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Regex: optional PCRE2 engine behind kte::Regex

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RegexEngine.h/.cc wrap the regex engine for search, regex replace-all and
the terminal and ImGui renderers' match highlighting:

- With KTE_USE_PCRE2 (default ON; used when pkg-config finds libpcre2-8,
  linked as -lpcre2-8) patterns are compiled by PCRE2 with its JIT and
  matched under a match limit: catastrophic backtracking stops with a
  status note instead of hanging the editor, and matching does not
  recurse on the C stack (no large-stack thread; the per-keystroke and
  per-frame line limit is 1 MiB instead of 2,000 bytes). Otherwise
  std::regex is used as before.
- Replacement strings follow std::regex_replace (ECMAScript as libstdc++
  reads it) with either engine: the PCRE2 path expands $&, $n, $`, $',
  $$ itself and steps over empty matches the same way.
- Regex search walks lines over the materialized text instead of calling
  GetLineView per row. The terminal renderer compiles the pattern once
  per frame (it compiled it for every row).
- Only one checkpoint per journal is queued at a time: whole-file edits
  in a row on a large buffer each queued a full copy of the buffer.
- default.nix and the Dockerfile add pcre2 and pkg-config.

On 26 MB: regex keystroke 1.6 -> 0.14 ms, next 62 -> 6 ms, replace-all
929 -> 438 ms; a rarely matching regex over 105 MB: 1.55 s -> 0.10 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB
This commit is contained in:
Claude
2026-09-24 09:16:04 -07:00
committed by Kyle Isom
parent a33c1759e7
commit e782d24e32
14 changed files with 670 additions and 107 deletions
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TerminalRenderer.cc
+19 -10
View File
@@ -6,11 +6,10 @@
#include <filesystem>
#include <cstdlib>
#include <ncurses.h>
#include <regex>
#include <string>
#include "TerminalRenderer.h"
#include "RegexGuard.h"
#include "RegexEngine.h"
#include "TermWidth.h"
#include "Buffer.h"
#include "Editor.h"
@@ -58,6 +57,16 @@ TerminalRenderer::Draw(Editor &ed)
buf->Highlighter()->PrefetchViewport(*buf, fr, rc, buf->Version());
}
// The search pattern, compiled once per frame (it was compiled for
// every row).
kte::Regex draw_rx;
bool draw_rx_ok = false;
if (ed.SearchActive() && !ed.SearchQuery().empty() && ed.PromptActive() &&
(ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch ||
ed.CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
std::string rx_err;
draw_rx_ok = draw_rx.Compile(ed.SearchQuery(), rx_err);
}
for (int r = 0; r < content_rows; ++r) {
move(r, 0);
std::size_t li = rowoffs + static_cast<std::size_t>(r);
@@ -72,15 +81,15 @@ TerminalRenderer::Draw(Editor &ed)
if (ed.PromptActive() && (
ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch || ed.
CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind)) {
// Long lines are not highlighted: std::regex recursion
// could overflow the stack (RegexGuard.h).
if (sline.size() <= kte::kRegexRenderLineLimit) try {
std::regex rx(ed.SearchQuery());
kte::ForEachRegexMatch(sline, rx, [&](std::size_t pos, std::size_t len) {
// Very long lines are not highlighted (see
// Regex::IncrementalLineLimit); an invalid pattern
// highlights nothing (the status shows the error).
if (draw_rx_ok && sline.size() <= kte::Regex::IncrementalLineLimit()) {
std::size_t from = 0, pos = 0, len = 0;
while (from <= sline.size() && draw_rx.Search(sline, from, pos, len)) {
ranges.emplace_back(pos, pos + len);
});
} catch (const std::regex_error &) {
// ignore invalid patterns here; status shows error
from = pos + std::max<std::size_t>(len, 1);
}
}
} else {
const std::string &q = ed.SearchQuery();