/*
 * File:    dbg.cpp
 * Author:  Pete Goodliffe
 * Version: 1.20
 * Created: 20 July 2003
 *
 * Purpose: C++ debugging support library
 *
 * Copyright (c) Pete Goodliffe 2001-2002 (pete@cthree.org)
 *
 * This file is modifiable/redistributable under the terms of the GNU
 * Lesser General Public License.
 *
 * You should have recieved a copy of the GNU General Public License along
 * with this program; see the file COPYING. If not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 0211-1307, USA.
 */

#ifndef DBG_ENABLED
#define DBG_ENABLED
#endif

#include "dbg.h"

#include <iostream>
#include <cstdlib>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <new>

    /**********************************************************************
     * Implementation notes
     **********************************************************************
     * Tested and found to work ok under
     *  - gcc 2.96
     *  - gcc 3.0
     *  - gcc 3.1
     *  - gcc 3.2
     *  - bcc32 5.5.1
     *  - MSVC 6.0
     *
     * MSVC v6.0
     *  - This platform makes me cry.
     *  - There are NUMEROUS hacks around it's deficient behaviour, just
     *    look for conditional complation based around _MSC_VER
     *  - The <ctime> header doesn't put all the definitions into the std
     *    namespace.
     *  - This means that we have to sacrifice our good namespace-based code
     *    for something more disgusting and primitve.
     *  - Where this has happened, and where in the future I'd really like to
     *    put the "std" namespace back in, I have instead used a STDCLK macro.
     *    See the implementation comment about this below for more grief.
     *  - A documented hack has been made in the dbg.h header file, of slightly
     *    less ghastly proportions. See dbgclock_t there.
     *  - Additionally, the dbg::array_size template utility could be (and was)
     *    more  elegantly be written:
     *         template <class T, int size>
     *         inline unsigned int array_size(T (&array)[size])
     *         {
     *             return size;
     *         }
     *    Of course, MSVC doesn't like that. Sigh. The version in dbg.h also
     *    works, its just not quite so nice.
     *  - The map implentation of MSVC doesn't provide data_type, so I have to
     *    hack around that.
     *  - The compiler doesn't like the dbg_ostream calling it's parent
     *    constructor by the name "ostream", it doesn't recognise the typedef.
     *    Ugh.
     *
     * Other thoughts:
     *  - Break out to debugger facility?
     *  - Only works for ostreams, not all basic_ostreams
     *  - Post-conditions are a bit limited, this is more of a C++
     *    language limitation, really.
     *********************************************************************/

/******************************************************************************
 * Tedious compiler-specific issues
 *****************************************************************************/

// Work around MSVC 6.0
#ifdef _MSC_VER
#define STDCLK
#pragma warning(disable:4786)
#else
// In an ideal world, the following line would be
//     namespace STDCLK = std;
// However, gcc 2.96 doesn't seem to cope well with namespace aliases.
// Sigh.
#define STDCLK std
#endif

// Quieten tedius build warnings on Borland C++ compiler
#ifdef __BCPLUSPLUS__
#pragma warn -8066
#pragma warn -8071
#pragma warn -8070
#endif

/******************************************************************************
 * General dbg library private declarations
 *****************************************************************************/

namespace
{
    /**************************************************************************
     * Constants
     *************************************************************************/

    const char *LEVEL_NAMES[] =
    {
        "info",
        "warning",
        "error",
        "fatal",
        "tracing",
        "debug",
        "none",
        "all"
    };
    const char *BEHAVIOUR_NAMES[] =
    {
        "assertions_abort",
        "assertions_throw",
        "assertions_continue"
    };
    enum constraint_type
    {
        why_assertion,
        why_sentinel,
        why_unimplemented,
        why_check_ptr
    };

    const char         *TRACE_IN         = "->";
    const char         *TRACE_OUT        = "<-";
    const char         *INDENT           = "  ";
    const char         *PREFIX           = "*** ";
    const char         *TRUE_STRING      = "true";
    const char         *FALSE_STRING     = "false";
    const unsigned int  ALL_SOURCES_MASK = 0xff;
    const unsigned int  NUM_DBG_LEVELS   = dbg::all-1;

    /**************************************************************************
     * Internal types
     *************************************************************************/

