No output is generated yet, this change is just on the parser.
The OpenType Feature File specification is surprisingly vague about
the exact syntax of chaining contextual positioning rules, so I expect
that we will have to iterate on this parser. However, the test case
in parser_test.py gets recognized by `makeotf`, so the current
implementation is unlikely to be completely wrong.
While not really documented in the OpenType Feature File specification,
the AFDKO makeotf tool handles the `markClass` statement this way.
Also, some examples in the specification seem to imply this semantics.
The class names of tree nodes for substitution and positioning rules
are now consistent with `builder.py`, which in turn is consistent with
`otTables.py`.
However, not sure how to build the otTables object graph for emitting
GPOS tables with device values; the current code thus silently strips
off any device values. Left a TODO comment for implementing this.
It is example 1 in section 5.f.i of the specification, and there
more examples in the same section. For consistency, use the same convention
as the other test cases.
An earlier change made sure that language tags would always be
four characters in length, even when ending in whitespace.
This made a few test cases in parser_test.py fail. By accident,
I had only run builder_test (instead of all unittest in fonttools)
before committing that change.
Also add ';' to some langaugesystem test cases. This makes the
snippets syntactically valid. The parser is still expected to
reject them for other reasons, just as before this change.
This simplifies the public API to the library. For clients, it does
not matter which exact component was detecting an error. And we will
soon have more components; there would be little point in declaring
CompilerError, TableBuilderError, and so forth.
We will soon support additional blocks beyond `feature`,
and keeping this refactoring separate from new functionality
makes it easier for code reviewers to follow the changes.
In Python 3, the method unittest.TestCase.assertRaisesRegexp
has been renamed to "assertRaisesRegex", and the frameworks spits
out deprecation warnings when using the method name from Python 2.
