* Try to detect when `from` in a `for` loop declaration is an identifier, not a keyword
* Handle destructured arrays
* from as a destructured, aliased object variable name in a for loop declaration
* Support JavaScript code blocks set apart by triple backticks (``` ... ```)
* Add test for escaped backticks
* Remove TODOs for things we’re never going to support
* Convert escaped backticks to backticks; update tests
* Block inline JavaScript can end with an escaped backtick character
* Updated JavaScript token regexes per @lydell
* In JavaScript blocks, escape backslashes when they immediately precede backticks; additional tests
* Test that we don’t break backslash escaping in JavaScript literals
* Added support for for-from loop, see #3832
* for-from: remove extra newline and add support for ranges
* for-from: tidy up the lexer
* for-from: add support for patterns
* for-from: fix bad alignment
* for-from: add two more tests
* for-from: fix test "for-from loops over generators"
See explanation here: https://github.com/jashkenas/coffeescript/pull/4306#issuecomment-257066877
* for-from: delete leftover console.log
* Refactor the big `if` block in the lexer to be as minimal a change from `master` as we can get away with
* Cleanup to make more idiomatic, remove trailing whitespace, minor performance improvements
* for-from: move code from one file to another
* for-from: clean up whitespace
* for-from: lexer bikeshedding
* Move "own is not supported in for-from loops" test into error_messages.coffee; improve error message so that "own" is underlined
* Revert unnecessary changes, to minimize the lines of code modified by this PR
This is an upstream port of https://github.com/decaffeinate/coffeescript/pull/9
The existing logic for computing the end location of a string was to take the
end of the string contents, then add the delimiter length to last_column. For
example, `"""abc"""` would have an end position three characters after the `c`.
However, if a string ended in a newline, then the end location for the string
contents would be one line above the end location for the string, so the proper
fix is to move the end location to the next line, not just to shift it to the
right.
This avoids a bug where the location data would sometimes reference a
non-existent location (one past the end of its line). It fixes the AST location
data, although as far as I know, it never has caused correctness issues in the
CoffeeScript output.
This is an upstream port for the patch https://github.com/decaffeinate/coffeescript/pull/8
See https://github.com/decaffeinate/decaffeinate/issues/291 for the bug that this fixed.
For the most part, CoffeeScript and JavaScript have the same precedence rules,
but in some cases, the intermediate AST format didn't represent the actual
evaluation order. For example, in the expression `a or b and c`, the `and` is
evaluated first, but the parser treated the two operators with equal precedence.
This was still correct end-to-end because CoffeeScript simply emitted the result
without parens, but any intermediate tools using the CoffeeScript parser could
become confused.
Here are the JS operator precedence rules:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence
For the most part, CoffeeScript already follows these. `COMPARE` operators
already behave differently due to chained comparisons, so I think we don't need
to worry about following JS precedence for those. So I think the only case where
it was behaving differently in an important way was for the binary/bitwise
operators that are being changed here.
As part of this change, I also introduced a new token tag, `BIN?`, for the
binary form of the `?` operator.
`"""` (and `"`) strings are lexed into an array of tokens, consisting of
strings and interpolations. Previously, the minimum indententation
inside `"""` strings was stripped from the beginning of _all_ of those
string tokens. Usually, the indentation is longer than any other
sequence of spaces in a `"""` string, so the problem didn't occur in
most cases. This commit makes sure to only strip indentation after
newlines.
Fixes#4314.
Very large decimal number literals, binary number literals and octal
literals are lexed into an INFINITY token (instead of a NUMBER token)
and compiled into `2e308`. That is is supposed to be the case for very
large hexdecimal dumber literals as well, but previously wasn't.
Before:
$ node -p 'require("./").tokens(`0x${Array(256 + 1).join("f")}`)[0][0]'
NUMBER
After:
$ node -p 'require("./").tokens(`0x${Array(256 + 1).join("f")}`)[0][0]'
INFINITY
This commit also cleans up `numberToken` in lexer.coffee a bit.
This pull request adds support for ES2015 modules, by recognizing `import` and `export` statements. The following syntaxes are supported, based on the MDN [import](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import) and [export](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export) pages:
```js
import "module-name"
import defaultMember from "module-name"
import * as name from "module-name"
import { } from "module-name"
import { member } from "module-name"
import { member as alias } from "module-name"
import { member1, member2 as alias2, … } from "module-name"
import defaultMember, * as name from "module-name"
import defaultMember, { … } from "module-name"
export default expression
export class name
export { }
export { name }
export { name as exportedName }
export { name as default }
export { name1, name2 as exportedName2, name3 as default, … }
export * from "module-name"
export { … } from "module-name"
```
As a subsitute for ECMAScript’s `export var name = …` and `export function name {}`, CoffeeScript also supports:
```js
export name = …
```
CoffeeScript also supports optional commas within `{ … }`.
This PR converts the supported `import` and `export` statements into ES2015 `import` and `export` statements; it **does not resolve the modules**. So any CoffeeScript with `import` or `export` statements will be output as ES2015, and will need to be transpiled by another tool such as Babel before it can be used in a browser. We will need to add a warning to the documentation explaining this.
This should be fully backwards-compatible, as `import` and `export` were previously reserved keywords. No flags are used.
