Rust Core¶

The native accelerator is a PyO3 crate at src/crxml_core/.

Crate structure¶

src/crxml_core/
├── Cargo.toml
└── src/
    └── lib.rs          # CrxmlReader class

`CrxmlReader`¶

A single Python-exposed class:

#[pyclass]
struct CrxmlReader {
    source: PathBuf,
    row_tag: String,
    buf: Vec<u8>,
    inner_buf: Vec<u8>,
}

__iter__, returns self
__next__, reads the next row as a PyDict

The reader walks the XML stream, finds <row_tag> elements, and extracts field key/value pairs from nested <Field> and <Text> elements.

Dependencies¶

Crate	Purpose
`pyo3`	Python bindings
`quick-xml`	Streaming XML reader
`simdutf8`	SIMD-accelerated UTF-8 validation for parse chunks
`memchr`	Fast byte searching (direct dependency, also used by quick-xml)
`mimalloc`	Fast allocator (replaces system malloc, ~27% CPU savings)

Building¶

# Development build (editable)
maturin develop --release

# Production wheel
maturin build --release

The pyproject.toml [tool.maturin] section controls the build:

[tool.maturin]
module-name = "crxml._crxml_core"
manifest-path = "src/crxml_core/Cargo.toml"

Code style¶

Rust 2021 edition
cargo fmt for formatting
cargo clippy, no warnings allowed
Unsafe code is denied by default (#![deny(unsafe_code)])

Testing¶

# Rust unit tests
cargo test --manifest-path src/crxml_core/Cargo.toml

# Integration via Python
python -c "from crxml._crxml_core import CrxmlReader; r = CrxmlReader('test.xml', 'Details'); print(next(r))"

Security¶

Unsafe denied by default (#![deny(unsafe_code)]). Two unsafe blocks guarded by #[allow(unsafe_code)] handle Mmap::map (mmap I/O) and from_utf8_unchecked (SIMD-validated UTF-8). The _PyDict_NewPresized private-CAPI call was removed after benchmarking showed only a 3.5% overall gain.
Input validation, XML is assumed trusted (users control their source files). Buffer sizes are managed by quick-xml.
Buffer limits, individual field values are bounded by the XML entity size. No unbounded allocations.