refactor(src/kernel/replace_fn): remove stack-less replace_fn it is slower than the simple one

This commit is contained in:
Leonardo de Moura 2015-03-12 16:22:49 -07:00
parent 9fe2d5c74c
commit 026622a790

View file

@ -58,151 +58,6 @@ struct replace_cache {
MK_CACHE_STACK(replace_cache, LEAN_DEFAULT_REPLACE_CACHE_CAPACITY)
/**
\brief Functional for applying <tt>F</tt> to the subexpressions of a given expression.
The signature of \c F is
expr const &, unsigned -> optional(expr)
F is invoked for each subexpression \c s of the input expression e.
In a call <tt>F(s, n)</tt>, n is the scope level, i.e., the number of
bindings operators that enclosing \c s. The replaces only visits children of \c e
if F return none_expr
*/
class replace_fn {
struct frame {
expr m_expr;
unsigned m_offset;
bool m_shared;
unsigned m_index;
frame(expr const & e, unsigned o, bool s):m_expr(e), m_offset(o), m_shared(s), m_index(0) {}
};
typedef buffer<frame> frame_stack;
typedef buffer<expr> result_stack;
std::function<optional<expr>(expr const &, unsigned)> m_f;
frame_stack m_fs;
result_stack m_rs;
replace_cache_ref m_cache;
bool m_use_cache;
void save_result(expr const & e, expr const & r, unsigned offset, bool shared) {
if (shared)
m_cache->insert(e, offset, r);
m_rs.push_back(r);
}
/**
\brief Visit \c e at the given offset. Return true iff the result is on the
result stack \c m_rs. Return false iff a new frame was pushed on the stack \c m_fs.
The idea is that after the frame is processed, the result will be on the result stack.
*/
bool visit(expr const & e, unsigned offset) {
bool shared = false;
if (m_use_cache && is_shared(e)) {
if (auto r = m_cache->find(e, offset)) {
m_rs.push_back(*r);
return true;
}
shared = true;
}
optional<expr> r = m_f(e, offset);
if (r) {
save_result(e, *r, offset, shared);
return true;
} else if (is_atomic(e)) {
save_result(e, e, offset, shared);
return true;
} else {
m_fs.emplace_back(e, offset, shared);
return false;
}
}
/**
\brief Return true iff <tt>f.m_index == idx</tt>.
When the result is true, <tt>f.m_index</tt> is incremented.
*/
bool check_index(frame & f, unsigned idx) {
if (f.m_index == idx) {
f.m_index++;
return true;
} else {
return false;
}
}
expr const & rs(int i) {
lean_assert(i < 0);
return m_rs[m_rs.size() + i];
}
void pop_rs(unsigned num) {
m_rs.shrink(m_rs.size() - num);
}
public:
template<typename F>
replace_fn(F const & f, bool use_cache):m_f(f), m_use_cache(use_cache) {}
expr operator()(expr const & e) {
expr r;
visit(e, 0);
while (!m_fs.empty()) {
begin_loop:
check_interrupted();
check_memory("replace");
frame & f = m_fs.back();
expr const & e = f.m_expr;
unsigned offset = f.m_offset;
switch (e.kind()) {
case expr_kind::Constant: case expr_kind::Sort:
case expr_kind::Var:
lean_unreachable(); // LCOV_EXCL_LINE
case expr_kind::Meta: case expr_kind::Local:
if (check_index(f, 0) && !visit(mlocal_type(e), offset))
goto begin_loop;
r = update_mlocal(e, rs(-1));
pop_rs(1);
break;
case expr_kind::App:
if (check_index(f, 0) && !visit(app_fn(e), offset))
goto begin_loop;
if (check_index(f, 1) && !visit(app_arg(e), offset))
goto begin_loop;
r = update_app(e, rs(-2), rs(-1));
pop_rs(2);
break;
case expr_kind::Pi: case expr_kind::Lambda:
if (check_index(f, 0) && !visit(binding_domain(e), offset))
goto begin_loop;
if (check_index(f, 1) && !visit(binding_body(e), offset + 1))
goto begin_loop;
r = update_binding(e, rs(-2), rs(-1));
pop_rs(2);
break;
case expr_kind::Macro:
while (f.m_index < macro_num_args(e)) {
unsigned idx = f.m_index;
f.m_index++;
if (!visit(macro_arg(e, idx), offset))
goto begin_loop;
}
r = update_macro(e, macro_num_args(e), &rs(-macro_num_args(e)));
pop_rs(macro_num_args(e));
break;
}
save_result(e, r, offset, f.m_shared);
m_fs.pop_back();
}
lean_assert(m_rs.size() == 1);
r = m_rs.back();
m_rs.pop_back();
return r;
}
};
class replace_rec_fn {
replace_cache_ref m_cache;
std::function<optional<expr>(expr const &, unsigned)> m_f;
@ -262,9 +117,6 @@ public:
};
expr replace(expr const & e, std::function<optional<expr>(expr const &, unsigned)> const & f, bool use_cache) {
if (get_weight(e) < LEAN_REPLACE_SMALL_TERM_THRESHOLD)
return replace_rec_fn(f, use_cache)(e);
else
return replace_fn(f, use_cache)(e);
return replace_rec_fn(f, use_cache)(e);
}
}