t, universal_newlines=True)
     if latex:
-        res = re.sub(r'\\href{(.*).abc}', r'\\hyperlink{\1}', res)
+        res = re.sub(r'\\href{(.*?).abc}', r'\\hyperlink{\1}', res)
     else:
-        res = re.sub(r'href="(.*).abc"', r'href="\1.html"', res)
+        res = re.sub(r'href="(.*?).abc"', r'href="\1.html"', res)
     return res
 
+# Implement a custom Markdown shorthand for referencing ABC files.
+# <foo.abc> will expand to ['title of foo'](foo.abc).
+def expandCustomMarkdown(t, latex):
+    # Given a match to (foo.abc), return a markdown link to the tune with the
+    # title of the tune as the text of the link.
+    def getTitle(m):
+        fname = m.group(1) + ".abc"
+        with pathlib.Path(fname).open() as f:
+            return "[" + getFieldDisplayText(f, "T", latex) + "](" + fname + ")"
+    return re.sub(r'<(.*?).abc>', getTitle, t)
+
 # Return the raw text for a given field. Optionally the nth field is taken,
 # or the field data must start with a designated string to be recognised.
 def getFieldText(inf, field, n = 1, starts = None):
@@ -209,7 +221,7 @@ def getFieldDisplayText(inf, field, n = 1, starts = None, latex = False):
         elif field.upper() == "K":
             res = convertKeyToDisplay(res)
         elif field.upper() in ["H", "N"]:
-            res = convertMarkdown(res, latex)
+            res = convertMarkdown(expandCustomMarkdown(res, latex), latex)
     return res
 
 if __name__ == "__main__":