139 lines
3.8 KiB
JavaScript
139 lines
3.8 KiB
JavaScript
"use strict";
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const filterParser = require("./filter-parser");
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const filterCnf = require("./filter-cnf");
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const satSolver = require("./sat-solver");
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function* permute(arr) {
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if (arr.length <= 1) {
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for (let i = 0; i < arr[0]; ++i) yield [i];
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return;
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}
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let slc = arr.slice(1);
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for (let i = 0; i < arr[0]; ++i)
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for (let innerArr of permute(slc)) yield [i].concat(innerArr);
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}
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class Filter {
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constructor(str) {
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if (Array.isArray(str)) this.ast = str;
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else if (str instanceof Filter) this.ast = str.ast;
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else if (!str) this.ast = null;
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else this.ast = filterParser.parse(str);
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}
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toString() {
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if (!this.string)
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if (this.ast) this.string = filterParser.stringify(this.ast);
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else this.string = "";
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return this.string;
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}
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or(fltr) {
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if (!fltr || !this.ast) return this;
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let f = ["OR"];
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if (this.ast[0] === "OR") f = f.concat(this.ast.slice(1));
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else f.push(this.ast);
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if (fltr.ast[0] === "OR") f = f.concat(fltr.ast.slice(1));
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else f.push(fltr.ast);
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return new Filter(f);
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}
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and(fltr) {
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if (!fltr) return this;
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else if (!this.ast) return fltr;
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let f = ["AND"];
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if (this.ast[0] === "AND") f = f.concat(this.ast.slice(1));
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else f.push(this.ast);
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if (fltr.ast[0] === "AND") f = f.concat(fltr.ast.slice(1));
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else f.push(fltr.ast);
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return new Filter(f);
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}
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not() {
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if (this.ast[0] === "NOT") return new Filter(this.ast[1]);
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else return new Filter(["NOT", this.ast]);
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}
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evaluateExpressions(now = Date.now()) {
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if (!this.ast) return this;
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let ast = filterParser.evaluateExpressions(this.ast, exp => {
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if (exp[0] === "FUNC" && exp[1] === "NOW") return now;
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});
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if (ast === this.ast) return this;
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else return new Filter(ast);
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}
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subset(fltr) {
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if (!fltr.ast) return true;
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else if (!this.ast) return false;
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const f = this.not()
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.or(fltr)
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.not();
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const { vars, clauses } = filterCnf.booleanCnf(f.ast);
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return !satSolver.naiveDpll(clauses, vars);
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}
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test(obj) {
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if (!this.ast) return true;
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return filterParser.map(this.ast, exp => {
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const op = exp[0];
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if (op === "AND") {
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for (let i = 1; i < exp.length; ++i) if (!exp[i]) return false;
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return true;
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} else if (op === "OR") {
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for (let i = 1; i < exp.length; ++i) if (exp[i]) return true;
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return false;
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} else if (op === "NOT") {
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return !exp[1];
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} else if (op === "=") {
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const val =
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typeof obj[exp[1]] === "object" ? obj[exp[1]].value[0] : obj[exp[1]];
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return val === exp[2];
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} else if (op === "<>") {
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const val =
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typeof obj[exp[1]] === "object" ? obj[exp[1]].value[0] : obj[exp[1]];
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return val !== exp[2];
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} else if (op === ">=") {
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const val =
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typeof obj[exp[1]] === "object" ? obj[exp[1]].value[0] : obj[exp[1]];
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return typeof val === typeof exp[2] && val >= exp[2];
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} else if (op === ">") {
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const val =
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typeof obj[exp[1]] === "object" ? obj[exp[1]].value[0] : obj[exp[1]];
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return typeof val === typeof exp[2] && val > exp[2];
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} else if (op === "<=") {
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const val =
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typeof obj[exp[1]] === "object" ? obj[exp[1]].value[0] : obj[exp[1]];
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return typeof val === typeof exp[2] && val <= exp[2];
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} else if (op === "<") {
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const val =
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typeof obj[exp[1]] === "object" ? obj[exp[1]].value[0] : obj[exp[1]];
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return typeof val === typeof exp[2] && val < exp[2];
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} else if (op === "IS NULL") {
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return obj[exp[1]] == null;
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} else if (op === "IS NOT NULL") {
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return obj[exp[1]] != null;
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} else {
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throw new Error(`Unsupported operator ${op}`);
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}
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});
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}
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}
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module.exports = Filter;
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