    /**
     * Period information about a particular @ref source_pos. Used if
     * assertion periods are enabled.
     *
     * @internal
     */
    struct period_data
    {
        size_t          no_triggers;
        STDCLK::clock_t triggered_at;

        period_data();
    };

    /**
     * Functor to provide comparison of @ref dbg::source_pos structs.
     *
     * @internal
     */
    struct lt_sp
    {
        bool operator()(const dbg::source_pos &a, const dbg::source_pos &b)
            const
        {
            if (a.file == b.file)
            {
                if (a.func == b.func)
                {
                    return a.line < b.line;
                }
                else
                {
                    return a.func < b.func;
                }
            }
            else
            {
                return a.file < b.file;
            }
        }
    };

    /**
     * A handy std::streambuf that sends its input to multiple output streams.
     *
     * This is the cornerstone of the dbg output stream magic.
     *
     * The multiple streams are recorded in a std::vector. The vector is
     * external to this class, and maintained by the @ref dbg_ostream which
     * uses this streambuf.
     *
     * @internal
     */
    class dbg_streambuf : public std::streambuf
    {
        public:

            dbg_streambuf(std::vector<std::ostream*> &ostreams, int bsize = 0);
            ~dbg_streambuf();

            int pubsync() { return sync(); }

        protected:

            int overflow(int);
            int sync();

        private:

            void put_buffer(void);
            void put_char(int);

            std::vector<std::ostream *> &ostreams;
    };

    /**
     * A handy streambuf that swallows its output and doesn't burp.
     *
     * This is used for disabled diagnostic output streams.
     *
     * There is a single stream object created using this streambuf,
     * null_ostream.
     *
     * @internal
     */
    class null_streambuf : public std::streambuf
    {
        public:

            null_streambuf()  {}
            ~null_streambuf() {}

        protected:

            int overflow(int) { return 0; }
            int sync()        { return 0; }
    };

    /**
     * This class provides an ostream using the @ref dbg_streambuf. It manages
     * the vector on which the @ref dbg_streambuf relies. It provides methods
     * to add/remove and clear streams.
     *
     * There are some minor hacks to support MSVC which cause small headaches.
     *
     * @internal
     */
    class dbg_ostream : public std::ostream
    {
        public:

#ifndef _MSC_VER
            dbg_ostream() : std::ostream(&dbg_buf), dbg_buf(streams) {}
            dbg_ostream(const dbg_ostream &rhs)
                : std::ostream(&dbg_buf), streams(rhs.streams),
                  dbg_buf(streams) {}
#else
            // MSVC workaround. Sigh. It won't let us call the parent ctor as
            // "ostream" - it doesn't like the use of a typedef. On the other
            // hand gcc 2.96 doesn't provide basic_ostream, so I can't call the
            // base basic_ostream<> class there.
            dbg_ostream()
                : std::basic_ostream<char>(&dbg_buf), dbg_buf(streams) {}
            dbg_ostream(const dbg_ostream &rhs)
                : std::basic_ostream<char>(&dbg_buf), streams(rhs.streams),
                  dbg_buf(streams) {}
#endif
            ~dbg_ostream() { dbg_buf.pubsync(); }

            void add(std::ostream &o);
            void remove(std::ostream &o);
            void clear();

        private:

            dbg_ostream &operator=(const dbg_ostream&);

            typedef std::vector<std::ostream*> stream_vec_type;

            stream_vec_type streams;
            dbg_streambuf   dbg_buf;
    };

    /**
     * The source_info class holds all the information associated with a
     * debugging source. That is, the level enable settings and the
     * set of output streams for each level.
     *
     * source_info objects are held in the @ref source_map. The default
     * constructor magically takes settings from the @ref dbg::default_source.
     * This actually makes the constructor code a little tortuous, but it's
     * worth it.
     *
     * @internal
     */
    class source_info
    {
        public:

            /**
             * The source_info can either be constructed as a copy of the
             * default_source or not. The only time we choose not to is
             * when constructing default_source!
             */
            enum ConstructionStyle
            {
                ConstructTheDefaultSource    = 0,
                ConstructCopyOfDefaultSource = 1
            };

            source_info(ConstructionStyle cs = ConstructCopyOfDefaultSource);
            source_info(const source_info &rhs);
            ~source_info();

