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29x 29x 24x 24x 5x 5x 5x 5x 5x 5x 29x 29x 29x 9x 9x 9x 9x 504x | /**
* @file parser.js
* @description A JavaScript expression parser for Avenx template expressions.
*
* ## Why Avenx needs its own
*
* Template expressions used to be handed straight to the engine:
*
* ```js
* new Function(`with(this) { return (${expression}) }`)
* ```
*
* Two consequences followed from that line, and neither could be fixed while
* it stood.
*
* **`unsafe-eval` was structural.** Any Content-Security-Policy without
* `'unsafe-eval'` stopped the framework working, which excludes it from
* regulated environments, browser extensions, and a good many default
* enterprise policies.
*
* **The sandbox was not a boundary.** `AvenxSandbox` wrapped values that
* reached an expression *through the scope* and blocked the literal identifiers
* `constructor`, `__proto__` and `prototype` with a regular expression over the
* source text. An object created *inside* the expression never passed through
* the scope, so it was never wrapped, and the text check fell to string
* concatenation:
*
* ```js
* ({})['const'+'ructor']['const'+'ructor']('return 1')() // executed
* ```
*
* There is no version of a source-text blacklist that closes that. The value
* being guarded is produced by the engine, inside code the guard has already
* handed over.
*
* ## What parsing changes
*
* Once Avenx holds the AST, it decides what every operation means. A member
* access is a call into {@link module:lib/core/expression/evaluator}, with the
* property key already resolved — so `x['const'+'ructor']` and `x.constructor`
* arrive at the same check, because by then they are the same string. Nothing
* is handed to the engine as code, so nothing needs `unsafe-eval`.
*
* ## Scope
*
* This parses the expression language Avenx templates use — everything up to
* and including arrow functions, which templates need for `items.filter(i =>
* i.done)`. It is not a full ECMAScript parser and does not try to be:
* statements, classes, generators, `async`/`await`, destructuring patterns and
* regular-expression literals are out of scope. An expression it cannot parse
* raises {@link ExpressionParseError} rather than guessing, and the caller
* decides what to do about it.
* @module lib/core/expression/parser
*/
/**
* Raised when an expression is outside the supported language.
*/
export class ExpressionParseError extends Error {
/**
* @param {string} message - What went wrong.
* @param {number} position - Character offset in the expression.
* @param {string} source - The expression being parsed.
*/
constructor(message, position, source) {
super(message);
this.name = 'ExpressionParseError';
/** @type {number} */
this.position = position;
/** @type {string} */
this.source = source;
}
}
/**
* Binary operator precedence, higher binds tighter.
* @type {Object<string, number>}
*/
const BINARY_PRECEDENCE = {
'??': 1,
'||': 2,
'&&': 3,
'|': 4,
'^': 5,
'&': 6,
'==': 7, '!=': 7, '===': 7, '!==': 7,
'<': 8, '>': 8, '<=': 8, '>=': 8, 'in': 8, 'instanceof': 8,
'<<': 9, '>>': 9, '>>>': 9,
'+': 10, '-': 10,
'*': 11, '/': 11, '%': 11,
'**': 12,
};
/**
* Operators sorted longest-first, so `>>>=` is matched before `>>>`.
* @type {string[]}
*/
const PUNCTUATORS = [
'>>>=', '===', '!==', '**=', '<<=', '>>=', '&&=', '||=', '??=', '...', '>>>',
'=>', '==', '!=', '<=', '>=', '&&', '||', '??', '?.', '++', '--', '**',
'+=', '-=', '*=', '/=', '%=', '&=', '|=', '^=', '<<', '>>',
'{', '}', '(', ')', '[', ']', ';', ',', '<', '>', '+', '-', '*', '/', '%',
'&', '|', '^', '!', '~', '?', ':', '=', '.',
];
/**
* Assignment operators.
* @type {Set<string>}
*/
const ASSIGNMENT_OPERATORS = new Set([
'=', '+=', '-=', '*=', '/=', '%=', '**=', '<<=', '>>=', '>>>=', '&=', '|=', '^=', '&&=', '||=', '??=',
]);
/**
* Keywords that are values rather than identifiers.
* @type {Object<string, any>}
*/
const LITERAL_KEYWORDS = {
true: true,
false: false,
null: null,
undefined: undefined,
};
/**
* Prefix operators.
* @type {Set<string>}
*/
const UNARY_OPERATORS = new Set(['!', '-', '+', '~', 'typeof', 'void']);
/**
* Whether a character can start an identifier.
* @param {string} ch - A single character.
* @returns {boolean} True when it can begin an identifier.
*/
function isIdentStart(ch) {
return !!ch && /[A-Za-z_$]/.test(ch);
}
/**
* Whether a character can continue an identifier.
* @param {string} ch - A single character.
* @returns {boolean} True when it can continue an identifier.
*/
function isIdentPart(ch) {
return !!ch && /[\w$]/.test(ch);
}
/**
* Turns an expression into tokens.
*
* Template literals are tokenised whole and re-parsed by the parser, because
* their `${}` holes contain expressions and nesting them in the tokenizer would
* require a second stack for no benefit.
* @param {string} source - The expression source.
* @returns {Array<object>} The token stream, terminated by an `eof` token.
* @throws {ExpressionParseError} On an unterminated string or unknown character.
*/
export function tokenize(source) {
const tokens = [];
let i = 0;
while (i < source.length) {
const ch = source[i];
if (ch === ' ' || ch === '\t' || ch === '\n' || ch === '\r') {
i++;
continue;
}
// Comments are legal inside an action body and harmless in an expression.
if (ch === '/' && source[i + 1] === '/') {
while (i < source.length && source[i] !== '\n') i++;
continue;
}
if (ch === '/' && source[i + 1] === '*') {
const end = source.indexOf('*/', i + 2);
i = end === -1 ? source.length : end + 2;
continue;
}
if (ch === '"' || ch === "'") {
const start = i;
i++;
let value = '';
let closed = false;
while (i < source.length) {
const c = source[i];
if (c === '\\') {
value += unescapeChar(source, i);
i += escapeLength(source, i);
continue;
}
if (c === ch) {
i++;
closed = true;
break;
}
value += c;
i++;
}
if (!closed) {
throw new ExpressionParseError('Unterminated string literal', start, source);
}
tokens.push({ type: 'string', value, start });
continue;
}
if (ch === '`') {
const start = i;
const raw = readTemplateLiteral(source, i);
i = raw.end;
tokens.push({ type: 'template', value: raw.text, start });
continue;
}
if (/[0-9]/.test(ch) || (ch === '.' && /[0-9]/.test(source[i + 1]))) {
const start = i;
while (i < source.length && /[0-9a-fA-FxXoObBeE._]/.test(source[i])) {
// An exponent sign is part of the number; a following `-` otherwise is not.
if ((source[i] === 'e' || source[i] === 'E') && (source[i + 1] === '+' || source[i + 1] === '-')) {
i += 2;
continue;
}
i++;
}
const text = source.slice(start, i).replace(/_/g, '');
const value = Number(text);
if (Number.isNaN(value) && text.toLowerCase() !== 'nan') {
throw new ExpressionParseError(`Invalid number "${text}"`, start, source);
}
tokens.push({ type: 'number', value, start });
continue;
}
if (isIdentStart(ch)) {
const start = i;
while (i < source.length && isIdentPart(source[i])) i++;
tokens.push({ type: 'name', value: source.slice(start, i), start });
continue;
}
const punctuator = PUNCTUATORS.find((p) => source.startsWith(p, i));
if (punctuator) {
tokens.push({ type: 'punct', value: punctuator, start: i });
i += punctuator.length;
continue;
}
throw new ExpressionParseError(`Unexpected character "${ch}"`, i, source);
}
tokens.push({ type: 'eof', value: null, start: source.length });
return tokens;
}
/**
* How many source characters an escape sequence occupies.
* @param {string} source - The source.
* @param {number} i - Offset of the backslash.
* @returns {number} The sequence length including the backslash.
*/
function escapeLength(source, i) {
const next = source[i + 1];
if (next === 'u') {
return source[i + 2] === '{' ? source.indexOf('}', i) - i + 1 : 6;
}
if (next === 'x') return 4;
return 2;
}
/**
* Resolves an escape sequence to the character it denotes.
* @param {string} source - The source.
* @param {number} i - Offset of the backslash.
* @returns {string} The unescaped character.
