refactor: Content, Tree

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@eu-ge-ne/text-buf",
-  "version": "0.14.1",
+  "version": "0.14.2",
   "license": "MIT",
   "exports": "./src/mod.ts",
   "imports": {

src/content.ts

@@ -0,0 +1,89 @@
+import { Buffer } from "./buffer.ts";
+import { bubble, create as create_node, type Node, successor } from "./node.ts";
+
+export class Content {
+  readonly buffers: Buffer[] = [];
+
+  create(text: string): Node {
+    const buf = new Buffer(text);
+    const buf_index = this.buffers.push(buf) - 1;
+
+    return create_node(buf_index, 0, buf.len, 0, buf.eols_len);
+  }
+
+  split(x: Node, index: number, gap: number): Node {
+    const buf = this.buffers[x.buf]!;
+
+    const start = x.slice_start + index + gap;
+    const len = x.slice_len - index - gap;
+
+    this.#resize(x, index);
+    bubble(x);
+
+    const eols_start = buf.find_eol_index(start, x.eols_start + x.eols_len);
+    const eols_end = buf.find_eol_index(start + len, eols_start);
+    const eols_len = eols_end - eols_start;
+
+    return create_node(x.buf, start, len, eols_start, eols_len);
+  }
+
+  *read(x: Node, offset: number, n: number): Generator<string> {
+    while (!x.nil && (n > 0)) {
+      const count = Math.min(x.slice_len - offset, n);
+
+      yield this.buffers[x.buf]!.text.slice(
+        x.slice_start + offset,
+        x.slice_start + offset + count,
+      );
+
+      x = successor(x);
+      offset = 0;
+      n -= count;
+    }
+  }
+
+  growable(x: Node): boolean {
+    const buf = this.buffers[x.buf]!;
+
+    return (buf.len < 100) && (x.slice_start + x.slice_len === buf.len);
+  }
+
+  grow(x: Node, text: string): void {
+    this.buffers[x.buf]!.append(text);
+
+    this.#resize(x, x.slice_len + text.length);
+  }
+
+  trim_start(x: Node, n: number): void {
+    const buf = this.buffers[x.buf]!;
+
+    x.slice_start += n;
+    x.slice_len -= n;
+
+    x.eols_start = buf.find_eol_index(x.slice_start, x.eols_start);
+
+    const eols_end = buf.find_eol_index(
+      x.slice_start + x.slice_len,
+      x.eols_start,
+    );
+
+    x.eols_len = eols_end - x.eols_start;
+  }
+
+  trim_end(x: Node, n: number): void {
+    this.#resize(x, x.slice_len - n);
+  }
+
+  #resize(x: Node, len: number): void {
+    const buf = this.buffers[x.buf]!;
+
+    x.slice_len = len;
+
+    const eols_end = buf.find_eol_index(
+      x.slice_start + x.slice_len,
+      x.eols_start,
+    );
+
+    x.eols_len = eols_end - x.eols_start;
+  }
+}

src/node.ts

@@ -27,7 +27,7 @@ export interface Node {
   eols_len: number;
 }
 
-export function create_node(
+export function create(
   buf: number,
   slice_start: number,
   slice_len: number,
@@ -50,6 +50,27 @@ export function create_node(
   };
 }
 
+export function find(
+  x: Node,
+  index: number,
+): { node: Node; offset: number } | undefined {
+  while (!x.nil) {
+    if (index < x.left.total_len) {
+      x = x.left;
+      continue;
+    }
+
+    index -= x.left.total_len;
+
+    if (index < x.slice_len) {
+      return { node: x, offset: index };
+    }
+
+    index -= x.slice_len;
+    x = x.right;
+  }
+}
+
 export function bubble(x: Node): void {
   while (!x.nil) {
     x.total_len = x.left.total_len + x.slice_len + x.right.total_len;