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Rest element support in array destructuring declarations

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This commit is contained in:
Anders Hejlsberg 2014-12-11 18:27:08 -08:00
parent 6babef417f
commit a42df7547e
4 changed files with 28 additions and 3 deletions
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1
src/compiler/diagnosticInformationMap.generated.ts
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@ -144,6 +144,7 @@ module ts {
Array_element_destructuring_pattern_expected: { code: 1181, category: DiagnosticCategory.Error, key: "Array element destructuring pattern expected." },
A_destructuring_declaration_must_have_an_initializer: { code: 1182, category: DiagnosticCategory.Error, key: "A destructuring declaration must have an initializer." },
Destructuring_declarations_are_not_allowed_in_ambient_contexts: { code: 1183, category: DiagnosticCategory.Error, key: "Destructuring declarations are not allowed in ambient contexts." },
A_rest_element_cannot_have_an_initializer: { code: 1184, category: DiagnosticCategory.Error, key: "A rest element cannot have an initializer." },
Duplicate_identifier_0: { code: 2300, category: DiagnosticCategory.Error, key: "Duplicate identifier '{0}'." },
Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor: { code: 2301, category: DiagnosticCategory.Error, key: "Initializer of instance member variable '{0}' cannot reference identifier '{1}' declared in the constructor." },
Static_members_cannot_reference_class_type_parameters: { code: 2302, category: DiagnosticCategory.Error, key: "Static members cannot reference class type parameters." },

4
src/compiler/diagnosticMessages.json
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@ -568,6 +568,10 @@
"category": "Error",
"code": 1183
},
"A rest element cannot have an initializer.": {
"category": "Error",
"code": 1184
},
"Duplicate identifier '{0}'.": {
"category": "Error",

13
src/compiler/emitter.ts
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@ -3022,8 +3022,17 @@ module ts {
emitBindingElement(element, createPropertyAccess(value, propName));
}
else if (element.kind !== SyntaxKind.OmittedExpression) {
// Rewrite element to a declaration that accesses array element at index i
emitBindingElement(element, createElementAccess(value, createNumericLiteral(i)));
if (!element.dotDotDotToken) {
// Rewrite element to a declaration that accesses array element at index i
emitBindingElement(element, createElementAccess(value, createNumericLiteral(i)));
}
else {
if (i === elements.length - 1) {
value = ensureIdentifier(value);
emitAssignment(<Identifier>element.name, value);
write(".slice(" + i + ")");
}
}
}
}
}

13
src/compiler/parser.ts
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@ -1585,7 +1585,7 @@ module ts {
case ParsingContext.VariableDeclarations:
return isIdentifierOrPattern();
case ParsingContext.ArrayBindingElements:
return token === SyntaxKind.CommaToken || isIdentifierOrPattern();
return token === SyntaxKind.CommaToken || token === SyntaxKind.DotDotDotToken || isIdentifierOrPattern();
case ParsingContext.TypeParameters:
return isIdentifier();
case ParsingContext.ArgumentExpressions:
@ -3886,6 +3886,7 @@ module ts {
}
}
else {
node.dotDotDotToken = parseOptionalToken(SyntaxKind.DotDotDotToken);
node.name = parseIdentifierOrPattern();
}
node.initializer = parseInitializer(/*inParameter*/ false);
@ -5748,6 +5749,16 @@ module ts {
}
function checkBindingElement(node: BindingElement) {
if (node.dotDotDotToken) {
var elements = (<BindingPattern>node.parent).elements;
if (node !== elements[elements.length - 1]) {
return grammarErrorOnNode(node, Diagnostics.A_rest_element_must_be_last_in_an_array_destructuring_pattern);
}
if (node.initializer) {
// Error on equals token which immediate precedes the initializer
return grammarErrorAtPos(node.initializer.pos - 1, 1, Diagnostics.A_rest_element_cannot_have_an_initializer);
}
}
if (node.parserContextFlags & ParserContextFlags.StrictMode && isEvalOrArgumentsIdentifier(node.name)) {
// It is a SyntaxError if a VariableDeclaration or VariableDeclarationNoIn occurs within strict code
// and its Identifier is eval or arguments