*/
function unescapeChar(source, i) {
const next = source[i + 1];
switch (next) {
case 'n': return '\n';
case 't': return '\t';
case 'r': return '\r';
case 'b': return '\b';
case 'f': return '\f';
case 'v': return '\v';
case '0': return '\0';
case 'x': return String.fromCharCode(parseInt(source.slice(i + 2, i + 4), 16));
case 'u': {
if (source[i + 2] === '{') {
const close = source.indexOf('}', i);
return String.fromCodePoint(parseInt(source.slice(i + 3, close), 16));
}
return String.fromCharCode(parseInt(source.slice(i + 2, i + 6), 16));
}
default: return next;
}
}
/**
* Reads a template literal, tracking nested braces and strings inside holes.
* @param {string} source - The source.
* @param {number} start - Offset of the opening backtick.
* @returns {{text: string, end: number}} The literal text and the offset after it.
* @throws {ExpressionParseError} When the literal is unterminated.
*/
function readTemplateLiteral(source, start) {
let i = start + 1;
while (i < source.length) {
const ch = source[i];
if (ch === '\\') {
i += 2;
continue;
}
if (ch === '`') {
return { text: source.slice(start + 1, i), end: i + 1 };
}
if (ch === '$' && source[i + 1] === '{') {
let depth = 1;
i += 2;
while (i < source.length && depth > 0) {
if (source[i] === '{') depth++;
else if (source[i] === '}') depth--;
else if (source[i] === '"' || source[i] === "'" || source[i] === '`') {
const quote = source[i];
i++;
while (i < source.length && source[i] !== quote) {
if (source[i] === '\\') i++;
i++;
}
}
i++;
}
continue;
}
i++;
}
throw new ExpressionParseError('Unterminated template literal', start, source);
}
/**
* Parses a semicolon-separated run of expression statements.
*
* Most inline handlers and short action bodies are one or more expressions:
* `count++`, `busy = true; count++`, `state.text = event.target.value`. Those
* take the AST path and need no eval. A body with real statement syntax --
* `if`, `for`, `return`, a declaration -- is not an expression program and
* raises, so the caller falls back.
* @param {string} source - The statement source.
* @returns {object} A Program node.
* @throws {ExpressionParseError} When the source is not a run of expressions.
*/
export function parseExpressionProgram(source) {
const parser = new Parser(source);
const body = [];
for (;;) {
while (parser.eat(';')) {
// Empty statement.
}
if (parser.peek().type === 'eof') break;
body.push(parser.parseExpressionStatement());
if (parser.eat(';')) continue;
break;
}
parser.expectEnd();
return { type: 'Program', body };
}
/**
* Parses an expression into an AST.
* @param {string} source - The expression source.
* @returns {object} The root AST node.
* @throws {ExpressionParseError} When the source is outside the supported language.
*/
export function parseExpression(source) {
const parser = new Parser(source);
const node = parser.parseExpressionStatement();
parser.expectEnd();
return node;
}
/**
* A recursive-descent parser over a token stream.
*/
class Parser {
/**
* @param {string} source - The expression source.
*/
constructor(source) {
/** @type {string} */
this.source = source;
/** @type {Array<object>} */
this.tokens = tokenize(source);
/** @type {number} */
this.index = 0;
}
/**
* The token at the cursor.
* @returns {object} The current token.
*/
peek() {
return this.tokens[this.index];
}
/**
* Advances past the current token.
* @returns {object} The token consumed.
*/
next() {
return this.tokens[this.index++];
}
/**
* Whether the current token is a given punctuator.
* @param {string} value - The punctuator.
* @returns {boolean} True when it matches.
*/
atPunct(value) {
const token = this.peek();
return token.type === 'punct' && token.value === value;
}
/**
* Whether the current token is a given keyword.
* @param {string} value - The keyword.
* @returns {boolean} True when it matches.
*/
atName(value) {
const token = this.peek();
return token.type === 'name' && token.value === value;
}
/**
* Consumes a punctuator if present.
* @param {string} value - The punctuator.
* @returns {boolean} Whether it was consumed.
*/
eat(value) {
if (this.atPunct(value)) {
this.index++;
return true;
}
return false;
}
/**
* Consumes a punctuator, or fails.
* @param {string} value - The punctuator.
* @throws {ExpressionParseError} When the token does not match.
*/
expect(value) {
if (!this.eat(value)) {
const token = this.peek();
throw new ExpressionParseError(
`Expected "${value}" but found ${token.type === 'eof' ? 'end of expression' : `"${token.value}"`}`,
token.start,
this.source,
);
}
}
/**
* Asserts the token stream is exhausted.
