71 lines
2.1 KiB
C++
71 lines
2.1 KiB
C++
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/*
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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 <vector>
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#include "expr.h"
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#include "expr_functors.h"
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namespace lean {
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namespace max_shared_ns {
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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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static thread_local expr_cache g_cache;
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expr apply(expr const & a) {
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auto r = g_cache.find(a);
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if (r != g_cache.end())
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return *r;
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switch (a.kind()) {
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case expr_kind::Var: case expr_kind::Constant: case expr_kind::Prop: case expr_kind::Type: case expr_kind::Numeral:
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g_cache.insert(a);
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return a;
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case expr_kind::App: {
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std::vector<expr> new_args;
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bool modified = false;
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for (expr const & old_arg : app_args(a)) {
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new_args.push_back(apply(old_arg));
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if (!eqp(old_arg, new_args.back()))
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modified = true;
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}
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if (!modified) {
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g_cache.insert(a);
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return a;
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}
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else {
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expr r = app(static_cast<unsigned>(new_args.size()), new_args.data());
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g_cache.insert(r);
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return r;
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}
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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 const & old_t = get_abs_type(a);
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expr const & old_e = get_abs_expr(a);
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expr t = apply(old_t);
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expr e = apply(old_e);
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if (!eqp(t, old_t) || !eqp(e, old_e)) {
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name const & n = get_abs_name(a);
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expr r = is_pi(a) ? pi(n, t, e) : lambda(n, t, e);
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g_cache.insert(r);
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return r;
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}
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else {
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g_cache.insert(a);
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return a;
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}
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}}
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lean_unreachable();
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return a;
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}
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} // namespace max_shared_ns
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expr max_shared(expr const & a) {
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max_shared_ns::g_cache.clear();
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expr r = max_shared_ns::apply(a);
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max_shared_ns::g_cache.clear();
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return r;
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}
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} // namespace lean
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