From 3950ee0433aaed3c35eaee7548bae5b00ee22a80 Mon Sep 17 00:00:00 2001
From: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Date: Mon, 3 Nov 2014 18:33:08 +0100
Subject: XPath: Refactor predicate application
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).
---
src/pugixml.cpp | 85 +++++++++++++++++++++++++++++++++------------------------
1 file changed, 50 insertions(+), 35 deletions(-)
diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 59e8f79..c8de68a 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -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_boolean(c, stack))
{
- if (expr->eval_number(c, stack) == i)
- {
- *last++ = *it;
+ *last++ = *it;
- if (once) break;
- }
+ if (once) break;
}
- else
+ }
+
+ ns.truncate(last);
+ }
+
+ 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)
{
- 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_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;
}
--
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