* @throws {ExpressionParseError} When tokens remain.
*/
expectEnd() {
const token = this.peek();
if (token.type !== 'eof') {
throw new ExpressionParseError(`Unexpected "${token.value}"`, token.start, this.source);
}
}
/**
* Parses a full expression, including the comma operator.
* @returns {object} The AST node.
*/
parseExpressionStatement() {
const first = this.parseAssignment();
if (!this.atPunct(',')) {
return first;
}
const expressions = [first];
while (this.eat(',')) {
expressions.push(this.parseAssignment());
}
return { type: 'Sequence', expressions };
}
/**
* Parses an assignment, arrow function or conditional.
* @returns {object} The AST node.
*/
parseAssignment() {
const arrow = this.tryParseArrow();
if (arrow) {
return arrow;
}
const left = this.parseConditional();
const token = this.peek();
if (token.type === 'punct' && ASSIGNMENT_OPERATORS.has(token.value)) {
if (left.type !== 'Identifier' && left.type !== 'Member') {
throw new ExpressionParseError('Invalid assignment target', token.start, this.source);
}
this.next();
const right = this.parseAssignment();
return { type: 'Assignment', operator: token.value, target: left, value: right };
}
return left;
}
/**
* Attempts to parse an arrow function at the cursor.
*
* Speculative because `(a, b)` is ambiguous until `=>` is or is not found.
* The cursor is restored when the guess is wrong, which is cheap: the token
* stream is already materialised.
* @returns {object|null} The arrow node, or null when this is not one.
*/
tryParseArrow() {
const start = this.index;
// `x => …`
const token = this.peek();
if (token.type === 'name' && !Object.prototype.hasOwnProperty.call(LITERAL_KEYWORDS, token.value)) {
const after = this.tokens[this.index + 1];
if (after && after.type === 'punct' && after.value === '=>') {
this.next();
this.next();
return { type: 'Arrow', params: [token.value], body: this.parseArrowBody() };
}
}
// `(a, b) => …`
if (this.atPunct('(')) {
const params = [];
this.next();
let valid = true;
if (!this.atPunct(')')) {
for (;;) {
const param = this.peek();
if (param.type !== 'name') {
valid = false;
break;
}
params.push(param.value);
this.next();
if (this.eat(',')) continue;
break;
}
}
if (valid && this.eat(')') && this.atPunct('=>')) {
this.next();
return { type: 'Arrow', params, body: this.parseArrowBody() };
}
this.index = start;
}
return null;
}
/**
* Parses a parenthesised parameter name list.
* @returns {string[]} The parameter names.
*/
parseParameterList() {
this.expect('(');
const params = [];
if (!this.atPunct(')')) {
for (;;) {
const param = this.next();
if (param.type !== 'name') {
throw new ExpressionParseError('Expected a parameter name', param.start, this.source);
}
params.push(param.value);
if (this.eat(',')) continue;
break;
}
}
this.expect(')');
return params;
}
/**
* Parses an arrow function's body.
*
* A braced body is supported only when it is a single `return`; anything more
* is a statement list, which belongs to the statement evaluator rather than
* here.
* @returns {object} The body expression.
*/
parseArrowBody() {
if (this.atPunct('{')) {
this.next();
if (this.atName('return')) {
this.next();
const value = this.parseAssignment();
this.eat(';');
this.expect('}');
return value;
}
if (this.eat('}')) {
return { type: 'Literal', value: undefined };
}
const token = this.peek();
throw new ExpressionParseError(
'An arrow function body must be an expression or a single return statement',
token.start,
this.source,
);
}
return this.parseAssignment();
}
/**
* Parses a conditional expression.
* @returns {object} The AST node.
*/
parseConditional() {
const test = this.parseBinary(0);
if (this.eat('?')) {
const consequent = this.parseAssignment();
this.expect(':');
const alternate = this.parseAssignment();
return { type: 'Conditional', test, consequent, alternate };
}
return test;
}
/**
* Parses a binary expression using precedence climbing.
* @param {number} minPrecedence - The lowest precedence to accept.
* @returns {object} The AST node.
