bslfmt_formatparsecontext.h

Go to the documentation of this file.

/// @file bslfmt_formatparsecontext.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslfmt_formatparsecontext.h                                        -*-C++-*-
 
#ifndef INCLUDED_BSLFMT_FORMATPARSECONTEXT
#define INCLUDED_BSLFMT_FORMATPARSECONTEXT
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslfmt_formatparsecontext bslfmt_formatparsecontext
/// @brief  Provides access to formatting parsing string and parsing state.
/// @addtogroup bsl
/// @{
/// @addtogroup bslfmt
/// @{
/// @addtogroup bslfmt_formatparsecontext
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslfmt_formatparsecontext-purpose"> Purpose</a>
/// * <a href="#bslfmt_formatparsecontext-classes"> Classes </a>
/// * <a href="#bslfmt_formatparsecontext-canonical-header"> Canonical Header </a>
/// * <a href="#bslfmt_formatparsecontext-description"> Description </a>
///
/// # Purpose {#bslfmt_formatparsecontext-purpose}
/// Provides access to formatting parsing string and parsing state.
///
/// # Classes {#bslfmt_formatparsecontext-classes}
///
/// -  bslfmt::basic_format_parse_context: compliant format spec parse context
///
/// # Canonical Header {#bslfmt_formatparsecontext-canonical-header}
/// bsl_format.h
///
/// # Description {#bslfmt_formatparsecontext-description}
/// This component provides an implementation of the C++20 Standard
/// Library's `std::basic_format_parse_context`, which provides access to
/// formatting specification string, the parsing state, and the auto-indexing
/// argument counter (where applicable).
///
/// This header is not intended to be included directly.  Please include
/// `<bsl_format.h>` to be able to use `bsl::basic_format_parse_context`.
///
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslfmt
 * @{
 */
/** @addtogroup bslfmt_formatparsecontext
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslfmt_formaterror.h>
 
#include <bsls_exceptionutil.h>
#include <bsls_keyword.h>
 
#include <bslstl_stringview.h>
 
 
 
namespace bslfmt {
 
                 // ================================
                 // class basic_format_parse_context
                 // ================================
 
/// A format context for use by `formatter::parse()` partial specialization.
/// It provides access to iterators for the start and end of the remaining
/// (unparsed) format string, as well as argument counters.
///
/// See @ref bslfmt_formatparsecontext 
template <class t_CHAR>
class basic_format_parse_context {
  public:
    // TYPES
    typedef
        typename bsl::basic_string_view<t_CHAR>::const_iterator const_iterator;
    typedef const_iterator                                      iterator;
 
  private:
    // PRIVATE TYPES
    enum IndexingMode { e_UNKNOWN, e_MANUAL, e_AUTOMATIC };
 
    // DATA
    iterator     d_origBegin;  // start of format string
    iterator     d_unparsed;   // start of unparsed portion of format string
    iterator     d_end;        // end of format string
    IndexingMode d_indexing;   // current indexing mode
    size_t       d_nextArgId;  // next arg id for automatic indexing
    size_t       d_numArgs;    // number of args
 
  private:
    // NOT IMPLEMENTED
    basic_format_parse_context(
                       const basic_format_parse_context&) BSLS_KEYWORD_DELETED;
    basic_format_parse_context& operator=(
                       const basic_format_parse_context&) BSLS_KEYWORD_DELETED;
 
  public:
    // TYPES
    typedef t_CHAR char_type;
 
    // CREATORS
 
    /// Create an instance of this type with the specified `fmt` parse string
    /// and number of arguments set to zero.  The string is stored by reference,
    /// so `fmt` must outlive this object.
    BSLS_KEYWORD_CONSTEXPR_CPP20 explicit basic_format_parse_context(
                     bsl::basic_string_view<t_CHAR> fmt) BSLS_KEYWORD_NOEXCEPT;
 
    /// Create an instance of this type with the specified `fmt` parse string
    /// and number of arguments set to the specified `numArgs`.  The string is
    /// stored by reference, so `fmt` must outlive this object.
    BSLS_KEYWORD_CONSTEXPR_CPP20 explicit basic_format_parse_context(
                 bsl::basic_string_view<t_CHAR> fmt,
                 size_t                         numArgs) BSLS_KEYWORD_NOEXCEPT;
 
    // MANIPULATORS
 
    /// Update the held iterator to the unparsed portion of the format string
    /// to be the specified `it`.  Subsequent calls to `begin` will return this value.  
    /// 
    /// \pre The behavior is undefined   unless `it` is a valid iterator to
    /// the format string used in construction of this context.
    BSLS_KEYWORD_CONSTEXPR_CPP20 void advance_to(const_iterator it);
 
