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Cyrus Najmabadi 2014-11-30 19:23:06 -08:00
parent 092475166c
commit f057d4efd8
1 changed files with 11 additions and 5 deletions
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16
src/compiler/checker.ts
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@ -4420,19 +4420,25 @@ module ts {
return type;
function narrowTypeByEquality(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type {
var left = <TypeOfExpression>expr.left;
var right = <LiteralExpression>expr.right;
// Check that we have 'typeof <symbol>' on the left and string literal on the right
if (left.kind !== SyntaxKind.TypeOfExpression ||
left.expression.kind !== SyntaxKind.Identifier || right.kind !== SyntaxKind.StringLiteral ||
getResolvedSymbol(<Identifier>left.expression) !== symbol) {
if (expr.left.kind !== SyntaxKind.TypeOfExpression || expr.right.kind !== SyntaxKind.StringLiteral) {
return type;
}
var left = <TypeOfExpression>expr.left;
var right = <LiteralExpression>expr.right;
if (left.expression.kind !== SyntaxKind.Identifier ||
getResolvedSymbol(<Identifier>left.expression) !== symbol) {
return type;
}
var t = right.text;
var checkType: Type = t === "string" ? stringType : t === "number" ? numberType : t === "boolean" ? booleanType : emptyObjectType;
if (expr.operator === SyntaxKind.ExclamationEqualsEqualsToken) {
assumeTrue = !assumeTrue;
}
if (assumeTrue) {
// The assumed result is true. If check was for a primitive type, that type is the narrowed type. Otherwise we can
// remove the primitive types from the narrowed type.