check_constraint.hpp

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#pragma once
 
#include "core.hpp"
#include "fixed_string.hpp"
#include "meta.hpp"
 
#include <string>
#include <string_view>
 
namespace relx::schema {
 
template <fixed_string Condition, fixed_string Name = "">
class table_check_constraint {
public:
  constexpr std::string sql_definition() const {
    std::string result;
 
    // Add constraint name if provided
    if constexpr (!Name.empty()) {
      result = "CONSTRAINT " + std::string(std::string_view(Name)) + " ";
    }
 
    // Use the condition as-is
    result += "CHECK (" + std::string(std::string_view(Condition)) + ")";
    return result;
  }
 
  constexpr std::string_view condition() const { return std::string_view(Condition); }
 
  constexpr std::string_view name() const { return std::string_view(Name); }
};
 
template <auto ColumnPtr, fixed_string Condition, fixed_string Name = "">
class column_check_constraint {
public:
  constexpr std::string sql_definition() const {
    std::string result;
 
    // Add constraint name if provided
    if constexpr (!Name.empty()) {
      result = "CONSTRAINT " + std::string(std::string_view(Name)) + " ";
    }
 
    // Use the column name and condition
    using column_type = typename member_pointer_type<decltype(ColumnPtr)>::type;
 
    // Append the condition, replacing "column" or "COLUMN" with the actual column name if needed
    std::string condition_str = std::string(std::string_view(Condition));
    result += "CHECK (" + condition_str + ")";
 
    return result;
  }
 
  constexpr std::string_view condition() const { return std::string_view(Condition); }
 
  constexpr std::string_view name() const { return std::string_view(Name); }
 
  std::string_view column_name() const {
    using column_type = typename member_pointer_type<decltype(ColumnPtr)>::type;
    return column_type::name;
  }
};
 
template <fixed_string Condition, fixed_string Name>
constexpr auto named_check() {
  return table_check_constraint<Condition, Name>();
}
 
template <fixed_string Condition>
constexpr auto table_check() {
  return table_check_constraint<Condition, "">();
}
 
template <auto ColumnPtr, fixed_string Condition>
constexpr auto column_check() {
  return column_check_constraint<ColumnPtr, Condition, "">();
}
 
template <auto ColumnPtr, fixed_string Condition, fixed_string Name>
constexpr auto named_column_check() {
  return column_check_constraint<ColumnPtr, Condition, Name>();
}
 
}  // namespace relx::schema