    /// Return the index of the next-unused argument.  If the indexing mode is
    /// unset, the indexing mode is set to `e_AUTOMATIC`.  If the indexing mode
    /// is `e_MANUAL`, caused by a previous call to @ref check_arg_id  then an
    /// exception of type @ref format_error  is thrown.  If there are no remaining
    /// unused arguments then an exception of type @ref format_error  is thrown.
    BSLS_KEYWORD_CONSTEXPR_CPP20 size_t next_arg_id();
 
    /// Check that the specified `id` is a valid argument index.  If the
    /// indexing mode is unset, the indexing mode is set to `e_MANUAL`.  If the
    /// indexing mode is `e_AUTOMATIC`, caused by a previous call to
    /// @ref next_arg_id  then an exception of type @ref format_error  is thrown.  If
    /// `id` is not less than the number of arguments then an exception of type
    /// @ref format_error  is thrown.
    BSLS_KEYWORD_CONSTEXPR_CPP20 void check_arg_id(size_t id);
 
    // ACCESSORS
 
    /// Return an iterator to the start of the unparsed portion of the format
    /// string.
    BSLS_KEYWORD_CONSTEXPR_CPP20 const_iterator
    begin() const BSLS_KEYWORD_NOEXCEPT;
 
    /// Return an iterator to the start of the unparsed portion of the format
    /// string.
    BSLS_KEYWORD_CONSTEXPR_CPP20 const_iterator
    end() const BSLS_KEYWORD_NOEXCEPT;
 
};
 
// TYPEDEFS
typedef basic_format_parse_context<char>     format_parse_context;
typedef basic_format_parse_context<wchar_t> wformat_parse_context;
 
// ============================================================================
//                           INLINE DEFINITIONS
// ============================================================================
 
                 // ---------------------------------
                  // class basic_format_parse_context
                  // --------------------------------
 
// CREATORS
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
basic_format_parse_context<t_CHAR>::basic_format_parse_context(
                      bsl::basic_string_view<t_CHAR> fmt) BSLS_KEYWORD_NOEXCEPT
: d_origBegin(fmt.begin())
, d_unparsed(fmt.begin())
, d_end(fmt.end())
, d_indexing(e_UNKNOWN)
, d_nextArgId(0)
, d_numArgs(0)
{
}
 
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
basic_format_parse_context<t_CHAR>::basic_format_parse_context(
                  bsl::basic_string_view<t_CHAR> fmt,
                  size_t                         numArgs) BSLS_KEYWORD_NOEXCEPT
: d_origBegin(fmt.begin())
, d_unparsed(fmt.begin())
, d_end(fmt.end())
, d_indexing(e_UNKNOWN)
, d_nextArgId(0)
, d_numArgs(numArgs)
{
}
 
// MANIPULATORS
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
void basic_format_parse_context<t_CHAR>::advance_to(const_iterator it)
{
    // This check is safe as, in our implementation, it is guaranteed that
    // const_iterator is a random access iterator.
    if (!((it >= d_origBegin) && (it <= d_end))) {
        BSLS_THROW(format_error(
               "Parse error: attempt to advance to an out-of-range iterator"));
    }
    d_unparsed = it;
}
 
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
size_t basic_format_parse_context<t_CHAR>::next_arg_id()
{
    if (d_indexing == e_MANUAL) {
        BSLS_THROW(format_error("Mixing of automatic and manual indexing"));
    }
    if (d_nextArgId >= d_numArgs) {
        BSLS_THROW(format_error("Number of conversion specifiers exceeds "
        "number of arguments"));
    }
    if (d_indexing == e_UNKNOWN) {
        d_indexing = e_AUTOMATIC;
    }
    return d_nextArgId++;
}
 
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
void basic_format_parse_context<t_CHAR>::check_arg_id(size_t id)
{
    if (d_indexing == e_AUTOMATIC) {
        BSLS_THROW(format_error("Mixing of automatic and manual indexing"));
    }
    if (id >= d_numArgs) {
        BSLS_THROW(format_error("Invalid argument index"));
    }
    if (d_indexing == e_UNKNOWN) {
        d_indexing = e_MANUAL;
    }
}
 
// ACCESSORS
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
typename basic_format_parse_context<t_CHAR>::const_iterator
basic_format_parse_context<t_CHAR>::begin() const BSLS_KEYWORD_NOEXCEPT
{
    return d_unparsed;
}
 
template <class t_CHAR>
inline
BSLS_KEYWORD_CONSTEXPR_CPP20
typename basic_format_parse_context<t_CHAR>::const_iterator
basic_format_parse_context<t_CHAR>::end() const BSLS_KEYWORD_NOEXCEPT
{
    return d_end;
}
 
}  // close package namespace
 
 
 
#endif  // INCLUDED_BSLFMT_FORMATPARSECONTEXT
 
// ----------------------------------------------------------------------------
// Copyright 2023 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */