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Merge pull request #203 from Microsoft/arrowLookAhead

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Improved lookahead for arrow functions.
This commit is contained in:
Daniel Rosenwasser 2014-07-24 18:41:34 -07:00
parent cb98c5aa17 b0c59e7c37
commit c625cd9259
14 changed files with 276 additions and 106 deletions
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93
src/compiler/parser.ts
View file

@ -1637,64 +1637,87 @@ module ts {
function tryParseParenthesizedArrowFunctionExpression(): Expression {
var pos = getNodePos();
// Indicates whether we are certain that we should parse an arrow expression.
var triState = isParenthesizedArrowFunctionExpression();
// It is not a parenthesized arrow function.
if (triState === Tristate.False) {
return undefined;
}
// If we're certain that we have an arrow function expression, then just parse one out.
if (triState === Tristate.True) {
var sig = parseSignature(SyntaxKind.CallSignature, SyntaxKind.ColonToken);
// If we have an arrow, then try to parse the body.
if (parseExpected(SyntaxKind.EqualsGreaterThanToken)) {
return parseArrowExpressionTail(pos, sig, /*noIn:*/ false);
// Even if not, try to parse if we have an opening brace, just in case we're in an error state.
if (parseExpected(SyntaxKind.EqualsGreaterThanToken) || token === SyntaxKind.OpenBraceToken) {
return parseArrowExpressionTail(pos, sig, /* noIn: */ false);
}
// If not, we're probably better off bailing out and returning a bogus function expression.
else {
// If not, we're probably better off bailing out and returning a bogus function expression.
return makeFunctionExpression(SyntaxKind.ArrowFunction, pos, /* name */ undefined, sig, createMissingNode());
}
}
// Otherwise, *maybe* we had an arrow function and we need to *try* to parse it out
// (which will ensure we rollback if we fail).
var sig = tryParse(parseSignatureAndArrow);
if (sig === undefined) {
return undefined;
// *Maybe* we had an arrow function and we need to try to parse it out,
// rolling back and trying other parses if we fail.
var sig = tryParseSignatureIfArrowOrBraceFollows();
if (sig) {
parseExpected(SyntaxKind.EqualsGreaterThanToken);
return parseArrowExpressionTail(pos, sig, /*noIn:*/ false);
}
else {
return parseArrowExpressionTail(pos, sig, /*noIn:*/ false);
return undefined;
}
}
// True -> There is definitely a parenthesized arrow function here.
// False -> There is definitely *not* a parenthesized arrow function here.
// True -> We definitely expect a parenthesized arrow function here.
// False -> There *cannot* be a parenthesized arrow function here.
// Unknown -> There *might* be a parenthesized arrow function here.
// Speculatively look ahead to be sure.
// Speculatively look ahead to be sure, and rollback if not.
function isParenthesizedArrowFunctionExpression(): Tristate {
if (token === SyntaxKind.OpenParenToken || token === SyntaxKind.LessThanToken) {
return lookAhead(() => {
var first = token;
nextToken();
var second = nextToken();
if (first === SyntaxKind.OpenParenToken) {
if (token === SyntaxKind.CloseParenToken || token === SyntaxKind.DotDotDotToken) {
// Simple cases. if we see () or (... then presume that presume
// that this must be an arrow function. Note, this may be too aggressive
// for the "()" case. It's not uncommon for this to appear while editing
// code. We should look to see if there's actually a => before proceeding.
if (second === SyntaxKind.CloseParenToken) {
// Simple cases: "() =>", "(): ", and "() {".
// This is an arrow function with no parameters.
// The last one is not actually an arrow function,
// but this is probably what the user intended.
var third = nextToken();
switch (third) {
case SyntaxKind.EqualsGreaterThanToken:
case SyntaxKind.ColonToken:
case SyntaxKind.OpenBraceToken:
return Tristate.True;
default:
return Tristate.False;
}
}
// Simple case: "(..."
// This is an arrow function with a rest parameter.
if (second === SyntaxKind.DotDotDotToken) {
return Tristate.True;
}
// If we had "(" followed by something that's not an identifier,
// then this definitely doesn't look like a lambda.
// Note: we could be a little more lenient and allow
// "(public" or "(private". These would not ever actually be allowed,
// but we could provide a good error message instead of bailing out.
if (!isIdentifier()) {
// We had "(" not followed by an identifier. This definitely doesn't
// look like a lambda. Note: we could be a little more lenient and allow
// (public or (private. These would not ever actually be allowed,
// but we could provide a good error message instead of bailing out.
return Tristate.False;
}
// If we have something like "(a:", then we must have a
// type-annotated parameter in an arrow function expression.
if (nextToken() === SyntaxKind.ColonToken) {
return Tristate.True;
}
// This *could* be a parenthesized arrow function.
// Return Unknown to let the caller know.
return Tristate.Unknown;
@ -1718,10 +1741,24 @@ module ts {
return Tristate.False;
}
function parseSignatureAndArrow(): ParsedSignature {
var sig = parseSignature(SyntaxKind.CallSignature, SyntaxKind.ColonToken);
parseExpected(SyntaxKind.EqualsGreaterThanToken);
return sig;
function tryParseSignatureIfArrowOrBraceFollows(): ParsedSignature {
return tryParse(() => {
var sig = parseSignature(SyntaxKind.CallSignature, SyntaxKind.ColonToken);
// Parsing a signature isn't enough.
// Parenthesized arrow signatures often look like other valid expressions.
// For instance:
// - "(x = 10)" is an assignment expression parsed as a signature with a default parameter value.
// - "(x,y)" is a comma expression parsed as a signature with two parameters.
// - "a ? (b): c" will have "(b):" parsed as a signature with a return type annotation.
//
// So we need just a bit of lookahead to ensure that it can only be a signature.
if (token === SyntaxKind.EqualsGreaterThanToken || token === SyntaxKind.OpenBraceToken) {
return sig;
}
return undefined;
});
}
function parseArrowExpressionTail(pos: number, sig: ParsedSignature, noIn: boolean): FunctionExpression {

