Auditing the documentation against the actual code (not against what I
remembered writing) surfaced a real, previously undocumented defect:
README.md claimed a backreference-free, unbounded-lookahead-free
pattern "runs in linear time", but that is only true of Pattern_match/
Pattern_fullmatch (one anchored attempt). Pattern_search tries every
candidate start position as an independent from-scratch attempt, so it
is quadratic in the worst case even for the simplest pattern, since
concept.md Section 7.2's engine (which shares work across start
positions in one linear pass) is not implemented yet. Measured directly
with a*b over a run of plain a's: 0.32s at n=10,000, 19.2s at n=80,000,
an ~4x slowdown per doubling. Pattern_finditer/Pattern_split/
Pattern_sub all build on the same search loop and inherit it.
README.md and docs/API.md now state this precisely, with the measured
numbers, wherever the affected functions are documented, rather than
repeating the incorrect blanket "linear time" claim. No code changed;
this is a documentation correction only.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EjuMk8kY9SDus1wWe2K9xY
concept.md is the full design document: the objective (Python re parity
plus binary/ASCII/UTF-8 modes, gigabyte-scale input, single C file), the
automata-theory argument for why unrestricted backreferences/lookaround
are incompatible with strict single-pass constant memory, the resulting
two-engine architecture, the exact Python-mirroring naming convention,
and a full comparison against POSIX regex.h for C-background readers.
regexx.c/regexx.h are the v1 implementation: parser, compiler to a
Pike/backtracking-style bytecode, and a single recursive backtracking
engine covering the pattern syntax and operations listed in README.md,
validated against CPython's own re module output (tests/), clean under
AddressSanitizer/UBSan, and stress-tested (50MB simple-quantifier match,
graceful failure rather than a crash on complex repeats over large
input, clean rejection of every intentionally unsupported construct).
Also included: examples/rxgrep.c (a small grep-like program exercising
all three data modes and the substitution API), the Makefile, the MIT
LICENSE, and docs/API.md, an exhaustive reference for every type, flag,
and function's exact return-value and memory-ownership convention,
checked against the current source and against a real CPython
interpreter rather than against memory.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EjuMk8kY9SDus1wWe2K9xY
retoorandClaude Sonnet 5