[feaLib] Simplify parser API by removing the ignore_comments option

https://github.com/fonttools/fonttools/pull/879#discussion_r104947968
https://github.com/fonttools/fonttools/issues/829

Lib/fontTools/feaLib/parser.py

@@ -14,10 +14,8 @@ log = logging.getLogger(__name__)
 
 
 class Parser(object):
-
     extensions = {}
     ast = ast
-    ignore_comments = True
 
     def __init__(self, featurefile, glyphMap):
         self.glyphMap_ = glyphMap
@@ -791,7 +789,7 @@ class Parser(object):
 
     def parse_table_GDEF_(self, table):
         statements = table.statements
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -813,7 +811,7 @@ class Parser(object):
 
     def parse_table_head_(self, table):
         statements = table.statements
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -828,7 +826,7 @@ class Parser(object):
     def parse_table_hhea_(self, table):
         statements = table.statements
         fields = ("CaretOffset", "Ascender", "Descender", "LineGap")
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -849,7 +847,7 @@ class Parser(object):
     def parse_table_vhea_(self, table):
         statements = table.statements
         fields = ("VertTypoAscender", "VertTypoDescender", "VertTypoLineGap")
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -869,7 +867,7 @@ class Parser(object):
 
     def parse_table_name_(self, table):
         statements = table.statements
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -954,7 +952,7 @@ class Parser(object):
 
     def parse_table_BASE_(self, table):
         statements = table.statements
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -981,7 +979,7 @@ class Parser(object):
                    "winAscent", "winDescent", "XHeight", "CapHeight",
                    "WeightClass", "WidthClass", "LowerOpSize", "UpperOpSize")
         ranges = ("UnicodeRange", "CodePageRange")
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -1192,7 +1190,7 @@ class Parser(object):
             symtab.enter_scope()
 
         statements = block.statements
-        while self.next_token_ != "}" or (not self.ignore_comments and len(self.cur_comments_)):
+        while self.next_token_ != "}" or self.cur_comments_:
             self.advance_lexer_(comments=True)
             if self.cur_token_type_ is Lexer.COMMENT:
                 statements.append(self.ast.Comment(self.cur_token_location_, self.cur_token_))
@@ -1369,8 +1367,8 @@ class Parser(object):
             return self.cur_token_
         raise FeatureLibError("Expected a string", self.cur_token_location_)
 
-    def advance_lexer_(self, comments = False):
-        if not self.ignore_comments and comments and len(self.cur_comments_):
+    def advance_lexer_(self, comments=False):
+        if comments and self.cur_comments_:
             self.cur_token_type_ = Lexer.COMMENT
             self.cur_token_, self.cur_token_location_ = self.cur_comments_.pop(0)
             return

Tests/feaLib/builder_test.py

@@ -138,27 +138,21 @@ class BuilderTest(unittest.TestCase):
     def check_fea2fea_file(self, name, base=None, parser=Parser):
         font = makeTTFont()
         fname = (name + ".fea") if '.' not in name else name
-        temp = parser.ignore_comments
-        parser.ignore_comments = False
-        try:
-            p = parser(self.getpath(fname), glyphMap=font.getReverseGlyphMap())
-            doc = p.parse()
-            actual = self.normal_fea(doc.asFea().split("\n"))
+        p = parser(self.getpath(fname), glyphMap=font.getReverseGlyphMap())
+        doc = p.parse()
+        actual = self.normal_fea(doc.asFea().split("\n"))
+        with open(self.getpath(base or fname), "r", encoding="utf-8") as ofile:
+            expected = self.normal_fea(ofile.readlines())
 
-            with open(self.getpath(base or fname), "r", encoding="utf-8") as ofile:
-                expected = self.normal_fea(ofile.readlines())
-
-            if expected != actual:
-                fname = name.rsplit(".", 1)[0] + ".fea"
-                for line in difflib.unified_diff(
-                        expected, actual,
-                        fromfile=fname + " (expected)",
-                        tofile=fname + " (actual)"):
-                    sys.stderr.write(line+"\n")
-                self.fail("Fea2Fea output is different from expected. "
-                          "Generated:\n{}\n".format("\n".join(actual)))
-        finally:
-            parser.ignore_comments = temp
+        if expected != actual:
+            fname = name.rsplit(".", 1)[0] + ".fea"
+            for line in difflib.unified_diff(
+                    expected, actual,
+                    fromfile=fname + " (expected)",
+                    tofile=fname + " (actual)"):
+                sys.stderr.write(line+"\n")
+            self.fail("Fea2Fea output is different from expected. "
+                      "Generated:\n{}\n".format("\n".join(actual)))
 
     def normal_fea(self, lines):
         output = []

Tests/feaLib/parser_test.py

@@ -1246,7 +1246,7 @@ class ParserTest(unittest.TestCase):
 
     def test_substitute_lookups(self):  # GSUB LookupType 6
         doc = Parser(self.getpath("spec5fi1.fea"), GLYPHMAP).parse()
-        [langsys, ligs, sub, feature] = doc.statements
+        [_, _, _, langsys, ligs, sub, feature] = doc.statements
         self.assertEqual(feature.statements[0].lookups, [ligs, None, sub])
         self.assertEqual(feature.statements[1].lookups, [ligs, None, sub])
 
@@ -1463,7 +1463,6 @@ class ParserTest(unittest.TestCase):
     def parse(self, text, glyphMap=GLYPHMAP):
         featurefile = UnicodeIO(text)
         p = Parser(featurefile, glyphMap)
-        p.ignore_comments = False
         return p.parse()
 
     @staticmethod