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Avoid unnecessary work during lookahead (#9982)

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* Do not call pushComment when doing lookahead

* Do no updateContext when doing lookahead

* Do not clone contexts anymore
This commit is contained in:
Daniel Tschinder 2019-05-15 17:02:12 -07:00 committed by GitHub
parent 47eb1ddfe0
commit 4da7a01aa9
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 13 additions and 7 deletions
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18
packages/babel-parser/src/tokenizer/index.js
View File

@ -226,11 +226,9 @@ export default class Tokenizer extends LocationParser {
loc: new SourceLocation(startLoc, endLoc), loc: new SourceLocation(startLoc, endLoc),
}; };
if (!this.isLookahead) { if (this.options.tokens) this.state.tokens.push(comment);
if (this.options.tokens) this.state.tokens.push(comment); this.state.comments.push(comment);
this.state.comments.push(comment); this.addComment(comment);
this.addComment(comment);
}
} }
skipBlockComment(): void { skipBlockComment(): void {
@ -250,6 +248,10 @@ export default class Tokenizer extends LocationParser {
this.state.lineStart = match.index + match[0].length; this.state.lineStart = match.index + match[0].length;
} }
// If we are doing a lookahead right now we need to advance the position (above code)
// but we do not want to push the comment to the state.
if (this.isLookahead) return;
this.pushComment( this.pushComment(
true, true,
this.input.slice(start + 2, end), this.input.slice(start + 2, end),
@ -276,6 +278,10 @@ export default class Tokenizer extends LocationParser {
} }
} }
// If we are doing a lookahead right now we need to advance the position (above code)
// but we do not want to push the comment to the state.
if (this.isLookahead) return;
this.pushComment( this.pushComment(
false, false,
this.input.slice(start + startSkip, this.state.pos), this.input.slice(start + startSkip, this.state.pos),
@ -350,7 +356,7 @@ export default class Tokenizer extends LocationParser {
this.state.type = type; this.state.type = type;
this.state.value = val; this.state.value = val;
this.updateContext(prevType); if (!this.isLookahead) this.updateContext(prevType);
} }
// ### Token reading // ### Token reading

2
packages/babel-parser/src/tokenizer/state.js
View File

@ -170,7 +170,7 @@ export default class State {
// $FlowIgnore // $FlowIgnore
let val = this[key]; let val = this[key];
if ((!skipArrays || key === "context") && Array.isArray(val)) { if (!skipArrays && Array.isArray(val)) {
val = val.slice(); val = val.slice();
} }