Module builder 

Ownership and Borrowing - Rust Book Chapter 4

This module demonstrates ownership, borrowing, and references from The Rust Book Chapter 4.

Key Concepts Demonstrated

1. Borrowing with & References (Chapter 4.2)

   • The build() method takes &SearchResult instead of SearchResult
   • Allows reading data without taking ownership
   • Multiple borrows can exist simultaneously for reading

2. Ownership Transfer with .clone() (Chapter 4.1)

   • result.query.clone() creates a new owned String
   • Necessary when building nodes that need to own their data
   • Trade-off: memory cost vs. ownership flexibility

3. Iterators and Borrowing (Chapter 4.2 + 13.2)

   • .iter() creates an iterator of references (&T)
   • Allows processing collections without taking ownership
   • The original collection remains usable after iteration

4. References in Collections (Chapter 4.2)

   • Vec<_> with .iter() creates Vec<&T>
   • Temporary collections of references avoid cloning
   • References must not outlive the data they point to

Learning Notes

Why use &SearchResult instead of SearchResult?

• Caller retains ownership and can reuse the data
• More efficient - no need to clone the entire structure
• Follows Rust convention: borrow when you don’t need ownership

When to clone vs. when to borrow?

• Clone: When you need to store data in a new structure (like TreeNode)
• Borrow: When you only need to read data temporarily

The .iter() pattern:

for entry in &result.translation_entries {  // Borrows each element
    // entry is &TranslationEntry
}
// vs
for entry in result.translation_entries {   // Takes ownership
    // entry is TranslationEntry (moved)
}

Structs

ReferenceTreeBuilder

Builder for constructing reference trees from search results.