1 files changed, 140 insertions, 0 deletions

diff --git a/Blog/Components/Pages/Calc.razor.js b/Blog/Components/Pages/Calc.razor.js
new file mode 100644
index 0000000..d18634e
--- /dev/null
+++ b/Blog/Components/Pages/Calc.razor.js
@@ -0,0 +1,140 @@
+import { getById, div, span, h, writeError } from "/common.module.js"
+
+export function onLoad() {
+    console.log('Loaded');
+    const form = getById("form");
+    const input = getById("input");
+    const log = getById("log");
+
+    form.addEventListener("submit", submitForm);
+
+    const urlParams = new URLSearchParams(window.location.search);
+    const queryInput = urlParams.get('in');
+
+    if (input.value.length === 0) {
+        input.value = queryInput;
+    }
+}
+
+export function onUpdate() {
+    console.log('Updated');
+}
+
+export function onDispose() {
+    console.log('Disposed');
+}
+
+/** @param {SubmitEvent} event */
+function submitForm(event) {
+    console.log(input.value);
+    resetLog();
+    try {
+        const stack = evalString(input.value);
+        console.log(stack);
+
+        const path = window.location.pathname;
+        const params = new URLSearchParams(window.location.search);
+        const hash = window.location.hash;
+
+        params.set("in", input.value);
+        window.history.replaceState({}, '', `${path}?${params.toString()}${hash}`);
+    }
+    catch (error) {
+        writeError(error);
+    }
+    event.preventDefault();
+}
+
+/** @param {string} input */
+function evalString(input) {
+    let words = input.trim().split(' ').filter(i => i);
+    return evalWords([], words);
+}
+
+function effect2(f) {
+    return (stack) => {
+        if (stack.length <= 1) throw "stack underflow";
+        let [x, y, ...rest] = stack;
+        return [f(y, x), ...rest];
+    }
+}
+
+const plus = effect2((a, b) => a + b);
+const subtract = effect2((a, b) => a - b);
+const multiply = effect2((a, b) => a * b);
+const divide = effect2((a, b) => a / b);
+
+
+function evalWords(stack, words) {
+    writeLog(stack, words);
+    if (words.length === 0) return stack;
+
+    let [word, ...rest] = words;
+    return evalWords(evalWord(word, stack), rest);
+}
+
+function evalWord(word, stack, rest) {
+    switch (word) {
+        case "+": return plus(stack);
+        case "-": return subtract(stack);
+        case "*": return multiply(stack);
+        case "/": return divide(stack);
+        case "dup": return dup(stack);
+        case "drop": return drop(stack);
+        case "swap": return swap(stack);
+        default: return parse(word, stack);
+    }
+}
+
+function dup(stack) {
+    let [x, ...rest] = stack;
+    return [x, x, ...rest];
+}
+
+function drop(stack) {
+    let [_, ...rest] = stack;
+    return rest;
+}
+
+function swap(stack) {
+    let [x, y, ...rest] = stack;
+    return [y, x, ...rest];
+}
+
+function parse(word, stack) {
+    let num = Number(word);
+    if (isNaN(num)) {
+        throw `word '${word}' not recognised`;
+    }
+    return [num, ...stack];
+}
+
+function writeLog(stack, words) {
+    let log_left = span(`[${stack.join(', ')}]`);
+    let log_right = span(words.join(' '));
+
+    if (words.length === 0) {
+        log_left.textContent += " <=="
+    }
+
+    let log_row = div(log_left, log_right);
+    log_row.className = "flex-spread";
+
+    log.appendChild(log_row);
+}
+
+function resetLog() {
+    if (!log.hasChildNodes()) return;
+
+    let summary = h("summary");
+    summary.textContent = log.firstChild.lastChild.textContent;
+
+    let old_log = log.cloneNode(true);
+    old_log.id = '';
+
+    let details = h("details", summary, old_log);
+    details.className = "history"
+
+    log.insertAdjacentElement("afterend", details);
+    log.replaceChildren(); //remove children, clear log
+}
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