bdljsn_error.h

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/// @file bdljsn_error.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdljsn_error.h                                                     -*-C++-*-
#ifndef INCLUDED_BDLJSN_ERROR
#define INCLUDED_BDLJSN_ERROR
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdljsn_error bdljsn_error
/// @brief  Provide a description of an error processing a document.
/// @addtogroup bdl
/// @{
/// @addtogroup bdljsn
/// @{
/// @addtogroup bdljsn_error
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdljsn_error-purpose"> Purpose</a>
/// * <a href="#bdljsn_error-classes"> Classes </a>
/// * <a href="#bdljsn_error-description"> Description </a>
///   * <a href="#bdljsn_error-attributes"> Attributes </a>
///   * <a href="#bdljsn_error-usage"> Usage </a>
///     * <a href="#bdljsn_error-example-1-populating-an-bdljsn-error-object"> Example 1: Populating an bdljsn::Error Object </a>
///
/// # Purpose {#bdljsn_error-purpose}
/// Provide a description of an error processing a document.
///
/// # Classes {#bdljsn_error-classes}
///
/// -  bdljsn::Error: a description of a document processing error
///
/// @see  bdljsn_jsonutil, bdljsn_json
///
/// # Description {#bdljsn_error-description}
/// This component provides a single, un-constrained
/// (value-semantic) attribute class, `bdljsn::Error`, that is used to describe
/// an error in the occured processing a (JSON) document.
///
/// ## Attributes {#bdljsn_error-attributes}
///
///
/// @code
/// Name                Type          Default
/// ------------------  -----------   -------
/// location            Location      Location(0)
/// message             string        ""
/// @endcode
/// * `location`: the location in the document where the error occured
/// * `message`: a description of the error that occured
///
/// ## Usage {#bdljsn_error-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Populating an bdljsn::Error Object {#bdljsn_error-example-1-populating-an-bdljsn-error-object}
///
///
/// This component is designed to describe an error that occured when processing
/// a (JSON) document.  Suppose we are implementing a function,
/// `extractIntegerToken`, that parses a numeric token and obtains an `int`
/// value:
///
/// First, we define the function signature:
/// @code
/// int extractIntegerToken(int              *value,
///                         bdljsn::Error    *error,
///                         bsl::string_view  inputText)
///     // Load to the specified 'value' the 'int' value represented by the
///     // specified 'inputText'.  Return 0 on success, and a non-zero value
///     // otherwise with no effect on '*value' and the specified 'error' is
///     // set.
/// {
///     BSLS_ASSERT(value);
///     BSLS_ASSERT(error);
///
///     enum { e_SUCCESS, e_FAILURE };
///     // ...
/// @endcode
/// Then, we attempt to exact a `int` value from the `inputText`:
/// @code
///     int                                      result;
///     bsl::pair<MyParseStatus::Enum, unsigned> status =
///                                MyNumericUtil::parseInt(&result, inputText);
/// @endcode
/// Now, we check the parse status and if unsuccessful, we use the status
/// information to set the `bsljsn::Error` object expected by our caller:
/// @code
///     if (MyParseStatus::e_OK != status.first) {
///         unsigned position = status.second;
///         error->setLocation(bdljsn::Location(static_cast<bsl::uint64_t>(
///                                                                position)));
///         error->setMessage(MyParseStatus::toAscii(status.first));
///         return e_FAILURE;                                         // RETURN
///     }
/// @endcode
/// Finally, if the parse was successful, set the output parameter and return
/// with status value that indicates success.
/// @code
///     *value = result;
///     return e_SUCCESS;
/// }
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdljsn
 * @{
 */
/** @addtogroup bdljsn_error
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bdljsn_location.h>
 
#include <bslh_hash.h>     // 'bslh::hashAppend'
 
#include <bslalg_swaputil.h>
 
#include <bslmf_isbitwisemoveable.h>
#include <bslmf_nestedtraitdeclaration.h>
 
#include <bsls_assert.h>
#include <bsls_keyword.h>
 
#include <bsl_ostream.h>
#include <bsl_string.h>
#include <bsl_string_view.h>
 
 
namespace bdljsn {
 
                                // ===========
                                // class Error
                                // ===========
 
/// This unconstrained (value-semantic) attribute class specifies a
/// description of an error in processing a (JSON) document.  See the
/// {Attributes} section under {DESCRIPTION} in the component-level
/// documentation for information on the class attributes.  Note that the
/// class invariants are identically the constraints on the individual
/// attributes.
///
/// See @ref bdljsn_error 
class Error {
 
    // DATA
    Location    d_location;  // location where the error occurred
    bsl::string d_message;   // a description of the error
 
    // FRIENDS
    friend void swap(Error& , Error& );
 
  public:
    // TRAITS
    BSLMF_NESTED_TRAIT_DECLARATION(Error, bslma::UsesBslmaAllocator);
    BSLMF_NESTED_TRAIT_DECLARATION(Error, bslmf::IsBitwiseMoveable);
 
