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.
This will allow to use ES2015 constructs in spec code.
The change required introducing a small server, which serves both PEG.js
and spec code passed through Babel and bundled together. This allowed to
convert the specs to regular modules and get rid of the hackery that was
previously needed to make them run both in Node.js and in the browser.
Note the specs no longer exercise the browser version. This will allow
to spec PEG.js internals in the future.
See #442.
So far, PEG.js was exported in a "PEG" global variable when no module
loader was detected. The same variable name was also conventionally used
when requiring it in Node.js or otherwise referring to it. This was
reflected in various places in the code, documentation, examples, etc.
This commit changes the variable name to "peg" and fixes all relevant
occurrences. The main reason for the change is that in Node.js, modules
are generally referred to by lower-case variable names, so "PEG" was
sticking out when used in Node.js projects.
Instead of testing arguments.length to see whether an optional parameter
was passed to a function, compare its value to "undefined". This
approach has two advantages:
* It is in line with handling of default parameters in ES6.
* Optional parameters are actually spelled out in the parameter
list.
There is also one important disadvantage, namely that it's impossible to
pass "undefined" as an optional parameter value. This required a small
change in two tests.
Additional notes:
* Default parameter values are set in assignments immediately
after the function header. This reflects the fact that these
assignments really belong to the parameter list (which is where they
are in ES6).
* Parameter values are checked against "void 0" in places where
"undefined" can potentially be redefiend.
The "toParse" matcher in generated-parser-behavior.spec.js effectively
had these signatures:
toParse(input)
toParse(input, expected)
toParse(input, options, expected)
This commit regularizes them to:
toParse(input)
toParse(input, expected)
toParse(input, expected, options)
Similarly, the "toFailToParse" matcher in
generated-parser-behavior.spec.js effectively had these signatures:
toFailToParse(input)
toFailToParse(input, details)
toFailToParse(input, options, details)
This commit regularizes them to:
toFailToParse(input)
toFailToParse(input, details)
toFailToParse(input, details, options)
Finally, the "toChangeAST" matcher in helpers.js effectively had these
signatures:
toChangeAST(grammar, details)
toChangeAST(grammar, options, details)
This commit regularizes them to:
toChangeAST(grammar, details)
toChangeAST(grammar, details, options)
The overall purpose of these changes is to avoid different parameters
appearing at the same position, which is hard to manage without using
"arguments".
Instead of setting ESLint environment to "node" globally, set it on
per-directory basis using separate .eslintrc.json files:
Directory Environment
-----------------------
bin node
lib commonjs
spec jasmine
It was impossible to use this approach for the "benchmark" directory
which contains a mix of files used in various environments. For
benchmark/run, the environment is set inline. For the other files, as
well as spec/helpers.js, the globals are declared manually (it is
impossible to express how these files are used just by a list of
environments).
Fixes#408.
Implement the swap and change various directives in the source code. The
"make hint" target becomes "make lint".
The change leads to quite some errors being reported by ESLint. These
will be fixed in subsequent commits.
Note the configuration enables just the recommended rules. Later I plan
to enable more rules to enforce the coding standard. The configuration
also sets the environment to "node", which is far from ideal as the
codebase contains a mix of CommonJS, Node.js and browser code. I hope to
clean this up at some point.
Unit specs are unit tests of internal stuff. API specs are tests of the
user-visible APIs and behavior.
I think it makes sense to make this distinction because then the public
API line is more clearly visible e.g. when using the specs as
documentation.
David Majda
Arlo Breault