143 lines
3.8 KiB
JavaScript
143 lines
3.8 KiB
JavaScript
// @flow
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// The algorithm used to determine whether a regexp can appear at a
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// given point in the program is loosely based on sweet.js' approach.
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// See https://github.com/mozilla/sweet.js/wiki/design
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import { types as tt } from "./types";
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import { lineBreak } from "../util/whitespace";
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export class TokContext {
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constructor(
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token: string,
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isExpr?: boolean,
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preserveSpace?: boolean,
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override?: ?Function, // Takes a Tokenizer as a this-parameter, and returns void.
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) {
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this.token = token;
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this.isExpr = !!isExpr;
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this.preserveSpace = !!preserveSpace;
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this.override = override;
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}
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token: string;
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isExpr: boolean;
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preserveSpace: boolean;
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override: ?Function;
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}
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export const types: {
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[key: string]: TokContext,
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} = {
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braceStatement: new TokContext("{", false),
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braceExpression: new TokContext("{", true),
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templateQuasi: new TokContext("${", false),
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parenStatement: new TokContext("(", false),
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parenExpression: new TokContext("(", true),
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template: new TokContext("`", true, true, p => p.readTmplToken()),
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functionExpression: new TokContext("function", true),
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functionStatement: new TokContext("function", false),
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};
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// Token-specific context update code
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tt.parenR.updateContext = tt.braceR.updateContext = function () {
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if (this.state.context.length === 1) {
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this.state.exprAllowed = true;
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return;
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}
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let out = this.state.context.pop();
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if (out === types.braceStatement && this.curContext().token === "function") {
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out = this.state.context.pop();
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}
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this.state.exprAllowed = !out.isExpr;
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};
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tt.name.updateContext = function (prevType) {
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let allowed = false;
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if (prevType !== tt.dot) {
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if (
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(this.state.value === "of" &&
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!this.state.exprAllowed &&
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prevType !== tt._function &&
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prevType !== tt._class) ||
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(this.state.value === "yield" && this.prodParam.hasYield)
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) {
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allowed = true;
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}
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}
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this.state.exprAllowed = allowed;
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if (this.state.isIterator) {
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this.state.isIterator = false;
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}
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};
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tt.braceL.updateContext = function (prevType) {
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this.state.context.push(
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this.braceIsBlock(prevType) ? types.braceStatement : types.braceExpression,
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);
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this.state.exprAllowed = true;
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};
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tt.dollarBraceL.updateContext = function () {
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this.state.context.push(types.templateQuasi);
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this.state.exprAllowed = true;
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};
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tt.parenL.updateContext = function (prevType) {
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const statementParens =
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prevType === tt._if ||
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prevType === tt._for ||
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prevType === tt._with ||
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prevType === tt._while;
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this.state.context.push(
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statementParens ? types.parenStatement : types.parenExpression,
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);
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this.state.exprAllowed = true;
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};
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tt.incDec.updateContext = function () {
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// tokExprAllowed stays unchanged
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};
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tt._function.updateContext = tt._class.updateContext = function (prevType) {
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if (prevType === tt.dot || prevType === tt.questionDot) {
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// when function/class follows dot/questionDot, it is part of
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// (optional)MemberExpression, then we don't need to push new token context
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} else if (
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prevType.beforeExpr &&
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prevType !== tt.semi &&
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prevType !== tt._else &&
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!(
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prevType === tt._return &&
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lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start))
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) &&
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!(
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(prevType === tt.colon || prevType === tt.braceL) &&
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this.curContext() === types.b_stat
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)
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) {
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this.state.context.push(types.functionExpression);
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} else {
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this.state.context.push(types.functionStatement);
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}
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this.state.exprAllowed = false;
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};
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tt.backQuote.updateContext = function () {
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if (this.curContext() === types.template) {
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this.state.context.pop();
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} else {
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this.state.context.push(types.template);
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}
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this.state.exprAllowed = false;
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};
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tt.star.updateContext = function () {
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this.state.exprAllowed = false;
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};
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