    // CREATORS
 
    Error();
    /// Create an `Error` object having the default value (see
    /// {Attributes}).  Optionally specify a `basicAllocator` used to supply
    /// memory.  If `basicAllocator` is 0, the currently installed default
    /// allocator is used.
    explicit Error(bslma::Allocator *basicAllocator);
 
    /// Create an `Error` object having the specified `location` and
    /// `message`.  Optionally specify a `basicAllocator` used to supply
    /// memory.  If `basicAllocator` is 0, the currently installed default
    /// allocator is used.
    Error(const Location&          location,
          const bsl::string_view&  message,
          bslma::Allocator        *basicAllocator = 0);
 
    /// Create an `Error` object having the value of the specified
    /// `original` object.  Optionally specify a `basicAllocator` used to
    /// supply memory.  If `basicAllocator` is 0, the currently installed
    /// default allocator is used.
    Error(const Error& original, bslma::Allocator *basicAllocator = 0);
 
    /// Create a `Error` object having the same value and the same allocator
    /// as the specified `original` object.  The value of `original` becomes
    /// unspecified but valid, and its allocator remains unchanged.
    Error(bslmf::MovableRef<Error> original) BSLS_KEYWORD_NOEXCEPT;
 
    /// Create a `Error` object having the same value as the specified
    /// `original` object, and using the specified `basicAllocator` to
    /// supply memory.  If `basicAllocator` is 0, the currently installed
    /// default allocator is used.  The allocator of `original` remains
    /// unchanged.  If `original` and the newly created object have the same
    /// allocator then the value of `original` becomes unspecified but
    /// valid, and no exceptions will be thrown; otherwise `original` is
    /// unchanged and an exception may be thrown.
    Error(bslmf::MovableRef<Error>  original,
          bslma::Allocator         *basicAllocator);
 
    /// Destroy this object.
    ~Error();
 
    // MANIPULATORS
 
    /// Assign to this object the value of the specified `rhs` object, and
    /// return a non-`const` reference to this object.
    Error& operator=(const Error& rhs);
 
    /// Assign to this object the value of the specified `rhs` object, and
    /// return a non-`const` reference to this object.  The allocators of
    /// this object and `rhs` both remain unchanged.  If `rhs` and this
    /// object have the same allocator then the value of `rhs` becomes
    /// unspecified but valid, and no exceptions will be thrown; otherwise
    /// `rhs` is unchanged (and an exception may be thrown).
    Error& operator=(bslmf::MovableRef<Error> rhs);
 
    /// Reset this object to the default value (i.e., its value upon default
    /// construction).
    Error& reset();
 
    /// Set the `location` attribute of this object to the specified
    /// `value`.
    Error& setLocation(const Location& value);
 
    /// Set the `message` attribute of this object to the specified `value`.
    Error& setMessage(const bsl::string_view& value);
 
                        // Aspects
 
    /// Efficiently exchange the value of this object with the value of the
    /// specified `other` object.  This method provides the no-throw
    /// exception-safety guarantee.  The behavior is undefined unless this
    /// object was created with the same allocator as `other`.
    void swap(Error& other);
 
    // ACCESSORS
 
    /// Return the `location` attribute of this object.
    const Location& location() const;
 
    /// Return the `message` attribute of this object.
    const bsl::string&  message() const;
 
                                  // Aspects
 
    /// Return the allocator used by this object to supply memory.  Note
    /// that if no allocator was supplied at construction the default
    /// allocator in effect at construction is used.
    bslma::Allocator *allocator() const;
 
    /// Write the value of this object to the specified output `stream` in a
    /// human-readable format, and return a non-`const` reference to
    /// `stream`.  Optionally specify an initial indentation `level`, whose
    /// absolute value is incremented recursively for nested objects.  If
    /// `level` is specified, optionally specify `spacesPerLevel`, whose
    /// absolute value indicates the number of spaces per indentation level
    /// for this and all of its nested objects.  If `level` is negative,
    /// suppress indentation of the first line.  If `spacesPerLevel` is
    /// negative, format the entire output on one line, suppressing all but
    /// the initial indentation (as governed by `level`).  If `stream` is
    /// not valid on entry, this operation has no effect.  Note that the
    /// format is not fully specified, and can change without notice.
    bsl::ostream& print(bsl::ostream& stream,
                        int           level = 0,
                        int           spacesPerLevel = 4) const;
};
 
// FREE OPERATORS
 
/// Return `true` if the specified `lhs` and `rhs` attribute objects have
/// the same value, and `false` otherwise.  Two attribute objects have the
/// same value if each respective attribute has the same value.
bool operator==(const Error& lhs, const Error& rhs);
 
/// Return `true` if the specified `lhs` and `rhs` attribute objects do not
/// have the same value, and `false` otherwise.  Two attribute objects do
/// not have the same value if one or more respective attributes differ in
/// values.
bool operator!=(const Error& lhs, const Error& rhs);
 
