feat: 🎸 add print utils

Author: streamich

src/print/__tests__/printBinary.spec.ts

@@ -0,0 +1,44 @@
+import {printBinary} from '../printBinary';
+
+test('renders a single left child', () => {
+  const str = 'Node' + printBinary('', [() => `foo`]);
+  expect(str).toBe(
+    `Node
+← foo`,
+  );
+});
+
+test('renders a single right child', () => {
+  const str = 'Node' + printBinary('', [null, () => `foo`]);
+  expect(str).toBe(
+    `Node
+→ foo`,
+  );
+});
+
+test('renders one level of left and right children', () => {
+  const str = 'Node' + printBinary('', [() => 'left', () => 'right']);
+  expect(str).toBe(
+    `Node
+← left
+→ right`,
+  );
+});
+
+test('renders two levels of left and right children', () => {
+  const str =
+    'Node' +
+    printBinary('', [
+      (tab) => 'left' + printBinary(tab, [() => 'left', () => 'right']),
+      (tab) => 'right' + printBinary(tab, [() => 'left', () => 'right']),
+    ]);
+  expect(str).toBe(
+    `Node
+← left
+  ← left
+  → right
+→ right
+  ← left
+  → right`,
+  );
+});

src/print/__tests__/printTree.spec.ts

@@ -0,0 +1,45 @@
+import {printTree} from '../printTree';
+
+test('renders a single child node', () => {
+  const str = 'Node' + printTree('', [() => `foo`]);
+
+  expect(str).toBe(
+    `Node
+└─ foo`,
+  );
+});
+
+test('renders two children node', () => {
+  const str = 'Node' + printTree('', [() => `foo`, () => `bar`]);
+
+  expect(str).toBe(
+    `Node
+├─ foo
+└─ bar`,
+  );
+});
+
+test('renders two levels of nodes', () => {
+  const str = 'Node' + printTree('', [() => `foo`, (tab) => `bar` + printTree(tab, [() => `baz`])]);
+
+  expect(str).toBe(
+    `Node
+├─ foo
+└─ bar
+   └─ baz`,
+  );
+});
+
+test('renders two levels of nodes, with double tree line', () => {
+  const str =
+    'Node' +
+    printTree('', [(tab) => `foo` + printTree(tab, [() => `baz`]), (tab) => `bar` + printTree(tab, [() => `baz`])]);
+
+  expect(str).toBe(
+    `Node
+├─ foo
+│  └─ baz
+└─ bar
+   └─ baz`,
+  );
+});

src/print/printBinary.ts

@@ -0,0 +1,9 @@
+type Child = (tab: string) => string;
+
+export const printBinary = (tab = '', children: [left?: null | Child, right?: null | Child]): string => {
+  const [left, right] = children;
+  let str = '';
+  if (left) str += `\n${tab}← ${left(tab + '  ')}`;
+  if (right) str += `\n${tab}→ ${right(tab + '  ')}`;
+  return str;
+};

src/print/printTree.ts

@@ -0,0 +1,15 @@
+type Child = (tab: string) => string;
+
+export const printTree = (tab = '', children: (Child | null)[]): string => {
+  children = children.filter(Boolean);
+  let str = '';
+  for (let i = 0; i < children.length; i++) {
+    const isLast = i >= children.length - 1;
+    const fn = children[i];
+    if (!fn) continue;
+    const child = fn(tab + `${isLast ? ' ' : '│'}  `);
+    const branch = child ? (isLast ? '└─' : '├─') : '│ ';
+    str += `\n${tab}${branch} ${child}`;
+  }
+  return str;
+};

src/print/types.ts

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+export interface Printable {
+  /**
+   * Returns a human-readable tabbed string representation of the object as a tree.
+   *
+   * @param tab String to use for indentation.
+   */
+  toString(tab?: string): string;
+}