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perf(kernel/metavar): avoid destructive update in occurs method

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2014-07-23 13:12:29 -07:00
parent 4286f5dd36
commit adddf06e44
2 changed files with 21 additions and 8 deletions
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24
src/kernel/metavar.cpp
View file

@ -186,15 +186,20 @@ expr substitution::instantiate_metavars_wo_jst(expr const & e) {
return instantiate_metavars_fn(*this, false)(e);
}
bool substitution::occurs_expr(name const & m, expr const & e) {
if (!has_expr_metavar(e))
return false;
expr new_e = instantiate(e);
bool substitution::occurs_expr_core(name const & m, expr const & e, name_set & visited) const {
bool found = false;
for_each(new_e, [&](expr const & e, unsigned) {
for_each(e, [&](expr const & e, unsigned) {
if (found || !has_expr_metavar(e)) return false;
if (is_metavar(e)) {
if (mlocal_name(e) == m)
name const & n = mlocal_name(e);
if (n == m)
found = true;
auto s = get_expr(e);
if (!s || visited.contains(n))
return false; // do not visit type
visited.insert(n);
if (s && occurs_expr_core(m, *s, visited))
found = true;
return false; // do not visit type
}
@ -203,4 +208,11 @@ bool substitution::occurs_expr(name const & m, expr const & e) {
});
return found;
}
bool substitution::occurs_expr(name const & m, expr const & e) const {
if (!has_expr_metavar(e))
return false;
name_set visited;
return occurs_expr_core(m, e, visited);
}
}

5
src/kernel/metavar.h
View file

@ -26,6 +26,7 @@ class substitution {
friend class instantiate_metavars_fn;
std::pair<level, justification> instantiate_metavars(level const & l, bool use_jst);
expr instantiate_metavars_wo_jst(expr const & e);
bool occurs_expr_core(name const & m, expr const & e, name_set & visited) const;
public:
substitution();
@ -78,7 +79,7 @@ public:
expr instantiate(expr const & e) { return instantiate_metavars_wo_jst(e); }
/** \brief Return true iff the metavariable \c m occurrs (directly or indirectly) in \c e. */
bool occurs_expr(name const & m, expr const & e);
bool occurs(expr const & m, expr const & e) { lean_assert(is_metavar(m)); return occurs_expr(mlocal_name(m), e); }
bool occurs_expr(name const & m, expr const & e) const;
bool occurs(expr const & m, expr const & e) const { lean_assert(is_metavar(m)); return occurs_expr(mlocal_name(m), e); }
};
}