*/
parseBinary(minPrecedence) {
let left = this.parseUnary();
for (;;) {
const token = this.peek();
const operator =
token.type === 'punct' || (token.type === 'name' && (token.value === 'in' || token.value === 'instanceof'))
? token.value
: null;
const precedence = operator ? BINARY_PRECEDENCE[operator] : undefined;
if (precedence === undefined || precedence < minPrecedence) {
break;
}
this.next();
// `**` is right-associative; everything else is left-associative.
const right = this.parseBinary(operator === '**' ? precedence : precedence + 1);
const type = operator === '&&' || operator === '||' || operator === '??' ? 'Logical' : 'Binary';
left = { type, operator, left, right };
}
return left;
}
/**
* Parses a prefix expression.
* @returns {object} The AST node.
*/
parseUnary() {
const token = this.peek();
if (token.type === 'punct' && (token.value === '++' || token.value === '--')) {
this.next();
const argument = this.parseUnary();
if (argument.type !== 'Identifier' && argument.type !== 'Member') {
throw new ExpressionParseError('Invalid update target', token.start, this.source);
}
return { type: 'Update', operator: token.value, prefix: true, argument };
}
if ((token.type === 'punct' || token.type === 'name') && UNARY_OPERATORS.has(token.value)) {
this.next();
return { type: 'Unary', operator: token.value, argument: this.parseUnary() };
}
return this.parsePostfix();
}
/**
* Parses a postfix update.
* @returns {object} The AST node.
*/
parsePostfix() {
const argument = this.parseCallMember();
const token = this.peek();
if (token.type === 'punct' && (token.value === '++' || token.value === '--')) {
if (argument.type !== 'Identifier' && argument.type !== 'Member') {
throw new ExpressionParseError('Invalid update target', token.start, this.source);
}
this.next();
return { type: 'Update', operator: token.value, prefix: false, argument };
}
return argument;
}
/**
* Parses the constructor of a `new` expression: member access only, no calls.
* @returns {object} The AST node.
*/
parseNewCallee() {
let node = this.parsePrimary();
for (;;) {
if (this.eat('.')) {
const name = this.next();
if (name.type !== 'name') {
throw new ExpressionParseError('Expected a property name after "."', name.start, this.source);
}
node = {
type: 'Member',
object: node,
property: { type: 'Literal', value: name.value },
computed: false,
optional: false,
};
continue;
}
if (this.eat('[')) {
const property = this.parseExpressionStatement();
this.expect(']');
node = { type: 'Member', object: node, property, computed: true, optional: false };
continue;
}
break;
}
return node;
}
/**
* Parses member access and calls, left to right.
* @returns {object} The AST node.
*/
parseCallMember() {
let node = this.parsePrimary();
for (;;) {
if (this.eat('.')) {
const name = this.next();
if (name.type !== 'name') {
throw new ExpressionParseError('Expected a property name after "."', name.start, this.source);
}
node = { type: 'Member', object: node, property: { type: 'Literal', value: name.value }, computed: false, optional: false };
continue;
}
if (this.atPunct('?.')) {
this.next();
if (this.atPunct('(')) {
node = { type: 'Call', callee: node, args: this.parseArguments(), optional: true };
continue;
}
if (this.atPunct('[')) {
this.next();
const property = this.parseExpressionStatement();
this.expect(']');
node = { type: 'Member', object: node, property, computed: true, optional: true };
continue;
}
const name = this.next();
if (name.type !== 'name') {
throw new ExpressionParseError('Expected a property name after "?."', name.start, this.source);
}
node = { type: 'Member', object: node, property: { type: 'Literal', value: name.value }, computed: false, optional: true };
continue;
}
if (this.eat('[')) {
const property = this.parseExpressionStatement();
this.expect(']');
node = { type: 'Member', object: node, property, computed: true, optional: false };
continue;
}
if (this.atPunct('(')) {
node = { type: 'Call', callee: node, args: this.parseArguments(), optional: false };
continue;
}
break;
}
return node;
}
/**
* Parses a parenthesised argument list.
* @returns {Array<object>} The argument nodes.
*/
parseArguments() {
this.expect('(');
const args = [];
if (!this.atPunct(')')) {
for (;;) {
if (this.eat('...')) {
args.push({ type: 'Spread', argument: this.parseAssignment() });
} else {
args.push(this.parseAssignment());
}
if (this.eat(',')) continue;
break;
}
}
this.expect(')');
return args;
}
/**
* Parses a primary expression.
* @returns {object} The AST node.
