Add LineSplitter

.eslintrc.js

@@ -16,6 +16,7 @@ module.exports = {
   rules: {
     "no-console": process.env.NODE_ENV === "production" ? "warn" : "off",
     "no-debugger": process.env.NODE_ENV === "production" ? "warn" : "off",
+    "@typescript-eslint/no-non-null-assertion": 0,
   },
   overrides: [
     {

src/domain/models/Line/LineSplitter.ts

@@ -0,0 +1,27 @@
+import { Line } from "./Line";
+
+export class LineSplitter {
+  constructor(private vocab: Map<string, number>, private maxWidth: number) {}
+
+  split(text: string): Line[] {
+    let accumulatedWidth = 0;
+    let startIndex = 0;
+    const lines = [] as Line[];
+
+    for (const [i, ch] of Array.from(text).entries()) {
+      const charWidth = this.vocab.get(ch)!;
+      accumulatedWidth += charWidth;
+      if (accumulatedWidth > this.maxWidth) {
+        const line = new Line(text.substring(startIndex, i));
+        lines.push(line);
+        startIndex = i;
+        accumulatedWidth = charWidth;
+      }
+    }
+    if (accumulatedWidth > 0) {
+      const line = new Line(text.substring(startIndex));
+      lines.push(line);
+    }
+    return lines;
+  }
+}

tests/unit/domain/models/Line/lineSplitter.spec.ts

@@ -0,0 +1,26 @@
+import { Line } from "@/domain/models/Line/Line";
+import { LineSplitter } from "@/domain/models/Line/LineSplitter";
+
+describe("LineSplitter component", () => {
+  it("can split text", () => {
+    const content = "example text";
+    const vocab = new Map();
+    const maxWidth = 3;
+
+    const characterSet = new Set(content);
+    const characterArray = Array.from(characterSet);
+    characterArray.forEach((ch: string) => {
+      vocab.set(ch, 1);
+    });
+
+    const lineSplitter = new LineSplitter(vocab, maxWidth);
+    const lines = lineSplitter.split(content);
+    const expected = [
+      new Line("exa"),
+      new Line("mpl"),
+      new Line("e t"),
+      new Line("ext"),
+    ];
+    expect(lines).toEqual(expected);
+  });
+});