# generate-exceptions: generate C++ files for Xapian's exception hierarchy.
#
# Copyright (C) 2003,2004,2006,2007,2008,2009 Olly Betts
# Copyright (C) 2007 Richard Boulton
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA

use strict;
use exception_data qw($copyright $generated_warning @baseclasses @classes);

open HDR, ">include/xapian/error.h" or die $!;
open DISPATCH, ">include/xapian/errordispatch.h" or die $!;

print HDR <<'EOF';
/** @file error.h
 *  @brief Hierarchy of classes which Xapian can throw as exceptions.
 */
EOF

print HDR $generated_warning;
print DISPATCH $generated_warning;

print HDR $copyright;
print DISPATCH $copyright;

print HDR <<'EOF';

#ifndef XAPIAN_INCLUDED_ERROR_H
#define XAPIAN_INCLUDED_ERROR_H

#include <string>
#include <xapian/visibility.h>

namespace Xapian {

class ErrorHandler;

/** All exceptions thrown by Xapian are subclasses of Xapian::Error.
 *
 *  This class can not be instantiated directly - instead a subclass should
 *  be used.
 */
class XAPIAN_VISIBILITY_DEFAULT Error {
    // ErrorHandler needs to be able to access Error::already_handled.
    friend class ErrorHandler;

    /// Message giving details of the error, intended for human consumption.
    std::string msg;

    /** Optional context information.
     *
     *  This context is intended for use by Xapian::ErrorHandler (for example
     *  so it can know which remote server is unreliable and report the problem
     *  and remove that server from those being searched).  But it's typically
     *  a plain-text string, and so also fit for human consumption.
     */
    std::string context;

    /// The type of this error (e.g. DocNotFoundError.)
    const char * type;

    /** Optional value of 'errno' associated with this error.
     *
     *  If no value is associated, this member variable will be 0.
     *
     *  On UNIX, if this value is < 0, it's a negated h_errno value (giving
     *  an error from gethostbyname() or similar).
     *
     *  On Windows, if this value is < 0, it's a negated Windows error code
     *  (as given by GetLastError()), while if it is >= WSABASEERR then it is a
     *  WinSock error code (as given by WSAGetLastError()).  Prior to Xapian
     *  1.2.20 and 1.3.3, WSAGetLastError() codes were also negated.
     *
     *  NB We don't just call this member "errno" to avoid problems on
     *  platforms where errno is a preprocessor macro.
     */
    int my_errno;

    /** The error string derived from my_errno.
     *
     *  This string is generated from my_errno lazily.
     */
    mutable std::string error_string;

    /// True if this error has already been passed to an ErrorHandler.
    bool already_handled;

    /// Don't allow assignment of the base class.
    void operator=(const Error &o);

  protected:
    /** @private @internal
     *  @brief Constructor for use by constructors of derived classes.
     */
    Error(const std::string &msg_, const std::string &context_,
	  const char * type_, const char * error_string_);

    /** @private @internal
     *  @brief Constructor for use by constructors of derived classes.
     */
    Error(const std::string &msg_, const std::string &context_,
	  const char * type_, int errno_)
	: msg(msg_), context(context_), type(type_), my_errno(errno_),
	  error_string(), already_handled(false) { }

  public:
    /// The type of this error (e.g. "DocNotFoundError".)
    const char * get_type() const { return type; }

    /// Message giving details of the error, intended for human consumption.
    const std::string & get_msg() const { return msg; }

    /** Optional context information.
     *
     *  This context is intended for use by Xapian::ErrorHandler (for example
     *  so it can know which remote server is unreliable and report the problem
     *  and remove that server from those being searched).  But it's typically
     *  a plain-text string, and so also fit for human consumption.
     */
    const std::string & get_context() const { return context; }

    /** Returns any system error string associated with this exception.
     *
     *  The system error string may come from errno, h_errno (on UNIX), or
     *  GetLastError() (on MS Windows).  If there is no associated system
     *  error string, NULL is returned.
     */
    const char * get_error_string() const;

    /// Return a string describing this object.
    std::string get_description() const;
};
EOF

print DISPATCH <<'EOF';

/* Note that this file isn't an external header - it's located in
 * include/xapian in the source tree because it's generated so this
 * is the simplest way to make inclusion work in a VPATH build.
 */

// DOXYGEN gets confused by this header-with-code.
#ifndef DOXYGEN
EOF

for (@baseclasses) {
    chomp;
    my ($class, $parent, $comment) = split /\t/, $_, 3;
    print HDR <<EOF;

$comment
class XAPIAN_VISIBILITY_DEFAULT $class : public $parent {
  protected:
    /** \@private \@internal
     *  \@brief Constructor for use by constructors of derived classes.
     */
    $class(const std::string \&msg_, const std::string \&context_, const char * type_, const char * error_string_)
	: $parent(msg_, context_, type_, error_string_) {}

    /** \@private \@internal
     *  \@brief Constructor for use by constructors of derived classes.
     */
    $class(const std::string \&msg_, const std::string \&context_, const char * type_, int errno_)
	: $parent(msg_, context_, type_, errno_) {}
};
EOF
}

for (@classes) {
    chomp;
    my ($class, $parent, $comment) = split /\t/, $_, 3;

    print DISPATCH "if (type == \"$class\") throw Xapian::$class(msg, context, error_string);\n";

    print HDR <<EOF;

$comment
class XAPIAN_VISIBILITY_DEFAULT $class : public $parent {
  public:
    /** \@private \@internal
     *  \@brief Private constructor for use by remote backend.
     *
     *  \@param error_string_	Optional string describing error.  May be NULL.
     */
    $class(const std::string \&msg_, const std::string \&context_, const char * error_string_)
	: $parent(msg_, context_, "$class", error_string_) {}
    /** General purpose constructor.
     *
     *  \@param msg_		Message giving details of the error, intended
     *				for human consumption.
     *  \@param context_	Optional context information for this error.
     *  \@param errno_		Optional errno value associated with this error.
     */
    explicit $class(const std::string \&msg_, const std::string \&context_ = std::string(), int errno_ = 0)
	: $parent(msg_, context_, "$class", errno_) {}
    /** Construct from message and errno value.
     *
     *  \@param msg_		Message giving details of the error, intended
     *				for human consumption.
     *  \@param errno_		Optional errno value associated with this error.
     */
    $class(const std::string \&msg_, int errno_)
	: $parent(msg_, std::string(), "$class", errno_) {}
  protected:
    /** \@private \@internal
     *  \@brief Constructor for use by constructors of derived classes.
     */
    $class(const std::string \&msg_, const std::string \&context_, const char * type_, const char * error_string_)
	: $parent(msg_, context_, type_, error_string_) {}

    /** \@private \@internal
     *  \@brief Constructor for use by constructors of derived classes.
     */
    $class(const std::string \&msg_, const std::string \&context_, const char * type_, int errno_)
	: $parent(msg_, context_, type_, errno_) {}
};
EOF
}

print HDR <<'EOF';

}

#endif /* XAPIAN_INCLUDED_ERROR_H */
EOF

print DISPATCH <<'EOF';
#endif /* DOXYGEN */
EOF

close HDR or die $!;
close DISPATCH or die $!;

# vim: set syntax=perl:
