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do not emit original variable statement if it was hoisted and all var…
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…iable declarations are non-initialized
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@vladima
vladima committed Apr 11, 2015
1 parent a281cad commit e2ba13e
Showing 1 changed file with 54 additions and 16 deletions.
70 changes: 54 additions & 16 deletions src/compiler/emitter.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1893,7 +1893,7 @@ var __param = this.__param || function(index, decorator) { return function (targ
emit(node.expression);
}

function shouldEmitPublishOfExportedValue(node: PrefixUnaryExpression | PostfixUnaryExpression): boolean {
function shouldEmitPublishOfExportedValueForUnaryExpressions(node: PrefixUnaryExpression | PostfixUnaryExpression): boolean {
if (!currentFileIsEmittedAsSystemModule() || node.operand.kind !== SyntaxKind.Identifier) {
return false;
}
Expand All @@ -1902,7 +1902,7 @@ var __param = this.__param || function(index, decorator) { return function (targ
}

function emitPrefixUnaryExpression(node: PrefixUnaryExpression) {
const emitPublishOfExportedValue = shouldEmitPublishOfExportedValue(node);
const emitPublishOfExportedValue = shouldEmitPublishOfExportedValueForUnaryExpressions(node);

if (emitPublishOfExportedValue) {
write(`${exportFunctionForFile}("`);
Expand Down Expand Up @@ -1940,7 +1940,7 @@ var __param = this.__param || function(index, decorator) { return function (targ
}

function emitPostfixUnaryExpression(node: PostfixUnaryExpression) {
const emitPublishOfExportedValue = shouldEmitPublishOfExportedValue(node);
const emitPublishOfExportedValue = shouldEmitPublishOfExportedValueForUnaryExpressions(node);
if (emitPublishOfExportedValue) {
write(`${exportFunctionForFile}("`);
emitNodeWithoutSourceMap(node.operand);
Expand Down Expand Up @@ -2118,10 +2118,10 @@ var __param = this.__param || function(index, decorator) { return function (targ
emitEmbeddedStatement(node.statement);
}

function emitStartOfVariableDeclarationList(decl: Node, startPos?: number): void {
function emitStartOfVariableDeclarationList(decl: Node, startPos?: number): boolean {

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@CyrusNajmabadi

CyrusNajmabadi Apr 21, 2015

Contributor

Comment what the return value indicates. If this tells you if it was actaully emitted or not, this should be called tryEmit.

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@vladima

vladima Apr 22, 2015

Author Contributor

done
if (currentFileIsEmittedAsSystemModule() && isSourceFileLevelDeclaration(decl)) {
Debug.assert(compilerOptions.module === ModuleKind.System);
return;
return false;
}
let tokenKind = SyntaxKind.VarKeyword;
if (decl && languageVersion >= ScriptTarget.ES6) {
Expand All @@ -2140,13 +2140,38 @@ var __param = this.__param || function(index, decorator) { return function (targ
else {
switch (tokenKind) {
case SyntaxKind.VarKeyword:
return write("var ");
write("var ");
break;
case SyntaxKind.LetKeyword:
return write("let ");
write("let ");
break;
case SyntaxKind.ConstKeyword:
return write("const ");
write("const ");
break;
}
}

return true;
}

function emitVariableDeclarationListSkippingUninitializedEntries(list: VariableDeclarationList): boolean {
let started = false;
for (let decl of list.declarations) {
if (!decl.initializer) {
continue;
}

if (!started) {
started = true;
}
else {
write(", ");
}

emit(decl);
}

return started;
}

function emitForStatement(node: ForStatement) {
Expand All @@ -2156,8 +2181,13 @@ var __param = this.__param || function(index, decorator) { return function (targ
if (node.initializer && node.initializer.kind === SyntaxKind.VariableDeclarationList) {
let variableDeclarationList = <VariableDeclarationList>node.initializer;
let declarations = variableDeclarationList.declarations;
emitStartOfVariableDeclarationList(declarations[0], endPos);
emitCommaList(declarations);
let startIsEmitted = emitStartOfVariableDeclarationList(declarations[0], endPos);
if (startIsEmitted) {
emitCommaList(declarations);
}
else {
emitVariableDeclarationListSkippingUninitializedEntries(variableDeclarationList);
}
}
else if (node.initializer) {
emit(node.initializer);
Expand Down Expand Up @@ -2938,16 +2968,25 @@ var __param = this.__param || function(index, decorator) { return function (targ
}

function emitVariableStatement(node: VariableStatement) {
let startIsEmitted = true;
if (!(node.flags & NodeFlags.Export)) {
emitStartOfVariableDeclarationList(node.declarationList);
startIsEmitted = emitStartOfVariableDeclarationList(node.declarationList);
}
else if (isES6ExportedDeclaration(node)) {
// Exported ES6 module member
write("export ");
emitStartOfVariableDeclarationList(node.declarationList);
startIsEmitted = emitStartOfVariableDeclarationList(node.declarationList);
}
if (startIsEmitted) {
emitCommaList(node.declarationList.declarations);
write(";");
}
else {
let atLeastOneItem = emitVariableDeclarationListSkippingUninitializedEntries(node.declarationList);
if (atLeastOneItem) {
write(";");
}
}
emitCommaList(node.declarationList.declarations);
write(";");
if (languageVersion < ScriptTarget.ES6 && node.parent === currentSourceFile) {
forEach(node.declarationList.declarations, emitExportVariableAssignments);
}
Expand Down Expand Up @@ -4799,7 +4838,6 @@ var __param = this.__param || function(index, decorator) { return function (targ
function writeLocalNamesForExternalImports(startWithComma: boolean): void {
let started = startWithComma;
for (let importNode of externalImports) {

if (started) {
write(", ");
}
Expand Down Expand Up @@ -4854,7 +4892,7 @@ var __param = this.__param || function(index, decorator) { return function (targ
write(", ");
}
if (local.kind === SyntaxKind.ClassDeclaration || local.kind === SyntaxKind.ModuleDeclaration) {
emitDeclarationName(<ClassDeclaration>local);
emitDeclarationName(<ClassDeclaration | ModuleDeclaration>local);
}
else {
emit(local);
Expand Down

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