🚴 perf(from): Use concatenation of medium-sized trees.

Author: make-github-pseudonymous-again

src/0-core/_fast/_from_iterable.js

@@ -0,0 +1,57 @@
+// Import {Empty} from '../../3-tree/index.js';
+
+import {Empty} from '../../3-tree/implementations/0-Empty.js';
+import {
+	THRESHOLD as MEDIUM_THRESHOLD,
+	_from_medium_list,
+	_from_largest_medium_list,
+} from './_from_medium_list.js';
+
+function increment(trees, tree) {
+	// eslint-disable-next-line no-bitwise,unicorn/prefer-math-trunc
+	const n = trees.length | 0;
+	// eslint-disable-next-line no-bitwise,unicorn/prefer-math-trunc
+	for (let i = 0; i !== n; i = (i + 1) | 0) {
+		if (trees[i] === null) {
+			trees[i] = tree;
+			return;
+		}
+
+		tree = trees[i].concat(tree);
+		trees[i] = null;
+	}
+
+	trees.push(tree);
+}
+
+function sum(M, trees) {
+	let result = new Empty(M);
+	for (const tree of trees) {
+		if (tree !== null) {
+			result = tree.concat(result);
+		}
+	}
+
+	return result;
+}
+
+export function _from_iterable(M, iterable) {
+	// Return new Empty(M).append(iterable);
+	const it = iterable[Symbol.iterator]();
+	const trees = [];
+	for (;;) {
+		const list = [];
+		// eslint-disable-next-line no-bitwise,unicorn/prefer-math-trunc
+		for (let i = MEDIUM_THRESHOLD; i !== 0; i = (i - 1) | 0) {
+			const event = it.next();
+			if (event.done) {
+				increment(trees, _from_medium_list(M, list));
+				return sum(M, trees);
+			}
+
+			list.push(event.value);
+		}
+
+		increment(trees, _from_largest_medium_list(M, list));
+	}
+}

src/0-core/concatenate/from.js

@@ -1,5 +1,5 @@
-import {Empty} from '../../3-tree/index.js';
+import {_from_iterable} from '../_fast/_from_iterable.js';
 
 export function from(M, iterable) {
-	return new Empty(M).append(iterable);
+	return _from_iterable(M, iterable);
 }