115
tests/baselines/reference/arrowFunctionsMissingTokens.errors.txt Normal file
View file

@ -0,0 +1,115 @@
==== tests/cases/compiler/arrowFunctionsMissingTokens.ts (24 errors) ====
module missingArrowsWithCurly {
var a = () { };
~
!!! '=>' expected.
var b = (): void { }
~
!!! '=>' expected.
var c = (x) { };
~
!!! '=>' expected.
var d = (x: number, y: string) { };
~
!!! '=>' expected.
var e = (x: number, y: string): void { };
~
!!! '=>' expected.
}
module missingCurliesWithArrow {
module withStatement {
var a = () => var k = 10;};
~~~
!!! '{' expected.
var b = (): void => var k = 10;}
~~~
!!! '{' expected.
var c = (x) => var k = 10;};
~~~
!!! '{' expected.
var d = (x: number, y: string) => var k = 10;};
~~~
!!! '{' expected.
var e = (x: number, y: string): void => var k = 10;};
~~~
!!! '{' expected.
var f = () => var k = 10;}
~~~
!!! '{' expected.
}
module withoutStatement {
var a = () => };
~
!!! Expression expected.
var b = (): void => }
~
!!! Expression expected.
var c = (x) => };
~
!!! Expression expected.
var d = (x: number, y: string) => };
~
!!! Expression expected.
var e = (x: number, y: string): void => };
~
!!! Expression expected.
var f = () => }
~
!!! Expression expected.
}
~
!!! Declaration or statement expected.
}
~
!!! Declaration or statement expected.
module ce_nEst_pas_une_arrow_function {
var a = ();
~
!!! Expression expected.
var b = (): void;
~
!!! '=>' expected.
var c = (x);
~
!!! Cannot find name 'x'.
var d = (x: number, y: string);
~
!!! '=>' expected.
var e = (x: number, y: string): void;
~
!!! '=>' expected.
}
module okay {
var a = () => { };
var b = (): void => { }
var c = (x) => { };
var d = (x: number, y: string) => { };
var e = (x: number, y: string): void => { };
}

8
tests/baselines/reference/emptyMemberAccess.errors.txt
View file

@ -1,11 +1,9 @@
==== tests/cases/compiler/emptyMemberAccess.ts (2 errors) ====
==== tests/cases/compiler/emptyMemberAccess.ts (1 errors) ====
function getObj() {
().toString();
~
!!! '=>' expected.
~~~~~~~~
!!! Cannot find name 'toString'.
~
!!! Expression expected.
}

4
tests/baselines/reference/es6ClassTest9.errors.txt
View file

@ -2,8 +2,8 @@
declare class foo();
~
!!! '{' expected.
~
!!! '=>' expected.
~
!!! Expression expected.
function foo() {}
~~~
!!! Duplicate identifier 'foo'.

22
tests/baselines/reference/fatarrowfunctionsErrors.errors.txt
View file

@ -1,4 +1,4 @@
==== tests/cases/compiler/fatarrowfunctionsErrors.ts (25 errors) ====
==== tests/cases/compiler/fatarrowfunctionsErrors.ts (18 errors) ====
foo((...Far:any[])=>{return 0;})
~~~
!!! Cannot find name 'foo'.
@ -39,25 +39,11 @@
~
!!! '=>' expected.
var x2 = (a:number) :void {};
~
!!! ')' expected.
~
!!! ',' expected.
~
!!! Variable declaration expected.
~~~~
!!! Variable declaration expected.
~
!!! Cannot find name 'a'.
~
!!! '=>' expected.
var x3 = (a:number) {};
~
!!! ')' expected.
~
!!! ',' expected.
~
!!! Variable declaration expected.
~
!!! Cannot find name 'a'.
!!! '=>' expected.
var x4= (...a: any[]) { };
~
!!! '=>' expected.

