The idea behind linting lib/parser.js was that it would improve quality
of code generated by PEG.js in general. However, there is a couple of
problems with it:
1. Code in lib/parser.js is ES5 while the rest of the code is ES2015.
This would mean a separate ESLint configuration and a separate set
of code style rules just for lib/parser.js once code style checks
are added.
2. Code in lib/parser.js is generated. This means that even today it
violates checks like "no-unused-var", which have to be disabled.
This would get worse once code style checks are added, again
requiring a separate ESLint configuration just for lib/parser.js.
3. Linting lib/parser.js checks only small portion of possible code
generator output. For example, code generated when optimizing for
size or when tracing is not checked at all. Thus, linting
lib/parser.js gives a false sense of security.
Because of these problems I decided not to lint lib/parser.js at all and
rely on ad-hoc linting of parser files produced by PEG.js with ignoring
false-positives. I consider this more of a pragmatic cost vs. benefits
decision than a principial one.
Part of #407.
Before this commit, continuation lines of multi-line values in variable
declaration initializers were aligned with the variable name:
let foo = {
a: 5,
b: 6
};
This was highly irregular, maintenance intensive, and made declarations
look different from assignments.
This commit changes the indentation to be more regular and similar to
assignments:
let foo = {
a: 5,
b: 6
};
The LICENSE file used weird word wrapping and it didn't explicitly name
the license. I'm not sure where I originally copied it from.
I decided to replace it with more standard form from here:
http://choosealicense.com/licenses/mit/
The content of the license stays exactly the same.
The lib/parser.js file is a CommonJS module like all the other files in
lib/, so setting the environment explicitly is not needed. Besides, the
environment set by "eslint-env" was wrong (since transitioning from the
AMD format).
This makes extractList identical to the same function in other grammars
and makes it so that nulls are dealt with in only one function (until
now, they were dealt with both in extractList and buildList).
The refactoring should be safe as extractList isn't by itself used in
contexts where it can be passed a list containing nulls.
Blocks of one-line rules with aligned "=" signs should be used only in
cases where the rules are symmetric and we want to emphasize that.
Follow-up to ff7193776e.
Move "use strict" directives to the first line of each file. In
particular, move them above any ESLint comments, which are far less
important.
There are few exceptions:
Executable files
In these, the "use strict" directive must give way to the shebang.
lib/parser.js
Here, the "Generated by..." comment comes first. Also, ESLint
comments are prepended in post-processing.
Use one var/let/const per variable, but only for initialized variables.
Uninitialized variables are still grouped into one var/let/const
declaration as I don't see any value in separating them. This approach
reflects the fact that initialized and uninitialized var/let/const
declarations are really two different things.
See #443.
The for-in statement in JavaScript iterates also over inherited
properties. This is typically not desired and requires adding a
check using Object.prototype.hasOwnProperty inside the loop.
This commit replaces all for-in statements and related checks inside
them with iteration over Object.keys(...). The iteration is performed
using either Array.prototype.forEach of a plain for loop.
David Majda
Mingun