src/support/env.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *
 *   http://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.
 */

/*!
 * \file support/env.h
 * \brief Typed environment variable access.
 */
#ifndef TVM_SUPPORT_ENV_H_
#define TVM_SUPPORT_ENV_H_

#include <cstdlib>
#include <sstream>
#include <string>
#include <type_traits>

namespace tvm {
namespace support {

/*!
 * \brief Get environment variable with a typed default value.
 * \tparam T The value type (must be arithmetic or std::string).
 * \param key The environment variable name.
 * \param default_value The value to return if the variable is unset or empty.
 * \return The parsed value or the default.
 */
template <typename T>
inline T GetEnv(const char* key, T default_value) {
  const char* val = std::getenv(key);
  if (val == nullptr || !*val) return default_value;
  if constexpr (std::is_same_v<T, std::string>) {
    return std::string(val);
  } else if constexpr (std::is_same_v<T, bool>) {
    // Accept "0"/"false" as false, anything else as true
    std::string s(val);
    return !(s == "0" || s == "false" || s == "False" || s == "FALSE");
  } else {
    T ret;
    std::istringstream is(val);
    is >> ret;
    return ret;
  }
}

}  // namespace support
}  // namespace tvm

#endif  // TVM_SUPPORT_ENV_H_