Before:
```
$ cat tmp.coffee.md
test
a
$ ./bin/coffee tmp.coffee.md
ReferenceError: a is not defined
at Object.<anonymous> (/src/coffee-script/tmp.coffee.md:2:3)
...
```
Note how the line and column numbers (2 and 3, respectively) are not
correct.
After:
```
$ ./bin/coffee tmp.coffee.md
ReferenceError: a is not defined
at Object.<anonymous> (/home/lydell/forks/coffee-script/tmp.coffee.md:3:5)
...
```
Line 3, column 5 is the actual position of the `a` in tmp.coffee.md.
Supersedes and fixes#4204.
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.
In for example `for` loops, a variable called `i` is generated (for the
loop index). If that name is unavailable, `j` is used instead, then `k`,
`l`, etc. all the way to `z`. Then, `aa`, `ab`, `ac` etc. are used.
This meant that, eventually, `do` would be used, but that's not a valid
variable name since `do` is a JavaScript keyword.
This logic was also inefficiently implemented. For example, going from
`aa` to `ab` or from `az` to `ba` required lots of loop iterations.
This commit changes the variable naming convention. Now, `i`, `j`, `k`,
etc. to `z` are used like before. Then comes `i1`, `j1`, `k1`, etc. Then
`i2`, `j2`, `k2` and so on. This is simpler, efficient and easier to
understand. `i1` is more obvious to be a loop index than `aa`.
Fixes#4267.
This should have been done in commit 841b3cd2, but I forgot to. Since
that commit, `SourceMap::generate` returns an object instead of
`JSON.stringify()` of that object, but the tests still compared strings.
Fixes#4269.
Note: `SourceMap::generate` is only used internally, so its change in
return type is not a breaking change. The "public API" is unchanged.
- Inline source maps are now shorter by not using pretty-printed JSON.
- `.register()`ed files are now given more information in their inline source
maps: The name and contents of the source file.
- Some code cleanup.
If you decode the inline source map generated (when using `.register()`) for a
file test.coffee with the contents `console.log "it works!"`, here is the
output:
Before:
{
"version": 3,
"file": "",
"sourceRoot": "",
"sources": [
""
],
"names": [],
"mappings": "AAAA;EAAA,OAAO,CAAC,GAAR,CAAY,eAAZ;AAAA"
}
After:
{"version":3,"file":"","sourceRoot":"","sources":["test.coffee"],"names":[],"mappings":"AAAA;EAAA,OAAO,CAAC,GAAR,CAAY,WAAZ;AAAA","sourcesContent":["console.log \"it works!\"\n"]}
Related: #4214.
- 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
Commit 347a6255 is a bit problematic:
- It doesn't include the built .js files.
- It breaks `CoffeeScript.register()`. This can be seen by running the tests;
four of them fails. The error is that `CoffeeScript.register()` calls
`CoffeeScript._compileFile()` with the `sourceMap` option enabled, which
returns an object while the code expected a string.
This commit fixes the broken `CoffeeScript.register()`, by setting the
`sourceMap` option to `false` (but still keeping the `inlineMap` option enabled,
which was the intention of commit 347a6255). It also commits the built .js
files. The tests now pass.
