bdlb_caselessstringviewequalto.h

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/// @file bdlb_caselessstringviewequalto.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlb_caselessstringviewequalto.h                                   -*-C++-*-
#ifndef INCLUDED_BDLB_CASELESSSTRINGVIEWEQUALTO
#define INCLUDED_BDLB_CASELESSSTRINGVIEWEQUALTO
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdlb_caselessstringviewequalto bdlb_caselessstringviewequalto
/// @brief  Provide a case-insensitive equality predicate for string views.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlb
/// @{
/// @addtogroup bdlb_caselessstringviewequalto
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlb_caselessstringviewequalto-purpose"> Purpose</a>
/// * <a href="#bdlb_caselessstringviewequalto-classes"> Classes </a>
/// * <a href="#bdlb_caselessstringviewequalto-description"> Description </a>
///   * <a href="#bdlb_caselessstringviewequalto-usage"> Usage </a>
///     * <a href="#bdlb_caselessstringviewequalto-example-1-basic-use-of-bdlb-caselessstringviewequalto"> Example 1: Basic Use of bdlb::CaselessStringViewEqualTo </a>
///
/// # Purpose {#bdlb_caselessstringviewequalto-purpose}
/// Provide a case-insensitive equality predicate for string views.
///
/// # Classes {#bdlb_caselessstringviewequalto-classes}
///
/// -  bdlb::CaselessStringViewEqualTo: case-insensitive string view comparison.
///
/// @see  bdlb_caselessstringviewhash, bdlb_caselessstringviewless
///
/// # Description {#bdlb_caselessstringviewequalto-description}
/// This component provides a `struct`,
/// `bdlb::CaselessStringViewEqualTo`, that defines a functor that checks two
/// string views for equality using a case-insensitive string comparison.  This
/// comparison functor is suitable for supporting `bsl::string`s or
/// `bsl::string_view`s as keys in unordered associative containers.
///
/// Note that using this component to do comparisons of keys in a container is
/// less efficient than converting all the keys to the same case prior to
/// insertion and then just doing straight string comparisons.
///
/// ## Usage {#bdlb_caselessstringviewequalto-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Basic Use of bdlb::CaselessStringViewEqualTo {#bdlb_caselessstringviewequalto-example-1-basic-use-of-bdlb-caselessstringviewequalto}
///
///
/// Suppose we have some strings that compare equal, some that don't, and some
/// of which are equal except for the cases of some of the letters.
/// @code
/// const bsl::string_view a = "To be or not to be, that is the question.";
/// const bsl::string_view b = "To be or not to be, THAT IS THE QUESTION.";
/// const bsl::string_view c = "Sein oder nicht sein, das ist die frage.";
/// @endcode
/// Now, we create an object of type `bdlb::CaselessStringViewEqualTo` to do the
/// comparisons:
/// @code
/// bdlb::CaselessStringViewEqualTo        eq;
/// const bdlb::CaselessStringViewEqualTo& equals = eq;
/// @endcode
/// Finally, we observe that `a` matches `b`, but neither matches `c`:
/// @code
/// assert( equals(a, b));
/// assert( equals(b, a));
/// assert(!equals(a, c));
/// assert(!equals(c, a));
/// assert(!equals(b, c));
/// assert(!equals(c, b));
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlb
 * @{
 */
/** @addtogroup bdlb_caselessstringviewequalto
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bdlb_stringviewutil.h>
 
#include <bslmf_istriviallycopyable.h>
#include <bslmf_istriviallydefaultconstructible.h>
#include <bslmf_nestedtraitdeclaration.h>
 
#include <bsl_string_view.h>
 
 
namespace bdlb {
 
                       // ================================
                       // struct CaselessStringViewEqualTo
                       // ================================
 
/// This `struct` defines a case-insensitive equality comparison functor on
/// string views, enabling them for use as keys in the standard unordered
/// associative containers such as `bsl::unordered_map` and
/// `bsl::unordered_set`.  Note that this `class` is an empty POD type.
struct CaselessStringViewEqualTo {
 
    // PUBLIC TYPES
    typedef bsl::string_view first_argument_type;
    typedef bsl::string_view second_argument_type;
    typedef bool             result_type;
 
    /// Type alias indicating this is a transparent hash functor.
    typedef void             is_transparent;
 
    // TRAITS
    BSLMF_NESTED_TRAIT_DECLARATION(CaselessStringViewEqualTo,
                                                    bsl::is_trivially_copyable)
    BSLMF_NESTED_TRAIT_DECLARATION(CaselessStringViewEqualTo,
                                       bsl::is_trivially_default_constructible)
 
    // CREATORS
 
    /// Create a `CaselessStringViewEqualTo` object.
     CaselessStringViewEqualTo() = default;
 
    /// Create a `CaselessStringViewEqualTo` object.  Note that as
    /// `CaselessStringViewEqualTo` is an empty (stateless) type, this
    /// operation has no observable effect.
     CaselessStringViewEqualTo(const CaselessStringViewEqualTo& original) =
                                                                    default;
 
    /// Destroy this object.
     ~CaselessStringViewEqualTo() = default;
 
    // MANIPULATORS
 
    /// Assign to this object the value of the specified `rhs` object, and
    /// return a reference providing modifiable access to this object.  Note
    /// that as `CaselessStringViewEqualTo` is an empty (stateless) type,
    /// this operation has no observable effect.
     CaselessStringViewEqualTo& operator=(const CaselessStringViewEqualTo&)
                                                                  = default;
 
    // ACCESSORS
 
    /// Return `true` if the specified `lhs` string view has the same (case
    /// insensitive) value as the specified `rhs` string view, and `false`
    /// otherwise.
    bool operator()(bsl::string_view lhs, bsl::string_view rhs) const;
};
 
// ============================================================================
//                              INLINE DEFINITIONS
// ============================================================================
 
                     // --------------------------------
                     // struct CaselessStringViewEqualTo
                     // --------------------------------
 
// ACCESSORS
inline
bool CaselessStringViewEqualTo::operator()(bsl::string_view lhs,
                                           bsl::string_view rhs) const
{
    return bdlb::StringViewUtil::areEqualCaseless(lhs, rhs);
}
 
}  // close package namespace
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2021 Bloomberg Finance L.P.
//
// 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
//
//     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.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */