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Simplifiy tracking of valid JSX positions (#13891)
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Remove `state.inPropertyName` and simplifies `state.canStartJSXElement` tracking
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@JLHwung
JLHwung committed Nov 4, 2021
1 parent de28707 commit 7250d25
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Showing 6 changed files with 32 additions and 37 deletions.
14 changes: 7 additions & 7 deletions packages/babel-parser/src/parser/expression.js
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Expand Up @@ -22,12 +22,12 @@ import {
tokenCanStartExpression,
tokenIsAssignment,
tokenIsIdentifier,
tokenIsKeyword,
tokenIsKeywordOrIdentifier,
tokenIsOperator,
tokenIsPostfix,
tokenIsPrefix,
tokenIsRightAssociative,
tokenKeywordOrIdentifierIsKeyword,
tokenLabelName,
tokenOperatorPrecedence,
tt,
Expand Down Expand Up @@ -2237,8 +2237,6 @@ export default class ExpressionParser extends LValParser {
prop.key = this.parseMaybeAssignAllowIn();
this.expect(tt.bracketR);
} else {
const oldInPropertyName = this.state.inPropertyName;
this.state.inPropertyName = true;
// We check if it's valid for it to be a private name when we push it.
const type = this.state.type;
(prop: $FlowFixMe).key =
Expand All @@ -2253,8 +2251,6 @@ export default class ExpressionParser extends LValParser {
// ClassPrivateProperty is never computed, so we don't assign in that case.
prop.computed = false;
}

this.state.inPropertyName = oldInPropertyName;
}

return prop.key;
Expand Down Expand Up @@ -2584,12 +2580,16 @@ export default class ExpressionParser extends LValParser {
throw this.unexpected();
}

const tokenIsKeyword = tokenKeywordOrIdentifierIsKeyword(type);

if (liberal) {
// If the current token is not used as a keyword, set its type to "tt.name".
// This will prevent this.next() from throwing about unexpected escapes.
this.state.type = tt.name;
if (tokenIsKeyword) {
this.replaceToken(tt.name);
}
} else {
this.checkReservedWord(name, start, tokenIsKeyword(type), false);
this.checkReservedWord(name, start, tokenIsKeyword, false);
}

this.next();
Expand Down
34 changes: 8 additions & 26 deletions packages/babel-parser/src/plugins/jsx/index.js
View file
Expand Up @@ -21,10 +21,6 @@ import { isIdentifierChar, isIdentifierStart } from "../../util/identifier";
import type { Position } from "../../util/location";
import { isNewLine } from "../../util/whitespace";
import { Errors, makeErrorTemplates, ErrorCodes } from "../../parser/error";
import type { LookaheadState } from "../../tokenizer/state";
import State from "../../tokenizer/state";

type JSXLookaheadState = LookaheadState & { inPropertyName: boolean };

const HEX_NUMBER = /^[\da-fA-F]+$/;
const DECIMAL_NUMBER = /^\d+$/;
Expand Down Expand Up @@ -106,7 +102,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
case charCodes.lessThan:
case charCodes.leftCurlyBrace:
if (this.state.pos === this.state.start) {
if (ch === charCodes.lessThan && this.state.exprAllowed) {
if (ch === charCodes.lessThan && this.state.canStartJSXElement) {
++this.state.pos;
return this.finishToken(tt.jsxTagStart);
}
Expand Down Expand Up @@ -556,24 +552,14 @@ export default (superClass: Class<Parser>): Class<Parser> =>
) {
// In case we encounter an lt token here it will always be the start of
// jsx as the lt sign is not allowed in places that expect an expression
this.finishToken(tt.jsxTagStart);
this.replaceToken(tt.jsxTagStart);
return this.jsxParseElement();
} else {
return super.parseExprAtom(refExpressionErrors);
}
}

createLookaheadState(state: State): JSXLookaheadState {
const lookaheadState = ((super.createLookaheadState(
state,
): any): JSXLookaheadState);
lookaheadState.inPropertyName = state.inPropertyName;
return lookaheadState;
}

getTokenFromCode(code: number): void {
if (this.state.inPropertyName) return super.getTokenFromCode(code);

const context = this.curContext();

if (context === tc.j_expr) {
Expand All @@ -600,7 +586,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>

if (
code === charCodes.lessThan &&
this.state.exprAllowed &&
this.state.canStartJSXElement &&
this.input.charCodeAt(this.state.pos + 1) !== charCodes.exclamationMark
) {
++this.state.pos;
Expand All @@ -617,7 +603,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
// do not consider JSX expr -> JSX open tag -> ... anymore
// reconsider as closing tag context
context.splice(-2, 2, tc.j_cTag);
this.state.exprAllowed = false;
this.state.canStartJSXElement = false;
} else if (type === tt.jsxTagStart) {
context.push(
tc.j_expr, // treat as beginning of JSX expression
Expand All @@ -627,17 +613,13 @@ export default (superClass: Class<Parser>): Class<Parser> =>
const out = context.pop();
if ((out === tc.j_oTag && prevType === tt.slash) || out === tc.j_cTag) {
context.pop();
this.state.exprAllowed = context[context.length - 1] === tc.j_expr;
this.state.canStartJSXElement =
context[context.length - 1] === tc.j_expr;
} else {
this.state.exprAllowed = true;
this.state.canStartJSXElement = true;
}
} else if (
tokenIsKeyword(type) &&
(prevType === tt.dot || prevType === tt.questionDot)
) {
this.state.exprAllowed = false;
} else {
this.state.exprAllowed = tokenComesBeforeExpression(type);
this.state.canStartJSXElement = tokenComesBeforeExpression(type);
}
}
};
2 changes: 1 addition & 1 deletion packages/babel-parser/src/plugins/typescript/index.js
View file
Expand Up @@ -2125,7 +2125,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
// When ! is consumed as a postfix operator (non-null assertion),
// disallow JSX tag forming after. e.g. When parsing `p! < n.p!`
// `<n.p` can not be a start of JSX tag
this.state.exprAllowed = false;
this.state.canStartJSXElement = false;
this.next();

const nonNullExpression: N.TsNonNullExpression = this.startNodeAt(
Expand Down
10 changes: 9 additions & 1 deletion packages/babel-parser/src/tokenizer/index.js
View file
Expand Up @@ -482,7 +482,7 @@ export default class Tokenizer extends ParserErrors {
}

// Called at the end of every token. Sets `end`, `val`, and
// maintains `context` and `exprAllowed`, and skips the space after
// maintains `context` and `canStartJSXElement`, and skips the space after
// the token, so that the next one's `start` will point at the
// right position.

Expand All @@ -498,6 +498,14 @@ export default class Tokenizer extends ParserErrors {
}
}

replaceToken(type: TokenType): void {
this.state.type = type;
// the prevType of updateContext is required
// only when the new type is tt.slash/tt.jsxTagEnd
// $FlowIgnore
this.updateContext();
}

// ### Token reading

// This is the function that is called to fetch the next token. It
Expand Down
3 changes: 1 addition & 2 deletions packages/babel-parser/src/tokenizer/state.js
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Expand Up @@ -68,7 +68,6 @@ export default class State {
maybeInArrowParameters: boolean = false;
inType: boolean = false;
noAnonFunctionType: boolean = false;
inPropertyName: boolean = false;
hasFlowComment: boolean = false;
isAmbientContext: boolean = false;
inAbstractClass: boolean = false;
Expand Down Expand Up @@ -127,7 +126,7 @@ export default class State {
// or ends a string template
context: Array<TokContext> = [ct.brace];
// Used to track whether a JSX element is allowed to form
exprAllowed: boolean = true;
canStartJSXElement: boolean = true;

// Used to signal to callers of `readWord1` whether the word
// contained any escape sequences. This is needed because words with
Expand Down
6 changes: 6 additions & 0 deletions packages/babel-parser/src/tokenizer/types.js
View file
Expand Up @@ -332,6 +332,12 @@ export function tokenIsIdentifier(token: TokenType): boolean {
return token >= tt._as && token <= tt.name;
}

export function tokenKeywordOrIdentifierIsKeyword(token: TokenType): boolean {
// we can remove the token >= tt._in check when we
// know a token is either keyword or identifier
return token <= tt._while;
}

export function tokenIsKeywordOrIdentifier(token: TokenType): boolean {
return token >= tt._in && token <= tt.name;
}
Expand Down

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