rspade_system/node_modules/@jqhtml/parser

JQHTML Parser

The JQHTML parser converts template files into JavaScript functions that use the component system.

Quick Start - Common Patterns

Basic Component with innerHTML (Most Common)

<!-- Define a component with default attributes -->
<Define:Card tag="article" class="card" style="padding: 10px">
  <div class="card-body">
    <%= content() %>  <!-- Outputs whatever innerHTML was passed -->
  </div>
</Define:Card>

<!-- Usage - just pass innerHTML like regular HTML -->
<Card class="featured">
  <h3>Card Title</h3>
  <p>This is the card content.</p>
  <button>Click me</button>
</Card>

<!-- Result: <article class="card featured Card Jqhtml_Component" style="padding: 10px"> -->

This content() pattern is the primary way to compose components in JQHTML. It works like regular HTML - the innerHTML you pass gets rendered where content() is called.

Container Component Example

<!-- A container with default size that can be overridden -->
<Define:Container $size="medium" class="container">
  <div class="container-inner <%= this.args.size %>">
    <%= content() %>  <!-- Simple innerHTML output -->
  </div>
</Define:Container>

<!-- Usage - override the default size -->
<Container $size="large">
  <p>Any content here</p>
  <UserList />
  <Footer />
</Container>

Note: Slots (<#slotname>) are an advanced feature only needed when you have multiple distinct content areas. For 95% of use cases, the simple content() pattern shown above is recommended.

Define Tag Attributes (Component Configuration)

Define tags support three types of attributes for configuring components:

<Define:Contacts_DataGrid
    extends="DataGrid_Abstract"
    $ajax_endpoint=Frontend_Contacts_Controller.datagrid_fetch
    $per_page=25
    class="card DataGrid">
  <div>Content here</div>
</Define:Contacts_DataGrid>

1. extends="" - Template Inheritance Explicitly declare parent template for inheritance (without requiring a JavaScript class).

2. $property=value - Default Args Set default values for this.args that component invocations can override:

• Quoted: $user_id="123" → String literal "123"
• Unquoted: $handler=MyController.fetch → Raw JavaScript expression
• These become defaults; invocations can override them

3. Regular Attributes Standard HTML attributes like class="", tag="" applied to root element.

Generated Output:

{
  name: 'Contacts_DataGrid',
  tag: 'div',
  defaultAttributes: {"class": "card DataGrid"},
  defineArgs: {"ajax_endpoint": Frontend_Contacts_Controller.datagrid_fetch, "per_page": "25"},
  extends: 'DataGrid_Abstract',
  render: function() { ... }
}

Slot-Based Template Inheritance

When a template contains ONLY slots (no HTML), it automatically inherits the parent class template:

<!-- Parent: DataGrid_Abstract.jqhtml -->
<Define:DataGrid_Abstract>
  <table>
    <thead><tr><%= content('header') %></tr></thead>
    <tbody>
      <% for (let record of this.data.records) { %>
        <tr><%= content('row', record) %></tr>
      <% } %>
    </tbody>
  </table>
</Define:DataGrid_Abstract>

<!-- Child: Users_DataGrid.jqhtml (slot-only) -->
<Define:Users_DataGrid>
  <#header>
    <th>ID</th><th>Name</th><th>Email</th>
  </#header>
  <#row>
    <td><%= row.id %></td>
    <td><%= row.name %></td>
    <td><%= row.email %></td>
  </#row>
</Define:Users_DataGrid>

The parser detects slot-only templates and generates {_slots: {...}} format. Runtime walks prototype chain to find parent templates. Data passing: content('row', record) passes data to slot parameter function(row) { ... }. Reserved words: Slot names cannot be JavaScript keywords (function, if, etc.) - parser rejects with fatal error.

Lexer (Task 1 - COMPLETE)

The lexer is the first stage of the parser. It converts raw JQHTML template text into a stream of tokens.

