Because arrow functions work rather differently than normal functions (a
bad design mistake if you ask me), I decided to be conservative with the
conversion.
I converted:
* event handlers
* callbacks
* arguments to Array.prototype.map & co.
* small standalone lambda functions
I didn't convert:
* functions assigned to object literal properties (the new shorthand
syntax would be better here)
* functions passed to "describe", "it", etc. in specs (because Jasmine
relies on dynamic "this")
See #442.
This is purely a mechanical change, not taking advantage of block scope
of "let" and "const". Minimizing variable scope will come in the next
commit.
In general, "var" is converted into "let" and "const" is used only for
immutable variables of permanent character (generally spelled in
ALL_CAPS). Using it for any immutable variable regardless on its
permanence would feel confusing.
Any code which is not transpiled and needs to run in ES6 environment
(examples, code in grammars embedded in specs, ...) is kept unchanged.
This is also true for code generated by PEG.js.
See #442.
The |visitor.build| function now supplies default visit functions for
visitors it builds. These functions don't do anything beside traversing
the tree and passing arguments around to child visit functions.
Having the default visit functions allowed to simplify several visitors.
Split lib/utils.js into multiple files. Some of the functions were
generic, these were moved into files in lib/utils. Other funtions were
specific for the compiler, these were moved to files in lib/compiler.
This commit only moves functions around -- there is no renaming and
cleanup performed. Both will come later.
Modules now generally store the exported object in a named variable or
function first and only assign |module.exports| at the very end. This is
a difference when compared to style used until now, where most modules
started with a |module.exports| assignment.
I think the explicit name helps readability and understandability.
Implement a new syntax to extract matched strings from expressions. For
example, instead of:
identifier = first:[a-zA-Z_] rest:[a-zA-Z0-9_]* { return first + rest.join(""); }
you can now just write:
identifier = $([a-zA-Z_] [a-zA-Z0-9_]*)
This is useful mostly for "lexical" rules at the bottom of many
grammars.
Note that structured match results are still built for the expressions
prefixed by "$", they are just ignored. I plan to optimize this later
(sometime after the code generator rewrite).
Includes:
* Moving the source code from /src to /lib.
* Adding an explicit file list to package.json
* Updating the Makefile.
* Updating the spec and benchmark suites and their READMEs.
Part of a fix for GH-32.
David Majda
Arlo Breault