Node Types and Structure

GraphNode Enumeration

IWE defines 9 distinct node types, each optimized for specific markdown elements:

pub enum GraphNode {
    Empty,                    // Deleted/placeholder nodes
    Document(Document),       // Root document container
    Section(Section),         // Headers (h1-h6)
    Quote(Quote),            // Blockquotes  
    BulletList(BulletList),  // Unordered lists
    OrderedList(OrderedList), // Numbered lists
    Leaf(Leaf),              // Paragraphs and simple blocks
    Raw(RawLeaf),            // Code blocks and raw content
    HorizontalRule(HorizontalRule), // Horizontal rules
    Reference(Reference),     // Block references to other documents
    Table(Table),            // Markdown tables
}

Node Relationships and Navigation

Each node (except Document and Empty) contains:

• id: Unique identifier within the graph
• prev: Reference to previous sibling or parent
• next: Optional reference to next sibling
• child: Optional reference to first child (container nodes only)

Navigation patterns:

• Siblings: Follow next pointers horizontally
• Children: Follow child pointer then next for all children
• Parent: Use prev pointer and traverse up

Content Storage Separation

Text content is stored separately from structure in Line objects:

pub struct Line {
    id: LineId,
    inlines: GraphInlines,  // Vector of inline elements (text, links, formatting)
}

This separation enables:

• Structure reuse: Multiple nodes can reference same content
• Efficient updates: Content changes don’t affect structure
• Memory optimization: Structure and content cached independently