Handle inclusion of OpenType feature files

Lib/fontTools/feaLib/lexer.py

@@ -1,5 +1,7 @@
 from __future__ import print_function, division, absolute_import
 from __future__ import unicode_literals
+import codecs
+import os
 
 
 class LexerError(Exception):
@@ -8,7 +10,7 @@ class LexerError(Exception):
         self.location = location
 
 
-class Lexer:
+class Lexer(object):
     NUMBER = "NUMBER"
     STRING = "STRING"
     NAME = "NAME"
@@ -129,3 +131,48 @@ class Lexer:
         while p < self.text_length_ and self.text_[p] not in stop_at:
             p += 1
         self.pos_ = p
+
+
+class IncludingLexer(object):
+    def __init__(self, filename):
+        self.lexers_ = [self.make_lexer_(filename, (filename, 0, 0))]
+
+    def __iter__(self):
+        return self
+
+    def next(self):  # Python 2
+        return self.__next__()
+
+    def __next__(self):  # Python 3
+        while self.lexers_:
+            lexer = self.lexers_[-1]
+            try:
+                token_type, token, location = lexer.next()
+            except StopIteration:
+                self.lexers_.pop()
+                continue
+            if token_type is Lexer.NAME and token == "include":
+                fname_type, fname_token, fname_location = lexer.next()
+                if fname_type is not Lexer.FILENAME:
+                    raise LexerError("Expected file name", fname_location)
+                semi_type, semi_token, semi_location = lexer.next()
+                if semi_type is not Lexer.SYMBOL or semi_token != ";":
+                    raise LexerError("Expected ';'", semi_location)
+                curpath, _ = os.path.split(lexer.filename_)
+                path = os.path.join(curpath, fname_token)
+                if len(self.lexers_) >= 5:
+                    raise LexerError("Too many recursive includes",
+                                     fname_location)
+                self.lexers_.append(self.make_lexer_(path, fname_location))
+                continue
+            else:
+                return (token_type, token, location)
+        raise StopIteration()
+
+    @staticmethod
+    def make_lexer_(filename, location):
+        try:
+            with codecs.open(filename, "rb", "utf-8") as f:
+                return Lexer(f.read(), filename)
+        except IOError as err:
+            raise LexerError(str(err), location)

Lib/fontTools/feaLib/lexer_test.py

@@ -1,6 +1,7 @@
 from __future__ import print_function, division, absolute_import
 from __future__ import unicode_literals
-from fontTools.feaLib.lexer import Lexer, LexerError
+from fontTools.feaLib.lexer import IncludingLexer, Lexer, LexerError
+import os
 import unittest
 
 
@@ -94,5 +95,40 @@ class LexerTest(unittest.TestCase):
         self.assertEqual(lexer.pos_, 3)
 
 
+class IncludingLexerTest(unittest.TestCase):
+    @staticmethod
+    def getpath(filename):
+        path, _ = os.path.split(__file__)
+        return os.path.join(path, "testdata", filename)
+
+    def test_include(self):
+        lexer = IncludingLexer(self.getpath("include4.fea"))
+        result = ['%s %s:%d' % (token, os.path.split(loc[0])[1], loc[1])
+                  for _, token, loc in lexer]
+        self.assertEqual(result, [
+            "I4a include4.fea:1",
+            "I3a include3.fea:1",
+            "I2a include2.fea:1",
+            "I1a include1.fea:1",
+            "I0 include0.fea:1",
+            "I1b include1.fea:3",
+            "I2b include2.fea:3",
+            "I3b include3.fea:3",
+            "I4b include4.fea:3"
+        ])
+
+    def test_include_limit(self):
+        lexer = IncludingLexer(self.getpath("include6.fea"))
+        self.assertRaises(LexerError, lambda: list(lexer))
+
+    def test_include_self(self):
+        lexer = IncludingLexer(self.getpath("includeself.fea"))
+        self.assertRaises(LexerError, lambda: list(lexer))
+
+    def test_include_missing_file(self):
+        lexer = IncludingLexer(self.getpath("includemissingfile.fea"))
+        self.assertRaises(LexerError, lambda: list(lexer))
+
+
 if __name__ == "__main__":
     unittest.main()

Lib/fontTools/feaLib/testdata/include0.fea

@@ -0,0 +1 @@
+I0

Lib/fontTools/feaLib/testdata/include1.fea

@@ -0,0 +1,3 @@
+I1a
+include(include0.fea);
+I1b

Lib/fontTools/feaLib/testdata/include2.fea

@@ -0,0 +1,3 @@
+I2a
+include(include1.fea);
+I2b

Lib/fontTools/feaLib/testdata/include3.fea

@@ -0,0 +1,4 @@
+I3a
+include(include2.fea);
+I3b
+

Lib/fontTools/feaLib/testdata/include4.fea

@@ -0,0 +1,4 @@
+I4a
+include(include3.fea);
+I4b
+

Lib/fontTools/feaLib/testdata/include5.fea

@@ -0,0 +1,3 @@
+I5a
+include(include4.fea);
+I5b

Lib/fontTools/feaLib/testdata/include6.fea

@@ -0,0 +1,3 @@
+I6a
+include(include5.fea);
+I6b

Lib/fontTools/feaLib/testdata/includemissingfile.fea

@@ -0,0 +1 @@
+include(missingfile.fea);

Lib/fontTools/feaLib/testdata/includeself.fea

@@ -0,0 +1 @@
+include(includeself.fea);