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Emit for decorators, updated to ES6 classes.
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@rbuckton
rbuckton committed Mar 17, 2015
1 parent 39001f5 commit bd4d7fc
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24 changes: 24 additions & 0 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11267,6 +11267,29 @@ module ts {
!hasProperty(getGeneratedNamesForSourceFile(getSourceFile(location)), name);
}

function getClassDeclarationVariableId(n: Identifier): number {

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@JsonFreeman

JsonFreeman Mar 20, 2015

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Why do we need this?

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@rbuckton

rbuckton Mar 21, 2015

Author Member

ES6 classes have a doubly-bound identifier:

class C {
  method() {
    C; // binding inside of class
  }
}
C; // binding in outer scope

This differs from function declarations (whose identifier is only bound in the containing scope), and function expressions (whose identifier is only bound inside the function). As a result, I need to alias the class to ensure we use the decorated C:

// TS
@dec
class C {
  method() {
    C; // needs to be the decorated C, not the undecorated C.
  }
}
// ES6
var C = (function() {
  let _C = class C {
    method() {
      _C; // uses _C, since C is always the undecorated C inside of the class body.
    }
  }
  _C = __decorate([dec], _C);
  return _C;
})();

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@JsonFreeman

JsonFreeman Mar 21, 2015

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Makes sense. So the binding in the outer scope is fine as is, but the binding in the class needs to be altered. Please explain in a comment in the code.

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@JsonFreeman

JsonFreeman Mar 22, 2015

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Is this also the case when you refer to 'this' inside a static method of a class? Will you get the undecorated class constructor?

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@JsonFreeman

JsonFreeman Mar 22, 2015

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Also, I think the IIFE needs to be assigned to a let, not a var.

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@rbuckton

rbuckton Mar 23, 2015

Author Member

this should be fine as it should be the this bound by the call site, which should decorated version of the class at all call sites.

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@JsonFreeman

JsonFreeman Mar 23, 2015

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Ah yes, true
Debug.assert(!nodeIsSynthesized(n));

let isClassDeclaration = n.parent.kind === SyntaxKind.ClassDeclaration;

let symbol =
(isClassDeclaration ? getSymbolOfNode(n.parent) : undefined) ||
getNodeLinks(n).resolvedSymbol ||
resolveName(n, n.text, SymbolFlags.Value | SymbolFlags.Alias, /*nodeNotFoundMessage*/ undefined, /*nameArg*/ undefined);

symbol = getExportSymbolOfValueSymbolIfExported(symbol);

let isClass = symbol && (symbol.flags & SymbolFlags.Class) !== 0;

if (isClass) {
// side-effect of calling this method:
// assign id to symbol if it was not yet set
getSymbolLinks(symbol);
return symbol.id;
}
return undefined;
}

function getBlockScopedVariableId(n: Identifier): number {
Debug.assert(!nodeIsSynthesized(n));

Expand Down Expand Up @@ -11309,6 +11332,7 @@ module ts {
getConstantValue,
isUnknownIdentifier,
getBlockScopedVariableId,
getClassDeclarationVariableId,
};
}

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1 comment on commit bd4d7fc

@JsonFreeman
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In general, I think the emitter needs a bunch of commenting with code samples. The comments should explain whatever caveats you need to account for, and the code examples are useful because the emitter's source code does not resemble the emitted code.

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