diff options
| -rw-r--r-- | src/pugixml.cpp | 48 |
1 files changed, 43 insertions, 5 deletions
diff --git a/src/pugixml.cpp b/src/pugixml.cpp index 28b805d..18c89e2 100644 --- a/src/pugixml.cpp +++ b/src/pugixml.cpp @@ -9328,8 +9328,26 @@ PUGI__NS_BEGIN return xpath_node_set_raw(); } } + + void optimize() + { + if (_left) _left->optimize(); + if (_right) _right->optimize(); + if (_next) _next->optimize(); + + // Replace descendant-or-self::node()/child::foo with descendant::foo + // The former is a full form of //foo, the latter is much faster since it executes the node test immediately + // Note that we only replace positionally invariant steps (//foo[1] != /descendant::foo[1]) + if (_type == ast_step && _axis == axis_child && _left && + _left->_type == ast_step && _left->_axis == axis_descendant_or_self && _left->_test == nodetest_type_node && !_left->_right && + is_posinv_step()) + { + _axis = axis_descendant; + _left = _left->_left; + } + } - bool is_posinv() + bool is_posinv_expr() const { switch (_type) { @@ -9351,15 +9369,33 @@ PUGI__NS_BEGIN return true; default: - if (_left && !_left->is_posinv()) return false; + if (_left && !_left->is_posinv_expr()) return false; for (xpath_ast_node* n = _right; n; n = n->_next) - if (!n->is_posinv()) return false; + if (!n->is_posinv_expr()) return false; return true; } } + bool is_posinv_step() const + { + assert(_type == ast_step); + + for (xpath_ast_node* n = _right; n; n = n->_next) + { + assert(n->_type == ast_predicate); + + xpath_ast_node* expr = n->_left; + bool posinv = expr->rettype() != xpath_type_number && expr->is_posinv_expr(); + + if (!posinv) + return false; + } + + return true; + } + xpath_value_type rettype() const { return static_cast<xpath_value_type>(_rettype); @@ -9773,7 +9809,7 @@ PUGI__NS_BEGIN if (n->rettype() != xpath_type_node_set) throw_error("Predicate has to be applied to node set"); - bool posinv = expr->rettype() != xpath_type_number && expr->is_posinv(); + bool posinv = expr->rettype() != xpath_type_number && expr->is_posinv_expr(); n = new (alloc_node()) xpath_ast_node(posinv ? ast_filter_posinv : ast_filter, xpath_type_node_set, n, expr); @@ -9930,7 +9966,7 @@ PUGI__NS_BEGIN last = pred; } - + return n; } @@ -10663,6 +10699,8 @@ namespace pugi if (qimpl->root) { + qimpl->root->optimize(); + _impl = static_cast<impl::xpath_query_impl*>(impl_holder.release()); _result.error = 0; } |