42 lines
1.2 KiB
C++
42 lines
1.2 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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#pragma once
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#include "kernel/for_each_fn.h"
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#include "kernel/expr.h"
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namespace lean {
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class find_fn {
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template<typename P>
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struct pred_fn {
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optional<expr> & m_result;
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P m_p;
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pred_fn(optional<expr> & result, P const & p):m_result(result), m_p(p) {}
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bool operator()(expr const & e, unsigned offset) {
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if (m_result) {
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return false; // already found result, stop the search
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} else if (m_p(e, offset)) {
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m_result = e;
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return false; // stop the search
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} else {
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return true; // continue the search
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}
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}
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};
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optional<expr> m_result;
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for_each_fn m_proc;
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public:
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template<typename P> find_fn(P const & p):m_proc(pred_fn<P>(m_result, p)) {}
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optional<expr> operator()(expr const & e) { m_proc(e); return m_result; }
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};
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/**
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\brief Return a subexpression of \c e that satisfies the predicate \c p.
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*/
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template<typename P> optional<expr> find(expr const & e, P p) {
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return find_fn(p)(e);
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}
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}
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