6
tests/baselines/reference/invalidTryStatements2.errors.txt
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@ -1,4 +1,4 @@
==== tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts (5 errors) ====
==== tests/cases/conformance/statements/tryStatements/invalidTryStatements2.ts (4 errors) ====
function fn() {
try {
} catch { // syntax error, missing '(x)'
@ -10,9 +10,7 @@
~~~~~
!!! Statement expected.
~
!!! ';' expected.
~
!!! Cannot find name 'x'.
!!! '=>' expected.
finally{ } // error missing try
~~~~~~~

4
tests/baselines/reference/parser566700.errors.txt
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@ -1,4 +1,4 @@
==== tests/cases/conformance/parser/ecmascript5/RegressionTests/parser566700.ts (1 errors) ====
var v = ()({});
~
!!! '=>' expected.
~
!!! Expression expected.

8
tests/baselines/reference/parserEmptyParenthesizedExpression1.errors.txt
View file

@ -1,8 +1,6 @@
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserEmptyParenthesizedExpression1.ts (2 errors) ====
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserEmptyParenthesizedExpression1.ts (1 errors) ====
function getObj() {
().toString();
~
!!! '=>' expected.
~~~~~~~~
!!! Cannot find name 'toString'.
~
!!! Expression expected.
}

4
tests/baselines/reference/parserErrorRecovery_Expression1.errors.txt
View file

@ -1,4 +1,4 @@
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Expressions/parserErrorRecovery_Expression1.ts (1 errors) ====
var v = ()({});
~
!!! '=>' expected.
~
!!! Expression expected.

12
tests/baselines/reference/parserErrorRecovery_ParameterList5.errors.txt
View file

@ -1,10 +1,6 @@
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList5.ts (4 errors) ====
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ParameterLists/parserErrorRecovery_ParameterList5.ts (2 errors) ====
(a:number => { }
~
!!! ')' expected.
~~
!!! ';' expected.
~
!!! Cannot find name 'a'.
~~~~~~
!!! Cannot find name 'number'.
!!! ',' expected.
~
!!! ')' expected.

22
tests/baselines/reference/parserUnterminatedGeneric2.errors.txt
View file

@ -1,4 +1,4 @@
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserUnterminatedGeneric2.ts (23 errors) ====
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/parserUnterminatedGeneric2.ts (15 errors) ====
declare module ng {
interfaceICompiledExpression {
~
@ -6,24 +6,8 @@
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! Cannot find name 'interfaceICompiledExpression'.
(context: any, locals?: any): any;
~
!!! ')' expected.
~
!!! Expression expected.
~
!!! ';' expected.
~
!!! Statement expected.
~~~~~~~
!!! Cannot find name 'context'.
~~~
!!! Cannot find name 'any'.
~~~~~~
!!! Cannot find name 'locals'.
~~~
!!! Cannot find name 'any'.
~~~
!!! Cannot find name 'any'.
~
!!! '=>' expected.
assign(context: any, value: any): any;
~
!!! ',' expected.

10
tests/baselines/reference/parserX_ArrowFunction1.errors.txt
View file

@ -1,12 +1,6 @@
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/parserX_ArrowFunction1.ts (4 errors) ====
==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ArrowFunctions/parserX_ArrowFunction1.ts (1 errors) ====
var v = (a: ) => {
~
!!! ')' expected.
~
!!! Variable declaration expected.
~~
!!! ';' expected.
~
!!! Cannot find name 'a'.
!!! Type expected.
};

8
tests/baselines/reference/uncaughtCompilerError2.errors.txt
View file

@ -1,9 +1,7 @@
==== tests/cases/compiler/uncaughtCompilerError2.ts (2 errors) ====
==== tests/cases/compiler/uncaughtCompilerError2.ts (1 errors) ====
function getObj() {
().toString();
~
!!! '=>' expected.
~~~~~~~~
!!! Cannot find name 'toString'.
~
!!! Expression expected.
}

66
tests/cases/compiler/arrowFunctionsMissingTokens.ts Normal file
View file

@ -0,0 +1,66 @@
module missingArrowsWithCurly {
var a = () { };
var b = (): void { }
var c = (x) { };
var d = (x: number, y: string) { };
var e = (x: number, y: string): void { };
}
module missingCurliesWithArrow {
module withStatement {
var a = () => var k = 10;};
var b = (): void => var k = 10;}
var c = (x) => var k = 10;};
var d = (x: number, y: string) => var k = 10;};
var e = (x: number, y: string): void => var k = 10;};
var f = () => var k = 10;}
}
module withoutStatement {
var a = () => };
var b = (): void => }
var c = (x) => };
var d = (x: number, y: string) => };
var e = (x: number, y: string): void => };
var f = () => }
}
}
module ce_nEst_pas_une_arrow_function {
var a = ();
var b = (): void;
var c = (x);
var d = (x: number, y: string);
var e = (x: number, y: string): void;
}
module okay {
var a = () => { };
var b = (): void => { }
var c = (x) => { };
var d = (x: number, y: string) => { };
var e = (x: number, y: string): void => { };
}