// Copyright 2021 Google LLC

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#include "internal/lexis.h"

#include "absl/base/call_once.h"

#include "absl/base/macros.h"

#include "absl/container/flat_hash_set.h"

#include "absl/strings/ascii.h"

namespace cel::internal {

namespace {

ABSL_CONST_INIT absl::once_flag reserved_keywords_once_flag = {};

ABSL_CONST_INIT absl::flat_hash_set<absl::string_view>* reserved_keywords =

    nullptr;

void InitializeReservedKeywords() {

  ABSL_ASSERT(reserved_keywords == nullptr);

  reserved_keywords = new absl::flat_hash_set<absl::string_view>();

  reserved_keywords->insert("false");

  reserved_keywords->insert("true");

  reserved_keywords->insert("null");

  reserved_keywords->insert("in");

  reserved_keywords->insert("as");

  reserved_keywords->insert("break");

  reserved_keywords->insert("const");

  reserved_keywords->insert("continue");

  reserved_keywords->insert("else");

  reserved_keywords->insert("for");

  reserved_keywords->insert("function");

  reserved_keywords->insert("if");

  reserved_keywords->insert("import");

  reserved_keywords->insert("let");

  reserved_keywords->insert("loop");

  reserved_keywords->insert("package");

  reserved_keywords->insert("namespace");

  reserved_keywords->insert("return");

  reserved_keywords->insert("var");

  reserved_keywords->insert("void");

  reserved_keywords->insert("while");

}

}  // namespace

bool LexisIsReserved(absl::string_view text) {

  absl::call_once(reserved_keywords_once_flag, InitializeReservedKeywords);

  return reserved_keywords->find(text) != reserved_keywords->end();

}

bool LexisIsIdentifier(absl::string_view text) {

  if (text.empty()) {

    return false;

  }

  char first = text.front();

  if (!absl::ascii_isalpha(first) && first != '_') {

    return false;

  }

  for (size_t index = 1; index < text.size(); index++) {

    if (!absl::ascii_isalnum(text[index]) && text[index] != '_') {

      return false;

    }

  }

  return !LexisIsReserved(text);

}

}  // namespace cel::internal