Lokad.Utf8Regex 0.4.0

Lokad.Utf8Regex

0.4.0, .NET 10. Regular expressions over strict UTF-8 ReadOnlySpan<byte> / Span<byte>, matching Unicode scalars with primary byte coordinates. Dot matches 😀 once across four bytes. UTF-16 coordinates and string APIs are derived interoperability conveniences.

using Lokad.Utf8Regex;

var regex = new Utf8Regex(".");
int count = regex.Count("A😀"u8); // 2
var match = regex.Match("😀"u8); // LengthInBytes == 4

The owned managed engine supports documented .NET-style grammar, captures/history, backreferences, assertions, RTL and a supported NonBacktracking subset, with native UTF-8 search paths. It does not execute BCL Regex matchers/results or promise UTF-16 parity. CultureInvariant is the primary supported mode. Whole subjects must be valid UTF-8, including suffixes after an early match. Core uses ordered alternatives, not POSIX leftmost-longest matching.

Optional IL preparation is skipped when the host disables dynamic code, including with Compiled; non-emitted execution preserves results. NativeAOT publishing and trimming have not been qualified.

Replacement callbacks can pass local stack buffers and formatting slices to Utf8ReplacementWriter.Append. Its scoped byte/char span inputs are copied or encoded before returning; the writer remains valid only during the callback.

Instances support finite Utf8ResourcePolicy work, depth, working-capacity and result-capacity limits. Defaults and static cached calls are unlimited. Original cancellation and absolute deadlines cover validation, matching, required shaping and cursor advances. Explicit Compile factories offer separate construction controls. Memory accounting admits modeled major capacity before allocation; it is not total heap/RSS, all preparation, callbacks or retained-host storage containment. See resource contract.

Keep borrowed subjects unchanged and their owners alive. Owned snapshots remain valid after advance/failure/disposal. Copied value cursors retain independent positions while sharing allowance/deadline. A host must separately account for retained results and its own storage.

Optional Lokad.Utf8Regex.PythonRe and Lokad.Utf8Regex.Pcre2 0.4.0 require exactly this Core version. Both are managed profile adapters with explicit compatibility boundaries; no native PCRE2 binary is shipped.

Read release notes and migration guide. The repository specification defines the target contract; qualification fixtures establish implemented scope. Performance snapshots retain their recorded source/package/runtime identities.