feat: add dynamic constant management to the calculator core

.memory/project.md

@@ -1,8 +1,9 @@
-# Project memory
+# State
-
+- Core engine: `src/rpn-calculator.js`
-- RPN calculator JS project.
+- Active demo: `samples/calc-02/` portrait-only HP48GX layout; display-adjacent button row stays in 4 columns and now shares the same base button styling as the function keys
-- Read `.memory/state.md` for current state.
+- Mode button shows the current angle mode only; selecting a mode uses a popup menu
-- Keep names and commands in English.
+- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`, `listConstants`, `setConstant`, `removeConstant`, `hasConstant`
-- Update memory files based on events: engine, demo, API, commands, exports, docs, or tasks.
+- Config: `maxSize`, `base`, `angleMode`, `enabledCommands`
-- Core arithmetic now includes `root` for y-th roots, and `samples/calc-02/` uses it for `y√x`.
+- Commands: arithmetic, stack, trigonometry, constants `pi` and `e`; arithmetic now includes `root` for y-th roots; constants can now be added or removed dynamically through the core API and the calc-02 constant menu reads from the engine
-- `samples/calc-02/` in portrait mode remains the active responsive demo.
+- Demo actions: keyboard focus is kept on the hidden input on desktop so typing keeps working; the keypad layout places Enter in the bottom-left, ± in the former Enter position, and Esc before Clear for safety; paste parses clipboard text as a number before pushing it to the stack; Ctrl+V is supported via the hidden input paste event; backspace is ignored when the stack is empty; operation errors are shown as an overlay bar on top of the calculator with a shorter timeout and darker red; the display button row uses a 4-column grid with a spacer cell to preserve alignment
+- Exports: browser `window.RpnCalculator`, CommonJS `module.exports`

.memory/state.md

@@ -2,8 +2,8 @@
 - Core engine: `src/rpn-calculator.js`
 - Active demo: `samples/calc-02/` portrait-only HP48GX layout; display-adjacent button row stays in 4 columns and now shares the same base button styling as the function keys
 - Mode button shows the current angle mode only; selecting a mode uses a popup menu
-- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`
+- Public API: `push`, `pop`, `clear`, `swap`, `remove`, `edit`, `isValidIndex`, `input`, `command`, `getOperationsByCategory`, `getConstants`, `listConstants`, `setConstant`, `removeConstant`, `hasConstant`
 - Config: `maxSize`, `base`, `angleMode`, `enabledCommands`
-- Commands: arithmetic, stack, trigonometry, constants `pi` and `e`; arithmetic now includes `root` for y-th roots
+- Commands: arithmetic, stack, trigonometry, constants `pi`, `e`, `phi`, `g`, and `c`; arithmetic now includes `root` for y-th roots; constants can now be added or removed dynamically through the core API
 - Demo actions: keyboard focus is kept on the hidden input on desktop so typing keeps working; the keypad layout places Enter in the bottom-left, ± in the former Enter position, and Esc before Clear for safety; paste parses clipboard text as a number before pushing it to the stack; Ctrl+V is supported via the hidden input paste event; backspace is ignored when the stack is empty; operation errors are shown as an overlay bar on top of the calculator with a shorter timeout and darker red; the display button row uses a 4-column grid with a spacer cell to preserve alignment
 - Exports: browser `window.RpnCalculator`, CommonJS `module.exports`

samples/calc-02/index.js

@@ -383,6 +383,7 @@ modeButton.addEventListener('click', (event) => {
 window.addEventListener('resize', () => {
 	closeModeMenu();
 	closeConstMenu();
+	render();
 });
 window.addEventListener('scroll', () => {
 	closeModeMenu();
@@ -422,13 +423,14 @@ hiddenInput.addEventListener('paste', (event) => {
 
 upButton.addEventListener('click', () => {});
 
