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exception.hpp
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/**
* @file svnxx/exception.hpp
* @copyright
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
* ====================================================================
* @endcopyright
*/
#ifndef SVNXX_EXCEPTION_HPP
#define SVNXX_EXCEPTION_HPP
#include "svn_types_impl.h"
#include <exception>
#include <memory>
#include <new>
#include <stdexcept>
#include <string>
#include <vector>
/**
* @defgroup svnxx_exceptions SVN++ Exceptions
* @brief Exceptions in SVN++
*
* Exceptions in SVN++
* ===================
*
* SVN++ uses exceptions for the following purposes:
* @li Reporting memory allocation failure; where Subversion's
* default hehaviour is to abort when an allocation from an APR
* pool fails, SVN++ throws an exception instead.
* @li Reporting errors; Subversion's error messages are wrapped in
* exceptions.
* @li Reporting cancelled operations; an operation that was
* cancelled from user code will report this by throwing a
* specific exception type.
* @li Terminating iteration; user-level callbacks may throw a
* specific exception type to cancel an ongoing operation that
* is generating the callback messages. Other exceptions from
* user-level callbacks will be propagated back to the calling
* application.
*
* The SVN++ implementation will also throw standard exceptions when
* appropriate. Their use is documented in the relevant modules.
*
* Exception Hierarchy
* -------------------
*
* All SVN++ exceptions are ultimately derived from @c std::exception.
*
* * <em>std::exception</em>
* + <em>std::bad_alloc</em>
* - apache::subversion::svnxx::allocation_failed\n
* Thrown when memory cannot be allocated from an APR pool
* + <em>std::runtime_error</em>
* - apache::subversion::svnxx::error\n
* Thrown when an operation failed (see @ref svn_error_t)
* - apache::subversion::svnxx::cancelled\n
* Thrown when an operation was cancelled, including by the
* user code throwing a @c stop_iteration exception (see
* below)
* + apache::subversion::svnxx::stop_iteration\n
* Thrown by user callbacks to terminate iteration
*
* @{
*/
namespace apache {
namespace subversion {
namespace svnxx {
/**
* @brief Exception type that will be thrown when memory allocation fails.
*/
class allocation_failed : public std::bad_alloc
{
public:
virtual ~allocation_failed() noexcept {}
virtual const char* what() const noexcept override
{
return reason;
}
protected:
explicit allocation_failed(const char* what_arg) noexcept
: reason(what_arg)
{}
private:
const char* reason;
};
namespace detail {
using error_ptr = std::shared_ptr<svn_error_t>;
} // namespace detail
/**
* Encapsulate a stack of Subversion error codes and messages.
*/
class error : public std::exception,
protected detail::error_ptr
{
public:
virtual ~error() {}
/**
* Returns the message associated with the top-level error that
* caused the exception.
*
* @note the returned string is valid only as long as this @c error
* object is in scope.
*/
virtual const char* what() const noexcept override;
/**
* Returns the error code associated with the top-level error that
* caused the exception.
*/
virtual int code() const noexcept;
/**
* Returns the symbolic name of the error code associated with the
* top-level error that caused the exception.
* @note The returned value may be @c nullptr.
*/
virtual const char* name() const noexcept;
/**
* Error message description.
*/
class message
{
public:
/**
* Return the error code.
*/
int code() const noexcept { return m_errno; }
/**
* Return the error name.
* @note The returned value may be @c nullptr.
*/
const char* name() const noexcept { return m_errname; }
/**
* Return the error message.
*/
const std::string& text() const noexcept { return m_message; }
/**
* Return the generic error message associated with the error code.
*/
std::string generic_text() const;
/**
* Check if this message is in fact a debugging traceback entry.
*/
bool trace() const noexcept { return m_trace; }
protected:
message(int errval, const char* errname,
const std::string& message_, bool trace)
: m_errno(errval),
m_errname(errname),
m_message(message_),
m_trace(trace)
{}
private:
int m_errno;
const char* m_errname;
std::string m_message;
bool m_trace;
};
/**
* Returns the complete list of error messages, including those from
* nested errors.
*/
virtual std::vector<message> messages() const
{
return compile_messages(false);
}
/**
* Like error::messages(), but includes debugging traceback.
*
* @note
* Traceback is only available if the Subversion libraries were
* compiled with tracing enabled.
*/
virtual std::vector<message> traced_messages() const
{
return compile_messages(true);
}
protected:
error(detail::error_ptr err);
const char* const m_message;
std::vector<message> compile_messages(bool show_traces) const;
};
/**
* Thrown instead of Error when the error chain contains a
* @c SVN_ERR_CANCELLED error code.
*/
class cancelled : public error
{
public:
virtual ~cancelled() {}
protected:
cancelled(detail::error_ptr err)
: error(err)
{}
};
/**
* User code should throw this exception from callbacks to
* cancel an operation.
*/
class stop_iteration : public std::exception
{
public:
stop_iteration() {}
virtual ~stop_iteration() {}
virtual const char* what() const noexcept override;
};
} // namespace svnxx
} // namespace subversion
} // namespace apache
/**
* @}
*/
#endif // SVNXX_EXCEPTION_HPP
apache::subversion::svnxx::error::message
Error message description.
Definition exception.hpp:149
apache::subversion::svnxx::error::message::trace
bool trace() const noexcept
Check if this message is in fact a debugging traceback entry.
Definition exception.hpp:175
apache::subversion::svnxx::error::message::text
const std::string & text() const noexcept
Return the error message.
Definition exception.hpp:165
apache::subversion::svnxx::error::message::name
const char * name() const noexcept
Return the error name.
Definition exception.hpp:160
apache::subversion::svnxx::error::message::code
int code() const noexcept
Return the error code.
Definition exception.hpp:154
apache::subversion::svnxx::error::message::generic_text
std::string generic_text() const
Return the generic error message associated with the error code.
apache::subversion::svnxx::error
Encapsulate a stack of Subversion error codes and messages.
Definition exception.hpp:119
apache::subversion::svnxx::error::what
virtual const char * what() const noexcept override
Returns the message associated with the top-level error that caused the exception.
apache::subversion::svnxx::error::traced_messages
virtual std::vector< message > traced_messages() const
Like error::messages(), but includes debugging traceback.
Definition exception.hpp:209
apache::subversion::svnxx::error::messages
virtual std::vector< message > messages() const
Returns the complete list of error messages, including those from nested errors.
Definition exception.hpp:197
apache::subversion::svnxx::error::name
virtual const char * name() const noexcept
Returns the symbolic name of the error code associated with the top-level error that caused the excep...
apache::subversion::svnxx::error::code
virtual int code() const noexcept
Returns the error code associated with the top-level error that caused the exception.
err
svn_error_t * err
Points to an error describing the reason for the failure when action is one of the following: svn_wc_...
Definition svn_wc.h:1417
svn_types_impl.h
Subversion's data types (common implementation).