Refactors feaLib, moving code which builds OpenType lookups into otlLib. Note that this changes feaLib's concept of `location` from a tuple to an object.
[docs] Document feaLib
* Rearrange docs by user intention, highlighting the things you can do with each component.
* Remove reference to lexer and error modules from documentation tree, since they’re not user-facing.
* I’ve added docstrings to the parser even though we only provide access to the user-facing part of the API in the main documentation, just to clarify what some of the more obscure methods do and provide links to the spec.
* AST *is* user-facing if you’re building your own feature files in code, so all classes are documented with the user in mind.
This allows for more than one "lookup ..." chaining statements at each glyph position in a chaining contextual substitution or positioning rule: e.g.
sub a b c' lookup lookup1 lookup lookup2 d;
The corresponding change in the Adobe OpenType Feature File Specification (and implementation in makeotf) happened in adobe-type-tools/afdko#1132.
The code tries to write the short format when some values as None, but
when writing the long format it would write any None value as is which
is invalid, use 0 for None values instead.
Glyph names matching reserved keywords were not consistently escaped;
they were escaped in GDEF classes but not elsewhere. Call module’s
asFea() function in GlyohName.asFea() to ensure they are consistently
escaped.
When a MarkClassDefinition is inside a block, it gets double indentation
compared to the rest of the block. It should ignore the indent argument
like other similar statements.
ValueRecord had a makeString() method that takes an optional “vertical”
argument, but no code outside the tests sets this argument. Renamed it
to asFea() and dropped the “vertical”, so that it consistent with the
rest of feaLib.ast classes.
This would make it easier to construct feaLib AST from code,
where the location is not defined and thus should be None.
Also, we can make other arguments as kwargs with a default
value, now that the first parameter is no longer 'location'.
Currently, the feature file parser always resolves included files,
parses their content and inserts it in the resulting AST. The original
`include` statement is lost.
This commit introduces an option to not follow inclusions. Instead, the
output AST will contain an `include` statement. This allows to process a
feature file on its own, and allows to round-trip it.
For example in glyphsLib, when going from a UFO to a .glyphs file, a
UFO feature file will be sliced up into Glyphs.app classes (e.g. a
GSFeaturePrefix with code `include(../family.fea);`) and when going back
from .glyphs to UFO, the feature file will be patched back together.
The syntax tree representation now reflects the syntax of feature files.
Before this change, FeatureNames did not have their own `ast.Block`,
which had made the code quite messy.
* [feaLib.ast] fix checking multiple markClass definitions don't redefine same glyphs
As pointed out by @mhosken, we are looking in the wrong list for glyphs
that have already been defined in a previous markClass definition.
With this patch, the current markClass.fea test case fails becuase it defines 'acute'
twice for the same @TOP_MARKS class:
fontTools.feaLib.error.FeatureLibError: Lib/fontTools/feaLib/testdata/markClass.fea:6:5: Glyph acute already defined at Lib/fontTools/feaLib/testdata/markClass.fea:3:1
Also see conversation at:
3b79d51755 (r94622074)
* feaLib/testdat/markClass.fea: remove duplicate 'acute' in @TOP_MARKS
Now the test pass, after 45c77b7
* [feaLib.builder_test] test case for redefined glyph in multiple markClass definitions
This should be a bit more efficient as we don't need to create a temporary list
object before passing it to "".join() method of str; the latter accepts any
Iterable
