@shubham-patil/pcbuild

v1.0.0

Published

2 months ago

Custom HTML bundler/compiler from scratch

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shubham-patil

pcbuild — HTML Bundler / Compiler

A custom HTML bundler built from scratch in TypeScript. No Webpack, Rollup, Vite, Parcel, esbuild, or template engines. Designed as a compiler with multiple distinct phases operating on an HTML AST.

Pipeline

Input HTML
    ↓
HTML Parser (tokenizer + recursive descent → AST)
    ↓
Directive Resolver (validates all @directives)
    ↓
IncludePass  — recursively resolves @include, detects circular includes
    ↓
CSSPass      — collects @css files, inlines into a single <style> tag
    ↓
JSPass       — collects @js entry points, triggers JS bundler
    ↓
AssetPass    — copies @asset files to dist, rewrites paths
    ↓
InlinePass   — inlines @inline text files as text nodes
    ↓
OptimizationPass — removes empty text nodes, merges adjacent text, strips comments
    ↓
MinifyPass   — collapses whitespace (when --minify is set)
    ↓
Emitter      — generates index.html from the final AST
    ↓
dist/index.html

Every transformation modifies the AST. No string-based replacements.

Directives

Place these in your HTML:

@include("./components/header.html")

Recursively loads and inlines the file. Nested includes work. Circular includes throw an error with a readable stack trace.

@css("./styles/main.css")

Reads the CSS file and inlines it inside a single <style> tag in <head>.

@js("./scripts/main.js")

Parses the entry module with acorn, builds a dependency graph, detects circular imports, and bundles every imported module into a single <script> tag wrapped in a runtime module loader.

@asset("./images/logo.png")

Copies the file into dist preserving the relative path.

@inline("./shaders/basic.glsl")

Reads the file and inlines its contents as a text node in the HTML.

JavaScript Bundler

The JS bundler (no eval):

Parses every module with acorn
Resolves relative imports (with extension resolution)
Builds a directed dependency graph
Detects circular imports
Generates a single script with a runtime module loader

The runtime uses a module registry and cache:

(function() {
  var __def = {}, __cache = {};
  function __r(id) { /* require implementation */ }
  __def["scripts/utils.js"] = function(module, exports, require) { /* ... */ };
  __def["scripts/main.js"] = function(module, exports, require) { /* ... */ };
  __r("scripts/main.js");
})();

Supports:

import default from './module'
import { named } from './module'
import * as namespace from './module'
export default
export const / function / class
export { named }
export * from and export { } from (re-exports)
Circular module references (pre-cached exports)

CLI

# Build once
pcbuild build --entry src/index.html --output dist

# Watch mode (incremental rebuilds)
pcbuild watch --entry src/index.html --output dist

# Dev server (watch + HTTP server)
pcbuild dev --entry src/index.html --output dist --port 3000

# Options
--entry, -e <path>    Entry HTML file (default: ./src/index.html)
--output, -o <path>   Output directory     (default: ./dist)
--minify, -m          Enable minification
--port, -p <number>   Dev server port      (default: 3000)
--root, -r <path>     Root directory       (default: cwd)

Programmatic API

import { compile, watch, dev } from 'pcbuild';

// Single build
await compile({
  entry: './src/index.html',
  output: './dist',
  minify: true,
});

// Watch mode
await watch({ entry: './src/index.html', output: './dist' });

// Dev server
await dev({ entry: './src/index.html', output: './dist' }, 3000);

Architecture

src/
├── index.ts                  # Public API
├── cli.ts                    # CLI entry point
├── compiler.ts               # Compiler orchestrator, plugin hooks
├── project.ts                # Project management, file cache
├── types.ts                  # All interfaces, AST enums, context types
├── ast/
│   └── traverser.ts          # Visitor-pattern AST traversal
├── parser/
│   ├── html-parser.ts        # HTML lexer + recursive descent parser → AST
│   └── js-parser.ts          # Acorn-based JS module analysis
├── graph/
│   └── dependency-graph.ts   # Directed graph with cycle detection
├── resolver/
│   ├── directive-resolver.ts # Directive validation
│   └── asset-resolver.ts     # Asset path resolution
├── passes/
│   ├── include-pass.ts       # @include resolution
│   ├── css-pass.ts           # @css → <style>
│   ├── js-pass.ts            # @js → JS bundler trigger
│   ├── asset-pass.ts         # @asset copy + path rewrite
│   ├── inline-pass.ts        # @inline text inlining
│   ├── optimization-pass.ts  # Empty text removal, comment stripping
│   └── minify-pass.ts        # Whitespace collapse
├── bundler/
│   └── js-bundler.ts         # ES module bundler + runtime generator
├── emitter.ts                # AST → HTML string output
├── watcher.ts                # File watching (fs.watch recursive)
├── diagnostics.ts            # Error types, circular error classes
├── reporter.ts               # Colored terminal output
└── fs.ts                     # File system abstraction

Design principles

Modular: every subsystem is an independent class
AST-first: all transforms operate on the AST, never on strings
Visitor-based: traversal uses a visitor pattern for extensibility
Dependency injection: FileSystem, Project, and context are injected
Plugin system: hooks at 6 lifecycle points (beforeParse → afterEmit)

Plugin API

class MyPlugin {
  name = 'my-plugin';

  beforeParse(context: CompilerContext) {}
  afterParse(context: CompilerContext) {}
  beforeTransform(context: CompilerContext) {}
  afterTransform(context: CompilerContext) {}
  beforeEmit(context: CompilerContext) {}
  afterEmit(context: CompilerContext) {}
}

import { Compiler } from 'pcbuild';

const compiler = new Compiler({ entry: 'src/index.html', output: 'dist' });
compiler.addPlugin(new MyPlugin());
await compiler.compile();

Example

<!-- src/index.html -->
<!DOCTYPE html>
<html>
<head>
  @css("./styles/main.css")
</head>
<body>
  @include("./components/header.html")
  <main>
    <h1>Welcome</h1>
    <img src="@asset("./images/logo.png")" alt="Logo">
  </main>
  @include("./components/footer.html")
  @js("./scripts/main.js")
  @inline("./shaders/basic.glsl")
</body>
</html>

Running pcbuild build produces a single dist/index.html with:

Inlined HTML partials
Inlined CSS
Bundled JavaScript (dependency graph resolved, one <script>)
Copied assets with rewritten paths
Inlined GLSL shader
Minified output (when --minify is set)

Diagnostics

Errors include source file, line, and column:

error: /project/src/index.html:5:3 - File not found: /project/src/components/missing.html
error: /project/src/index.html:8:1 - Unknown directive: @unknown
error: Circular include detected:
  -> components/a.html
    -> components/b.html
      -> components/a.html
error: Circular JS import detected:
  -> src/main.js
    -> src/a.js
      -> src/main.js

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