Refactor trimming utility

src/components/Code.astro

@@ -0,0 +1,7 @@
+---
+import { leftTrimDedent } from "./utils";
+
+const { thpcode } = Astro.props;
+---
+
+<pre class="language-thp" data-language="thp"><code class="language-thp">{leftTrimDedent(thpcode).join("\n")}</code></pre>

src/components/utils.test.ts

@@ -0,0 +1,133 @@
+import { expect, test } from 'vitest'
+import { leftTrimDedent } from "./utils"
+
+test("should trim empty string", () => {
+    const input = ``;
+
+    expect(leftTrimDedent(input)).toEqual([""]);
+})
+
+test("should work on a single line", () => {
+    const input = `hello`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello"
+    ]);
+})
+
+test("should trim a single line", () => {
+    const input = `  hello`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello"
+    ]);
+})
+
+test("should trim multiple lines", () => {
+    const input = `  hello\n  world`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "world"
+    ]);
+})
+
+test("should trim multiple lines without indentation", () => {
+    const input = `hello\nworld`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "world"
+    ]);
+})
+
+test("should consume only whitespace", () => {
+    const input = `  hello\nworld`;
+
+    try {
+        const res = leftTrimDedent(input);
+        expect(res).not.toEqual([
+            "hello",
+            "rld",
+        ]);
+    } catch (e) {
+        expect(e).toBeInstanceOf(Error);
+        expect(e).toHaveProperty("message", "Invalid indentation while trimming: Expected 2 spaces, got 0");
+    }
+})
+
+test("should preserve deeper indentation", () => {
+    const input = `  hello\n    world`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "  world",
+    ]);
+})
+
+test("should ignore empty lines", () => {
+    const input = `  hello\n\n  world`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "",
+        "world",
+    ]);
+})
+
+test("should ignore lines with only whitespace", () => {
+    const input = `  hello\n \n      \n  world`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "",
+        "    ",
+        "world",
+    ]);
+})
+
+test("should trim multiple without indentation", () => {
+    const input = `hello\nworld\n!`
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "world",
+        "!",
+    ]);
+})
+
+test("should ignore empty first line", () => {
+    const input = `
+hello
+world`;
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "world",
+    ]);
+})
+
+test("should ignore empty first line 2", () => {
+    const input = `
+    hello
+
+    world`;
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "",
+        "world",
+    ]);
+})
+
+test("should ignore empty last line", () => {
+    const input = `
+    hello
+    world
+`;
+
+    expect(leftTrimDedent(input)).toEqual([
+        "hello",
+        "world",
+    ]);
+});

src/components/utils.ts

@@ -45,7 +45,7 @@ export function trimAndDedent(input: string): Array<string> {
         let currentIndentation = 0;
         for (const c of characters) {
             if (c === " ") { currentIndentation += 1 }
-            else {break;}
+            else { break; }
         }
         if (currentIndentation < indentationLevel) {
             throw new Error("Invalid indentation while parsing THP code: " + lines[i]);
@@ -67,4 +67,58 @@ export function trimAndDedent(input: string): Array<string> {
     }
 
     return lines;
-}
+}
+
+export function leftTrimDedent(input: string): Array<string> {
+    let lines = input.split("\n");
+    let output: Array<string> = [];
+
+    // Ignore first line
+    if (lines[0] === "" && lines.length > 1) {
+        lines = lines.slice(1);
+    }
+
+    // Get indentation level of the first line
+    let indentationLevel = 0;
+    for (const char of lines[0]!) {
+        if (char === " ") {
+            indentationLevel += 1;
+        } else {
+            break;
+        }
+    }
+
+    for (const line of lines) {
+        // Ignore empty lines
+        if (line === "") {
+            output.push("");
+            continue;
+        }
+        output.push(trimWhitespace(line, indentationLevel));
+    }
+
+    if (output.length > 1 &&  output[output.length - 1] === "") {
+        output = output.slice(0, -1);
+    }
+
+    return output;
+}
+
+function trimWhitespace(input: string, count: number): string {
+    let indentCount = 0;
+
+    for (const char of input) {
+        if (char === " ") {
+            indentCount += 1;
+        } else {
+            break;
+        }
+    }
+
+    if (indentCount >= count || indentCount == input.length) {
+        return input.slice(count);
+    } else {
+        throw new Error(`Invalid indentation while trimming: Expected ${count} spaces, got ${indentCount}`);
+    }
+}
+

src/pages/learn/templating/intro.mdx

@@ -2,6 +2,7 @@
 layout: ../../../layouts/DocsLayout.astro
 title: Introduction
 ---
+import Code from "../../../components/Code.astro"
 
 # THP templating
 
@@ -71,7 +72,8 @@ fun Button(String name) -> Html {
 It is very similar to React. The HTML is inside the THP code, not the other
 way around, so you can have arbitrary logic in the component.
 
-```thp
+
+<Code thpcode={`
 fun User(String name) {
     // Get info from the database
     val user = try Model::get_user(name)
@@ -96,7 +98,7 @@ fun TransactionItem(Transaction t) {
         {t.date} - {t.name} ({t.price})
     </li>
 }
-```
+`} />