chore: bump pyo3 (#276)

* chore: bump pyo3

* fix: prevent double-escaping of XML attribute values in make_valid_xml_name

make_valid_xml_name was calling escape_xml(key) and storing the escaped
value. Later, make_attr_string would escape it again, producing output
like name="tag&name" instead of name="tag&name".

Now make_valid_xml_name operates on the raw key and lets make_attr_string
handle the single escaping pass.

Amp-Thread-ID: https://ampcode.com/threads/T-019ce197-0f45-7644-a010-590c20704f18
Co-authored-by: Amp <amp@ampcode.com>

* fix: use Python str() for float formatting to match Python output

Rust's f64::to_string() renders 1.0 as "1" while Python gives "1.0".
Since this is a drop-in replacement for the Python dicttoxml, use
obj.str() to get Python's native float representation.

Amp-Thread-ID: https://ampcode.com/threads/T-019ce197-0f45-7644-a010-590c20704f18
Co-authored-by: Amp <amp@ampcode.com>

* fix: propagate iteration errors instead of silently swallowing them

The try_iter() path used filter_map(|r| r.ok()) which silently dropped
any exceptions raised during iteration. Now uses collect::<PyResult<_>>()?
to properly propagate errors to the caller.

Amp-Thread-ID: https://ampcode.com/threads/T-019ce197-0f45-7644-a010-590c20704f18
Co-authored-by: Amp <amp@ampcode.com>

* fix: validate custom_root is a valid XML element name

Previously custom_root was written directly into XML tags without
validation, allowing arbitrary strings to produce invalid XML output.
Now raises ValueError for invalid root element names.

Amp-Thread-ID: https://ampcode.com/threads/T-019ce197-0f45-7644-a010-590c20704f18
Co-authored-by: Amp <amp@ampcode.com>

* refactor: collapse duplicate dispatch, single-buffer writes, byte-level escaping

Major restructuring of the Rust extension:

- Collapsed three identical type-dispatch chains (convert_value,
  convert_dict, convert_list) into a single write_value() function.
  Removes ~300 lines of duplicated if/else logic.

- All XML writing now appends to a single shared String buffer via
  write_value/write_dict_contents/write_list_contents instead of
  allocating intermediate Strings at every recursion level.

- Replaced char-by-char escape_xml with byte-scanning push_escaped_text
  (for text nodes, only escapes &<>) and push_escaped_attr (for
  attributes, also escapes quotes). Copies clean slices in bulk.

- Replaced format!-based wrap_cdata with push_cdata that writes
  directly to the buffer without intermediate allocations.

- Replaced to_lowercase().starts_with("xml") in is_valid_xml_name
  with eq_ignore_ascii_case to avoid allocating a lowercased copy.

- Removed unused std::fmt::Write import, added #[derive(Copy, Clone)]
  to ConvertConfig, gated helper functions behind cfg(python).

- Added tests for push_escaped_text, push_escaped_attr, push_cdata.

Amp-Thread-ID: https://ampcode.com/threads/T-019ce197-0f45-7644-a010-590c20704f18
Co-authored-by: Amp <amp@ampcode.com>

* Fix: rust clippy errors

* fix: test failures

* fix: do cargo fmt

* chore: update the version for the rust binding

* feat: update benchmark with the latest rust version

---------

Co-authored-by: Amp <amp@ampcode.com>

Author: vinitkumar

BENCHMARKS.md

@@ -6,7 +6,7 @@ Comprehensive performance comparison between all json2xml implementations.
 
 - **Machine**: Apple Silicon (M-series, aarch64)
 - **OS**: macOS
-- **Date**: January 28, 2026
+- **Date**: March 12, 2026
 
 ### Implementations Tested
 
@@ -22,32 +22,32 @@ Comprehensive performance comparison between all json2xml implementations.
 | Size | Description | Bytes |
 |------|-------------|-------|
 | Small | Simple object `{"name": "John", "age": 30, "city": "New York"}` | 47 |
-| Medium | 10 generated records with nested structures | ~3,208 |
+| Medium | 10 generated records with nested structures | ~3,211 |
 | bigexample.json | Real-world patent data | 2,018 |
-| Large | 100 generated records with nested structures | ~32,205 |
-| Very Large | 1,000 generated records with nested structures | ~323,119 |
+| Large | 100 generated records with nested structures | ~32,220 |
+| Very Large | 1,000 generated records with nested structures | ~323,114 |
 
 ## Results
 
 ### Performance Summary
 
 | Test Case | Python | Rust | Go | Zig |
 |-----------|--------|------|-----|-----|
-| Small (47B) | 41.88µs | 1.66µs | 4.52ms | 2.80ms |
-| Medium (3.2KB) | 2.19ms | 71.85µs | 4.33ms | 2.18ms |
-| bigexample (2KB) | 854.38µs | 30.89µs | 4.28ms | 2.12ms |
-| Large (32KB) | 21.57ms | 672.96µs | 4.47ms | 2.48ms |
-| Very Large (323KB) | 216.52ms | 6.15ms | 4.44ms | 5.54ms |
+| Small (47B) | 78.39µs | 1.05µs | 4.31ms | 1.96ms |
+| Medium (3.2KB) | 2.15ms | 15.47µs | 5.03ms | 2.34ms |
+| bigexample (2KB) | 862.12µs | 6.44µs | 4.47ms | 2.38ms |
+| Large (32KB) | 22.08ms | 150.91µs | 4.80ms | 2.89ms |
+| Very Large (323KB) | 218.63ms | 1.47ms | 4.75ms | 5.38ms |
 
