Allow computed class properties #5206
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| ObjAssignable: [ | ||
| o 'SimpleObjAssignable' | ||
| o '[ Expression ]', -> new Value new ComputedPropertyName $2 | ||
| o '@ [ Expression ]', -> new Value LOC(1)(new ThisLiteral $1), [LOC(3)(new ComputedPropertyName($3))], 'this' |
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Mostly copied this grammar rule from the rule for ThisProperty
| assign = @externalCtor = new Assign new Value, value | ||
| else if not assign.variable.this | ||
| name = new (if base.shouldCache() then Index else Access) base | ||
| name = |
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This is the fix for the invalid JS for non-static computed class properties (extracted from #5205)
| # The lexer has tagged the opening bracket of an indexing operation call. | ||
| # Match it with its paired close. | ||
| closeOpenIndexes: -> | ||
| startToken = null |
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Allowing static computed class properties/methods was a bit more complex. In addition to the new grammar rule above, in the rewriter here we first want to make sure that the [/] in eg @[b]: ... are not tagged as INDEX_START/INDEX_END since that would be inaccurate and creates an ambiguous grammar
I believe this is safe because there's not a scenario where an actual INDEX_END would be immediately followed by a : token
| # Go back to the (implicit) start of the object. | ||
| s = switch | ||
| when @tag(i - 1) in EXPRESSION_END then start[1] | ||
| when @tag(i - 1) in EXPRESSION_END |
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Then, we have to make sure that for an implicit object (whether an actual implicit object or a class body) starting with a static computed property eg @[b]: ->, the start of the implicit object comes before the @
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Thanks, this looks great. Seeing how complicated this got, I’m glad we split it off from the AST work. |
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Fixes #5204
@GeoffreyBooth this PR contains two things (both raised in #5204):
I extracted this fix from #5205 to target it here against
master