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parser: improve error tolerance when dealing with invalid expressions
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@Talv
Talv committed Aug 20, 2018
1 parent 1b56b91 commit bf2ffc5
Showing 1 changed file with 39 additions and 21 deletions.
60 changes: 39 additions & 21 deletions src/compiler/parser.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -168,11 +168,9 @@ export class Parser {
}

private createMissingNode<T extends Node>(kind: T['kind']): T {
this.parseErrorAtCurrentToken('Missing node: {0}', getKindName(kind));
this.parseErrorAtCurrentToken(`Missing node: ${getKindName(kind)}`);

const result = this.createNode(SyntaxKind.Unknown);

return this.finishNode(result) as T;
return this.createNode(SyntaxKind.Unknown, undefined, false) as T;
}

private createMissingList<T extends Node>(): NodeArray<T> {
Expand Down Expand Up @@ -255,10 +253,10 @@ export class Parser {
continue;
}

const start = this.scanner.getStartPos();
const start = this.scanner.getTokenPos();
this.nextToken();
this.parseErrorAtPosition(start, this.scanner.getTokenPos() - start, this.parsingContextErrors(kind));
if (kind !== ParsingContext.SourceElements) {
if (kind !== ParsingContext.SourceElements && kind !== ParsingContext.BlockStatements) {
break;
}
}
Expand Down Expand Up @@ -313,6 +311,7 @@ export class Parser {

this.parseErrorAtCurrentToken(this.parsingContextErrors(kind));
this.nextToken();
break;
}

if (commaStart >= 0) {
Expand Down Expand Up @@ -480,14 +479,20 @@ export class Parser {
return this.finishNode(node);
}

private parseIdentifier(diagnosticMessage?: string): Types.Identifier {
private parseIdentifier(alwaysAdvance: boolean = true): Types.Identifier {
const identifier = <Types.Identifier>this.createNode(SyntaxKind.Identifier);
this.parseExpected(SyntaxKind.Identifier, diagnosticMessage, false);
this.parseExpected(SyntaxKind.Identifier, null, false);
identifier.name = this.scanner.getTokenValue() || '';
this.nextToken();
if (alwaysAdvance || this.token() === SyntaxKind.Identifier) {
this.nextToken();
}
return this.finishNode(identifier);
}

private parseExpectedIdentifier(): Types.Identifier {
return this.parseIdentifier(false);
}

private parseTypeDefinition(): Types.TypeNode {
let baseType: Types.TypeNode;

Expand All @@ -514,7 +519,7 @@ export class Parser {
while (this.token() === SyntaxKind.OpenBracketToken) {
let arrayType = <Types.ArrayTypeNode>this.createNode(SyntaxKind.ArrayType, baseType.pos);
this.parseExpected(SyntaxKind.OpenBracketToken)
arrayType.size = this.parseExpression();
arrayType.size = this.parseExpectedExpression();
arrayType.elementType = baseType;
this.parseExpected(SyntaxKind.CloseBracketToken);
baseType = this.finishNode(arrayType)
Expand Down Expand Up @@ -701,15 +706,18 @@ export class Parser {
return this.parseTokenNode<Types.PrimaryExpression>();
case SyntaxKind.OpenParenToken:
return this.parseParenthesizedExpression();
case SyntaxKind.Identifier:
return this.parseIdentifier();
}

return this.parseIdentifier('expression expected');
this.parseErrorAtCurrentToken(`Invalid expression`);
return this.createNode(SyntaxKind.Unknown, undefined, false);
}

private parseParenthesizedExpression(): Types.ParenthesizedExpression {
const node = <Types.ParenthesizedExpression>this.createNode(SyntaxKind.ParenthesizedExpression);
this.parseExpected(SyntaxKind.OpenParenToken);
node.expression = this.parseExpression();
node.expression = this.parseExpectedExpression();
this.parseExpected(SyntaxKind.CloseParenToken);
return this.finishNode(node);
}
Expand All @@ -725,7 +733,7 @@ export class Parser {
const propertyAccess = <Types.PropertyAccessExpression>this.createNode(SyntaxKind.PropertyAccessExpression, expression.pos);
this.parseExpected(SyntaxKind.DotToken);
propertyAccess.expression = expression;
propertyAccess.name = this.parseIdentifier();
propertyAccess.name = this.parseExpectedIdentifier();
expression = this.finishNode(propertyAccess);
continue;
}
Expand All @@ -734,7 +742,7 @@ export class Parser {
const indexedAccess = <Types.ElementAccessExpression>this.createNode(SyntaxKind.ElementAccessExpression, expression.pos);
this.parseExpected(SyntaxKind.OpenBracketToken);
indexedAccess.expression = expression;
indexedAccess.argumentExpression = this.parseExpression();
indexedAccess.argumentExpression = this.parseExpectedExpression();
this.parseExpected(SyntaxKind.CloseBracketToken);
expression = this.finishNode(indexedAccess);
continue;
Expand Down Expand Up @@ -893,6 +901,16 @@ export class Parser {
return expr;
}

