set up tests and examples

radixtree/src/serialize.rs

@@ -0,0 +1,144 @@
+//! Serialization and deserialization for RadixTree nodes.
+
+use crate::error::Error;
+use crate::node::{Node, NodeRef};
+use std::convert::TryInto;
+use std::io::{Cursor, Read, Write};
+use std::mem::size_of;
+
+/// Current binary format version.
+const VERSION: u8 = 1;
+
+impl Node {
+    /// Serializes a node to bytes for storage.
+    pub fn serialize(&self) -> Vec<u8> {
+        let mut buffer = Vec::new();
+        
+        // Add version byte
+        buffer.push(VERSION);
+        
+        // Add key segment
+        write_string(&mut buffer, &self.key_segment);
+        
+        // Add value as []u8
+        write_u16(&mut buffer, self.value.len() as u16);
+        buffer.extend_from_slice(&self.value);
+        
+        // Add children
+        write_u16(&mut buffer, self.children.len() as u16);
+        for child in &self.children {
+            write_string(&mut buffer, &child.key_part);
+            write_u32(&mut buffer, child.node_id);
+        }
+        
+        // Add leaf flag
+        buffer.push(if self.is_leaf { 1 } else { 0 });
+        
+        buffer
+    }
+
+    /// Deserializes bytes to a node.
+    pub fn deserialize(data: &[u8]) -> Result<Self, Error> {
+        if data.is_empty() {
+            return Err(Error::Deserialization("Empty data".to_string()));
+        }
+        
+        let mut cursor = Cursor::new(data);
+        
+        // Read and verify version
+        let mut version_byte = [0u8; 1];
+        cursor.read_exact(&mut version_byte)
+            .map_err(|e| Error::Deserialization(format!("Failed to read version byte: {}", e)))?;
+            
+        if version_byte[0] != VERSION {
+            return Err(Error::Deserialization(
+                format!("Invalid version byte: expected {}, got {}", VERSION, version_byte[0])
+            ));
+        }
+        
+        // Read key segment
+        let key_segment = read_string(&mut cursor)
+            .map_err(|e| Error::Deserialization(format!("Failed to read key segment: {}", e)))?;
+        
+        // Read value as []u8
+        let value_len = read_u16(&mut cursor)
+            .map_err(|e| Error::Deserialization(format!("Failed to read value length: {}", e)))?;
+            
+        let mut value = vec![0u8; value_len as usize];
+        cursor.read_exact(&mut value)
+            .map_err(|e| Error::Deserialization(format!("Failed to read value: {}", e)))?;
+        
+        // Read children
+        let children_len = read_u16(&mut cursor)
+            .map_err(|e| Error::Deserialization(format!("Failed to read children length: {}", e)))?;
+            
+        let mut children = Vec::with_capacity(children_len as usize);
+        for _ in 0..children_len {
+            let key_part = read_string(&mut cursor)
+                .map_err(|e| Error::Deserialization(format!("Failed to read child key part: {}", e)))?;
+                
+            let node_id = read_u32(&mut cursor)
+                .map_err(|e| Error::Deserialization(format!("Failed to read child node ID: {}", e)))?;
+                
+            children.push(NodeRef {
+                key_part,
+                node_id,
+            });
+        }
+        
+        // Read leaf flag
+        let mut is_leaf_byte = [0u8; 1];
+        cursor.read_exact(&mut is_leaf_byte)
+            .map_err(|e| Error::Deserialization(format!("Failed to read leaf flag: {}", e)))?;
+            
+        let is_leaf = is_leaf_byte[0] == 1;
+        
+        Ok(Node {
+            key_segment,
+            value,
+            children,
+            is_leaf,
+        })
+    }
+}
+
+// Helper functions for serialization
+
+fn write_string(buffer: &mut Vec<u8>, s: &str) {
+    let bytes = s.as_bytes();
+    write_u16(buffer, bytes.len() as u16);
+    buffer.extend_from_slice(bytes);
+}
+
+fn write_u16(buffer: &mut Vec<u8>, value: u16) {
+    buffer.extend_from_slice(&value.to_le_bytes());
+}
+
+fn write_u32(buffer: &mut Vec<u8>, value: u32) {
+    buffer.extend_from_slice(&value.to_le_bytes());
+}
+
+// Helper functions for deserialization
+
+fn read_string(cursor: &mut Cursor<&[u8]>) -> std::io::Result<String> {
+    let len = read_u16(cursor)? as usize;
+    let mut bytes = vec![0u8; len];
+    cursor.read_exact(&mut bytes)?;
+    
+    String::from_utf8(bytes)
+        .map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e))
+}
+
+fn read_u16(cursor: &mut Cursor<&[u8]>) -> std::io::Result<u16> {
+    let mut bytes = [0u8; size_of::<u16>()];
+    cursor.read_exact(&mut bytes)?;
+    
+    Ok(u16::from_le_bytes(bytes))
+}
+
+fn read_u32(cursor: &mut Cursor<&[u8]>) -> std::io::Result<u32> {
+    let mut bytes = [0u8; size_of::<u32>()];
+    cursor.read_exact(&mut bytes)?;
+    
+    Ok(u32::from_le_bytes(bytes))
+}