*/
parsePrimary() {
const token = this.peek();
if (token.type === 'number' || token.type === 'string') {
this.next();
return { type: 'Literal', value: token.value };
}
if (token.type === 'template') {
this.next();
return this.parseTemplateParts(token.value);
}
if (token.type === 'name') {
if (Object.prototype.hasOwnProperty.call(LITERAL_KEYWORDS, token.value)) {
this.next();
return { type: 'Literal', value: LITERAL_KEYWORDS[token.value] };
}
if (token.value === 'function') {
// A function expression used as a callback -- `items.map(function (i) {
// return i.label; })` -- is ordinary template code, and refusing it
// would push the expression onto a path that no longer exists. The body
// is parsed on the same terms as an arrow's: an expression, or a single
// return.
this.next();
if (this.peek().type === 'name') {
this.next();
}
const params = this.parseParameterList();
return { type: 'Arrow', params, body: this.parseArrowBody(), isFunction: true };
}
if (token.value === 'new') {
this.next();
// The constructor is a member expression *without* calls: in
// `new Date().getTime()` the `new` binds to `Date`, and `.getTime()`
// applies to the instance. Parsing the whole call chain first and then
// unwrapping it gets that backwards.
const callee = this.parseNewCallee();
const args = this.atPunct('(') ? this.parseArguments() : [];
return { type: 'New', callee, args };
}
this.next();
return { type: 'Identifier', name: token.value, start: token.start };
}
if (this.atPunct('(')) {
this.next();
const inner = this.parseExpressionStatement();
this.expect(')');
return inner;
}
if (this.atPunct('[')) {
this.next();
const elements = [];
if (!this.atPunct(']')) {
for (;;) {
if (this.atPunct(']')) break;
if (this.eat('...')) {
elements.push({ type: 'Spread', argument: this.parseAssignment() });
} else {
elements.push(this.parseAssignment());
}
if (this.eat(',')) continue;
break;
}
}
this.expect(']');
return { type: 'ArrayLiteral', elements };
}
if (this.atPunct('{')) {
this.next();
const properties = [];
if (!this.atPunct('}')) {
for (;;) {
if (this.atPunct('}')) break;
if (this.eat('...')) {
properties.push({ kind: 'spread', value: this.parseAssignment() });
if (this.eat(',')) continue;
break;
}
const key = this.parseObjectKey();
if (this.eat(':')) {
properties.push({ kind: 'init', key, value: this.parseAssignment() });
} else if (key.computed) {
throw new ExpressionParseError('A computed key needs a value', this.peek().start, this.source);
} else {
// Shorthand: `{ count }`.
properties.push({
kind: 'init',
key,
value: { type: 'Identifier', name: key.node.value },
});
}
if (this.eat(',')) continue;
break;
}
}
this.expect('}');
return { type: 'ObjectLiteral', properties };
}
throw new ExpressionParseError(
token.type === 'eof' ? 'Unexpected end of expression' : `Unexpected "${token.value}"`,
token.start,
this.source,
);
}
/**
* Parses an object literal key.
* @returns {{computed: boolean, node: object}} The key description.
*/
parseObjectKey() {
if (this.eat('[')) {
const node = this.parseAssignment();
this.expect(']');
return { computed: true, node };
}
const token = this.next();
if (token.type === 'name' || token.type === 'string' || token.type === 'number') {
return { computed: false, node: { type: 'Literal', value: String(token.value) } };
}
throw new ExpressionParseError('Expected a property name', token.start, this.source);
}
/**
* Splits a template literal into its static and interpolated parts.
* @param {string} raw - The text between the backticks.
* @returns {object} A TemplateLiteral node.
*/
parseTemplateParts(raw) {
const quasis = [];
const expressions = [];
let text = '';
let i = 0;
while (i < raw.length) {
if (raw[i] === '\\') {
text += unescapeChar(raw, i);
i += escapeLength(raw, i);
continue;
}
if (raw[i] === '$' && raw[i + 1] === '{') {
let depth = 1;
let j = i + 2;
while (j < raw.length && depth > 0) {
if (raw[j] === '{') depth++;
else if (raw[j] === '}') depth--;
if (depth === 0) break;
j++;
}
quasis.push(text);
text = '';
expressions.push(parseExpression(raw.slice(i + 2, j)));
i = j + 1;
continue;
}
text += raw[i];
i++;
}
quasis.push(text);
return { type: 'TemplateLiteral', quasis, expressions };
}
}
|