            /**
             * Enable or disable the given level, depending on the value
             * of the boolean.
             */
            void enable(dbg::level lvl, bool enable);

            /**
             * Returns whether or not the level is enabled.
             */
            bool enabled(dbg::level lvl) const
            {
                return (levels & dbg_source_mask(lvl)) != 0;
            }

            /**
             * Add an ostream to catch output at the specified level.
             */
            void add_ostream(dbg::level lvl, std::ostream &o);

            /**
             * Remove an ostream from the specified level.
             */
            void remove_ostream(dbg::level lvl, std::ostream &o);

            /**
             * Clear all ostreams from the given level.
             */
            void clear_ostream(dbg::level lvl);

            /**
             * Return a stream to write to for the given level, or the
             * @ref null_ostream if the level is not enabled for this source.
             */
            std::ostream &out(dbg::level lvl);

        private:

            /**
             * Creates a unsigned int mask that is used as the second value
             * of the sources map.
             */
            static unsigned int dbg_source_mask(dbg::level lvl)
            {
                return (lvl != dbg::all) ? 1 << lvl : ALL_SOURCES_MASK;
            }

            unsigned int levels;

            // We do a placement new of the dbg_streams array.
            // It looks somewhat tacky, but it allows us to have a single
            // constructor, which simplifies the client interface of this class.
            // It specifically avoids tonnes of grotesque unused dbg_ostream
            // constructions, as you'd create an array, and then copy the
            // default_source elements directly over these freshly constructed
            // elements. dbg_ostream is complex enough that this matters.
            // If we didn't have a clever cloning constructor, these lines
            // would just be "dbg_ostream dbg_streams[NUM_DBG_LEVELS];" and
            // we'd suffer a whole load of redundant dbg_ostream constructions.
            /*
            typedef        dbg_ostream array_type[NUM_DBG_LEVELS];
            dbg_ostream   *dbg_streams;
            unsigned char  raw_dbg_streams[sizeof(array_type)];
            */
            struct array_type
            {
                // I wrap this up in an enclosing struct to make it obvious
                // how to destroy the array "in place". To be honest I couldn't
                // figure the syntax for the corresponding delete for a
                // placement new array constrution.
                dbg_ostream dbg_streams[NUM_DBG_LEVELS];
            };
            dbg_ostream   *dbg_streams;
            unsigned char  raw_dbg_streams[sizeof(array_type)];

            array_type &raw_cast()
            {
                return *reinterpret_cast<array_type*>(raw_dbg_streams);
            }
            const array_type &raw_cast() const
            {
                return *reinterpret_cast<const array_type*>(raw_dbg_streams);
            }
    };

    /**
     * This class provides a "map" type for the source_map. It's a thin veneer
     * around a std::map. The only reason for it's existance is the ctor which
     * creates the default source_info, and inserts it into the map.
     *
     * Only the member functions that are needed below have been implemented,
     * each as forwards to the std::map methods.
     *
     * @internal
     */
    class source_map_type
    {
        public:

            typedef std::map<std::string, source_info> map_type;
            typedef map_type::iterator                 iterator;
            typedef map_type::key_type                 key_type;
#ifndef _MSC_VER
            typedef map_type::data_type                data_type; // pre 3.3
            typedef map_type::mapped_type              data_type; // gcc 3.3
#else
            // MSVC. Just don't ask.
            typedef source_info                        data_type;
#endif
            source_map_type()
            {
                // Insert the default_source into the map
                _map.insert(
                    std::make_pair(dbg::default_source,
                    source_info(source_info::ConstructTheDefaultSource)));
                // Insert the unnamed source into the map too
                _map.insert(
                    std::make_pair(dbg::dbg_source(""),
                    source_info(source_info::ConstructTheDefaultSource)));
            }
            iterator   begin()                  { return _map.begin(); }
            iterator   end()                    { return _map.end();   }
            data_type &operator[](key_type key) { return _map[key];    }

        private:

            map_type _map;
    };

    typedef std::map<dbg::source_pos, period_data, lt_sp> period_map_type;

    /**************************************************************************
     * Internal variables
     *************************************************************************/

