/*
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 "expr.h"
#include "list.h"

namespace lean {
class context_entry;
typedef list<context_entry> context;
class context_entry {
    name     m_name;
    expr     m_domain;
    expr     m_body;
    friend context extend(context const & c, name const & n, expr const & d, expr const & b);
    friend context extend(context const & c, name const & n, expr const & d);
    context_entry(name const & n, expr const & d, expr const & b):m_name(n), m_domain(d), m_body(b) {}
    context_entry(name const & n, expr const & d):m_name(n), m_domain(d) {}
public:
    ~context_entry() {}
    name const & get_name() const   { return m_name; }
    expr const & get_domain() const { return m_domain; }
    expr const & get_body() const   { return m_body; }
};
/**
   \brief Return the context entry for the free variable with de
   Bruijn index \c i, and the context for this entry.
*/
std::pair<context_entry const &, context const &> lookup_ext(context const & c, unsigned i);
/**
   \brief Return the context entry for the free variable with de
   Bruijn index \c i.
*/
context_entry const & lookup(context const & c, unsigned i);

inline context extend(context const & c, name const & n, expr const & d, expr const & b) {
    return context(context_entry(n, d, b), c);
}
inline context extend(context const & c, name const & n, expr const & d) {
    return context(context_entry(n, d), c);
}
inline bool empty(context const & c) {
    return is_nil(c);
}

/**
    \brief Return a new context where the names used in the context
    entries of \c c do not shadow constants occurring in \c c and \c es[sz].

    Recall that the names in context entries are just "suggestions".
    These names are used to name free variables in \c es[sz] (and
    dependent entries in \c c).
*/
context sanitize_names(context const & c, unsigned sz, expr const * es);
inline context sanitize_names(context const & c, expr const & e) { return sanitize_names(c, 1, &e); }
inline context sanitize_names(context const & c, std::initializer_list<expr> const & l) { return sanitize_names(c, l.size(), l.begin()); }

class expr_formatter;
format pp(expr_formatter & f, context const & c);
std::ostream & operator<<(std::ostream & out, context const & c);
}