Currently, the compiler uses them to figure out which set of
languagesystems would apply for the current scope. However, this
information is not yet used for anything.
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.
In the new version, the parse_languagesystem_() function returns
an ast.LanguageSystemStatement, which then gets appended to the
current list of statements by the caller. Before this change,
the parse_languagesystem_() function would always append the
newly parsed statement to the list of top-level statements.
In practice, it does not matter because `languagesystem` is
only valid at the top level, but there is no good reason why
the parser method would have to be different from all other
constructs.
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.
The OpenType Feature File specification does not specify hex numbers
as explicit token type, but they appear several times in the examples
given by the spec.
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.
When the lexer encounters the "include" keyword, it now enters
a special mode for scanning file names. After having scanned over
the file name, the lexer goes back to normal. The exact format
of file name strings is not defined by the OpenType feature file
specification, so we accept any character that is not a closing
parenthesis.
This simplifies the implementation of the parser for
OpenType feature files, since it can now just keep
token locations returned by the lexer. Before this
change, the parser had to un-pack the location tuples
and build new tuples that included the file path.
