1 files changed, 105 insertions, 0 deletions
diff --git a/lib/silfont/feax_lexer.py b/lib/silfont/feax_lexer.py
new file mode 100644
index 0000000..58ea72d
--- /dev/null
+++ b/lib/silfont/feax_lexer.py
@@ -0,0 +1,105 @@
+from fontTools.feaLib.lexer import IncludingLexer, Lexer
+from fontTools.feaLib.error import FeatureLibError
+import re, io
+
+VARIABLE = "VARIABLE"
+
+class feax_Lexer(Lexer):
+
+    def __init__(self, *a):
+        Lexer.__init__(self, *a)
+        self.tokens_ = None
+        self.stack_ = []
+        self.empty_ = False
+
+    def next_(self, recurse=False):
+        while (not self.empty_):
+            if self.tokens_ is not None:
+                res = self.tokens_.pop(0)
+                if not len(self.tokens_):
+                    self.popstack()
+                if res[0] != VARIABLE:
+                    return (res[0], res[1], self.location_())
+                return self.parse_variable(res[1])
+
+            try:
+                res = Lexer.next_(self)
+            except IndexError as e:
+                self.popstack()
+                continue
+            except StopIteration as e:
+                self.popstack()
+                continue
+            except FeatureLibError as e:
+                if u"Unexpected character" not in str(e):
+                    raise e
+
+                # only executes if exception occurred
+                location = self.location_()
+                text = self.text_
+                start = self.pos_
+                cur_char = text[start]
+                if cur_char == '$':
+                    self.pos_ += 1
+                    self.scan_over_(Lexer.CHAR_NAME_CONTINUATION_)
+                    varname = text[start+1:self.pos_]
+                    if len(varname) < 1 or len(varname) > 63:
+                        raise FeatureLibError("Bad variable name length", location)
+                    res = (VARIABLE, varname, location)
+                else:
+                    raise FeatureLibError("Unexpected character: %r" % cur_char, location)
+            return res
+        raise StopIteration
+
+    def __repr__(self):
+        if self.tokens_ is not None:
+            return str(self.tokens_)
+        else:
+            return str((self.text_[self.pos_:self.pos_+20], self.pos_, self.text_length_))
+
+    def popstack(self):
+        if len(self.stack_) == 0:
+            self.empty_ = True
+            return
+        t = self.stack_.pop()
+        if t[0] == 'tokens':
+            self.tokens_ = t[1]
+        else:
+            self.text_, self.pos_, self.text_length_ = t[1]
+            self.tokens_ = None
+
+    def pushstack(self, v):
+        if self.tokens_ is None:
+            self.stack_.append(('text', (self.text_, self.pos_, self.text_length_)))
+        else:
+            self.stack_.append(('tokens', self.tokens_))
+        self.stack_.append(v)
+        self.popstack()
+
+    def pushback(self, token_type, token):
+        if self.tokens_ is not None:
+            self.tokens_.append((token_type, token))
+        else:
+            self.pushstack(('tokens', [(token_type, token)]))
+        
+    def parse_variable(self, vname):
+        t = str(self.scope.get(vname, ''))
+        if t != '':
+            self.pushstack(['text', (t + " ", 0, len(t)+1)])
+        return self.next_()
+
+class feax_IncludingLexer(IncludingLexer):
+
+    @staticmethod
+    def make_lexer_(file_or_path):
+        if hasattr(file_or_path, "read"):
+            fileobj, closing = file_or_path, False
+        else:
+            filename, closing = file_or_path, True
+            fileobj = io.open(filename, mode="r", encoding="utf-8")
+        data = fileobj.read()
+        filename = getattr(fileobj, "name", None)
+        if closing:
+            fileobj.close()
+        return feax_Lexer(data, filename)
+