chore: documentation and optimization

What a rhyme.

.config/build.js

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+import * as esbuild from "esbuild";
+
+const result = esbuild.buildSync({
+	entryPoints: ["src/index.ts"],
+	bundle: true,
+	minify: true,
+	outdir: "dist",
+	define: {
+		"import.meta.vitest": "undefined",
+	},
+});

.config/generateSwizzle.js

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+import { writeFileSync } from "fs";
+import { relative } from "path";
+
+function capitalize(/** @type {string} */ s) {
+	return s.slice(0, 1).toUpperCase() + s.slice(1).toLowerCase();
+}
+
+const script = import.meta.filename;
+
+const path = "./src/mixin/math/swizzlePermutations.d.ts";
+const axis = ["x", "y", "z", "w", "v"];
+
+const property = ["first", "second", "third", "fourth", "fifth"];
+
+const mixin = "./src/mixin/base/mixin";
+
+let conditional = "";
+
+for (let n = 0; n < axis.length; n++) {
+	if (n === axis.length - 1) {
+		conditional += `Swizzle${n + 1}D<T, t>`;
+		break;
+	}
+	const type = new Array(n + 1).fill("number").join(", ");
+	const indent = "\t".repeat(n + 1);
+	conditional += `T extends readonly [${type}]\n`;
+	conditional += `${indent}? Swizzle${n + 1}D<T, t>\n`;
+	conditional += `${indent}: `;
+}
+
+const type = new Array(axis.length).fill("number").join(", ");
+
+let src = `
+// .d.ts file auto-generated by ${relative(path, script)}
+// Do not edit
+
+import type { Props, Return } from '${relative(path, mixin)}';
+
+type IsValid<T extends readonly number[]> = number extends T['length'] 
+    ? false 
+    : T extends readonly [] 
+        ? false 
+        : true; 
+
+export type SwizzleProps<T extends readonly number[], t extends Props> =
+    IsValid<T> extends false
+        ? {}
+        : ${conditional
+			.split("\n")
+			.map((line) => "\t\t" + line)
+			.join("\n")
+			.trimStart()};
+
+export interface ISwizzle<
+    T extends readonly [${type}] = 
+        readonly [${type}], 
+    t extends Props = Props
+> extends Swizzle${axis.length}D<T, t> {};
+
+`.trimStart();
+
+for (let n = 0; n < axis.length; n++) {
+	const state = new Array(axis.length).fill(-1);
+
+	const props = [];
+
+	outer: do {
+		for (let i = state.length - 1; i >= 0; i--)
+			if (++state[i] > n) {
+				state[i] = -1;
+			} else break;
+
+		let nulled = false;
+		for (const item of state) {
+			if (item === -1) {
+				nulled = true;
+				continue;
+			}
+			if (nulled) continue outer;
+		}
+		if (state.every((x) => x === -1)) break;
+
+		const key = state
+			.filter((x) => x !== -1)
+			.map((x) => axis[x])
+			.join("");
+		if (state.slice(1).every((x) => x === -1)) {
+			const arr = [5, 3, 8, 2, 1].map((x) =>
+				Math.abs(x - n - state[0]),
+			);
+			props.push({
+				doc: `
+/**
+ * Vector-style accessor, ${property[state[0]]} property of the value
+ * @from {@link Math \`Math\`}
+ * @example
+ * \`\`\`ts
+ * const vec = [${arr
+		.slice(0, Math.max(n + 1, 2))
+		.map((n) => n.toString())
+		.join(", ")}] as const;
+ * 
+ * const ${axis[state[0]]} = $(vec).${axis[state[0]]}.value;
+ * expect(${axis[state[0]]}).toBe(${arr[state[0]]})
+ * \`\`\`
+ */`.trimStart(),
+				property: `readonly ${key}: Return<T[${state[0]}], t>`,
+			});
+			continue;
+		}
+
+		let count = 0;
+		if (state.every((x) => x === count++)) continue;
+
+		const arr = [6, 2, 3, 5, 4, 7].map((x, idx) =>
+			Math.abs(x - state[idx]),
+		);
+
+		const type = state
+			.filter((x) => x !== -1)
+			.map((x) => `T[${x}]`)
+			.join(", ");
+		props.push({
+			doc: `
+/**
+ * Vector-style swizzle accessor, rearannges the elements of the value
+ * 
+ * Equivalent to \`[${state
+		.filter((x) => x !== -1)
+		.map((x) => `vec[${x}]`)
+		.join(", ")}]\`
+ * @from {@link Math \`Math\`}
+ * @example
+ * \`\`\`ts
+ * const vec = [${arr.slice(0, n + 1).join(", ")}] as const;
+ * 
+ * const ${key} = $(vec).${key}().value;
+ * expect(${key}).toMatchObject([${state
+		.filter((x) => x !== -1)
+		.map((x) => arr[x])
+		.join(", ")}])
+ * \`\`\`
+ */
+`.trimStart(),
+			property: `readonly ${key}: () => Return<[${type}], t>`,
+		});
+	} while (state.some((x) => x !== -1));
+
+	props.sort((a, b) => a.property.length - b.property.length);
+
+	src += `interface Swizzle${n + 1}D<T extends readonly [${new Array(n + 1).fill("number").join(", ")}], t extends Props> {\n`;
+	src += `${props
+		.map((x) =>
+			[x.doc, x.property]
+				.join("\n")
+				.split("\n")
+				.map((line) => "\t" + line)
+				.join("\n"),
+		)
+		.join("\n")}\n`;
+	src += "}\n";
+	src += "\n";
+}
+
+writeFileSync(path, src);