From e93f7384a52cbd8fd1776f88fd1201902be6aecc Mon Sep 17 00:00:00 2001
From: moyogo <moyogo@gmail.com>
Date: Wed, 10 Feb 2016 14:35:59 +0000
Subject: [PATCH] [voltLib] parse substitution as single, multiple or ligature
 sub

---
 Lib/fontTools/voltLib/ast.py         | 15 ++++++++++++
 Lib/fontTools/voltLib/parser.py      | 17 +++++++++++++-
 Lib/fontTools/voltLib/parser_test.py | 35 ++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/Lib/fontTools/voltLib/ast.py b/Lib/fontTools/voltLib/ast.py
index 4210ce4ba..097e418e1 100644
--- a/Lib/fontTools/voltLib/ast.py
+++ b/Lib/fontTools/voltLib/ast.py
@@ -81,6 +81,21 @@ class SubstitutionDefinition(ast.Statement):
         self.mapping = zip(src, dest)
 
 
+class SubstitutionSingleDefinition(SubstitutionDefinition):
+    def __init__(self, location, src, dest):
+        SubstitutionDefinition.__init__(self, location, src, dest)
+
+
+class SubstitutionMultipleDefinition(SubstitutionDefinition):
+    def __init__(self, location, src, dest):
+        SubstitutionDefinition.__init__(self, location, src, dest)
+
+
+class SubstitutionLigatureDefinition(SubstitutionDefinition):
+    def __init__(self, location, src, dest):
+        SubstitutionDefinition.__init__(self, location, src, dest)
+
+
 class PositionAttachDefinition(ast.Statement):
     def __init__(self, location, coverage, coverage_to):
         ast.Statement.__init__(self, location)
diff --git a/Lib/fontTools/voltLib/parser.py b/Lib/fontTools/voltLib/parser.py
index 193a24cf0..f7738fc82 100644
--- a/Lib/fontTools/voltLib/parser.py
+++ b/Lib/fontTools/voltLib/parser.py
@@ -288,7 +288,22 @@ class Parser(object):
             dest.append(self.parse_coverage_())
             self.expect_keyword_("END_SUB")
         self.expect_keyword_("END_SUBSTITUTION")
-        sub = ast.SubstitutionDefinition(location, src, dest)
+        max_src = max([len(cov) for cov in src])
+        max_dest = max([len(cov) for cov in dest])
+        # many to many or mixed is invalid
+        if (max_src > 1 and max_dest > 1):
+            raise VoltLibError(
+                "Invalid substitution type",
+                location)
+        elif (max_src == 1 and
+                max_dest == 1):
+            sub = ast.SubstitutionSingleDefinition(location, src, dest)
+        elif (max_src == 1 and
+                max_dest > 1):
+            sub = ast.SubstitutionMultipleDefinition(location, src, dest)
+        elif (max_src > 1 and
+                max_dest == 1):
+            sub = ast.SubstitutionLigatureDefinition(location, src, dest)
         return sub
 
     def parse_position_(self):
diff --git a/Lib/fontTools/voltLib/parser_test.py b/Lib/fontTools/voltLib/parser_test.py
index e4b87918a..fcc2d77a7 100644
--- a/Lib/fontTools/voltLib/parser_test.py
+++ b/Lib/fontTools/voltLib/parser_test.py
@@ -443,6 +443,41 @@ class ParserTest(unittest.TestCase):
                 'END_SUBSTITUTION'
             ).statements
 
+    def test_substitution_invalid_many_to_many(self):
+        with self.assertRaisesRegex(
+                VoltLibError,
+                r'Invalid substitution type'):
+            [lookup] = self.parse(
+                'DEF_LOOKUP "invalid_substitution" PROCESS_BASE PROCESS_MARKS '
+                'ALL DIRECTION LTR\n'
+                'IN_CONTEXT\n'
+                'END_CONTEXT\n'
+                'AS_SUBSTITUTION\n'
+                'SUB GLYPH "f" GLYPH "i"\n'
+                'WITH GLYPH "f.alt" GLYPH "i.alt"\n'
+                'END_SUB\n'
+                'END_SUBSTITUTION'
+            ).statements
+
+    def test_substitution_invalid_mixed(self):
+        with self.assertRaisesRegex(
+                VoltLibError,
+                r'Invalid substitution type'):
+            [lookup] = self.parse(
+                'DEF_LOOKUP "invalid_substitution" PROCESS_BASE PROCESS_MARKS '
+                'ALL DIRECTION LTR\n'
+                'IN_CONTEXT\n'
+                'END_CONTEXT\n'
+                'AS_SUBSTITUTION\n'
+                'SUB GLYPH "fi"\n'
+                'WITH GLYPH "f" GLYPH "i"\n'
+                'END_SUB\n'
+                'SUB GLYPH "f" GLYPH "l"\n'
+                'WITH GLYPH "f_l"\n'
+                'END_SUB\n'
+                'END_SUBSTITUTION'
+            ).statements
+
     def test_substitution_single(self):
         [lookup] = self.parse(
             'DEF_LOOKUP "smcp" PROCESS_BASE PROCESS_MARKS ALL '