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import { getById, h, writeError } from "/common.module.js" |
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|
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const form = getById("form"); |
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const input = getById("input"); |
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const log = getById("log"); |
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|
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form.addEventListener("submit", submitForm); |
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|
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const urlParams = new URLSearchParams(window.location.search); |
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const queryInput = urlParams.get('in'); |
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|
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if (input.value.length === 0) { |
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input.value = queryInput; |
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} |
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|
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function submitForm(event) { |
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console.log(input.value); |
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resetLog(); |
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try { |
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const stack = evalString(input.value); |
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console.log(stack); |
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|
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const path = window.location.pathname; |
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const params = new URLSearchParams(window.location.search); |
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const hash = window.location.hash; |
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|
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params.set("in", input.value); |
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window.history.replaceState({}, '', `${path}?${params.toString()}${hash}`); |
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} |
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catch (error) { |
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writeError(error); |
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} |
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event.preventDefault(); |
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} |
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|
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|
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function evalString(input) { |
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let words = input.trim().split(' ').filter(i => i); |
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return evalWords([], words); |
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} |
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|
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function effect2(f) { |
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return (stack) => { |
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if (stack.length <= 1) throw "stack underflow"; |
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let [x, y, ...rest] = stack; |
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return [f(y, x), ...rest]; |
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} |
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} |
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|
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const plus = effect2((a, b) => a + b); |
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const subtract = effect2((a, b) => a - b); |
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const multiply = effect2((a, b) => a * b); |
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const divide = effect2((a, b) => a / b); |
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|
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|
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function evalWords(stack, words) { |
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writeLog(stack, words); |
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if (words.length === 0) return stack; |
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|
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let [word, ...rest] = words; |
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return evalWords(evalWord(word, stack), rest); |
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} |
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|
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function evalWord(word, stack, rest) { |
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switch (word) { |
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case "+": return plus(stack); |
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case "-": return subtract(stack); |
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case "*": return multiply(stack); |
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case "/": return divide(stack); |
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case "dup": return dup(stack); |
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case "drop": return drop(stack); |
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case "swap": return swap(stack); |
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default: return parse(word, stack); |
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} |
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} |
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|
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function dup(stack) { |
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let [x, ...rest] = stack; |
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return [x, x, ...rest]; |
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} |
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|
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function drop(stack) { |
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let [_, ...rest] = stack; |
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return rest; |
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} |
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|
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function swap(stack) { |
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let [x, y, ...rest] = stack; |
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return [y, x, ...rest]; |
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} |
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|
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function parse(word, stack) { |
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let num = Number(word); |
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if (isNaN(num)) { |
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throw `word '${word}' not recognised`; |
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} |
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return [num, ...stack]; |
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} |
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|
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function writeLog(stack, words) { |
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let log_left = h("span", `[${stack.join(', ')}]`); |
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let log_right = h("span", words.join(' ')); |
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|
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if (words.length === 0) { |
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log_left.textContent += " <==" |
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} |
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|
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let log_row = h("div", {class: "stack-step"}, [log_left, log_right]); |
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|
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log.appendChild(log_row); |
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} |
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function resetLog() { |
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if (!log.hasChildNodes()) return; |
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|
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let summary = h("summary", log.firstChild.lastChild.textContent); |
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|
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let old_log = log.cloneNode(true); |
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old_log.id = ''; |
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|
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let details = h("details", {class: "history"}, [summary, old_log]); |
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|
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log.insertAdjacentElement("afterend", details); |
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log.replaceChildren(); |
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} |