initial commit

src/Regex.cpp

@@ -0,0 +1,87 @@
+#include "sedpp/Regex.h"
+
+#include <stdexcept>
+
+namespace sedpp {
+
+Regex::Regex(const std::string &pattern, const Options &options,
+             bool ignoreCase, bool multiline) {
+  int flags = 0;
+  // Keep regex flavor decisions here so compiler-normalized patterns can be
+  // reused by addresses and substitutions without duplicating regcomp flags.
+  if (options.extendedRegex) {
+    flags |= REG_EXTENDED;
+  }
+  if (ignoreCase) {
+    flags |= REG_ICASE;
+  }
+  if (multiline) {
+    flags |= REG_NEWLINE;
+  }
+
+  const int rc = ::regcomp(&regex_, pattern.c_str(), flags);
+  if (rc != 0) {
+    char message[256];
+    ::regerror(rc, &regex_, message, sizeof(message));
+    throw std::runtime_error(message);
+  }
+  compiled_ = true;
+}
+
+Regex::Regex(Regex &&other) noexcept {
+  // regex_t is a C resource; moving transfers the compiled object and prevents
+  // the source wrapper from freeing it.
+  regex_ = other.regex_;
+  compiled_ = other.compiled_;
+  other.compiled_ = false;
+}
+
+Regex &Regex::operator=(Regex &&other) noexcept {
+  if (this != &other) {
+    if (compiled_) {
+      ::regfree(&regex_);
+    }
+    regex_ = other.regex_;
+    compiled_ = other.compiled_;
+    other.compiled_ = false;
+  }
+  return *this;
+}
+
+Regex::~Regex() {
+  if (compiled_) {
+    ::regfree(&regex_);
+  }
+}
+
+std::optional<Match> Regex::search(const std::string &text,
+                                   std::size_t start) const {
+  constexpr std::size_t kMaxGroups = 10;
+  Match match;
+  match.groups.resize(kMaxGroups);
+
+  const char *base = text.c_str();
+  // Searches after byte 0 should not let ^ match the original beginning again.
+  const int eflags = start == 0 ? 0 : REG_NOTBOL;
+  const int rc = ::regexec(&regex_, base + start, match.groups.size(),
+                           match.groups.data(), eflags);
+  if (rc == REG_NOMATCH) {
+    return std::nullopt;
+  }
+  if (rc != 0) {
+    char message[256];
+    ::regerror(rc, &regex_, message, sizeof(message));
+    throw std::runtime_error(message);
+  }
+
+  for (regmatch_t &group : match.groups) {
+    if (group.rm_so >= 0) {
+      // regexec saw base + start, so convert offsets back into the full string.
+      group.rm_so += static_cast<regoff_t>(start);
+      group.rm_eo += static_cast<regoff_t>(start);
+    }
+  }
+  return match;
+}
+
+} // namespace sedpp