Data Model

Graph-Based Document Representation

Unlike traditional parsers that work with document trees, IWE represents text as a directed graph where every header, paragraph, list, list item, code block, table, and reference becomes a node. Each node can have up to two primary relationships:

• next-element: Points to the sibling node at the same hierarchical level
• child-element: Points to the first child node (for container elements)

This creates a hybrid tree-graph structure that preserves both document hierarchy and enables complex cross-document relationships.

Arena-Based Memory Management

IWE uses an arena pattern for efficient memory management and fast graph operations:

#[derive(Clone, Default)]
pub struct Arena {
    nodes: Vec<GraphNode>,      // All graph nodes stored contiguously
    lines: Vec<Line>,           // Text content stored separately
}

Benefits of arena storage:

• Fast access: O(1) node lookup using NodeId as array index
• Memory efficiency: Contiguous storage reduces memory fragmentation
• Cache locality: Related nodes stored close together in memory
• Safe deletion: Empty nodes marked rather than removed