1 files changed, 94 insertions, 0 deletions
diff --git a/app/_re2.cc b/app/_re2.cc
new file mode 100644
index 0000000..a63313e
--- /dev/null
+++ b/app/_re2.cc
@@ -0,0 +1,94 @@
+// Copyright 2022 The RE2 Authors.  All Rights Reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <memory>
+#include <string>
+
+#include <emscripten/bind.h>
+#include "re2/prog.h"
+#include "re2/re2.h"
+#include "re2/regexp.h"
+
+namespace re2_app {
+
+struct Info {
+  std::string pattern;
+  std::string error;
+  std::string prefix;
+  bool prefix_foldcase = false;
+  std::string accel_prefix;
+  bool accel_prefix_foldcase = false;
+  int num_captures;
+  bool is_one_pass;
+  bool can_bit_state;
+  std::string bytecode;
+  std::string bytemap;
+};
+
+Info GetInfo(const std::string& pattern) {
+  Info info;
+  info.pattern = pattern;
+
+  RE2::Options options;
+  re2::RegexpStatus status;
+  re2::Regexp* regexp = re2::Regexp::Parse(
+      pattern, static_cast<re2::Regexp::ParseFlags>(options.ParseFlags()),
+      &status);
+  if (regexp == nullptr) {
+    info.error = "failed to parse pattern: " + status.Text();
+    return info;
+  }
+
+  std::string prefix;
+  bool prefix_foldcase;
+  re2::Regexp* suffix;
+  if (regexp->RequiredPrefix(&prefix, &prefix_foldcase, &suffix)) {
+    info.prefix = prefix;
+    info.prefix_foldcase = prefix_foldcase;
+  } else {
+    suffix = regexp->Incref();
+  }
+
+  std::unique_ptr<re2::Prog> prog(suffix->CompileToProg(options.max_mem()));
+  if (prog == nullptr) {
+    info.error = "failed to compile forward Prog";
+    suffix->Decref();
+    regexp->Decref();
+    return info;
+  }
+
+  if (regexp->RequiredPrefixForAccel(&prefix, &prefix_foldcase)) {
+    info.accel_prefix = prefix;
+    info.accel_prefix_foldcase = prefix_foldcase;
+  }
+
+  info.num_captures = suffix->NumCaptures();
+  info.is_one_pass = prog->IsOnePass();
+  info.can_bit_state = prog->CanBitState();
+  info.bytecode = prog->Dump();
+  info.bytemap = prog->DumpByteMap();
+
+  suffix->Decref();
+  regexp->Decref();
+  return info;
+}
+
+EMSCRIPTEN_BINDINGS(_re2) {
+  emscripten::value_object<Info>("Info")
+      .field("pattern", &Info::pattern)
+      .field("error", &Info::error)
+      .field("prefix", &Info::prefix)
+      .field("prefix_foldcase", &Info::prefix_foldcase)
+      .field("accel_prefix", &Info::accel_prefix)
+      .field("accel_prefix_foldcase", &Info::accel_prefix_foldcase)
+      .field("num_captures", &Info::num_captures)
+      .field("is_one_pass", &Info::is_one_pass)
+      .field("can_bit_state", &Info::can_bit_state)
+      .field("bytecode", &Info::bytecode)
+      .field("bytemap", &Info::bytemap);
+
+  emscripten::function("getInfo", &GetInfo);
+}
+
+}  // namespace re2_app