/*
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 "kernel/expr.h"
#include "util/rb_map.h"
#include "kernel/local_ctx.h"

namespace lean {
/** \brief Total order on expressions.

    \remark If \c use_hash is true, then we use the hash_code to
    partially order expressions. Setting use_hash to false is useful
    for testing the code.

    \remark If lctx is not nullptr, then we use the local_decl index to compare local constants.
*/
bool is_lt(expr const & a, expr const & b, bool use_hash, local_ctx const * lctx = nullptr);
/** \brief Similar to is_lt, but universe level parameter names are ignored. */
bool is_lt_no_level_params(expr const & a, expr const & b);
inline bool is_hash_lt(expr const & a, expr const & b) { return is_lt(a, b, true); }
inline bool operator<(expr const & a, expr const & b)  { return is_lt(a, b, true); }
inline bool operator>(expr const & a, expr const & b)  { return is_lt(b, a, true); }
inline bool operator<=(expr const & a, expr const & b) { return !is_lt(b, a, true); }
inline bool operator>=(expr const & a, expr const & b) { return !is_lt(a, b, true); }
struct expr_quick_cmp {
    typedef expr type;
    int operator()(expr const & e1, expr const & e2) const { return is_lt(e1, e2, true) ? -1 : (e1 == e2 ? 0 : 1); }
};
struct expr_cmp_no_level_params { int operator()(expr const & e1, expr const & e2) const; };

template<typename T>
using rb_expr_map = rb_map<expr, T, expr_quick_cmp>;

typedef rb_tree<expr, expr_quick_cmp> rb_expr_tree;
}