/// Write the value of the specified `object` to the specified output
/// `stream` in a single-line format, and return a non-`const` reference to
/// `stream`.  If `stream` is not valid on entry, this operation has no
/// effect.  Note that this human-readable format is not fully specified and
/// can change without notice.  Also note that this method has the same
/// behavior as `object.print(stream, 0, -1)`, but with the attribute names
/// elided.
bsl::ostream& operator<<(bsl::ostream& stream, const Error& object);
 
// FREE FUNCTIONS
 
/// Pass the specified `object` to the specified `hashAlgorithm`.  This
/// function integrates with the `bslh` modular hashing system and
/// effectively provides a `bsl::hash` specialization for `ErroError`.
template <class HASHALG>
void hashAppend(HASHALG& hashAlgorithm, const Error& object);
 
/// Exchange the values of the specified `a` and `b` objects.  This function
/// provides the no-throw exception-safety guarantee if the two objects were
/// created with the same allocator and the basic guarantee otherwise.
void swap(Error& a, Error& b);
 
// ============================================================================
//                         INLINE DEFINITIONS
// ============================================================================
 
                                // -----------
                                // class Error
                                // -----------
 
// CREATORS
inline
Error::Error()
: d_location()
, d_message()
{
}
 
inline
Error::Error(bslma::Allocator *basicAllocator)
: d_location()
, d_message(basicAllocator)
{
}
 
inline
Error::Error(const Location&          location,
             const bsl::string_view&  message,
             bslma::Allocator        *basicAllocator)
: d_location(location)
, d_message(message, basicAllocator)
{
}
 
inline
Error::Error(const Error& original, bslma::Allocator *basicAllocator)
: d_location(original.d_location)
, d_message(original.d_message, basicAllocator)
{
}
 
inline
Error::Error(bslmf::MovableRef<Error> original) BSLS_KEYWORD_NOEXCEPT
: d_location(bslmf::MovableRefUtil::move(
                           bslmf::MovableRefUtil::access(original).d_location))
, d_message(bslmf::MovableRefUtil::move(
                            bslmf::MovableRefUtil::access(original).d_message))
{
}
 
inline
Error::Error(bslmf::MovableRef<Error>  original,
             bslma::Allocator         *basicAllocator)
: d_location(bslmf::MovableRefUtil::move(
                           bslmf::MovableRefUtil::access(original).d_location))
, d_message(bslmf::MovableRefUtil::move(
                            bslmf::MovableRefUtil::access(original).d_message),
            basicAllocator)
{
}
 
inline
Error::~Error()
{
}
 
// MANIPULATORS
inline
Error& Error::operator=(const Error& rhs)
{
    if (this != &rhs) {
        d_message  = rhs.d_message;  // do first for strong guarantee
        d_location = rhs.d_location;
    }
 
    return *this;
}
 
inline
Error& Error::operator=(bslmf::MovableRef<Error> rhs)
{
    Error error(bslmf::MovableRefUtil::move(rhs), allocator());
    error.swap(*this);
    return *this;
}
 
inline
Error& Error::reset()
{
    d_location.reset();
    d_message.clear();
    return *this;
}
 
inline
Error& Error::setLocation(const Location& value)
{
    d_location = value;
    return *this;
}
 
inline
Error& Error::setMessage(const bsl::string_view& value)
{
    d_message = value;
    return *this;
}
 
                        // Aspects
 
inline
void Error::swap(Error& other)
{
    BSLS_ASSERT(allocator() == other.allocator());
 
    bslalg::SwapUtil::swap(&d_location, &other.d_location);
    bslalg::SwapUtil::swap(&d_message,  &other.d_message);
}
 
// ACCESSORS
inline
const Location& Error::location() const
{
    return d_location;
}
 
inline
const bsl::string& Error::message() const
{
    return d_message;
}
 
                        // Aspects
 
inline
bslma::Allocator *Error::allocator() const
{
    return d_message.get_allocator().mechanism();
}
 
}  // close package namespace
 
// FREE OPERATORS
inline
bool bdljsn::operator==(const bdljsn::Error& lhs, const bdljsn::Error& rhs)
{
    return lhs.location() == rhs.location() && lhs.message() == rhs.message();
}
 
inline
bool bdljsn::operator!=(const bdljsn::Error& lhs, const bdljsn::Error& rhs)
{
    return lhs.location() != rhs.location() || lhs.message() != rhs.message();
}
 
// FREE FUNCTIONS
template <class HASHALG>
inline
void bdljsn::hashAppend(HASHALG& hashAlgorithm, const Error& object)
{
    using ::BloombergLP::bslh::hashAppend;
    hashAppend(hashAlgorithm, object.location());
    hashAppend(hashAlgorithm, object.message());
}
 
inline
void bdljsn::swap(Error& a, Error& b)
{
    bslalg::SwapUtil::swap(&a.d_location, &b.d_location);
    bslalg::SwapUtil::swap(&a.d_message,  &b.d_message);
}
 
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2022 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */