/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "utils/regex-match.h"
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#include <memory>
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#include "annotator/types.h"
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#include "utils/lua-utils.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lauxlib.h"
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#include "lualib.h"
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#ifdef __cplusplus
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}
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#endif
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namespace libtextclassifier3 {
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namespace {
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// Provide a lua environment for running regex match post verification.
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// It sets up and exposes the match data as well as the context.
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class LuaVerifier : private LuaEnvironment {
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public:
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static std::unique_ptr<LuaVerifier> Create(
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const std::string& context, const std::string& verifier_code,
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const UniLib::RegexMatcher* matcher);
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bool Verify(bool* result);
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private:
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explicit LuaVerifier(const std::string& context,
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const std::string& verifier_code,
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const UniLib::RegexMatcher* matcher)
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: context_(context), verifier_code_(verifier_code), matcher_(matcher) {}
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bool Initialize();
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// Provides details of a capturing group to lua.
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int GetCapturingGroup();
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const std::string& context_;
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const std::string& verifier_code_;
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const UniLib::RegexMatcher* matcher_;
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};
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bool LuaVerifier::Initialize() {
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// Run protected to not lua panic in case of setup failure.
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return RunProtected([this] {
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LoadDefaultLibraries();
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// Expose context of the match as `context` global variable.
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PushString(context_);
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lua_setglobal(state_, "context");
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// Expose match array as `match` global variable.
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// Each entry `match[i]` exposes the ith capturing group as:
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// * `begin`: span start
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// * `end`: span end
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// * `text`: the text
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BindTable<LuaVerifier, &LuaVerifier::GetCapturingGroup>("match");
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lua_setglobal(state_, "match");
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return LUA_OK;
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}) == LUA_OK;
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}
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std::unique_ptr<LuaVerifier> LuaVerifier::Create(
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const std::string& context, const std::string& verifier_code,
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const UniLib::RegexMatcher* matcher) {
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auto verifier = std::unique_ptr<LuaVerifier>(
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new LuaVerifier(context, verifier_code, matcher));
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if (!verifier->Initialize()) {
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TC3_LOG(ERROR) << "Could not initialize lua environment.";
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return nullptr;
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}
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return verifier;
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}
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int LuaVerifier::GetCapturingGroup() {
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if (lua_type(state_, /*idx=*/-1) != LUA_TNUMBER) {
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TC3_LOG(ERROR) << "Unexpected type for match group lookup: "
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<< lua_type(state_, /*idx=*/-1);
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lua_error(state_);
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return 0;
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}
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const int group_id = static_cast<int>(lua_tonumber(state_, /*idx=*/-1));
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int status = UniLib::RegexMatcher::kNoError;
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const CodepointSpan span = {matcher_->Start(group_id, &status),
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matcher_->End(group_id, &status)};
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std::string text = matcher_->Group(group_id, &status).ToUTF8String();
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if (status != UniLib::RegexMatcher::kNoError) {
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TC3_LOG(ERROR) << "Could not extract span from capturing group.";
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lua_error(state_);
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return 0;
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}
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lua_newtable(state_);
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lua_pushinteger(state_, span.first);
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lua_setfield(state_, /*idx=*/-2, "begin");
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lua_pushinteger(state_, span.second);
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lua_setfield(state_, /*idx=*/-2, "end");
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PushString(text);
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lua_setfield(state_, /*idx=*/-2, "text");
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return 1;
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}
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bool LuaVerifier::Verify(bool* result) {
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if (luaL_loadbuffer(state_, verifier_code_.data(), verifier_code_.size(),
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/*name=*/nullptr) != LUA_OK) {
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TC3_LOG(ERROR) << "Could not load verifier snippet.";
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return false;
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}
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if (lua_pcall(state_, /*nargs=*/0, /*nresults=*/1, /*errfunc=*/0) != LUA_OK) {
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TC3_LOG(ERROR) << "Could not run verifier snippet.";
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return false;
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}
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if (RunProtected(
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[this, result] {
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if (lua_type(state_, /*idx=*/-1) != LUA_TBOOLEAN) {
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TC3_LOG(ERROR) << "Unexpected verification result type: "
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<< lua_type(state_, /*idx=*/-1);
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lua_error(state_);
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return LUA_ERRRUN;
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}
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*result = lua_toboolean(state_, /*idx=*/-1);
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return LUA_OK;
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},
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/*num_args=*/1) != LUA_OK) {
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TC3_LOG(ERROR) << "Could not read lua result.";
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return false;
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}
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return true;
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}
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} // namespace
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bool SetFieldFromCapturingGroup(const int group_id,
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const FlatbufferFieldPath* field_path,
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const UniLib::RegexMatcher* matcher,
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ReflectiveFlatbuffer* flatbuffer) {
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int status = UniLib::RegexMatcher::kNoError;
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std::string group_text = matcher->Group(group_id, &status).ToUTF8String();
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if (status != UniLib::RegexMatcher::kNoError || group_text.empty()) {
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return false;
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}
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return flatbuffer->ParseAndSet(field_path, group_text);
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}
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bool VerifyMatch(const std::string& context,
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const UniLib::RegexMatcher* matcher,
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const std::string& lua_verifier_code) {
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bool status = false;
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auto verifier = LuaVerifier::Create(context, lua_verifier_code, matcher);
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if (verifier == nullptr) {
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TC3_LOG(ERROR) << "Could not create verifier.";
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return false;
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}
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if (!verifier->Verify(&status)) {
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TC3_LOG(ERROR) << "Could not create verifier.";
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return false;
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}
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return status;
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}
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} // namespace libtextclassifier3
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