Desmos Simulation Warp

DesmosSimulationWarp.user.js

// ==UserScript==
// @name        Desmos Simulation Warp
// @namespace   http://github.com/jared-hughes
// @version     0.1
// @author      fireflame241
// @description Execute a simulation at warp speed
// @grant       none
// @match       https://*.desmos.com/calculator*
// ==/UserScript==

/*jshint esversion: 6 */

/**
 * Limitations: Only applies to simulations of the form x_i ← f_i(x_j) where f_i:R→R
 *   i.e. single-variable functions of numbers that return a number, applied only to
 *   variables that are changed in the simualation.
 *
 * Example graph: https://www.desmos.com/calculator/vkwa9dovn5. Try `warp(0, 1000)` in the console
 * (0 is the index of the first simulation).
 */

const rModelList = window.require('graphing-calc/models/list')

function getItemModelByIdentifier(name) {
    return rModelList.getItemsByIdentifier(window.Calc.controller.listModel, name)[0]
}

function getValue (expr) {
    return new Promise((resolve, reject) => {
        // const helper = window.Calc.HelperExpression({latex: expr})
        // helper.observe('numericValue', () => resolve(helper.numericValue))
        resolve(getItemModelByIdentifier(expr).formula.constant_value)
    })
}

const variableRegex = '(\\w+(?:_\\{\\w+\\})?)'
const functionArgsRegex = `\\\\left\\((${variableRegex})\\\\right\\)`
const functionCallRegex = variableRegex + functionArgsRegex

window.warp = function warp (simulationIndex, numTicks) {
    const exprs = window.Calc.getState().expressions.list
    const rules = exprs[simulationIndex].clickableInfo.rules;
    Promise.all(rules.map(e => getValue(e.assignment))).then(valuesList => {
        let values = Object.fromEntries(rules.map((e,i) => [e.assignment, valuesList[i]]))
        rules.forEach(e => {
            const match = e.expression.match(new RegExp(functionCallRegex))
            e.arg = match[2]
            const funcName = match[1]
            const funcID = exprs.find(({latex}) => latex && latex.match(new RegExp(funcName + functionArgsRegex))).id
            // to access compiled function from Calc.controller.grapher.graphSketches, the function must
            // take a single variable as argument.
            e.fn = window.Calc.controller.grapher.graphSketches[funcID].branches[0].compiled.fn
        })
        const apply = ({assignment, fn, arg}) => [assignment,fn(values[arg])]
        for (let i=0; i<numTicks; i++) {
            const newValues = Object.fromEntries(rules.map(apply))
            values = newValues
        }
        console.log(values)
        Object.entries(values).forEach(([assignment, value]) => {
            window.Calc.setExpression({
                id: getItemModelByIdentifier(assignment).id,
                latex: `${assignment}=${value}`
            })
        })
    })
}