 ### Speedup vs Pure Python
 
 | Test Case | Rust | Go | Zig |
 |-----------|------|-----|-----|
-| Small (47B) | **25.2x** | 0.0x* | 0.0x* |
-| Medium (3.2KB) | **30.5x** | 0.5x* | 1.0x* |
-| bigexample (2KB) | **27.7x** | 0.2x* | 0.4x* |
-| Large (32KB) | **32.1x** | 4.8x | **8.7x** |
-| Very Large (323KB) | **35.2x** | **48.8x** | **39.1x** |
+| Small (47B) | **74.9x** | 0.0x* | 0.0x* |
+| Medium (3.2KB) | **139.1x** | 0.4x* | 0.9x* |
+| bigexample (2KB) | **133.9x** | 0.2x* | 0.4x* |
+| Large (32KB) | **146.3x** | 4.6x | **7.6x** |
+| Very Large (323KB) | **149.2x** | **46.1x** | **40.6x** |
 
 *CLI tools have process spawn overhead (~2-4ms) which dominates for small inputs
 
@@ -56,23 +56,23 @@ Comprehensive performance comparison between all json2xml implementations.
 ### 1. Rust Extension is the Best Choice for Python Users 🦀
 
 The Rust extension (json2xml-rs) provides:
-- **~25-35x faster** than pure Python consistently across all input sizes
+- **~75-149x faster** than pure Python consistently across all input sizes
 - **Zero process overhead** - called directly from Python
 - **Automatic fallback** - pure Python used if Rust unavailable
 - **Easy install**: `pip install json2xml[fast]`
 
 ### 2. Go Excels for Very Large CLI Workloads 🚀
 
 For very large inputs (323KB+):
-- **48.8x faster** than Python
+- **46.1x faster** than Python
 - But ~4ms startup overhead hurts small file performance
 - Best for batch processing or large file conversions
 
 ### 3. Zig is Now Highly Competitive ⚡
 
 After recent optimizations:
-- **39.1x faster** than Python for very large files
-- **8.7x faster** for large files (32KB)
+- **40.6x faster** than Python for very large files
+- **7.6x faster** for large files (32KB)
 - Faster startup than Go (~2ms vs ~4ms)
 - Best balance of startup time and throughput
 
@@ -89,7 +89,7 @@ CLI tools (Go, Zig) have process spawn overhead:
 
 | Use Case | Recommended | Why |
 |----------|-------------|-----|
-| Python library calls | **Rust** (`pip install json2xml[fast]`) | 25-35x faster, no overhead |
+| Python library calls | **Rust** (`pip install json2xml[fast]`) | 75-149x faster, no overhead |
 | Small files via CLI | **Zig** (json2xml-zig) | Fastest startup (~2ms) |
 | Large files via CLI | **Go** or **Zig** | Both excellent (Go slightly faster) |
 | Batch processing | **Go** or **Rust** | Both excellent |

README.rst

@@ -43,7 +43,7 @@ Installation
 
     pip install json2xml
 
-**With Native Rust Acceleration (28x faster)**
+**With Native Rust Acceleration (up to 149x faster)**
 
 For maximum performance, install the optional Rust extension:
 
@@ -55,7 +55,7 @@ For maximum performance, install the optional Rust extension:
     # Or install the Rust extension separately
     pip install json2xml-rs
 
-The Rust extension provides **28x faster** conversion compared to pure Python. It's automatically used when available, with seamless fallback to pure Python.
+The Rust extension provides **75-149x faster** conversion compared to pure Python. It's automatically used when available, with seamless fallback to pure Python.
 
 **As a CLI Tool**
 
@@ -301,7 +301,7 @@ Using tools directly:
 
 **Rust Extension Development**
 
-The optional Rust extension (``json2xml-rs``) provides 29x faster performance. To develop or build the Rust extension:
+The optional Rust extension (``json2xml-rs``) provides up to 149x faster performance. To develop or build the Rust extension:
 
 Prerequisites:
 
@@ -428,21 +428,21 @@ For users who need maximum performance within Python, json2xml includes an optio
      - Rust Extension
      - Speedup
    * - **Small JSON** (47 bytes)
-     - 40µs
-     - 1.5µs
-     - **27x**
+     - 78µs
+     - 1.05µs
+     - **75x**
    * - **Medium JSON** (3.2 KB)
-     - 2.1ms
-     - 71µs
-     - **30x**
+     - 2.15ms
+     - 15µs
+     - **139x**
    * - **Large JSON** (32 KB)
-     - 21ms
-     - 740µs
-     - **28x**
+     - 22ms
+     - 151µs
+     - **146x**
    * - **Very Large JSON** (323 KB)
-     - 213ms
-     - 7.5ms
-     - **28x**
+     - 219ms
+     - 1.47ms
+     - **149x**
 
 **Usage with Rust Extension:**
 

rust/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "json2xml_rs"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 description = "Fast native JSON to XML conversion for Python"
 license = "Apache-2.0"
@@ -14,7 +14,7 @@ default = ["python"]
 python = ["pyo3/extension-module", "dep:pyo3"]
 
 [dependencies]
-pyo3 = { version = "0.27", optional = true }
+pyo3 = { version = "0.28.2", optional = true }
 
 [profile.release]
 lto = true

rust/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "maturin"
 
 [project]
 name = "json2xml_rs"
-version = "0.1.0"
+version = "0.2.0"
 description = "Fast native JSON to XML conversion - Rust extension for json2xml"
 readme = "README.md"
 requires-python = ">=3.9"