116 lines
4.4 KiB
JavaScript
116 lines
4.4 KiB
JavaScript
/**
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* LogarithmPlotter - 2D plotter software to make BODE plots, sequences and distribution functions.
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* Copyright (C) 2021-2024 Ad5001
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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import { Module } from "./common.mjs"
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import { Parser } from "../lib/expr-eval/parser.mjs"
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const evalVariables = {
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// Variables not provided by expr-eval.js, needs to be provided manually
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"pi": Math.PI,
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"PI": Math.PI,
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"π": Math.PI,
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"inf": Infinity,
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"infinity": Infinity,
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"Infinity": Infinity,
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"∞": Infinity,
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"e": Math.E,
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"E": Math.E,
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"true": true,
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"false": false
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}
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class ExprParserAPI extends Module {
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#parser = new Parser()
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constructor() {
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super("ExprParser")
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this.currentVars = {}
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this.#parser = new Parser()
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this.#parser.consts = Object.assign({}, this.#parser.consts, evalVariables)
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this.#parser.functions.integral = this.integral.bind(this)
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this.#parser.functions.derivative = this.derivative.bind(this)
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}
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/**
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* Parses arguments for a function, returns the corresponding JS function if it exists.
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* Throws either usage error otherwise.
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* @param {array} args - Arguments of the function, either [ ExecutableObject ] or [ string, variable ].
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* @param {string} usage1 - Usage for executable object.
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* @param {string} usage2 - Usage for string function.
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* @return {function} JS function to call.
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*/
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parseArgumentsForFunction(args, usage1, usage2) {
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let f, variable
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if(args.length === 1) {
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// Parse object
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f = args[0]
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if(typeof f !== "object" || !f.execute)
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throw EvalError(qsTranslate("usage", "Usage:\n%1").arg(usage1))
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let target = f
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f = (x) => target.execute(x)
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} else if(args.length === 2) {
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// Parse variable
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[f, variable] = args
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if(typeof f !== "string" || typeof variable !== "string")
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throw EvalError(qsTranslate("usage", "Usage:\n%1").arg(usage2))
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f = this.#parser.parse(f).toJSFunction(variable, this.currentVars)
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} else
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throw EvalError(qsTranslate("usage", "Usage:\n%1\n%2").arg(usage1).arg(usage2))
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return f
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}
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/**
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* @param {string} expression - Expression to parse
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* @returns {ExprEvalExpression}
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*/
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parse(expression) {
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return this.#parser.parse(expression)
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}
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integral(a = null, b = null, ...args) {
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let usage1 = qsTranslate("usage", "integral(<from: number>, <to: number>, <f: ExecutableObject>)")
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let usage2 = qsTranslate("usage", "integral(<from: number>, <to: number>, <f: string>, <variable: string>)")
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let f = this.parseArgumentsForFunction(args, usage1, usage2)
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if(typeof a !== "number" || typeof b !== "number")
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throw EvalError(qsTranslate("usage", "Usage:\n%1\n%2").arg(usage1).arg(usage2))
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// https://en.wikipedia.org/wiki/Simpson%27s_rule
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// Simpler, faster than tokenizing the expression
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return (b - a) / 6 * (f(a) + 4 * f((a + b) / 2) + f(b))
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}
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derivative(...args) {
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let usage1 = qsTranslate("usage", "derivative(<f: ExecutableObject>, <x: number>)")
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let usage2 = qsTranslate("usage", "derivative(<f: string>, <variable: string>, <x: number>)")
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let x = args.pop()
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let f = this.parseArgumentsForFunction(args, usage1, usage2)
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if(typeof x !== "number")
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throw EvalError(qsTranslate("usage", "Usage:\n%1\n%2").arg(usage1).arg(usage2))
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let derivative_precision = 1e-8
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return (f(x + derivative_precision / 2) - f(x - derivative_precision / 2)) / derivative_precision
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}
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}
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/** @type {ExprParserAPI} */
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Modules.ExprParser = Modules.ExprParser || new ExprParserAPI()
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export default Modules.ExprParser
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