- Split out a PROPERTY token from the IDENTIFIER token.
- Split out Property from the Identifier in the grammar.
- Split out PropertyLiteral from IdentifierLiteral.
Previously, the parser created `Literal` nodes for many things. This resulted in
information loss. Instead of being able to check the node type, we had to use
regexes to tell the different types of `Literal`s apart. That was a bit like
parsing literals twice: Once in the lexer, and once (or more) in the compiler.
It also caused problems, such as `` `this` `` and `this` being indistinguishable
(fixes#2009).
Instead returning `new Literal` in the grammar, subtypes of it are now returned
instead, such as `NumberLiteral`, `StringLiteral` and `IdentifierLiteral`. `new
Literal` by itself is only used to represent code chunks that fit no category.
(While mentioning `NumberLiteral`, there's also `InfinityLiteral` now, which is
a subtype of `NumberLiteral`.)
`StringWithInterpolations` has been added as a subtype of `Parens`, and
`RegexWithInterpolations` as a subtype of `Call`. This makes it easier for other
programs to make use of CoffeeScript's "AST" (nodes). For example, it is now
possible to distinguish between `"a #{b} c"` and `"a " + b + " c"`. Fixes#4192.
`SuperCall` has been added as a subtype of `Call`.
Note, though, that some information is still lost, especially in the lexer. For
example, there is no way to distinguish a heredoc from a regular string, or a
heregex without interpolations from a regular regex. Binary and octal number
literals are indistinguishable from hexadecimal literals.
After the new subtypes were added, they were taken advantage of, removing most
regexes in nodes.coffee. `SIMPLENUM` (which matches non-hex integers) had to be
kept, though, because such numbers need special handling in JavaScript (for
example in `1..toString()`).
An especially nice hack to get rid of was using `new String()` for the token
value for reserved identifiers (to be able to set a property on them which could
survive through the parser). Now it's a good old regular string.
In range literals, slices, splices and for loop steps when number literals
are involved, CoffeeScript can do some optimizations, such as precomputing the
value of, say, `5 - 3` (outputting `2` instead of `5 - 3` literally). As a side
bonus, this now also works with hexadecimal number literals, such as `0x02`.
Finally, this also improves the output of `coffee --nodes`:
# Before:
$ bin/coffee -ne 'while true
"#{a}"
break'
Block
While
Value
Bool
Block
Value
Parens
Block
Op +
Value """"
Value
Parens
Block
Value "a" "break"
# After:
$ bin/coffee -ne 'while true
"#{a}"
break'
Block
While
Value BooleanLiteral: true
Block
Value
StringWithInterpolations
Block
Op +
Value StringLiteral: ""
Value
Parens
Block
Value IdentifierLiteral: a
StatementLiteral: break
The following is now allowed:
o =
a: 1
b: 2
"#{'c'}": 3
"#{'d'}": 4
e: 5
"#{'f'}": 6
g: 7
It compiles to:
o = (
obj = {
a: 1,
b: 2
},
obj["" + 'c'] = 3,
obj["" + 'd'] = 4,
obj.e = 5,
obj["" + 'f'] = 6,
obj.g = 7,
obj
);
- Closes#3039. Empty interpolations in object keys are now _supposed_ to be
allowed.
- Closes#1131. No need to improve error messages for attempted key
interpolation anymore.
- Implementing this required fixing the following bug: `("" + a): 1` used to
error out on the colon, saying "unexpected colon". But really, it is the
attempted object key that is unexpected. Now the error is on the opening
parenthesis instead.
- However, the above fix broke some error message tests for regexes. The easiest
way to fix this was to make a seemingly unrelated change: The error messages
for unexpected identifiers, numbers, strings and regexes now say for example
'unexpected string' instead of 'unexpected """some #{really long} string"""'.
In other words, the tag _name_ is used instead of the tag _value_.
This was way easier to implement, and is more helpful to the user. Using the
tag value is good for operators, reserved words and the like, but not for
tokens which can contain any text. For example, 'unexpected identifier' is
better than 'unexpected expected' (if a variable called 'expected' was used
erraneously).
- While writing tests for the above point I found a few minor bugs with string
locations which have been fixed.
Any variables generated by CoffeeScript are now made sure to be named to
something not present in the source code being compiled. This way you can no
longer interfere with them, either on purpose or by mistake. (#1500, #1574)
For example, `({a}, _arg) ->` now compiles correctly. (#1574)
As opposed to the somewhat complex implementations discussed in #1500, this
commit takes a very simple approach by saving all used variables names using a
single pass over the token stream. Any generated variables are then made sure
not to exist in that list.
`(@a) -> a` used to be equivalent to `(@a) -> @a`, but now throws a runtime
`ReferenceError` instead (unless `a` exists in an upper scope of course). (#3318)
`(@a) ->` used to compile to `(function(a) { this.a = a; })`. Now it compiles to
`(function(_at_a) { this.a = _at_a; })`. (But you cannot access `_at_a` either,
of course.)
Because of the above, `(@a, a) ->` is now valid; `@a` and `a` are not duplicate
parameters.
Duplicate this-parameters with a reserved word, such as `(@case, @case) ->`,
used to compile but now throws, just like regular duplicate parameters.
* Supplement missing block before `ELSE` token only for multi-line `if`.
* Don't prematurely remove `TERMINATOR` before `ELSE` (so we can differentiate single- and multi-line forms).
* Cleanup: Remove `WHEN` from `EXPRESSION_CLOSE`. (Only `LEADING_WHEN` tokens are preceded by a `TERMINATOR`.)
* Cleanup: Remove really old, inapplicable text from comment.
