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WHATWG HTML5 spec-compliant parser for MoonBit

html
html5
parser
whatwg
moon add moonbit-community/html@0.1.2
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Version
0.1.2
License
Apache-2.0
Repository
Last updated
2 months ago
Downloads
340

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README

#MoonBit HTML Parser

A fully WHATWG-compliant HTML5 parser implemented in MoonBit.

#Features

  • Full WHATWG HTML5 specification compliance
  • 80 tokenizer states
  • 25 tree construction insertion modes
  • 49 parse error types with graceful recovery
  • 2,231 named character references
  • 100% conformance with html5lib tree construction tests (8251/8251 tests passing)

#Basic Usage

Parse an HTML string and inspect the document tree:

///|
test "basic parsing" {
  let doc = @html5.parse(
    "<html><head><title>Hello</title></head><body><p>World</p></body></html>",
  )
  @debug.assert_eq(
    doc.dump(),
    (
      #|<html>
      #|  <head>
      #|    <title>
      #|      "Hello"
      #|  <body>
      #|    <p>
      #|      "World"
    ),
  )
}

#Error Recovery

The parser handles malformed HTML gracefully, just like browsers:

///|
test "error recovery - unclosed tags" {
  let doc = @html5.parse("<p>First<p>Second<p>Third")
  @debug.assert_eq(
    doc.dump(),
    (
      #|<html>
      #|  <head>
      #|  <body>
      #|    <p>
      #|      "First"
      #|    <p>
      #|      "Second"
      #|    <p>
      #|      "Third"
    ),
  )
}

///|
test "error recovery - misnested tags" {
  let doc = @html5.parse("<b><i>Bold and Italic</b> Just Italic</i>")
  @debug.assert_eq(
    doc.dump(),
    (
      #|<html>
      #|  <head>
      #|  <body>
      #|    <b>
      #|      <i>
      #|        "Bold and Italic"
      #|    <i>
      #|      " Just Italic"
    ),
  )
}

#HTML Serialization

Convert the document back to HTML:

///|
test "serialize to html" {
  let doc = @html5.parse("<div class=\"container\"><span>Hello</span></div>")
  assert_true(
    doc.to_html()
    is "<html><head></head><body><div class=\"container\"><span>Hello</span></div></body></html>",
  )
}

#Parse with Error Collection

Collect parse errors for diagnostics:

///|
test "parse with errors" {
  let (doc, errors) = @html5.parse_with_errors("<p>Test</p attr>")
  assert_true((errors.length() > 0) is true)
  @debug.assert_eq(
    doc.dump(),
    (
      #|<html>
      #|  <head>
      #|  <body>
      #|    <p>
      #|      "Test"
    ),
  )
}

#Tokenization

Tokenize HTML without building a tree:

///|
test "tokenization" {
  let (tokens, _errors) = @html5.tokenize("<div>Hello</div>")
  assert_true(
    tokens[0] is @html5.StartTag(name="div", attrs=[], self_closing=false),
  )
  assert_true(tokens[1] is @html5.Character('H'))
  assert_true(tokens[2] is @html5.Character('e'))
}

#DOM Navigation

Access elements and attributes:

///|
test "dom access" {
  let doc = @html5.parse("<div id=\"main\"><p class=\"text\">Content</p></div>")

  // Get body element
  let body_id = doc.body_element
  let children = doc.get_children(body_id)

  // Get the div
  let div_id = children[0]
  assert_true(doc.get_tag_name(div_id) is Some("div"))
  assert_true(doc.get_attribute(div_id, "id") is Some("main"))

  // Get the p element
  let p_id = doc.get_children(div_id)[0]
  assert_true(doc.get_attribute(p_id, "class") is Some("text"))
  assert_true(doc.get_text_content(p_id) is "Content")
}

#Character References

The parser correctly handles named and numeric character references:

///|
test "character references" {
  let doc = @html5.parse("<p>&amp; &lt; &gt; &copy; &#169; &#x00A9;</p>")
  let p_id = doc.get_children(doc.body_element)[0]
  assert_true(doc.get_text_content(p_id) is "& < > \u{00A9} \u{00A9} \u{00A9}")
}

#Foreign Content (SVG/MathML)

The parser correctly handles SVG and MathML embedded in HTML:

///|
test "svg support" {
  let doc = @html5.parse(
    "<div><svg><circle cx=\"50\" cy=\"50\" r=\"40\"/></svg></div>",
  )
  @debug.assert_eq(
    doc.dump(),
    (
      #|<html>
      #|  <head>
      #|  <body>
      #|    <div>
      #|      <svg svg>
      #|        <svg circle>
      #|          cx="50"
      #|          cy="50"
      #|          r="40"
    ),
  )
}

#API Reference

#Main Functions

  • parse(String) -> Document - Parse HTML and return a Document
  • parse_with_errors(String) -> (Document, Array[ParseError]) - Parse with error collection
  • parse_with_scripting(String) -> Document - Parse with scripting enabled (affects <noscript>)
  • tokenize(String) -> (Array[Token], Array[ParseError]) - Tokenize without tree construction

#Document Methods

  • dump() -> String - Pretty-print the document tree
  • to_html() -> String - Serialize to HTML string
  • get_children(Int) -> Array[Int] - Get child node IDs
  • get_parent(Int) -> Int - Get parent node ID
  • get_tag_name(Int) -> String? - Get element tag name
  • get_attribute(Int, String) -> String? - Get attribute value
  • get_text_content(Int) -> String - Get text content of a node

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