    // The stream to write to when no output is required.
    std::ostream null_ostream(new null_streambuf());

    dbg::assertion_behaviour behaviour[dbg::all+1] =
    {
        dbg::assertions_abort,
        dbg::assertions_abort,
        dbg::assertions_abort,
        dbg::assertions_abort,
        dbg::assertions_abort,
        dbg::assertions_abort,
        dbg::assertions_abort,
        dbg::assertions_abort
    };

    unsigned int    indent_depth  = 0;
    std::string     indent_prefix = PREFIX;
    bool            level_prefix  = false;
    bool            time_prefix   = false;
    STDCLK::clock_t period        = 0;
    source_map_type source_map;
    period_map_type period_map;

    /**************************************************************************
     * Function declarations
     *************************************************************************/

    /**
     * Prints a source_pos to the given ostream.
     */
    void print_pos(std::ostream &out, const dbg::source_pos &where);

    /**
     * Prints a source_pos to the given ostream in short format
     * (suitable for trace).
     */
    void print_pos_short(std::ostream &out, const dbg::source_pos &where);

    /**
     * Prints period information to the given ostream, if a period has been
     * enabled.
     */
    void print_period_info(std::ostream &out, const dbg::source_pos &where);

    /**
     * Does whatever the assertion_behaviour is set to. If an assertion
     * is triggered, then this will be called.
     */
    void do_assertion_behaviour(dbg::level lvl, constraint_type why,
                                const dbg::source_pos &pos);

    /**
     * Produces a level prefix for the specified level to the
     * given ostream.
     */
    void do_prefix(dbg::level lvl, std::ostream &s);

    /**
     * Used by period_allows below.
     */
    bool period_allows_impl(const dbg::source_pos &where);

    /**
     * Returns whether the period allows the constraint at the specified
     * @ref dbg::source_pos to trigger. This presumes that the assertion
     * at this position has shown to be broken already.
     *
     * This is a small inline function to make code that uses the period
     * implementation easier to read.
     */
    inline bool period_allows(const dbg::source_pos &where)
    {
        return !period || period_allows_impl(where);
    }

    /**
     * Given a dbg_source (which could be a zero pointer, or a source string)
     * and the source_pos (which could contain a DBG_SOURCE defintion, or
     * zero), work out what the dbg_source name to use is.
     */
    void determine_source(dbg::dbg_source &src, const dbg::source_pos &here);
}


/******************************************************************************
 * Miscellaneous public bobbins
 *****************************************************************************/

dbg::dbg_source dbg::default_source = "dbg::private::default_source";


/******************************************************************************
 * Enable/disable dbg facilities
 *****************************************************************************/

void dbg::enable(dbg::level lvl, bool enabled)
{
    out(debug) << prefix(debug) << "dbg::enable(" << LEVEL_NAMES[lvl]
               << "," << (enabled ? TRUE_STRING : FALSE_STRING) << ")\n";

    source_map[""].enable(lvl, enabled);
}


void dbg::enable(dbg::level lvl, dbg::dbg_source src, bool enabled)
{
    out(debug) << prefix(debug) << "dbg::enable(" << LEVEL_NAMES[lvl]
               << ",\"" << src << "\","
               << (enabled ? TRUE_STRING : FALSE_STRING) << ")\n";

    source_map[src].enable(lvl, enabled);
}


void dbg::enable_all(dbg::level lvl, bool enabled)
{
    out(debug) << prefix(debug) << "dbg::enable_all("
               << LEVEL_NAMES[lvl] << ","
               << (enabled ? TRUE_STRING : FALSE_STRING) << ")\n";

    source_map_type::iterator i = source_map.begin();
    for ( ; i != source_map.end(); ++i)
    {
        (i->second).enable(lvl, enabled);
    }
}


