espree.js
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/* eslint-disable no-param-reassign*/
import TokenTranslator from "./token-translator.js";
import { normalizeOptions } from "./options.js";
const STATE = Symbol("espree's internal state");
const ESPRIMA_FINISH_NODE = Symbol("espree's esprimaFinishNode");
/**
* Converts an Acorn comment to a Esprima comment.
* @param {boolean} block True if it's a block comment, false if not.
* @param {string} text The text of the comment.
* @param {int} start The index at which the comment starts.
* @param {int} end The index at which the comment ends.
* @param {Location} startLoc The location at which the comment starts.
* @param {Location} endLoc The location at which the comment ends.
* @param {string} code The source code being parsed.
* @returns {Object} The comment object.
* @private
*/
function convertAcornCommentToEsprimaComment(block, text, start, end, startLoc, endLoc, code) {
let type;
if (block) {
type = "Block";
} else if (code.slice(start, start + 2) === "#!") {
type = "Hashbang";
} else {
type = "Line";
}
const comment = {
type,
value: text
};
if (typeof start === "number") {
comment.start = start;
comment.end = end;
comment.range = [start, end];
}
if (typeof startLoc === "object") {
comment.loc = {
start: startLoc,
end: endLoc
};
}
return comment;
}
export default () => Parser => {
const tokTypes = Object.assign({}, Parser.acorn.tokTypes);
if (Parser.acornJsx) {
Object.assign(tokTypes, Parser.acornJsx.tokTypes);
}
return class Espree extends Parser {
constructor(opts, code) {
if (typeof opts !== "object" || opts === null) {
opts = {};
}
if (typeof code !== "string" && !(code instanceof String)) {
code = String(code);
}
// save original source type in case of commonjs
const originalSourceType = opts.sourceType;
const options = normalizeOptions(opts);
const ecmaFeatures = options.ecmaFeatures || {};
const tokenTranslator =
options.tokens === true
? new TokenTranslator(tokTypes, code)
: null;
/*
* Data that is unique to Espree and is not represented internally
* in Acorn.
*
* For ES2023 hashbangs, Espree will call `onComment()` during the
* constructor, so we must define state before having access to
* `this`.
*/
const state = {
originalSourceType: originalSourceType || options.sourceType,
tokens: tokenTranslator ? [] : null,
comments: options.comment === true ? [] : null,
impliedStrict: ecmaFeatures.impliedStrict === true && options.ecmaVersion >= 5,
ecmaVersion: options.ecmaVersion,
jsxAttrValueToken: false,
lastToken: null,
templateElements: []
};
// Initialize acorn parser.
super({
// do not use spread, because we don't want to pass any unknown options to acorn
ecmaVersion: options.ecmaVersion,
sourceType: options.sourceType,
ranges: options.ranges,
locations: options.locations,
allowReserved: options.allowReserved,
// Truthy value is true for backward compatibility.
allowReturnOutsideFunction: options.allowReturnOutsideFunction,
// Collect tokens
onToken: token => {
if (tokenTranslator) {
// Use `tokens`, `ecmaVersion`, and `jsxAttrValueToken` in the state.
tokenTranslator.onToken(token, state);
}
if (token.type !== tokTypes.eof) {
state.lastToken = token;
}
},
// Collect comments
onComment: (block, text, start, end, startLoc, endLoc) => {
if (state.comments) {
const comment = convertAcornCommentToEsprimaComment(block, text, start, end, startLoc, endLoc, code);
state.comments.push(comment);
}
}
}, code);
/*
* We put all of this data into a symbol property as a way to avoid
* potential naming conflicts with future versions of Acorn.
*/
this[STATE] = state;
}
tokenize() {
do {
this.next();
} while (this.type !== tokTypes.eof);
// Consume the final eof token
this.next();
const extra = this[STATE];
const tokens = extra.tokens;
if (extra.comments) {
tokens.comments = extra.comments;
}
return tokens;
}
finishNode(...args) {
const result = super.finishNode(...args);
return this[ESPRIMA_FINISH_NODE](result);
}
finishNodeAt(...args) {
const result = super.finishNodeAt(...args);
return this[ESPRIMA_FINISH_NODE](result);
}
parse() {
const extra = this[STATE];
const program = super.parse();
program.sourceType = extra.originalSourceType;
if (extra.comments) {
program.comments = extra.comments;
}
if (extra.tokens) {
program.tokens = extra.tokens;
}
/*
* Adjust opening and closing position of program to match Esprima.
* Acorn always starts programs at range 0 whereas Esprima starts at the
* first AST node's start (the only real difference is when there's leading
* whitespace or leading comments). Acorn also counts trailing whitespace
* as part of the program whereas Esprima only counts up to the last token.
*/
if (program.body.length) {
const [firstNode] = program.body;
if (program.range) {
program.range[0] = firstNode.range[0];
}
if (program.loc) {
program.loc.start = firstNode.loc.start;
}
program.start = firstNode.start;
}
if (extra.lastToken) {
if (program.range) {
program.range[1] = extra.lastToken.range[1];
}
if (program.loc) {
program.loc.end = extra.lastToken.loc.end;
}
program.end = extra.lastToken.end;
}
/*
* https://github.com/eslint/espree/issues/349
* Ensure that template elements have correct range information.
* This is one location where Acorn produces a different value
* for its start and end properties vs. the values present in the
* range property. In order to avoid confusion, we set the start
* and end properties to the values that are present in range.
* This is done here, instead of in finishNode(), because Acorn
* uses the values of start and end internally while parsing, making
* it dangerous to change those values while parsing is ongoing.
* By waiting until the end of parsing, we can safely change these
* values without affect any other part of the process.
*/
this[STATE].templateElements.forEach(templateElement => {
const startOffset = -1;
const endOffset = templateElement.tail ? 1 : 2;
templateElement.start += startOffset;
templateElement.end += endOffset;
if (templateElement.range) {
templateElement.range[0] += startOffset;
templateElement.range[1] += endOffset;
}
if (templateElement.loc) {
templateElement.loc.start.column += startOffset;
templateElement.loc.end.column += endOffset;
}
});
return program;
}
parseTopLevel(node) {
if (this[STATE].impliedStrict) {
this.strict = true;
}
return super.parseTopLevel(node);
}
/**
* Overwrites the default raise method to throw Esprima-style errors.
* @param {int} pos The position of the error.
* @param {string} message The error message.
* @throws {SyntaxError} A syntax error.
* @returns {void}
*/
raise(pos, message) {
const loc = Parser.acorn.getLineInfo(this.input, pos);
const err = new SyntaxError(message);
err.index = pos;
err.lineNumber = loc.line;
err.column = loc.column + 1; // acorn uses 0-based columns
throw err;
}
/**
* Overwrites the default raise method to throw Esprima-style errors.
* @param {int} pos The position of the error.
* @param {string} message The error message.
* @throws {SyntaxError} A syntax error.
* @returns {void}
*/
raiseRecoverable(pos, message) {
this.raise(pos, message);
}
/**
* Overwrites the default unexpected method to throw Esprima-style errors.
* @param {int} pos The position of the error.
* @throws {SyntaxError} A syntax error.
* @returns {void}
*/
unexpected(pos) {
let message = "Unexpected token";
if (pos !== null && pos !== void 0) {
this.pos = pos;
if (this.options.locations) {
while (this.pos < this.lineStart) {
this.lineStart = this.input.lastIndexOf("\n", this.lineStart - 2) + 1;
--this.curLine;
}
}
this.nextToken();
}
if (this.end > this.start) {
message += ` ${this.input.slice(this.start, this.end)}`;
}
this.raise(this.start, message);
}
/*
* Esprima-FB represents JSX strings as tokens called "JSXText", but Acorn-JSX
* uses regular tt.string without any distinction between this and regular JS
* strings. As such, we intercept an attempt to read a JSX string and set a flag
* on extra so that when tokens are converted, the next token will be switched
* to JSXText via onToken.
*/
jsx_readString(quote) { // eslint-disable-line camelcase
const result = super.jsx_readString(quote);
if (this.type === tokTypes.string) {
this[STATE].jsxAttrValueToken = true;
}
return result;
}
/**
* Performs last-minute Esprima-specific compatibility checks and fixes.
* @param {ASTNode} result The node to check.
* @returns {ASTNode} The finished node.
*/
[ESPRIMA_FINISH_NODE](result) {
// Acorn doesn't count the opening and closing backticks as part of templates
// so we have to adjust ranges/locations appropriately.
if (result.type === "TemplateElement") {
// save template element references to fix start/end later
this[STATE].templateElements.push(result);
}
if (result.type.includes("Function") && !result.generator) {
result.generator = false;
}
return result;
}
};
};