organicmaps/pugixml
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XPath: Refactor predicate application

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Split number/boolean filtering logic into two functions. This creates an
extra copy of a remove_if-like algorithm, but moves the type check out of
the loop and results in better organized filtering code.

Consolidate test-based dispatch into apply_predicate (which is now a member
function).
This commit is contained in:
Arseny Kapoulkine 2014-11-03 18:33:08 +01:00
parent 97a515f873
commit 3950ee0433
1 changed files with 52 additions and 37 deletions
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89
src/pugixml.cpp
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@ -8503,44 +8503,59 @@ PUGI__NS_BEGIN
}
}
static void apply_predicate(xpath_node_set_raw& ns, size_t first, xpath_ast_node* expr, const xpath_stack& stack, bool once)
static void apply_predicate_boolean(xpath_node_set_raw& ns, size_t first, xpath_ast_node* expr, const xpath_stack& stack, bool once)
{
assert(ns.size() >= first);
assert(expr->rettype() != xpath_type_number);
size_t i = 1;
size_t size = ns.size() - first;
xpath_node* last = ns.begin() + first;
// remove_if... or well, sort of
for (xpath_node* it = last; it != ns.end(); ++it, ++i)
{
xpath_context c(*it, i, size);
if (expr->rettype() == xpath_type_number)
{
if (expr->eval_number(c, stack) == i)
{
*last++ = *it;
if (once) break;
}
}
else
if (expr->eval_boolean(c, stack))
{
if (expr->eval_boolean(c, stack))
{
*last++ = *it;
*last++ = *it;
if (once) break;
}
if (once) break;
}
}
ns.truncate(last);
}
static void apply_predicate_const(xpath_node_set_raw& ns, size_t first, xpath_ast_node* expr, const xpath_stack& stack)
static void apply_predicate_number(xpath_node_set_raw& ns, size_t first, xpath_ast_node* expr, const xpath_stack& stack, bool once)
{
assert(ns.size() >= first);
assert(expr->rettype() == xpath_type_number);
size_t i = 1;
size_t size = ns.size() - first;
xpath_node* last = ns.begin() + first;
// remove_if... or well, sort of
for (xpath_node* it = last; it != ns.end(); ++it, ++i)
{
xpath_context c(*it, i, size);
if (expr->eval_number(c, stack) == i)
{
*last++ = *it;
if (once) break;
}
}
ns.truncate(last);
}
static void apply_predicate_number_const(xpath_node_set_raw& ns, size_t first, xpath_ast_node* expr, const xpath_stack& stack)
{
assert(ns.size() >= first);
assert(expr->rettype() == xpath_type_number);
@ -8568,21 +8583,28 @@ PUGI__NS_BEGIN
ns.truncate(last);
}
void apply_predicate(xpath_node_set_raw& ns, size_t first, const xpath_stack& stack, bool once)
{
if (ns.size() == first) return;
assert(_type == ast_filter || _type == ast_predicate);
if (_test == predicate_constant || _test == predicate_constant_one)
apply_predicate_number_const(ns, first, _right, stack);
else if (_right->rettype() == xpath_type_number)
apply_predicate_number(ns, first, _right, stack, once);
else
apply_predicate_boolean(ns, first, _right, stack, once);
}
void apply_predicates(xpath_node_set_raw& ns, size_t first, const xpath_stack& stack, nodeset_eval_t eval)
{
if (ns.size() == first) return;
bool last_once = eval_once(ns.type() == xpath_node_set::type_sorted, eval);
for (xpath_ast_node* pred = _right; pred; pred = pred->_next)
{
assert(pred->_type == ast_predicate);
if (pred->_test == predicate_constant || pred->_test == predicate_constant_one)
apply_predicate_const(ns, first, pred->_right, stack);
else
apply_predicate(ns, first, pred->_right, stack, !pred->_next && last_once);
}
pred->apply_predicate(ns, first, stack, !pred->_next && last_once);
}
bool step_push(xpath_node_set_raw& ns, xml_attribute_struct* a, xml_node_struct* parent, xpath_allocator* alloc)
@ -9660,16 +9682,9 @@ PUGI__NS_BEGIN
// either expression is a number or it contains position() call; sort by document order
if (_test != predicate_posinv) set.sort_do();
if (_test == predicate_constant || _test == predicate_constant_one)
{
apply_predicate_const(set, 0, _right, stack);
}
else
{
bool once = eval_once(set.type() == xpath_node_set::type_sorted, eval);
bool once = eval_once(set.type() == xpath_node_set::type_sorted, eval);
apply_predicate(set, 0, _right, stack, once);
}
apply_predicate(set, 0, stack, once);
return set;
}