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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
Download Patch File Download Diff File Expand all files Collapse all files
ImGuiRenderer.cc
+11 -18
View File
@@ -7,10 +7,9 @@
#include <string>
#include <imgui.h>
#include <regex>
#include "ImGuiRenderer.h"
#include "RegexGuard.h"
#include "RegexEngine.h"
#include "Highlight.h"
#include "GUITheme.h"
#include "Buffer.h"
@@ -164,15 +163,11 @@ ImGuiRenderer::Draw(Editor &ed)
const bool regex_mode = search_mode && ed.PromptActive() && (
ed.CurrentPromptKind() == Editor::PromptKind::RegexSearch ||
ed.CurrentPromptKind() == Editor::PromptKind::RegexReplaceFind);
std::regex search_rx;
kte::Regex search_rx; // RegexEngine.h
bool search_rx_valid = false;
if (regex_mode) {
try {
search_rx = std::regex(ed.SearchQuery());
search_rx_valid = true;
} catch (const std::regex_error &) {
search_rx_valid = false;
}
std::string rx_err;
search_rx_valid = search_rx.Compile(ed.SearchQuery(), rx_err);
}
// Compute the visible row range and skip rendering work for off-screen
@@ -360,15 +355,13 @@ ImGuiRenderer::Draw(Editor &ed)
if (search_mode) {
// In regex mode, reuse the compiled regex hoisted above the loop.
if (regex_mode) {
// std::regex recursion is kept off the main stack for long
// lines (RegexGuard.h); very long lines are not highlighted.
if (search_rx_valid && line.size() <= kte::kRegexRenderLineLimit) {
try {
kte::ForEachRegexMatch(line, search_rx, [&](std::size_t pos, std::size_t len) {
hl_src_ranges.emplace_back(pos, pos + len);
});
} catch (const std::regex_error &) {
// ignore invalid patterns here; status line already shows the error
// Very long lines are not highlighted (see
// Regex::IncrementalLineLimit).
if (search_rx_valid && line.size() <= kte::Regex::IncrementalLineLimit()) {
std::size_t from = 0, pos = 0, len = 0;
while (from <= line.size() && search_rx.Search(line, from, pos, len)) {
hl_src_ranges.emplace_back(pos, pos + len);
from = pos + std::max<std::size_t>(len, 1);
}
}
} else {