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Merge pull request #2109 from Microsoft/sideEffects

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Emit downlevel parameter initializers unless we are certain they don't have any side effects.
This commit is contained in:
CyrusNajmabadi
2015-02-23 15:43:56 -08:00
parent eaba1804f0 cfe3bb8f8d
commit e26de71d9c
96 changed files with 889 additions and 168 deletions
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46
src/compiler/emitter.ts
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@@ -3899,7 +3899,9 @@ module ts {
emitSignatureParameters(node);
}
if (isSingleLineEmptyBlock(node.body) || !node.body) {
if (!node.body) {
// There can be no body when there are parse errors. Just emit an empty block
// in that case.
write(" { }");
}
else if (node.body.kind === SyntaxKind.Block) {
@@ -3979,15 +3981,57 @@ module ts {
}
function emitBlockFunctionBody(node: FunctionLikeDeclaration, body: Block) {
// If the body has no statements, and we know there's no code that would cause any
// prologue to be emitted, then just do a simple emit if the empty block.
if (body.statements.length === 0 && !anyParameterHasBindingPatternOrInitializer(node)) {
emitFunctionBodyWithNoStatements(node, body);
}
else {
emitFunctionBodyWithStatements(node, body);
}
}
function anyParameterHasBindingPatternOrInitializer(func: FunctionLikeDeclaration) {
return forEach(func.parameters, hasBindingPatternOrInitializer);
}
function hasBindingPatternOrInitializer(parameter: ParameterDeclaration) {
return parameter.initializer || isBindingPattern(parameter.name);
}
function emitFunctionBodyWithNoStatements(node: FunctionLikeDeclaration, body: Block) {
var singleLine = isSingleLineEmptyBlock(node.body);
write(" {");
if (singleLine) {
write(" ");
}
else {
increaseIndent();
writeLine();
}
emitLeadingCommentsOfPosition(body.statements.end);
if (!singleLine) {
decreaseIndent();
}
emitToken(SyntaxKind.CloseBraceToken, body.statements.end);
}
function emitFunctionBodyWithStatements(node: FunctionLikeDeclaration, body: Block) {
write(" {");
scopeEmitStart(node);
var outPos = writer.getTextPos();
increaseIndent();
emitDetachedComments(body.statements);
var startIndex = emitDirectivePrologues(body.statements, /*startWithNewLine*/ true);
emitFunctionBodyPreamble(node);
decreaseIndent();
var preambleEmitted = writer.getTextPos() !== outPos;
if (!preambleEmitted && nodeEndIsOnSameLineAsNodeStart(body, body)) {