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110 lines
3.0 KiB
JavaScript
110 lines
3.0 KiB
JavaScript
// 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 {Parser} from "./state"
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import {types as tt} from "./tokentype"
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import {lineBreak} from "./whitespace"
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export class TokContext {
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constructor(token, isExpr, preserveSpace, override) {
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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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}
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export const types = {
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b_stat: new TokContext("{", false),
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b_expr: new TokContext("{", true),
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b_tmpl: new TokContext("${", true),
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p_stat: new TokContext("(", false),
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p_expr: new TokContext("(", true),
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q_tmpl: new TokContext("`", true, true, p => p.readTmplToken()),
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f_expr: new TokContext("function", true)
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}
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const pp = Parser.prototype
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pp.initialContext = function() {
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return [types.b_stat]
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}
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pp.braceIsBlock = function(prevType) {
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if (prevType === tt.colon) {
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let parent = this.curContext()
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if (parent === types.b_stat || parent === types.b_expr)
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return !parent.isExpr
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}
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if (prevType === tt._return)
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return lineBreak.test(this.input.slice(this.lastTokEnd, this.start))
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if (prevType === tt._else || prevType === tt.semi || prevType === tt.eof || prevType === tt.parenR)
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return true
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if (prevType == tt.braceL)
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return this.curContext() === types.b_stat
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return !this.exprAllowed
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}
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pp.updateContext = function(prevType) {
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let update, type = this.type
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if (type.keyword && prevType == tt.dot)
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this.exprAllowed = false
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else if (update = type.updateContext)
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update.call(this, prevType)
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else
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this.exprAllowed = type.beforeExpr
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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.context.length == 1) {
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this.exprAllowed = true
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return
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}
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let out = this.context.pop()
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if (out === types.b_stat && this.curContext() === types.f_expr) {
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this.context.pop()
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this.exprAllowed = false
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} else if (out === types.b_tmpl) {
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this.exprAllowed = true
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} else {
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this.exprAllowed = !out.isExpr
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}
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}
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tt.braceL.updateContext = function(prevType) {
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this.context.push(this.braceIsBlock(prevType) ? types.b_stat : types.b_expr)
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this.exprAllowed = true
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}
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tt.dollarBraceL.updateContext = function() {
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this.context.push(types.b_tmpl)
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this.exprAllowed = true
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}
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tt.parenL.updateContext = function(prevType) {
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let statementParens = prevType === tt._if || prevType === tt._for || prevType === tt._with || prevType === tt._while
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this.context.push(statementParens ? types.p_stat : types.p_expr)
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this.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 = function() {
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if (this.curContext() !== types.b_stat)
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this.context.push(types.f_expr)
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this.exprAllowed = false
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}
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tt.backQuote.updateContext = function() {
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if (this.curContext() === types.q_tmpl)
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this.context.pop()
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else
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this.context.push(types.q_tmpl)
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this.exprAllowed = false
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}
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