63 lines
2.3 KiB
C++
63 lines
2.3 KiB
C++
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#pragma once
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#include <string>
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#include <string_view>
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#include <expected>
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/**
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* @brief The namespace providing environment variable operations.
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* @details
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* When I programming with Rust, I was astonished that
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* Rust standard library have so much robust environment variable operations.
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* Oppositly, C++ STL still lake in this even in today.
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*
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* The functions manipulating environment variable is different in different OS.
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* I create this namespace inspired from Rust standard library
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* to glue all these things up and make a uniform interface.
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*/
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namespace yycc::rust::env {
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/// @brief The error occurs in this module.
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enum class EnvError {
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NoSuchName, ///< The variable with given name is not presented.
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BadEncoding, ///< Error when performing encoding convertion.
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BadArithmetic, ///< Error when performing arithmetic operations.
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BadCall, ///< Error occurs when calling backend functions.
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BadName, ///< Given name is ill-formated (empty string or has "=" character).
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NoMemory, ///< No enough memory to finish this operation.
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};
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/// @brief The result type in this module.
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template<typename T>
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using EnvResult = std::expected<T, EnvError>;
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/**
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* @brief Get the value of given environment variable name.
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* @param[in] name The name of environment variable
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* @return Gotten value, or error occurs.
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*/
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EnvResult<std::u8string> get_var(const std::u8string_view& name);
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/**
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* @brief Set the value of given environment variable name.
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* @details
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* If there is no such name variable presented in environment,
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* a new variable will be created,
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* otherwise, new value will overwrite old value.
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* @param[in] name The name of environment variable
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* @param[in] value The value to be written into.
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* @return Nothing or error occurs.
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*/
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EnvResult<void> set_var(const std::u8string_view& name, const std::u8string_view& value);
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/**
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* @brief Delete environment variable with given name.
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* @details
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* If given variable is not presented in environment,
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* this function will NOT return error.
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* @param[in] name The name of environment variable
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* @return Nothing, or error occurs.
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*/
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EnvResult<void> del_var(const std::u8string_view& name);
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} // namespace yycc::rust::env
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