-const constants = [
+const constantLabels = {
-	{ label: 'π', value: Math.PI },
+	pi: 'π',
-	{ label: 'e', value: Math.E },
+	e: 'e',
-	{ label: 'φ', value: (1 + Math.sqrt(5)) / 2 },
+	phi: 'φ',
-	{ label: 'g', value: 9.80665 },
+	g: 'g',
-	{ label: 'c', value: 299792458 },
+	c: 'c',
-];
+};
+const constantOrder = ['pi', 'e', 'phi', 'g', 'c'];
 
 let constMenuEl = null;
 
@@ -449,14 +451,19 @@ function toggleConstMenu() {
 	constMenuEl = document.createElement('div');
 	constMenuEl.className = 'mode-menu';
 	constMenuEl.style.top = `${rect.bottom + 6 + window.scrollY}px`;
-	constants.forEach((constant) => {
+	const availableConstants = calc.listConstants();
+	const keys = [...constantOrder, ...Object.keys(availableConstants).filter((name) => !constantOrder.includes(name))];
+	keys.forEach((name) => {
 		const button = document.createElement('button');
 		button.type = 'button';
 		button.className = 'mode-menu-item';
-		button.textContent = constant.label;
+		if (!Object.prototype.hasOwnProperty.call(availableConstants, name)) {
+			return;
+		}
+		button.textContent = constantLabels[name] ?? name;
 		button.addEventListener('click', () => {
 			pushEditingValueIfNeeded();
-			calc.push(constant.value);
+			calc.push(availableConstants[name]);
 			render();
 			clearStatus();
 			closeConstMenu();

src/rpn-calculator.js

@@ -2,6 +2,9 @@ class RpnCalculator {
   static CONSTANTS = {
     pi: Math.PI,
     e: Math.E,
+    phi: (1 + Math.sqrt(5)) / 2,
+    g: 9.80665,
+    c: 299792458,
   };
 
   static OPERATIONS = {
@@ -212,6 +215,15 @@ class RpnCalculator {
     this.enabledCommands = new Set(selectedCommands.map((name) => this.normalizeCommandName(name)).filter((name) => RpnCalculator.OPERATIONS[name]));
   }
 
+  static isValidConstantName(name) {
+    return typeof name === 'string' && name.trim() !== '';
+  }
+
+  static isReservedName(name) {
+    const normalized = typeof name === 'string' ? name.toLowerCase() : '';
+    return Boolean(RpnCalculator.OPERATIONS[normalized]);
+  }
+
   toRadians(value) {
     if (this.angleMode === 'grad') {
       return (value * Math.PI) / 200;
@@ -257,6 +269,45 @@ class RpnCalculator {
     return typeof name === 'string' && Object.prototype.hasOwnProperty.call(this.constants, name.toLowerCase());
   }
 
+  setConstant(name, value) {
+    if (!RpnCalculator.isValidConstantName(name)) {
+      throw new Error('Invalid constant name');
+    }
+    if (!Number.isFinite(value)) {
+      throw new Error('Invalid constant value');
+    }
+
+    const normalized = name.trim().toLowerCase();
+    if (RpnCalculator.isReservedName(normalized)) {
+      throw new Error(`Constant name conflicts with a command: ${name}`);
+    }
+
+    this.constants[normalized] = value;
+    return value;
+  }
+
+  removeConstant(name) {
+    if (!RpnCalculator.isValidConstantName(name)) {
+      throw new Error('Invalid constant name');
+    }
+
+    const normalized = name.trim().toLowerCase();
+    if (!this.isConstantName(normalized)) {
+      return false;
+    }
+
+    delete this.constants[normalized];
+    return true;
+  }
+
+  hasConstant(name) {
+    if (!RpnCalculator.isValidConstantName(name)) {
+      return false;
+    }
+
+    return this.isConstantName(name.trim().toLowerCase());
+  }
+
   push(value) {
     if (this.stack.length >= this.maxSize) {
       throw new Error('Stack overflow');
@@ -408,6 +459,10 @@ class RpnCalculator {
   getConstants() {
     return { ...this.constants };
   }
+
+  listConstants() {
+    return this.getConstants();
+  }
 }
 
 if (typeof window !== 'undefined') {