Features

• No regex - Uses simple character scanning for maintainability
• Position tracking - Every token includes line, column, and absolute positions for source maps
• Simple token types - Clear, unambiguous token categories
• Efficient scanning - Single pass through the input

Token Types

• TEXT - Plain HTML/text content
• EXPRESSION_START - <%= opening tag
• CODE_START - <% opening tag
• TAG_END - %> closing tag
• IF, ELSE, ELSEIF, ENDIF - Conditional keywords
• FOR, ENDFOR - Loop keywords
• DEFINE_START, DEFINE_END - Component definition tags
• COMPONENT_NAME - Component identifier
• JAVASCRIPT - JavaScript code within tags

Usage

import { Lexer } from '@jqhtml/parser';

const template = `
<Define:MyComponent>
  <h1><%= this.data.title %></h1>
  <% if (this.data.show): %>
    <p>Content here</p>
  <% endif; %>
</Define:MyComponent>
`;

const lexer = new Lexer(template);
const tokens = lexer.tokenize();

// tokens is an array of Token objects with:
// - type: TokenType
// - value: string
// - line: number
// - column: number  
// - start: number (absolute position)
// - end: number

Testing

# Build the parser
npm run build

# Run the test suite
node test-lexer.js

# Run the demo
node demo-lexer.js

Implementation Notes

The lexer uses a simple state machine approach:

1. Text scanning - Default mode, captures plain text
2. Tag detection - Looks for <%, <%=, %> sequences
3. Keyword matching - After <%, checks for control flow keywords
4. JavaScript capture - Captures code between tags
5. Position tracking - Updates line/column for every character

No regex patterns are used. All scanning is done with:

• match_sequence() - Check for exact string match
• match_keyword() - Check for keyword with word boundary
• Character-by-character advancement

Parser/AST Builder (Task 2 - COMPLETE)

The parser takes the token stream from the lexer and builds an Abstract Syntax Tree (AST) representing the template structure.

Features

• Recursive descent parsing - Simple, predictable parsing algorithm
• Clear node types - Each AST node represents a specific construct
• Position preservation - All nodes include source positions
• Error reporting - Clear messages with line/column information

AST Node Types

• Program - Root node containing all top-level definitions
• ComponentDefinition - Component template definition
• Text - Plain text/HTML content
• Expression - JavaScript expressions (<%= ... %>)
• IfStatement - Conditional rendering with optional else
• ForStatement - Loop constructs
• CodeBlock - Generic JavaScript code blocks

Usage

import { Lexer, Parser } from '@jqhtml/parser';

const template = `
<Define:Card>
  <div class="card">
    <h3><%= title %></h3>
    <% if (showContent): %>
      <p><%= content %></p>
    <% endif; %>
  </div>
</Define:Card>
`;

// Tokenize
const lexer = new Lexer(template);
const tokens = lexer.tokenize();

// Parse to AST
const parser = new Parser(tokens);
const ast = parser.parse();

// AST structure:
// {
//   type: 'Program',
//   body: [{
//     type: 'ComponentDefinition',
//     name: 'Card',
//     body: [...]
//   }]
// }

Testing

# Run the parser test suite
node test-parser.js

# Run the interactive demo
node demo-parser.js

Implementation Notes

The parser uses straightforward techniques:

1. Token consumption - Advances through tokens one at a time
2. Lookahead - Peeks at upcoming tokens to decide parsing path
3. Context tracking - Knows when inside components, loops, etc.
4. Error recovery - Provides helpful error messages

No parser generators or complex algorithms - just simple recursive functions that build nodes.

Code Generator (Task 3 - COMPLETE)

The code generator takes the AST and produces executable JavaScript functions that work with the JQHTML component system.