There are extensive tests included, though because no current JavaScript runtime supports `import` or `export`, the tests compare strings of what the compiled CoffeeScript output is against what the expected ES2015 should be. I also conducted two more elaborate tests:
* I forked the [ember-piqu](https://github.com/pauc/piqu-ember) project, which was an Ember CLI app that used ember-cli-coffeescript and [ember-cli-coffees6](https://github.com/alexspeller/ember-cli-coffees6) (which adds “support” for `import`/`export` by wrapping such statements in backticks before passing the result to the CoffeeScript compiler). I removed `ember-cli-coffees6` and replaced the CoffeeScript compiler used in the build chain with this code, and the app built without errors. [Demo here.](https://github.com/GeoffreyBooth/coffeescript-modules-test-piqu)
* I also forked the [CoffeeScript version of Meteor’s Todos example app](https://github.com/meteor/todos/tree/coffeescript), and replaced all of its `require` statements with the `import` and `export` statements from the original ES2015 version of the app on its `master` branch. I then updated the `coffeescript` Meteor package in the app to use this new code, and again the app builds without errors. [Demo here.](https://github.com/GeoffreyBooth/coffeescript-modules-test-meteor-todos)
The discussion history for this work started [here](https://github.com/jashkenas/coffeescript/pull/4160) and continued [here](https://github.com/GeoffreyBooth/coffeescript/pull/2). @lydell provided guidance, and @JimPanic and @rattrayalex contributed essential code.
In f609036bee, a line was changed from
`if length > 0 then (length - 1) else 0` to `Math.max 0, length - 1`. However,
in some cases, the `length` variable can be `undefined`. The previous code would
correctly compute `lastCharacter` as 0, but the new code would compute it as
`NaN`. This would cause trouble later on: the end location would just be the end
of the current chunk, which would be incorrect.
Here's a specific case where the parser was behaving incorrectly:
```
a {
b: ->
return c d,
if e
f
}
g
```
The OUTDENT tokens after the `f` had an undefined length, so the `NaN` made it
so the end location was at the end of the file. That meant that various nodes in
the AST, like the `return` node, would incorrectly have an end location at the
end of the file.
To fix, I just reverted the change to that particular line.
- Split out a PROPERTY token from the IDENTIFIER token.
- Split out Property from the Identifier in the grammar.
- Split out PropertyLiteral from IdentifierLiteral.
- Show the same type of error message for compound assignment as for `=`
assignment when the LHS is invalid.
- Show the same type of error message when trying to assign to a CoffeeScript
keyword as when trying to assign to a JavaScript keyword.
- Now longer treat `&& =` as `&&=`. The same goes for `and=`, `||=` and `or=`.
- Unify the error message to: `<optional type> '<value>' can't be assigned`.
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
This breaks compatibility with
->
yield for i in [1..3]
i * 2
and
->
yield
i * 2
yield's behaviour now mirrors that of return in that it can be used stand alone as well as with expressions. Thus, it currently also inherits the above limitations.
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.
- Invalid `\x` and `\u` escapes now throw errors.
- U+2028 and U+2029 (which JavaScript treats as newline characters) are now
escaped to `\u2028` and `\u2029`, respectively.
- Octal escapes are now forbidden not only in strings, but in regexes as well.
- `\0` escapes are now escaped if needed (so that they do not form an octal
literal by mistake). Note that `\01` is an octal escape in a regex, while `\1`
is a backreference. (Added a test for backreferences while at it.)
- Fixed a bug where newlines in strings weren't removed if preceded by an
escaped character.
The third element in a token should just be an object containing line
number and column info. This PR fixes the problem with one of the tokens
being set incorrectly.
Instead of compiling to `"" + + (+"-");`, `"#{+}-"'` now gives an appropriate
error message:
[stdin]:1:5: error: unexpected end of interpolation
"#{+}-"
^
This is done by _always_ (instead of just sometimes) wrapping the interpolations
in parentheses in the lexer. Unnecessary parentheses won't be output anyway.
I got tired of updating the tests in test/location.coffee (which I had enough of
in #3770), which relies on implementation details (the exact amount of tokens
generated for a given string of code) to do their testing, so I refactored them
to be less fragile.
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.
A regex may not follow a specific set of tokens. These were already known before
in the `NOT_REGEX` and `NOT_SPACED_REGEX` arrays. (However, I've refactored them
to be more correct and to add a few missing tokens). In all other cases (except
after a spaced callable) a slash is the start of a regex, and may now start with
a space or an equals sign. It’s really that simple!
A slash after a spaced callable is the only ambigous case. We cannot know if
that's division or function application with a regex as the argument. The
spacing determines which is which:
Space on both sides:
- `a / b/i` -> `a / b / i`
- `a /= b/i` -> `a /= b / i`
No spaces:
- `a/b/i` -> `a / b / i`
- `a/=b/i` -> `a /= b / i`
Space on the right side:
- `a/ b/i` -> `a / b / i`
- `a/= b/i` -> `a /= b / i`
Space on the left side:
- `a /b/i` -> `a(/b/i)`
- `a /=b/i` -> `a(/=b/i)`
The last case used to compile to `a /= b / i`, but that has been changed to be
consistent with the `/` operator. The last case really looks like a regex, so it
should be parsed as one.
Moreover, you may now also space the `/` and `/=` operators with other
whitespace characters than a space (such as tabs and non-breaking spaces) for
consistency.
Lastly, unclosed regexes are now reported as such, instead of generating some
other confusing error message.
It should perhaps also be noted that apart from escaping (such as `a /\ b/`) you
may now also use parentheses to disambiguate division and regex: `a (/ b/)`. See
https://github.com/jashkenas/coffeescript/issues/3182#issuecomment-26688427.