/******************************************************************************
 * Logging
 *****************************************************************************/

std::ostream &dbg::out(dbg::level lvl, dbg::dbg_source src)
{
    return source_map[src ? src : ""].out(lvl);
}


void dbg::attach_ostream(dbg::level lvl, std::ostream &o)
{
    out(debug) << prefix(debug) << "dbg::attach_ostream("
               << LEVEL_NAMES[lvl] << ",ostream)\n";

    source_map[""].add_ostream(lvl, o);
}


void dbg::attach_ostream(dbg::level lvl, dbg::dbg_source src, std::ostream &o)
{
    out(debug) << prefix(debug) << "dbg::attach_ostream("
               << LEVEL_NAMES[lvl]
               << ", \"" << src
               << "\" ,ostream)\n";

    source_map[src].add_ostream(lvl, o);
}


void dbg::detach_ostream(dbg::level lvl, std::ostream &o)
{
    out(debug) << prefix(debug) << "dbg::detach_ostream("
               << LEVEL_NAMES[lvl] << ")\n";

    source_map[""].remove_ostream(lvl, o);
}


void dbg::detach_ostream(dbg::level lvl, dbg::dbg_source src, std::ostream &o)
{
    out(debug) << prefix(debug) << "dbg::detach_ostream("
               << LEVEL_NAMES[lvl]
               << ", \"" << src
               << "\" ,ostream)\n";

    source_map[src].remove_ostream(lvl, o);
}


void dbg::detach_all_ostreams(dbg::level lvl)
{
    out(debug) << prefix(debug) << "dbg::detach_all_ostreams("
               << LEVEL_NAMES[lvl]
               << ")\n";

    source_map[""].clear_ostream(lvl);
}


void dbg::detach_all_ostreams(dbg::level lvl, dbg::dbg_source src)
{
    out(debug) << prefix(debug) << "dbg::detach_all_ostreams("
               << LEVEL_NAMES[lvl]
               << ", \"" << src << "\")\n";

    source_map[src].clear_ostream(lvl);
}


/******************************************************************************
 * Output formatting
 *****************************************************************************/

void dbg::set_prefix(const char *pfx)
{
    out(debug) << prefix(debug) << "dbg::set_prefix(" << pfx << ")\n";

    indent_prefix = pfx;
}


void dbg::enable_level_prefix(bool enabled)
{
    out(debug) << prefix(debug) << "dbg::enable_level_prefix("
               << (enabled ? TRUE_STRING : FALSE_STRING) << ")\n";

    level_prefix = enabled;
}


void dbg::enable_time_prefix(bool enabled)
{
    out(debug) << prefix(debug) << "dbg::enable_time_prefix("
               << (enabled ? TRUE_STRING : FALSE_STRING) << ")\n";

    time_prefix = enabled;
}


std::ostream &dbg::operator<<(std::ostream &s, const prefix &p)
{
    s << indent_prefix.c_str();
    do_prefix(p.l, s);
    return s;
}


std::ostream &dbg::operator<<(std::ostream &s, const indent &i)
{
    s << indent_prefix.c_str();
    do_prefix(i.l, s);
    for (unsigned int n = 0; n < indent_depth; n++) s << INDENT;
    return s;
}


std::ostream &dbg::operator<<(std::ostream &s, const source_pos &pos)
{
    print_pos(s, pos);
    return s;
}


/******************************************************************************
 * Behaviour
 *****************************************************************************/

void dbg::set_assertion_behaviour(level lvl, dbg::assertion_behaviour b)
{
    out(debug) << prefix(debug) << "dbg::set_assertion_behaviour("
               << LEVEL_NAMES[lvl] << "," << BEHAVIOUR_NAMES[b] << ")\n";

    if (lvl < dbg::all)
    {
        behaviour[lvl] = b;
    }
    else
    {
        for (int n = 0; n < dbg::all; n++)
        {
            behaviour[n] = b;
        }
    }
}


void dbg::set_assertion_period(dbgclock_t p)
{
    out(debug) << prefix(debug) << "dbg::set_assertion_period("
               << p << ")\n";

    if (!p && period)
    {
        period_map.clear();
    }

    period = p;

    if (p && STDCLK::clock() == -1)
    {
        period = p;
        out(debug) << prefix(debug)
                   << "*** WARNING ***\n"
                   << "Platform does not support std::clock, and so\n"
                   << "dbg::set_assertion_period is not supported.\n";
    }
}


