/*
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"
#include "kernel/pos_info_provider.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; }
protected:
    static void add_pos_info(format & r, expr const & e, pos_info_provider const * p);
public:
    trace_cell():m_rc(0) {}
    virtual ~trace_cell() {}
    virtual format pp_header(formatter const & fmt, options const & opts) const = 0;
    virtual format pp(formatter const & fmt, options const & opts, pos_info_provider const * p, bool display_children) const;
    virtual void get_children(buffer<trace_cell*> & r) const = 0;
    virtual expr const & get_main_expr() const { return expr::null(); }
    bool is_shared() const { return get_rc() > 1; }
};

/**
   \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, pos_info_provider const * p = nullptr, bool display_children = true) const {
        lean_assert(m_ptr);
        return m_ptr->pp(fmt, opts, p, display_children);
    }
    expr const & get_main_expr() const { return m_ptr ? m_ptr->get_main_expr() : expr::null(); }
    void get_children(buffer<trace_cell*> & r) const { if (m_ptr) m_ptr->get_children(r); }
    bool has_children() const;
};

/**
   \brief Return true iff \c t depends on \c d.
   That is \c t is a descendant of \c d.
*/
bool depends_on(trace const & t, trace const & d);
}