ZCString

ZCString is a context-aware string wrapper for arcstr::Substr designed for efficient, zero-copy string management. It uses thread-local storage to track a "source" string, allowing substrings to be derived from existing memory buffers without triggering new allocations. The currently supported use case is parsing of json strings with serde_json.

Why ZCString?

When parsing or processing large strings, you often want to derive substrings that point back to the original memory. ZCString simplifies this by:

• Tracking Source Memory: It maintains a thread-local SOURCE reference that acts as the active memory context.
• Identity-Based Slicing: When creating a string via from_str_with_source, it checks if the pointer resides within the current SOURCE. If it does, it returns a sub-slice; otherwise, it falls back to a standard allocation.
• Recursive Safety: It uses RAII guards to allow nesting of different source contexts, automatically restoring the previous source when a scope ends.

Capabilities

• Zero-allocation: Sub-slices share the same reference-counted buffer as the parent ArcStr.
• RAII Contexts: Safely manage the active "source" using with_source or get_source_guard.
• Serde Support: Optional integration for zero-copy deserialization of JSON and other formats.

Usage

Add this to your Cargo.toml:

[dependencies]
# by default the std and serde features are enable
zcstring = "0.2.0"

## Example code
cargo run --example json_example