/******************************************************************************
 * Assertion
 *****************************************************************************/

void dbg::assertion(dbg::level lvl, dbg::dbg_source src,
                    const assert_info &info)
{
    determine_source(src, info);

    if (source_map[src].enabled(lvl) && !info.asserted && period_allows(info))
    {
        std::ostream &o = out(lvl, src);

        o << indent(lvl) << "assertion \"" << info.text << "\" failed ";
        if (strcmp(src, ""))
        {
            o << "for \"" << src << "\" ";
        }
        o << "at ";
        print_pos(o, info);
        print_period_info(o, info);
        o << "\n";

        do_assertion_behaviour(lvl, why_assertion, info);
    }
}


/******************************************************************************
 * Sentinel
 *****************************************************************************/

void dbg::sentinel(dbg::level lvl, dbg::dbg_source src, const source_pos &here)
{
    determine_source(src, here);

    if (source_map[src].enabled(lvl) && period_allows(here))
    {
        std::ostream &o = out(lvl, src);
        o << indent(lvl) << "sentinel reached at ";
        print_pos(o, here);
        print_period_info(o, here);
        o << "\n";

        do_assertion_behaviour(lvl, why_sentinel, here);
    }
}


/******************************************************************************
 * Unimplemented
 *****************************************************************************/

void dbg::unimplemented(dbg::level lvl, dbg::dbg_source src,
                        const source_pos &here)
{
    determine_source(src, here);

    if (source_map[src].enabled(lvl) && period_allows(here))
    {
        std::ostream &o = out(lvl, src);
        o << indent(lvl) << "behaviour not yet implemented at ";
        print_pos(o, here);
        print_period_info(o, here);
        o << "\n";

        do_assertion_behaviour(lvl, why_unimplemented, here);
    }
}


/******************************************************************************
 * Pointer checking
 *****************************************************************************/

void dbg::check_ptr(dbg::level lvl, dbg::dbg_source src,
                    const void *p, const source_pos &here)
{
    determine_source(src, here);

    if (source_map[src].enabled(lvl) && p == 0 && period_allows(here))
    {
        std::ostream &o = out(lvl, src);
        o << indent(lvl) << "pointer is zero at ";
        print_pos(o, here);
        print_period_info(o, here);
        o << "\n";

        do_assertion_behaviour(lvl, why_check_ptr, here);
    }
}


/******************************************************************************
 * Bounds checking
 *****************************************************************************/

void dbg::check_bounds(dbg::level lvl, dbg::dbg_source src,
                       int index, int bound, const source_pos &here)
{
    determine_source(src, here);

    if (source_map[src].enabled(lvl)
        && index >= 0 && index >= bound
        && period_allows(here))
    {
        std::ostream &o = out(lvl, src);
        o << indent(lvl) << "index " << index << " is out of bounds ("
          << bound << ") at ";
        print_pos(o, here);
        print_period_info(o, here);
        o << "\n";

        do_assertion_behaviour(lvl, why_check_ptr, here);
    }
}


/******************************************************************************
 * Tracing
 *****************************************************************************/

dbg::trace::trace(func_name_t name)
: m_src(0), m_name(name), m_pos(DBG_HERE), m_triggered(false)
{
    determine_source(m_src, m_pos);

    if (source_map[m_src].enabled(dbg::tracing))
    {
        trace_begin();
    }
}


dbg::trace::trace(dbg_source src, func_name_t name)
: m_src(src), m_name(name), m_pos(DBG_HERE), m_triggered(false)
{
    determine_source(m_src, m_pos);

    if (source_map[m_src].enabled(dbg::tracing))
    {
        trace_begin();
    }
}


dbg::trace::trace(const source_pos &where)
: m_src(0), m_name(0), m_pos(where), m_triggered(false)
{
    determine_source(m_src, m_pos);

    if (source_map[m_src].enabled(dbg::tracing))
    {
        trace_begin();
    }
}


dbg::trace::trace(dbg_source src, const source_pos &where)
: m_src(src), m_name(0), m_pos(where), m_triggered(false)
{
    determine_source(m_src, m_pos);

    if (source_map[src].enabled(dbg::tracing))
    {
        trace_begin();
    }
}


dbg::trace::~trace()
{
    if (m_triggered)
    {
        trace_end();
    }
}


void dbg::trace::trace_begin()
{
    std::ostream &o = out(dbg::tracing, m_src);
    o << indent(tracing);
    indent_depth++;
    o << TRACE_IN;
    if (m_name)
    {
        o << m_name;
    }
    else
    {
        print_pos_short(o, m_pos);
    }
    if (m_src && strcmp(m_src, ""))
    {
        o << " (for \"" << m_src << "\")";
    }
    o << std::endl;

    m_triggered = true;
}


void dbg::trace::trace_end()
{
    std::ostream &o = out(dbg::tracing, m_src);
    indent_depth--;
    o << indent(tracing);
    o << TRACE_OUT;
    if (m_name)
    {
        o << m_name;
    }
    else
    {
        print_pos_short(o, m_pos);
    }
    if (m_src && strcmp(m_src, ""))
    {
        o << " (for \"" << m_src << "\")";
    }
    o << std::endl;
}


