devsite/node_modules/sucrase/dist/transformers/OptionalChainingNullishTransformer.js
2024-07-07 18:49:38 -07:00

156 lines
6.3 KiB
JavaScript

"use strict";Object.defineProperty(exports, "__esModule", {value: true}); function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
var _types = require('../parser/tokenizer/types');
var _Transformer = require('./Transformer'); var _Transformer2 = _interopRequireDefault(_Transformer);
/**
* Transformer supporting the optional chaining and nullish coalescing operators.
*
* Tech plan here:
* https://github.com/alangpierce/sucrase/wiki/Sucrase-Optional-Chaining-and-Nullish-Coalescing-Technical-Plan
*
* The prefix and suffix code snippets are handled by TokenProcessor, and this transformer handles
* the operators themselves.
*/
class OptionalChainingNullishTransformer extends _Transformer2.default {
constructor( tokens, nameManager) {
super();this.tokens = tokens;this.nameManager = nameManager;;
}
process() {
if (this.tokens.matches1(_types.TokenType.nullishCoalescing)) {
const token = this.tokens.currentToken();
if (this.tokens.tokens[token.nullishStartIndex].isAsyncOperation) {
this.tokens.replaceTokenTrimmingLeftWhitespace(", async () => (");
} else {
this.tokens.replaceTokenTrimmingLeftWhitespace(", () => (");
}
return true;
}
if (this.tokens.matches1(_types.TokenType._delete)) {
const nextToken = this.tokens.tokenAtRelativeIndex(1);
if (nextToken.isOptionalChainStart) {
this.tokens.removeInitialToken();
return true;
}
}
const token = this.tokens.currentToken();
const chainStart = token.subscriptStartIndex;
if (
chainStart != null &&
this.tokens.tokens[chainStart].isOptionalChainStart &&
// Super subscripts can't be optional (since super is never null/undefined), and the syntax
// relies on the subscript being intact, so leave this token alone.
this.tokens.tokenAtRelativeIndex(-1).type !== _types.TokenType._super
) {
const param = this.nameManager.claimFreeName("_");
let arrowStartSnippet;
if (
chainStart > 0 &&
this.tokens.matches1AtIndex(chainStart - 1, _types.TokenType._delete) &&
this.isLastSubscriptInChain()
) {
// Delete operations are special: we already removed the delete keyword, and to still
// perform a delete, we need to insert a delete in the very last part of the chain, which
// in correct code will always be a property access.
arrowStartSnippet = `${param} => delete ${param}`;
} else {
arrowStartSnippet = `${param} => ${param}`;
}
if (this.tokens.tokens[chainStart].isAsyncOperation) {
arrowStartSnippet = `async ${arrowStartSnippet}`;
}
if (
this.tokens.matches2(_types.TokenType.questionDot, _types.TokenType.parenL) ||
this.tokens.matches2(_types.TokenType.questionDot, _types.TokenType.lessThan)
) {
if (this.justSkippedSuper()) {
this.tokens.appendCode(".bind(this)");
}
this.tokens.replaceTokenTrimmingLeftWhitespace(`, 'optionalCall', ${arrowStartSnippet}`);
} else if (this.tokens.matches2(_types.TokenType.questionDot, _types.TokenType.bracketL)) {
this.tokens.replaceTokenTrimmingLeftWhitespace(`, 'optionalAccess', ${arrowStartSnippet}`);
} else if (this.tokens.matches1(_types.TokenType.questionDot)) {
this.tokens.replaceTokenTrimmingLeftWhitespace(`, 'optionalAccess', ${arrowStartSnippet}.`);
} else if (this.tokens.matches1(_types.TokenType.dot)) {
this.tokens.replaceTokenTrimmingLeftWhitespace(`, 'access', ${arrowStartSnippet}.`);
} else if (this.tokens.matches1(_types.TokenType.bracketL)) {
this.tokens.replaceTokenTrimmingLeftWhitespace(`, 'access', ${arrowStartSnippet}[`);
} else if (this.tokens.matches1(_types.TokenType.parenL)) {
if (this.justSkippedSuper()) {
this.tokens.appendCode(".bind(this)");
}
this.tokens.replaceTokenTrimmingLeftWhitespace(`, 'call', ${arrowStartSnippet}(`);
} else {
throw new Error("Unexpected subscript operator in optional chain.");
}
return true;
}
return false;
}
/**
* Determine if the current token is the last of its chain, so that we know whether it's eligible
* to have a delete op inserted.
*
* We can do this by walking forward until we determine one way or another. Each
* isOptionalChainStart token must be paired with exactly one isOptionalChainEnd token after it in
* a nesting way, so we can track depth and walk to the end of the chain (the point where the
* depth goes negative) and see if any other subscript token is after us in the chain.
*/
isLastSubscriptInChain() {
let depth = 0;
for (let i = this.tokens.currentIndex() + 1; ; i++) {
if (i >= this.tokens.tokens.length) {
throw new Error("Reached the end of the code while finding the end of the access chain.");
}
if (this.tokens.tokens[i].isOptionalChainStart) {
depth++;
} else if (this.tokens.tokens[i].isOptionalChainEnd) {
depth--;
}
if (depth < 0) {
return true;
}
// This subscript token is a later one in the same chain.
if (depth === 0 && this.tokens.tokens[i].subscriptStartIndex != null) {
return false;
}
}
}
/**
* Determine if we are the open-paren in an expression like super.a()?.b.
*
* We can do this by walking backward to find the previous subscript. If that subscript was
* preceded by a super, then we must be the subscript after it, so if this is a call expression,
* we'll need to attach the right context.
*/
justSkippedSuper() {
let depth = 0;
let index = this.tokens.currentIndex() - 1;
while (true) {
if (index < 0) {
throw new Error(
"Reached the start of the code while finding the start of the access chain.",
);
}
if (this.tokens.tokens[index].isOptionalChainStart) {
depth--;
} else if (this.tokens.tokens[index].isOptionalChainEnd) {
depth++;
}
if (depth < 0) {
return false;
}
// This subscript token is a later one in the same chain.
if (depth === 0 && this.tokens.tokens[index].subscriptStartIndex != null) {
return this.tokens.tokens[index - 1].type === _types.TokenType._super;
}
index--;
}
}
} exports.default = OptionalChainingNullishTransformer;