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XPath: Unify ast_filter/ast_predicate structure

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Now expression is always _right for filter/predicate nodes to make optimize()
simpler. Additionally we now use predicate metadata to make is_posinv_step()
faster.

This introduces a weak ordering dependency in rewrite rules to optimize() -
classification has to be performed before other optimizations.
This commit is contained in:
Arseny Kapoulkine 2014-10-26 10:07:01 -07:00
parent d5e29292c6
commit 11ce004e04
1 changed files with 16 additions and 15 deletions
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31
src/pugixml.cpp
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@ -8581,9 +8581,9 @@ PUGI__NS_BEGIN
assert(pred->_type == ast_predicate);
if (pred->_test == predicate_constant || pred->_test == predicate_constant_one)
apply_predicate_const(ns, first, pred->_left, stack);
apply_predicate_const(ns, first, pred->_right, stack);
else
apply_predicate(ns, first, pred->_left, stack, !pred->_next && last_once);
apply_predicate(ns, first, pred->_right, stack, !pred->_next && last_once);
}
}
@ -9066,6 +9066,12 @@ PUGI__NS_BEGIN
_data.nodetest = contents;
}
xpath_ast_node(ast_type_t type, xpath_ast_node* left, xpath_ast_node* right, predicate_t test):
_type(static_cast<char>(type)), _rettype(xpath_type_node_set), _axis(0), _test(static_cast<char>(test)), _left(left), _right(right), _next(0)
{
assert(type == ast_filter || type == ast_predicate);
}
void set_next(xpath_ast_node* value)
{
_next = value;
@ -9771,16 +9777,14 @@ PUGI__NS_BEGIN
// Classify filter/predicate ops to perform various optimizations during evaluation
if (_type == ast_filter || _type == ast_predicate)
{
xpath_ast_node* expr = (_type == ast_filter) ? _right : _left;
assert(_test == predicate_default);
if (expr->_type == ast_number_constant && expr->_data.number == 1.0)
if (_right->_type == ast_number_constant && _right->_data.number == 1.0)
_test = predicate_constant_one;
else if (expr->_type == ast_number_constant || expr->_type == ast_variable)
else if (_right->_type == ast_number_constant || _right->_type == ast_variable)
_test = predicate_constant;
else if (expr->rettype() != xpath_type_number && expr->is_posinv_expr())
else if (_right->_rettype != xpath_type_number && _right->is_posinv_expr())
_test = predicate_posinv;
else
_test = predicate_default;
}
// Replace descendant-or-self::node()/child::foo with descendant::foo
@ -9814,7 +9818,7 @@ PUGI__NS_BEGIN
// Use optimized path for @attr = 'value' or @attr = $value
if (_type == ast_op_equal &&
_left->_type == ast_step && _left->_axis == axis_attribute && _left->_test == nodetest_name && !_left->_left && !_left->_right &&
(_right->_type == ast_string_constant || (_right->_type == ast_variable && _right->rettype() == xpath_type_string)))
(_right->_type == ast_string_constant || (_right->_type == ast_variable && _right->_rettype == xpath_type_string)))
{
_type = ast_opt_compare_attribute;
}
@ -9859,10 +9863,7 @@ PUGI__NS_BEGIN
{
assert(n->_type == ast_predicate);
xpath_ast_node* expr = n->_left;
bool posinv = expr->rettype() != xpath_type_number && expr->is_posinv_expr();
if (!posinv)
if (n->_test != predicate_posinv)
return false;
}
@ -10282,7 +10283,7 @@ PUGI__NS_BEGIN
if (n->rettype() != xpath_type_node_set) throw_error("Predicate has to be applied to node set");
n = new (alloc_node()) xpath_ast_node(ast_filter, xpath_type_node_set, n, expr);
n = new (alloc_node()) xpath_ast_node(ast_filter, n, expr, predicate_default);
if (_lexer.current() != lex_close_square_brace)
throw_error("Unmatched square brace");
@ -10426,7 +10427,7 @@ PUGI__NS_BEGIN
xpath_ast_node* expr = parse_expression();
xpath_ast_node* pred = new (alloc_node()) xpath_ast_node(ast_predicate, xpath_type_node_set, expr);
xpath_ast_node* pred = new (alloc_node()) xpath_ast_node(ast_predicate, 0, expr, predicate_default);
if (_lexer.current() != lex_close_square_brace)
throw_error("Unmatched square brace");