98 lines
2.9 KiB
C++
98 lines
2.9 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 <tuple>
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#include <unordered_set>
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#include <functional>
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#include "util/buffer.h"
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#include "kernel/max_sharing.h"
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namespace lean {
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/**
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\brief Implementation of the functional object for creating expressions with maximally
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shared sub-expressions.
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*/
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struct max_sharing_fn::imp {
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typedef typename std::unordered_set<expr, expr_hash, std::equal_to<expr>> 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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optional<expr> apply(optional<expr> const & a) {
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if (a)
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return some_expr(apply(*a));
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else
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return 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::Constant: {
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expr r = update_const(a, apply(const_type(a)));
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cache(r);
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return r;
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}
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case expr_kind::Var: 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::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, [=](optional<expr> const & t, expr const & v, expr const & b) {
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return std::make_tuple(apply(t), apply(v), apply(b));
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});
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cache(r);
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return r;
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}
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case expr_kind::MetaVar: {
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expr r = update_metavar(a, [=](local_entry const & e) -> local_entry {
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if (e.is_inst())
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return mk_inst(e.s(), apply(e.v()));
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else
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return e;
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});
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cache(r);
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return r;
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}}
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lean_unreachable(); // LCOV_EXCL_LINE
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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_ptr(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_ptr)(a); }
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void max_sharing_fn::clear() { m_ptr->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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