/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Author: Leonardo de Moura
*/
#pragma once
#include <algorithm>
#include "util/debug.h"
#include "util/rc.h"
#include "util/buffer.h"
#include "util/sexpr/format.h"
#include "kernel/expr.h"
#include "kernel/formatter.h"

namespace lean {
class trace;
/**
   \brief Base class used to represent trace objects.
   These objects are used to trace the execution of different engines in Lean.
   The traces may help users understanding why something did not work.
   The traces are particularly important for the elaborator.
*/
class trace_cell {
    MK_LEAN_RC();
    void dealloc() { delete this; }
public:
    trace_cell():m_rc(0) {}
    virtual ~trace_cell() {}
    virtual format pp(formatter const & fmt, options const & opts) const = 0;
    virtual void get_children(buffer<trace> & r) const = 0;
    virtual expr const & get_main_expr() const { return expr::null(); }
};

/**
   \brief Smart pointer for trace_cell's
*/
class trace {
    trace_cell * m_ptr;
public:
    trace():m_ptr(nullptr) {}
    trace(trace_cell * ptr):m_ptr(ptr) { if (m_ptr) m_ptr->inc_ref(); }
    trace(trace const & s):m_ptr(s.m_ptr) { if (m_ptr) m_ptr->inc_ref(); }
    trace(trace && s):m_ptr(s.m_ptr) { s.m_ptr = nullptr; }
    ~trace() { if (m_ptr) m_ptr->dec_ref(); }

    operator bool() const { return m_ptr != nullptr; }

    trace_cell * raw() const { return m_ptr; }

    friend void swap(trace & a, trace & b) { std::swap(a.m_ptr, b.m_ptr); }

    trace & operator=(trace const & s) { LEAN_COPY_REF(trace, s); }
    trace & operator=(trace && s) { LEAN_MOVE_REF(trace, s); }
    format pp(formatter const & fmt, options const & opts) const { lean_assert(m_ptr); return m_ptr->pp(fmt, opts); }
    expr const & get_main_expr() const { return m_ptr ? m_ptr->get_main_expr() : expr::null(); }
    void get_children(buffer<trace> & r) const { if (m_ptr) m_ptr->get_children(r); }
    bool has_children() const;
};
}