70 lines
1.9 KiB
C++
70 lines
1.9 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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#pragma once
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#include "kernel/for_each_fn.h"
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#include "kernel/context.h"
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namespace lean {
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template<typename P>
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class find_fn {
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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) {
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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)) {
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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<pred_fn> m_proc;
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public:
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find_fn(P const & p):m_proc(pred_fn(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>
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optional<expr> find(expr const & e, P p) {
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return find_fn<P>(p)(e);
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}
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/**
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\brief Return an expression \c e that satisfies \c p and occurs in \c c or \c es.
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*/
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template<typename P>
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optional<expr> find(context const * c, unsigned sz, expr const * es, P p) {
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find_fn<P> finder(p);
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if (c) {
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for (auto const & e : *c) {
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auto const & d = e.get_domain();
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if (d) {
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if (optional<expr> r = finder(*d))
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return r;
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}
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auto const & b = e.get_body();
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if (b) {
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if (optional<expr> r = finder(*b))
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return r;
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}
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}
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}
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for (unsigned i = 0; i < sz; i++) {
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if (optional<expr> r = finder(es[i]))
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return r;
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}
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return none_expr();
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}
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}
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