enh(std) enhance standard library plugin with math functionalities

lib/plugins/StandardLibrary/Math.js

@@ -0,0 +1,60 @@
+function inc(val, options = [1]) {
+	let [name, amount = 1, ..._rest] = options;
+	return {
+		varName: name,
+		new: val * 1 + amount * 1,
+		old: val * 1,
+	};
+}
+
+function dec(val, options = [1]) {
+	let [name, amount = 1, ..._rest] = options;
+	return {
+		varName: name,
+		new: val * 1 - amount * 1,
+		old: val * 1,
+	};
+}
+
+function mult(val, options = [1]) {
+	let [name, amount = 1, ..._rest] = options;
+	return {
+		varName: name,
+		new: val * 1 * amount * 1,
+		old: val * 1,
+	};
+}
+
+function div(val, options = [1]) {
+	let [name, amount = 1, ..._rest] = options;
+	return {
+		varName: name,
+		new: ((val * 1) / amount) * 1,
+		old: val * 1,
+	};
+}
+
+function pow(val, options = [1]) {
+	let [name, amount = 1, ..._rest] = options;
+	return {
+		varName: name,
+		new: Math.pow(val * 1, amount * 1),
+		old: val * 1,
+	};
+}
+
+const BasicArithmetic = new Map([
+	['increment', inc],
+	['increase', inc],
+	['inc', inc],
+	['decrement', dec],
+	['decrease', dec],
+	['dec', dec],
+	['multiply', mult],
+	['mult', mult],
+	['divide', div],
+	['div', div],
+	['pow', pow],
+]);
+
+export default new Map([...BasicArithmetic.entries()]);