lean2/src/kernel/expr_maps.h
Leonardo de Moura 691893258d feat(kernel/expr): add hash code based on allocation time
The new hash code has the property that given expr_cell * c1 and expr_cell * c2,
if c1 != c2 then there is a high propbability that c1->hash_alloc() != c2->hash_alloc().

The structural hash code hash() does not have this property because we may have
c1 != c2, but c1 and c2 are structurally equal.

The new hash code is only compatible with pointer equality.
By compatible we mean, if c1 == c2, then c1->hash_alloc() == c2->hash_alloc().
This property is obvious because hash_alloc() does not have side-effects.

The test tests/lua/big.lua exposes the problem fixed by this commit.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-11-14 02:43:11 -08:00

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C++

/*
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 <unordered_map>
#include "kernel/expr.h"
namespace lean {
template<typename T>
using expr_map = typename std::unordered_map<expr, T, expr_hash_alloc, expr_eqp>;
template<typename T>
using expr_offset_map = typename std::unordered_map<expr_offset, T, expr_offset_hash, expr_offset_eqp>;
template<typename T>
using expr_cell_map = typename std::unordered_map<expr_cell *, T, expr_cell_hash, expr_cell_eqp>;
template<typename T>
using expr_cell_offset_map = typename std::unordered_map<expr_cell_offset, T, expr_cell_offset_hash, expr_cell_offset_eqp>;
};