3e1fd06903
After this commit, a value of type 'expr' cannot be a reference to nullptr. This commit also fixes several bugs due to the use of 'null' expressions. TODO: do the same for kernel objects, sexprs, etc. Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
57 lines
1.6 KiB
C++
57 lines
1.6 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 "kernel/occurs.h"
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#include "kernel/metavar.h"
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#include "kernel/expr_maps.h"
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#include "kernel/replace_visitor.h"
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#include "library/expr_pair.h"
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#include "library/placeholder.h"
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namespace lean {
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static name g_placeholder_name("_");
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expr mk_placeholder(optional<expr> const & t) {
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return mk_constant(g_placeholder_name, t);
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}
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bool is_placeholder(expr const & e) {
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return is_constant(e) && const_name(e) == g_placeholder_name;
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}
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bool has_placeholder(expr const & e) {
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return occurs(mk_placeholder(), e);
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}
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class replace_placeholders_with_metavars_proc : public replace_visitor {
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metavar_env & m_menv;
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expr_map<expr> * m_new2old;
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protected:
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expr visit_constant(expr const & e, context const & c) {
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if (is_placeholder(e)) {
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return m_menv.mk_metavar(c, const_type(e));
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} else {
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return e;
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}
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}
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expr visit(expr const & e, context const & c) {
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expr r = replace_visitor::visit(e, c);
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if (!is_eqp(r, e) && m_new2old)
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m_new2old->insert(expr_pair(r, e));
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return r;
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}
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public:
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replace_placeholders_with_metavars_proc(metavar_env & menv, expr_map<expr> * new2old):
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m_menv(menv),
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m_new2old(new2old) {
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}
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};
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expr replace_placeholders_with_metavars(expr const & e, metavar_env & menv, expr_map<expr> * new2old) {
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replace_placeholders_with_metavars_proc proc(menv, new2old);
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return proc(e);
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}
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}
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