bdlb_guidformatter.h

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/// @file bdlb_guidformatter.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlb_guidformatter.h                                               -*-C++-*-
#ifndef INCLUDED_BDLB_GUIDFORMATTER
#define INCLUDED_BDLB_GUIDFORMATTER
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdlb_guidformatter bdlb_guidformatter
/// @brief  Provide `bsl::formatter` specialization for `bdlb::Guid`.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlb
/// @{
/// @addtogroup bdlb_guidformatter
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlb_guidformatter-purpose"> Purpose</a>
/// * <a href="#bdlb_guidformatter-classes"> Classes </a>
/// * <a href="#bdlb_guidformatter-description"> Description </a>
///   * <a href="#bdlb_guidformatter-format-specification"> Format Specification </a>
///   * <a href="#bdlb_guidformatter-usage"> Usage </a>
///     * <a href="#bdlb_guidformatter-example-1-formatting-a-bdlb-guid"> Example 1: Formatting a bdlb::Guid </a>
///
/// # Purpose {#bdlb_guidformatter-purpose}
/// Provide `bsl::formatter` specialization for `bdlb::Guid`.
///
/// # Classes {#bdlb_guidformatter-classes}
///
/// -  bsl::formatter<bdlb::Guid, t_CHAR>: specialization to format `bdlb::Guid`
///
/// @see  bdlb_guid, bslfmt_format
///
/// # Description {#bdlb_guidformatter-description}
/// This component provides a partial specialization of the
/// `bsl::formatter` class template for `bdlb::Guid`, enabling `bdlb::Guid`
/// values to be used with `bsl::format` and its variants.
///
/// ## Format Specification {#bdlb_guidformatter-format-specification}
///
///
/// The supported format specification is a subset of the standard `std::format`
/// grammar:
/// @code
///   format-spec ::= [ [fill] align ] [ width ]
///   fill        ::= any character other than '{' or '}'
///   align       ::= '<' | '>' | '^'
///   width       ::= non-negative-integer | '{' [ arg-id ] '}'
/// @endcode
/// No sign, alternate-form (`#`), zero-pad (`0`), precision, or type
/// specifiers are supported.  The default alignment is left, matching the
/// convention for string-like types.  The formatted representation is always
/// the canonical 36-character lowercase hexadecimal form
/// `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`.
///
/// ## Usage {#bdlb_guidformatter-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Formatting a bdlb::Guid {#bdlb_guidformatter-example-1-formatting-a-bdlb-guid}
///
///
/// Suppose we have a `bdlb::Guid` object and want to render it as a string:
/// @code
///   const unsigned char raw[bdlb::Guid::k_GUID_NUM_BYTES] = {
///       0x5c, 0x9d, 0x4e, 0x53, 0x0d, 0xf1, 0x11, 0xe4,
///       0x91, 0x91, 0x08, 0x00, 0x20, 0x0c, 0x9a, 0x66 };
///   bdlb::Guid guid(raw);
///
///   bsl::string s = bsl::format("{}", guid);
///   assert(s == "5c9d4e53-0df1-11e4-9191-0800200c9a66");
/// @endcode
/// Width, alignment, and fill are supported as they would be for a string:
/// @code
///   bsl::string padded = bsl::format("{:*^40}", guid);
///   assert(padded == "**5c9d4e53-0df1-11e4-9191-0800200c9a66**");
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlb
 * @{
 */
/** @addtogroup bdlb_guidformatter
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bdlb_guid.h>
 
#include <bslfmt_format.h>
#include <bslfmt_formatspecificationparser.h>
#include <bslfmt_formattercharutil.h>
#include <bslfmt_padutil.h>
 
#include <bslmf_assert.h>
#include <bslmf_issame.h>
 
#include <bsls_keyword.h>
#include <bsls_libraryfeatures.h>
 
#include <bsl_iterator.h>
#include <bsl_string_view.h>
 
#include <cstddef>  // for `std::ptrdiff_t`
 
 
namespace bdlb {
 
                    // ==============================
                    // class Guid_BslFmtFormatterImpl
                    // ==============================
 
/// This component-private class template provides the implementation of the
/// `bsl::formatter` specialization for `bdlb::Guid` values.  The specified
/// `t_CHAR` template parameter determines both the format-string and the output character type.  
/// 
/// \pre The behavior is undefined   unless `t_CHAR` is
/// `char` or `wchar_t`.
///
/// See @ref bdlb_guidformatter 
template <class t_CHAR>
class Guid_BslFmtFormatterImpl {
  private:
    // PRIVATE TYPES
 
    /// A type alias for the format-specification parser.
    typedef bslfmt::FormatSpecificationParser<t_CHAR> Specification;
 
    // DATA
    Specification d_spec;  // parsed specification
 
  public:
    // MANIPULATORS
 
    /// Parse the format specification contained in the specified
    /// `parseContext` and return an iterator, pointing to the beginning of the
    /// unparsed section of the format string.  Throw a `bsl::format_error`
    /// exception if the specification does not conform to the grammar
    /// documented at the top of this component.
    template <class t_PARSE_CONTEXT>
    BSLS_KEYWORD_CONSTEXPR_CPP20 typename t_PARSE_CONTEXT::iterator parse(
                                                t_PARSE_CONTEXT& parseContext);
 
