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perf: Minor optimizations

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This commit is contained in:
Daniel Tschinder 2019-01-15 00:03:39 -08:00
parent e9588061d7
commit ae154c86ed
1 changed files with 25 additions and 14 deletions
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37
packages/babel-parser/src/tokenizer/index.js
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@ -311,6 +311,11 @@ export default class Tokenizer extends LocationParser {
loop: while (this.state.pos < this.input.length) {
const ch = this.input.charCodeAt(this.state.pos);
switch (ch) {
case charCodes.space:
case charCodes.nonBreakingSpace:
case charCodes.tab:
++this.state.pos;
break;
case charCodes.carriageReturn:
if (
this.input.charCodeAt(this.state.pos + 1) === charCodes.lineFeed
@ -651,10 +656,6 @@ export default class Tokenizer extends LocationParser {
getTokenFromCode(code: number): void {
switch (code) {
case charCodes.numberSign:
this.readToken_numberSign();
return;
// The interpretation of a dot depends on whether it is followed
// by a digit or another two dots.
@ -720,10 +721,6 @@ export default class Tokenizer extends LocationParser {
case charCodes.questionMark:
this.readToken_question();
return;
case charCodes.atSign:
++this.state.pos;
this.finishToken(tt.at);
return;
case charCodes.graveAccent:
++this.state.pos;
@ -809,6 +806,15 @@ export default class Tokenizer extends LocationParser {
case charCodes.tilde:
this.finishOp(tt.tilde, 1);
return;
case charCodes.atSign:
++this.state.pos;
this.finishToken(tt.at);
return;
case charCodes.numberSign:
this.readToken_numberSign();
return;
}
this.raise(
@ -1266,10 +1272,11 @@ export default class Tokenizer extends LocationParser {
// as a micro-optimization.
readWord1(): string {
let word = "";
this.state.containsEsc = false;
let word = "",
first = true,
chunkStart = this.state.pos;
const start = this.state.pos;
let chunkStart = this.state.pos;
while (this.state.pos < this.input.length) {
const ch = this.input.codePointAt(this.state.pos);
if (isIdentifierChar(ch)) {
@ -1281,6 +1288,8 @@ export default class Tokenizer extends LocationParser {
word += this.input.slice(chunkStart, this.state.pos);
const escStart = this.state.pos;
const identifierCheck =
this.state.pos === start ? isIdentifierStart : isIdentifierChar;
if (this.input.charCodeAt(++this.state.pos) !== charCodes.lowercaseU) {
this.raise(
@ -1291,8 +1300,11 @@ export default class Tokenizer extends LocationParser {
++this.state.pos;
const esc = this.readCodePoint(true);
if (
// $FlowFixMe (thinks esc may be null, but throwOnInvalid is true)
if (!(first ? isIdentifierStart : isIdentifierChar)(esc, true)) {
!identifierCheck(esc, true)
) {
this.raise(escStart, "Invalid Unicode escape");
}
@ -1302,7 +1314,6 @@ export default class Tokenizer extends LocationParser {
} else {
break;
}
first = false;
}
return word + this.input.slice(chunkStart, this.state.pos);
}