/******************************************************************************
 * Internal implementation
 *****************************************************************************/

namespace
{
    /**************************************************************************
     * dbg_streambuf
     *************************************************************************/

    dbg_streambuf::dbg_streambuf(std::vector<std::ostream*> &o, int bsize)
    : ostreams(o)
    {
        if (bsize)
        {
            char *ptr = new char[bsize];
            setp(ptr, ptr + bsize);
        }
        else
        {
            setp(0, 0);
        }
        setg(0, 0, 0);
    }

    dbg_streambuf::~dbg_streambuf()
    {
        sync();
        delete [] pbase();
    }

    int dbg_streambuf::overflow(int c)
    {
        put_buffer();
        if (c != EOF)
        {
            if (pbase() == epptr())
            {
                put_char(c);
            }
            else
            {
                sputc(c);
            }
        }
        return 0;
    }

    int dbg_streambuf::sync()
    {
        put_buffer();
        return 0;
    }

    void dbg_streambuf::put_buffer(void)
    {
        if (pbase() != pptr())
        {
            std::vector<std::ostream *>::iterator i = ostreams.begin();
            while (i != ostreams.end())
            {
                (*i)->write(pbase(), pptr() - pbase());
                ++i;
            }
            setp(pbase(), epptr());
        }
    }

    void dbg_streambuf::put_char(int c)
    {
        std::vector<std::ostream *>::iterator i = ostreams.begin();
        while (i != ostreams.end())
        {
            (**i) << static_cast<char>(c);
            ++i;
        }
    }


    /**************************************************************************
     * dbg_ostream
     *************************************************************************/

    void dbg_ostream::add(std::ostream &o)
    {
        if (std::find(streams.begin(), streams.end(), &o) == streams.end())
        {
            streams.push_back(&o);
        }
    }

    void dbg_ostream::remove(std::ostream &o)
    {
        stream_vec_type::iterator i
            = std::find(streams.begin(), streams.end(), &o);
        if (i != streams.end())
        {
            streams.erase(i);
        }
    }

    void dbg_ostream::clear()
    {
        streams.clear();
    }


    /**************************************************************************
     * source_info
     *************************************************************************/

    source_info::source_info(ConstructionStyle cs)
    : levels(cs ? source_map[dbg::default_source].levels : 0),
      dbg_streams(raw_cast().dbg_streams)
    {
        if (cs)
        {
            new (raw_dbg_streams)
                array_type(source_map[dbg::default_source].raw_cast());
        }
        else
        {
            new (raw_dbg_streams) array_type;
            // add cerr to the error and fatal levels.
            add_ostream(dbg::error, std::cerr);
            add_ostream(dbg::fatal, std::cerr);
        }
    }

    source_info::source_info(const source_info &rhs)
    : levels(rhs.levels), dbg_streams(raw_cast().dbg_streams)
    {
        new (raw_dbg_streams) array_type(rhs.raw_cast());
    }

    source_info::~source_info()
    {
        raw_cast().~array_type();
    }

    void source_info::enable(dbg::level lvl, bool status)
    {
        levels &= ~dbg_source_mask(lvl);
        if (status)
        {
            levels |= dbg_source_mask(lvl);
        }
    }

    void source_info::add_ostream(dbg::level lvl, std::ostream &o)
    {
        if (lvl == dbg::all)
        {
            for (unsigned int n = 0; n < NUM_DBG_LEVELS; ++n)
            {
                dbg_streams[n].add(o);
            }
        }
        else
        {
            dbg_streams[lvl].add(o);
        }
    }

