Remove redundant, unnamed root XML node from parsed documents

XML_Node::build will make that node the root node (i.e. the 'ctml' node)
of the tree, instead of giving that node a child node containing the actual
root node.

include/cantera/base/xml.h

@@ -598,10 +598,7 @@ public:
     /*!
      * This is a wrapper around the static routine write_int(). All this does
      * is add an endl on to the output stream. write_int() is fine, but the
-     * last endl wasn't being written. It also checks for the special name
-     * "`--`". If found and we are at the root of the xml tree, then the block
-     * is skipped and the children are processed. "`--`" is used to denote the
-     * top of the tree.
+     * last endl wasn't being written.
      *
      *  @param s       ostream to write to
      *  @param level   Indentation level to work from

src/base/xml.cpp

@@ -757,6 +757,7 @@ void XML_Node::build(std::istream& f)
     string nm, nm2, val;
     XML_Node* node = this;
     map<string, string> node_attribs;
+    bool first = true;
     while (!f.eof()) {
         node_attribs.clear();
         nm = r.readTag(node_attribs);
@@ -770,14 +771,24 @@ void XML_Node::build(std::istream& f)
         int lnum = r.m_line;
         if (nm[nm.size() - 1] == '/') {
             nm2 = nm.substr(0,nm.size()-1);
-            node = &node->addChild(nm2);
+            if (first) {
+                node->setName(nm2);
+                first = false;
+            } else {
+                node = &node->addChild(nm2);
+            }
             node->addValue("");
             node->attribs() = node_attribs;
             node->setLineNumber(lnum);
             node = node->parent();
         } else if (nm[0] != '/') {
             if (nm[0] != '!' && nm[0] != '-' && nm[0] != '?') {
-                node = &node->addChild(nm);
+                if (first) {
+                    node->setName(nm);
+                    first = false;
+                } else {
+                    node = &node->addChild(nm);
+                }
                 val = r.readValue();
                 node->addValue(val);
                 node->attribs() = node_attribs;
@@ -1067,15 +1078,8 @@ void XML_Node::write_int(std::ostream& s, int level, int numRecursivesAllowed) c
 
 void XML_Node::write(std::ostream& s, const int level, int numRecursivesAllowed) const
 {
-    if (m_name == "--" && m_root == this) {
-        for (size_t i = 0; i < m_children.size(); i++) {
-            m_children[i]->write_int(s,level, numRecursivesAllowed-1);
-            s << endl;
-        }
-    } else {
-        write_int(s, level, numRecursivesAllowed);
-        s << endl;
-    }
+    write_int(s, level, numRecursivesAllowed);
+    s << endl;
 }
 
 XML_Node& XML_Node::root() const

src/thermo/Elements.cpp

@@ -529,14 +529,12 @@ void Elements::addElementsFromXML(const XML_Node& phase)
     }
 
     XML_Node* doc = get_XML_File(element_database);
-    XML_Node* dbe = &doc->child("ctml/elementData");
+    XML_Node* dbe = &doc->child("elementData");
 
     XML_Node& root = phase.root();
     XML_Node* local_db = 0;
-    if (root.hasChild("ctml")) {
-        if (root.child("ctml").hasChild("elementData")) {
-            local_db = &root.child("ctml/elementData");
-        }
+    if (root.hasChild("elementData")) {
+        local_db = &root.child("elementData");
     }
 
     int nel = static_cast<int>(enames.size());

src/thermo/ThermoFactory.cpp

@@ -513,14 +513,12 @@ void installElements(Phase& th, const XML_Node& phaseNode)
     }
 
     XML_Node* doc = get_XML_File(element_database);
-    XML_Node* dbe = &doc->child("ctml/elementData");
+    XML_Node* dbe = &doc->child("elementData");
 
     XML_Node& root = phaseNode.root();
     XML_Node* local_db = 0;
-    if (root.hasChild("ctml")) {
-        if (root.child("ctml").hasChild("elementData")) {
-            local_db = &root.child("ctml/elementData");
-        }
+    if (root.hasChild("elementData")) {
+        local_db = &root.child("elementData");
     }
 
     for (size_t i = 0; i < enames.size(); i++) {

test/general/test_xml.cpp

@@ -0,0 +1,30 @@
+#include "gtest/gtest.h"
+#include "cantera/base/xml.h"
+#include <fstream>
+
+namespace Cantera
+{
+
+TEST(XML_Node, read_write)
+{
+    // Check that we can re-read our own XML output
+    XML_Node node1, node2;
+    std::stringstream out;
+    std::ifstream xmlfile("../data/air-no-reactions.xml");
+    node1.build(xmlfile);
+    node1.write(out);
+
+    node2.build(out);
+    ASSERT_EQ(node2.name(), "ctml");
+    ASSERT_TRUE(node2.hasChild("speciesData"));
+
+    std::vector<XML_Node*> species1, species2;
+    species1 = node1.child("speciesData").getChildren("species");
+    species2 = node2.child("speciesData").getChildren("species");
+    ASSERT_EQ(species1.size(), species2.size());
+    for (size_t i = 0; i < species1.size(); i++) {
+        ASSERT_EQ(species1[i]->attrib("name"), species2[i]->attrib("name"));
+    }
+}
+
+}