Features

• jQuery-based DOM manipulation - Generates efficient jQuery code
• Component render functions - Each template becomes a render function
• Control flow handling - Properly handles if/else and for loops
• Expression evaluation - Safely evaluates and renders expressions
• Colon syntax support - Strips trailing colons from control statements

Generated Code Structure

// Each component gets a render function
jqhtml_components.set('ComponentName', {
  name: 'ComponentName',
  render: function render() {
    const $root = $('<div></div>');
    const $current = $root;
    
    // Generated DOM manipulation code here
    
    return $root.children();
  },
  dependencies: []
});

Usage

import { Lexer, Parser, CodeGenerator } from '@jqhtml/parser';

const template = `
<Define:MyComponent>
  <h1><%= this.data.title %></h1>
  <% if (this.data.items): %>
    <ul>
      <% for (const item of this.data.items): %>
        <li><%= item %></li>
      <% endfor; %>
    </ul>
  <% endif; %>
</Define:MyComponent>
`;

// Generate the code
const lexer = new Lexer(template);
const tokens = lexer.tokenize();
const parser = new Parser(tokens);
const ast = parser.parse();
const generator = new CodeGenerator();
const result = generator.generate(ast);

// Use in a component
class MyComponent extends Component {
  async on_render() {
    const template = result.components.get('MyComponent');
    const elements = template.render.call(this);
    this.$.append(elements);
  }
}

Testing

# Run the code generator test suite
node test-codegen.js

# Run the interactive demo
node demo-codegen.js

# View the integration example
# Open example-integration.html in a browser

Implementation Notes

The code generator:

1. Traverses the AST - Visits each node and generates appropriate code
2. Maintains context - Tracks current jQuery element for appending
3. Handles nesting - For loops create temporary containers
4. Strips syntax - Removes trailing colons from control flow
5. Escapes strings - Properly escapes text content for JavaScript

v1 JavaScript Compilation Analysis

A comprehensive analysis of how JQHTML v1 compiles templates to JavaScript has been documented in JQHTML_V1_JAVASCRIPT_COMPILATION_PATTERNS.md. This analysis reveals:

• Instruction-based output: Templates compile to arrays of rendering instructions
• Three instruction types: {tag:...}, {comp:...}, {block:...}
• Context preservation: The _that = this pattern for nested functions
• Single-pass DOM construction: Efficient rendering with one $.html() call
• Deferred component initialization: Two-phase process for component creation

These patterns inform v2 implementation decisions, particularly around maintaining the efficient instruction-based architecture while modernizing the JavaScript output.

Implementation Status (December 2024)

✅ Completed Tasks

1. Lexer - Full tokenization with position tracking
2. Parser - AST generation with all v2 syntax
3. Code Generator - Instruction array generation
4. Component Integration - Runtime integration complete
5. Slot System - <#name> syntax fully implemented
6. Nested Components - <ComponentName> recognition
7. Binding Syntax - :prop and @event support

Current Features

• Template Syntax: HTML with embedded JavaScript
• Control Flow: if/else/elseif and for loops (both colon and brace styles)
• Components: <Define:Name> definitions and <ComponentName> invocations
• Slots: <#name>content</#name> and <#name /> syntax
• Expressions: <%= expression %> for output
• Bindings: :text, :value, :class, :style for data binding
• Events: @click, @change, etc. for event handlers
• Scoped IDs: $id attribute for component-scoped IDs

Instruction Format

The parser generates v1-compatible instruction arrays:

// HTML tags
{tag: ["div", {"class": "card"}, false]}  // open tag
{tag: ["div", {}, true]}                   // close tag

// Components
{comp: ["UserCard", {name: "John"}]}

// Slots
{slot: ["header", {}, (props) => {
  const _output = [];
  _output.push("Header content");
  return [_output, this];
}]}

// Text content
"Plain text"

// Expressions
{expr: () => this.data.title}

Integration with Core

Templates compile to functions that return [instructions, context]:

function render() {
  const _output = [];
  
  // Generate instructions...
  _output.push({tag: ["h1", {}, false]});
  _output.push("Hello World");
  _output.push({tag: ["h1", {}, true]});
  
  return [_output, this];
}

The core runtime's instruction processor handles these arrays to create DOM.

Next Steps

1. Build Tools - Webpack loader for .jqhtml imports
2. Source Maps - Full debugging support
3. VS Code Extension - Syntax highlighting
4. Autoformatter - Code formatting for .jqhtml files