    void source_info::remove_ostream(dbg::level lvl, std::ostream &o)
    {
        if (lvl == dbg::all)
        {
            for (unsigned int n = 0; n < NUM_DBG_LEVELS; ++n)
            {
                dbg_streams[n].remove(o);
            }
        }
        else
        {
            dbg_streams[lvl].remove(o);
        }
    }

    void source_info::clear_ostream(dbg::level lvl)
    {
        if (lvl == dbg::all)
        {
            for (unsigned int n = 0; n < NUM_DBG_LEVELS; ++n)
            {
                dbg_streams[n].clear();
            }
        }
        else
        {
            dbg_streams[lvl].clear();
        }
    }

    std::ostream &source_info::out(dbg::level lvl)
    {
        if (lvl == dbg::none || !enabled(lvl))
        {
            return null_ostream;
        }
        else
        {
            return dbg_streams[lvl];
        }
    }


    /**************************************************************************
     * period_data
     *************************************************************************/

    period_data::period_data()
        : no_triggers(0), triggered_at(STDCLK::clock() - period*2)
    {
    }


    /**************************************************************************
     * Functions
     *************************************************************************/

    void print_pos(std::ostream &out, const dbg::source_pos &where)
    {
        if (where.file)
        {
           if (where.func)
           {
               out << "function: " << where.func << ", ";
           }
           out << "line: " << where.line << ", file: "    << where.file;
        }
    }

    void print_pos_short(std::ostream &out, const dbg::source_pos &where)
    {
        if (where.file)
        {
           if (where.func)
           {
               out << where.func << " (" << where.line
                   << " in " << where.file << ")";
           }
           else
           {
               out << "function at (" << where.line
                   << " in "    << where.file << ")";
           }
        }
    }

    void print_period_info(std::ostream &out, const dbg::source_pos &where)
    {
        if (period)
        {
            size_t no_triggers = period_map[where].no_triggers;
            out << " (triggered " << no_triggers << " time";
            if (no_triggers > 1)
            {
                out << "s)";
            }
            else
            {
                out << ")";
            }
        }
    }

    void do_assertion_behaviour(dbg::level lvl, constraint_type why,
                                const dbg::source_pos &pos)
    {
        switch (lvl != dbg::fatal ? behaviour[lvl] : dbg::assertions_abort)
        {
            case dbg::assertions_abort:
            {
                abort();
                break;
            }
            case dbg::assertions_throw:
            {
                switch (why)
                {
                    default:
                    case why_assertion:
                    {
                        throw dbg::assertion_exception(pos);
                        break;
                    }
                    case why_sentinel:
                    {
                        throw dbg::sentinel_exception(pos);
                        break;
                    }
                    case why_unimplemented:
                    {
                        throw dbg::unimplemented_exception(pos);
                        break;
                    }
                    case why_check_ptr:
                    {
                        throw dbg::check_ptr_exception(pos);
                        break;
                    }
                }
                break;
            }
            case dbg::assertions_continue:
            default:
            {
                break;
            }
        }
    }

    void do_prefix(dbg::level lvl, std::ostream &s)
    {
        if (time_prefix)
        {
            STDCLK::time_t t = STDCLK::time(0);
            if (t != -1)
            {
                s << std::string(STDCLK::ctime(&t), 24) << ": ";
            }
        }
        if (level_prefix)
        {
            switch (lvl)
            {
                case dbg::info:    { s << "   info: "; break; }
                case dbg::warning: { s << "warning: "; break; }
                case dbg::error:   { s << "  error: "; break; }
                case dbg::fatal:   { s << "  fatal: "; break; }
                case dbg::tracing: { s << "  trace: "; break; }
                case dbg::debug:   { s << "  debug: "; break; }
                case dbg::none:    {                   break; }
                case dbg::all:     { s << "    all: "; break; }
            }
        }
    }

    bool period_allows_impl(const dbg::source_pos &where)
    {
        period_data &data = period_map[where];
        data.no_triggers++;
        if (data.triggered_at < STDCLK::clock() - period)
        {
            data.triggered_at = STDCLK::clock();
            return true;
        }
        else
        {
            return false;
        }
    }

    void determine_source(dbg::dbg_source &src, const dbg::source_pos &here)
    {
        if (!src) src = "";
        if (src == "" && here.src)
        {
           src = here.src;
        }
    }
}