refactor: the Output class

Author: aradzie

packages/keybr-code/lib/output.test.ts

@@ -0,0 +1,87 @@
+import test from "ava";
+import { Output } from "./output.ts";
+
+test("append", (t) => {
+  const output = new Output(100);
+  t.is(String(output), "");
+
+  output.append("1");
+  t.is(String(output), "1");
+
+  output.separate(",");
+  t.is(String(output), "1");
+
+  output.append("2");
+  t.is(String(output), "1,2");
+
+  output.append("3");
+  t.is(String(output), "1,23");
+
+  output.separate("");
+  output.append("4");
+  t.is(String(output), "1,234");
+
+  output.separate(";");
+  output.append("");
+  t.is(String(output), "1,234");
+
+  output.append("5");
+  t.is(String(output), "1,234;5");
+});
+
+test("limits", (t) => {
+  const output = new Output(3);
+  t.is(output.length, 0);
+  t.is(output.remaining, 3);
+  t.is(String(output), "");
+
+  output.append("1");
+  t.is(output.length, 1);
+  t.is(output.remaining, 2);
+  t.is(String(output), "1");
+
+  t.throws(
+    () => {
+      output.append("234");
+    },
+    { is: Output.Stop },
+  );
+  t.is(output.length, 1);
+  t.is(output.remaining, 2);
+  t.is(String(output), "1");
+
+  t.throws(
+    () => {
+      output.separate(",,,");
+    },
+    { is: Output.Stop },
+  );
+  t.is(output.length, 1);
+  t.is(output.remaining, 2);
+  t.is(String(output), "1");
+
+  output.separate(",");
+  t.is(output.length, 2);
+  t.is(output.remaining, 1);
+  t.is(String(output), "1");
+
+  t.throws(
+    () => {
+      output.append("23");
+    },
+    { is: Output.Stop },
+  );
+  t.is(output.length, 2);
+  t.is(output.remaining, 1);
+  t.is(String(output), "1");
+
+  output.append("2");
+  t.is(output.length, 3);
+  t.is(output.remaining, 0);
+  t.is(String(output), "1,2");
+
+  output.clear();
+  t.is(output.length, 0);
+  t.is(output.remaining, 3);
+  t.is(String(output), "");
+});

packages/keybr-code/lib/output.ts

@@ -4,6 +4,7 @@ export class Output {
   readonly #limit: number;
   readonly #data: string[] = [];
   #length: number = 0;
+  #separator: string = "";
   #text: string | null = null;
 
   constructor(limit: number = 1000) {
@@ -12,21 +13,38 @@ export class Output {
 
   /** Returns the number of characters accumulated in the output. */
   get length(): number {
-    return this.#length;
+    return this.#length + this.#separator.length;
   }
 
   /** Returns the number of remaining characters before the limit is reached. */
   get remaining(): number {
-    return this.#limit - this.#length;
+    return this.#limit - (this.#length + this.#separator.length);
+  }
+
+  /** Appends the given text, but only if followed by the `append(...)` method. */
+  separate(text: string): this {
+    const { length } = text;
+    if (length > 0) {
+      if (this.#length + length > this.#limit) {
+        throw Output.Stop;
+      }
+    }
+    this.#separator = text;
+    return this;
   }
 
   /** Appends the given text, or throws the stop error if the limit is reached. */
   append(text: string): this {
     const { length } = text;
     if (length > 0) {
-      if (this.#length + length > this.#limit) {
+      if (this.#length + this.#separator.length + length > this.#limit) {
         throw Output.Stop;
       }
+      if (this.#separator.length > 0) {
+        this.#data.push(this.#separator);
+        this.#length += this.#separator.length;
+        this.#separator = "";
+      }
       this.#data.push(text);
       this.#length += length;
       this.#text = null;
@@ -38,6 +56,7 @@ export class Output {
   clear(): this {
     this.#data.length = 0;
     this.#length = 0;
+    this.#separator = "";
     this.#text = null;
     return this;
   }

packages/keybr-code/lib/syntax.ts

@@ -76,7 +76,7 @@ export class Syntax implements EnumItem {
     while (true) {
       try {
         if (output.length > 0) {
-          output.append(" ");
+          output.separate(" ");
         }
         generate(this.rules, this.start, { output, rng });
       } catch (err) {