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feat(kernel/expr): cache is_arrow result

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-12-21 13:59:45 -08:00
parent 1faf42e2e1
commit 90dbdaec40
2 changed files with 37 additions and 1 deletions
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28
src/kernel/expr.cpp
View file

@ -64,6 +64,25 @@ void expr_cell::dec_ref(optional<expr> & c, buffer<expr_cell*> & todelete) {
dec_ref(*c, todelete);
}
optional<bool> expr_cell::is_arrow() const {
// it is stored in bits 3-4
unsigned r = (m_flags & (8+16)) >> 3;
if (r == 0) {
return optional<bool>();
} else if (r == 1) {
return optional<bool>(true);
} else {
lean_assert(r == 2);
return optional<bool>(false);
}
}
void expr_cell::set_is_arrow(bool flag) {
unsigned mask = flag ? 8 : 16;
m_flags |= mask;
lean_assert(is_arrow() && *is_arrow() == flag);
}
expr_var::expr_var(unsigned idx):
expr_cell(expr_kind::Var, idx, false),
m_vidx(idx) {}
@ -227,7 +246,14 @@ bool operator==(expr const & a, expr const & b) {
}
bool is_arrow(expr const & t) {
return is_pi(t) && !has_free_var(abst_body(t), 0);
optional<bool> r = t.raw()->is_arrow();
if (r) {
return *r;
} else {
bool res = is_pi(t) && !has_free_var(abst_body(t), 0);
t.raw()->set_is_arrow(res);
return res;
}
}
bool is_eq(expr const & e, expr & lhs, expr & rhs) {

10
src/kernel/expr.h
View file

@ -68,6 +68,11 @@ typedef list<local_entry> local_context;
class expr_cell {
protected:
unsigned short m_kind;
// The bits of the following field mean:
// 0 - term is maximally shared
// 1 - term is closed
// 2 - term contains metavariables
// 3-4 - term is an arrow (0 - not initialized, 1 - is arrow, 2 - is not arrow)
atomic_ushort m_flags;
unsigned m_hash; // hash based on the structure of the expression (this is a good hash for structural equality)
unsigned m_hash_alloc; // hash based on 'time' of allocation (this is a good hash for pointer-based equality)
@ -80,6 +85,11 @@ protected:
bool is_closed() const { return (m_flags & 2) != 0; }
void set_closed() { m_flags |= 2; }
optional<bool> is_arrow() const;
void set_is_arrow(bool flag);
friend bool is_arrow(expr const & e);
friend class has_free_var_fn;
static void dec_ref(expr & c, buffer<expr_cell*> & todelete);
static void dec_ref(optional<expr> & c, buffer<expr_cell*> & todelete);