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import { GLib, GObject, property, readFile, register, writeFileAsync } from "astal";
import { derivative, evaluate, rationalize, simplify } from "mathjs/number";
import { math as config } from "../../config";
export interface HistoryItem {
equation: string;
result: string;
icon: string;
}
@register({ GTypeName: "Math" })
export default class Math extends GObject.Object {
static instance: Math;
static get_default() {
if (!this.instance) this.instance = new Math();
return this.instance;
}
readonly #maxHistory = config.maxHistory;
readonly #path = `${CACHE}/math-history.json`;
readonly #history: HistoryItem[] = [];
#variables: Record<string, string> = {};
#lastExpression: HistoryItem | null = null;
@property(Object)
get history() {
return this.#history;
}
#save() {
writeFileAsync(this.#path, JSON.stringify(this.#history)).catch(console.error);
}
/**
* Commits the last evaluated expression to the history
*/
commit() {
if (!this.#lastExpression) return;
// Try select first to prevent duplicates, if it fails, add it
if (!this.select(this.#lastExpression)) {
this.#history.unshift(this.#lastExpression);
if (this.#history.length > this.#maxHistory) this.#history.pop();
this.notify("history");
this.#save();
}
this.#lastExpression = null;
}
/**
* Moves an item in the history to the top
* @param item The item to select
* @returns If the item was successfully selected
*/
select(item: HistoryItem) {
const idx = this.#history.findIndex(i => i.equation === item.equation && i.result === item.result);
if (idx >= 0) {
this.#history.splice(idx, 1);
this.#history.unshift(item);
this.notify("history");
this.#save();
return true;
}
return false;
}
/**
* Clears the history and variables
*/
clear() {
if (this.#history.length > 0) {
this.#history.length = 0;
this.notify("history");
this.#save();
}
this.#lastExpression = null;
this.#variables = {};
}
/**
* Evaluates an equation and adds it to the history
* @param equation The equation to evaluate
* @returns A {@link HistoryItem} representing the result of the equation
*/
evaluate(equation: string): HistoryItem {
if (equation.startsWith("clear"))
return {
equation: "Clear history",
result: "Delete history and previously set variables",
icon: "delete_forever",
};
let result: string, icon: string;
try {
if (equation.startsWith("help")) {
equation = "Help";
result =
"This is a calculator powered by Math.js.\nAvailable functions:\n\thelp: show help\n\tclear: clear history\n\t<x> = <equation>: sets <x> to <equation>\n\tsimplify <equation>: simplifies <equation>\n\tderive <x> <equation>: derives <equation> with respect to <x>\n\tdd<x> <equation>: short form of derive\n\trationalize <equation>: rationalizes <equation>\n\t<equation>: evaluates <equation>\nSee the documentation for syntax and inbuilt functions.";
icon = "help";
} else if (equation.includes("=")) {
const [left, right] = equation.split("=");
try {
this.#variables[left.trim()] = simplify(right).toString();
} catch {
this.#variables[left.trim()] = right.trim();
}
result = this.#variables[left.trim()];
icon = "equal";
} else if (equation.startsWith("simplify")) {
result = simplify(equation.slice(8), this.#variables).toString();
icon = "function";
} else if (equation.startsWith("derive") || equation.startsWith("dd")) {
const isShortForm = equation.startsWith("dd");
const respectTo = isShortForm ? equation.split(" ")[0].slice(2) : equation.split(" ")[1];
if (!respectTo) throw new Error(`Format: ${isShortForm ? "dd" : "derive "}<respect-to> <equation>`);
result = derivative(equation.slice((isShortForm ? 2 : 7) + respectTo.length), respectTo).toString();
icon = "function";
} else if (equation.startsWith("rationalize")) {
result = rationalize(equation.slice(11), this.#variables).toString();
icon = "function";
} else {
result = evaluate(equation, this.#variables).toString();
icon = "calculate";
}
} catch (e) {
equation = "Invalid equation: " + equation;
result = String(e);
icon = "error";
}
return (this.#lastExpression = { equation, result, icon });
}
constructor() {
super();
// Load history
if (GLib.file_test(this.#path, GLib.FileTest.EXISTS)) {
try {
this.#history = JSON.parse(readFile(this.#path));
// Init eval to create variables and last expression
for (const item of this.#history) this.evaluate(item.equation);
} catch (e) {
console.error("Math - Unable to load history", e);
}
}
}
}
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