private parseExpectedExpression(allowAssignment: boolean = false): Types.Expression | null {
if (this.isStartOfExpression()) {
return this.parseExpression(allowAssignment);
}
else {
this.parseErrorAtCurrentToken('Expected expression');
return this.createNode(SyntaxKind.Unknown, undefined, false);
}
}

private parseTypedefDeclaration(): Types.TypedefDeclaration {
const node = <Types.TypedefDeclaration>this.createNode(SyntaxKind.TypedefDeclaration);
this.parseExpected(SyntaxKind.TypedefKeyword);
Expand All @@ -905,7 +923,7 @@ export class Parser {
const node = <Types.ReturnStatement>this.createNode(SyntaxKind.ReturnStatement);
this.parseExpected(SyntaxKind.ReturnKeyword);
if (this.token() !== SyntaxKind.SemicolonToken) {
node.expression = this.parseExpression();
node.expression = this.parseExpectedExpression();
}
this.parseExpected(SyntaxKind.SemicolonToken);
return this.finishNode(node);
Expand Down Expand Up @@ -948,7 +966,7 @@ export class Parser {
const node = <Types.IfStatement>this.createNode(SyntaxKind.IfStatement);
this.parseExpected(SyntaxKind.IfKeyword);
this.parseExpected(SyntaxKind.OpenParenToken);
node.expression = this.parseExpression();
node.expression = this.parseExpectedExpression();
this.parseExpected(SyntaxKind.CloseParenToken);
node.thenStatement = this.parseBlock();
if (this.parseOptional(SyntaxKind.ElseKeyword)) {
Expand All @@ -963,7 +981,7 @@ export class Parser {
node.statement = this.parseBlock();
this.parseExpected(SyntaxKind.WhileKeyword);
this.parseExpected(SyntaxKind.OpenParenToken);
node.expression = this.parseExpression();
node.expression = this.parseExpectedExpression();
this.parseExpected(SyntaxKind.CloseParenToken);
this.parseExpected(SyntaxKind.SemicolonToken);
return this.finishNode(node);
Expand All @@ -973,7 +991,7 @@ export class Parser {
const node = <Types.WhileStatement>this.createNode(SyntaxKind.WhileStatement);
this.parseExpected(SyntaxKind.WhileKeyword);
this.parseExpected(SyntaxKind.OpenParenToken);
node.expression = this.parseExpression();
node.expression = this.parseExpectedExpression();
this.parseExpected(SyntaxKind.CloseParenToken);
node.statement = this.parseBlock();
return this.finishNode(node);
Expand All @@ -984,15 +1002,15 @@ export class Parser {
this.parseExpected(SyntaxKind.ForKeyword);
this.parseExpected(SyntaxKind.OpenParenToken);
if (this.token() !== SyntaxKind.SemicolonToken && this.token() !== SyntaxKind.CloseParenToken) {
node.initializer = this.parseExpression(true);
node.initializer = this.parseExpectedExpression(true);
}
this.parseExpected(SyntaxKind.SemicolonToken);
if (this.token() !== SyntaxKind.SemicolonToken && this.token() !== SyntaxKind.CloseParenToken) {
node.condition = this.parseExpression();
node.condition = this.parseExpectedExpression();
}
this.parseExpected(SyntaxKind.SemicolonToken);
if (this.token() !== SyntaxKind.CloseParenToken) {
node.incrementor = this.parseExpression(true);
node.incrementor = this.parseExpectedExpression(true);
}
this.parseExpected(SyntaxKind.CloseParenToken);
node.statement = this.parseBlock();
Expand Down

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