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Add type narrow

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This commit is contained in:
kingwl
2020-04-08 12:09:56 +08:00
parent 67a4943e1f
commit d2be8900dc
15 changed files with 694 additions and 102 deletions
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3
src/compiler/binder.ts
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@@ -905,6 +905,9 @@ namespace ts {
function isNarrowingBinaryExpression(expr: BinaryExpression) {
switch (expr.operatorToken.kind) {
case SyntaxKind.EqualsToken:
case SyntaxKind.BarBarEqualsToken:
case SyntaxKind.AmpersandAmpersandEqualsToken:
case SyntaxKind.QuestionQuestionEqualsToken:
return containsNarrowableReference(expr.left);
case SyntaxKind.EqualsEqualsToken:
case SyntaxKind.ExclamationEqualsToken:

4
src/compiler/checker.ts
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@@ -20701,7 +20701,11 @@ namespace ts {
function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type {
switch (expr.operatorToken.kind) {
case SyntaxKind.EqualsToken:
case SyntaxKind.BarBarEqualsToken:
case SyntaxKind.AmpersandAmpersandEqualsToken:
case SyntaxKind.QuestionQuestionEqualsToken:
return narrowTypeByTruthiness(narrowType(type, expr.right, assumeTrue), expr.left, assumeTrue);
case SyntaxKind.EqualsEqualsToken:
case SyntaxKind.ExclamationEqualsToken:
case SyntaxKind.EqualsEqualsEqualsToken: