78 lines
2.3 KiB
C++
78 lines
2.3 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include <unordered_set>
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#include "buffer.h"
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#include "max_sharing.h"
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namespace lean {
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struct max_sharing_fn::imp {
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struct expr_struct_eq { unsigned operator()(expr const & e1, expr const & e2) const { return e1 == e2; }};
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typedef typename std::unordered_set<expr, expr_hash, expr_struct_eq> expr_cache;
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expr_cache m_cache;
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void cache(expr const & a) {
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a.raw()->set_max_shared();
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m_cache.insert(a);
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}
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expr apply(expr const & a) {
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auto r = m_cache.find(a);
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if (r != m_cache.end()) {
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lean_assert((*r).raw()->max_shared());
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return *r;
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}
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if (a.raw()->max_shared()) {
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m_cache.insert(a);
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return a;
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}
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switch (a.kind()) {
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case expr_kind::Var: case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value:
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cache(a);
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return a;
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case expr_kind::App: {
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expr r = update_app(a, [=](expr const & c){ return apply(c); });
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cache(r);
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return r;
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}
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case expr_kind::Eq : {
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expr r = update_eq(a, [=](expr const & l, expr const & r){ return std::make_pair(apply(l), apply(r)); });
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cache(r);
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return r;
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}
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case expr_kind::Lambda:
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case expr_kind::Pi: {
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expr r = update_abst(a, [=](expr const & t, expr const & b) { return std::make_pair(apply(t), apply(b)); });
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cache(r);
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return r;
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}
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case expr_kind::Let: {
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expr r = update_let(a, [=](expr const & v, expr const & b) { return std::make_pair(apply(v), apply(b)); });
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cache(r);
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return r;
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}}
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lean_unreachable();
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return a;
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}
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expr operator()(expr const & a) { return apply(a); }
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};
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max_sharing_fn::max_sharing_fn():m_imp(new imp) {}
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max_sharing_fn::~max_sharing_fn() {}
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expr max_sharing_fn::operator()(expr const & a) { return (*m_imp)(a); }
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void max_sharing_fn::clear() { m_imp->m_cache.clear(); }
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expr max_sharing(expr const & a) {
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if (a.raw()->max_shared())
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return a;
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else
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return max_sharing_fn::imp()(a);
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}
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} // namespace lean
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