    // ACCESSORS
 
    /// Create a string representation of the specified `value` in accordance
    /// with the format specification previously parsed by `parse` (see grammar
    /// documented at the top of this component) and the specified
    /// `formatContext`, and copy it to the output iterator held by
    /// `formatContext`.  Return the updated output iterator.  
    /// 
    /// \pre The behavior is undefined   unless `t_FORMAT_CONTEXT::char_type` is `t_CHAR`.
    template <class t_FORMAT_CONTEXT>
    typename t_FORMAT_CONTEXT::iterator format(
                                        const Guid&       value,
                                        t_FORMAT_CONTEXT& formatContext) const;
};
 
}  // close package namespace
 
 
 
// FORMATTER SPECIALIZATIONS
namespace bsl {
 
/// This template partial specialization defines `bsl::formatter` for
/// `bdlb::Guid` values for both `char` and `wchar_t` character types.
template <class t_CHAR>
struct formatter<BloombergLP::bdlb::Guid, t_CHAR>
: BloombergLP::bdlb::Guid_BslFmtFormatterImpl<t_CHAR> {
};
 
}  // close namespace bsl
 
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP23_RANGE_FORMAT
// Opt `bdlb::Guid` out of `std::formatter`'s range specialization; without
// this, C++23 standard libraries would consider both this component's
// `bsl::formatter<Guid, ...>` (via `bsl`'s `std::formatter<t_ARG, t_CHAR>`
// bridge) and `std::formatter<Range, CharT>` as viable partial
// specializations, because `bdlb::Guid` satisfies `std::ranges::input_range`.
template <>
inline constexpr std::range_format
    std::format_kind<BloombergLP::bdlb::Guid> = std::range_format::disabled;
#endif  // BSLS_LIBRARYFEATURES_HAS_CPP23_RANGE_FORMAT
 
 
// ============================================================================
//                            INLINE DEFINITIONS
// ============================================================================
 
 
namespace bdlb {
 
                    // ------------------------------
                    // class Guid_BslFmtFormatterImpl
                    // ------------------------------
 
// MANIPULATORS
template <class t_CHAR>
template <class t_PARSE_CONTEXT>
BSLS_KEYWORD_CONSTEXPR_CPP20 typename t_PARSE_CONTEXT::iterator
Guid_BslFmtFormatterImpl<t_CHAR>::parse(t_PARSE_CONTEXT& parseContext)
{
    const typename Specification::Sections sections =
                        static_cast<typename Specification::Sections>(
                             Specification::e_SECTIONS_FILL_ALIGN
                           | Specification::e_SECTIONS_WIDTH);
 
    d_spec.parse(&parseContext, sections);
 
    return parseContext.begin();
}
 
// ACCESSORS
template <class t_CHAR>
template <class t_FORMAT_CONTEXT>
typename t_FORMAT_CONTEXT::iterator
Guid_BslFmtFormatterImpl<t_CHAR>::format(const Guid&       value,
                                         t_FORMAT_CONTEXT& formatContext) const
{
    BSLMF_ASSERT((bsl::is_same<t_CHAR,
                             typename t_FORMAT_CONTEXT::char_type>::value));
 
    typedef bslfmt::PadUtil<t_CHAR>           PadUtil;
    typedef bslfmt::FormatterCharUtil<t_CHAR> CharUtil;
 
    // Postprocess a *copy* of the parsed spec so that this formatter object
    // may be reused across multiple `format` invocations with different
    // format contexts (each carrying different nested-argument values for
    // width).
 
    Specification finalSpec(d_spec);
    finalSpec.postprocess(formatContext);
 
    const bsl::basic_string_view<t_CHAR> filler(
                                              finalSpec.filler(),
                                              finalSpec.numFillerCharacters());
 
    std::ptrdiff_t leftPad  = 0;
    std::ptrdiff_t rightPad = 0;
    PadUtil::computePadding(&leftPad,
                            &rightPad,
                            finalSpec.postprocessedWidth(),
                            Guid::k_GUID_NUM_CHARS,
                            finalSpec.alignment(),
                            Specification::e_ALIGN_LEFT);
 
    // Render the guid as ASCII.  `Guid::format` always writes exactly
    // `k_GUID_NUM_CHARS` characters and never a trailing null.
 
    char buffer[Guid::k_GUID_NUM_CHARS];
    value.format(buffer);
 
    typename t_FORMAT_CONTEXT::iterator outIt = formatContext.out();
 
    outIt = PadUtil::pad(outIt, leftPad, filler);
    outIt = CharUtil::outputFromChar(bsl::begin(buffer),
                                     bsl::end(buffer),
                                     outIt);
    outIt = PadUtil::pad(outIt, rightPad, filler);
 
    return outIt;
}
 
}  // close package namespace
 
 
#endif  // INCLUDED_BDLB_GUIDFORMATTER
 
// ----------------------------------------------------------------------------
// Copyright 2026 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */