Allow choice within choice in nameClass in RELAX NG

The pattern nameClass allows for nested choice elements, for example

  <name>
    <choice>
      <choice>
        <name>a</name>
        <name>b</name>
      </choice>
      <name>c</name>
    </choice>
  </name>

which is semantically equivalent to

  <name>
    <choice>
      <name>a</name>
      <name>b</name>
      <name>c</name>
    </choice>
  </name>

The old code didn’t handle this correctly, as it never expected a choice inside
another choice.  This patch fixes this by flattening any nested choices.

This pattern of nested choice elements comes up in RELAX NG simplification,
where all choice elements are rewritten in this nested manner, see section 4.12
of the RELAX NG specification.

1 files changed, 10 insertions, 6 deletions

diff --git a/relaxng.c b/relaxng.c
index a3088cbd..8725444b 100644
--- a/relaxng.c
+++ b/relaxng.c
@@ -5363,11 +5363,15 @@ xmlRelaxNGParseNameClass(xmlRelaxNGParserCtxtPtr ctxt, xmlNodePtr node,
         xmlNodePtr child;
         xmlRelaxNGDefinePtr last = NULL;
 
-        ret = xmlRelaxNGNewDefine(ctxt, node);
-        if (ret == NULL)
-            return (NULL);
-        ret->parent = def;
-        ret->type = XML_RELAXNG_CHOICE;
+        if (def->type == XML_RELAXNG_CHOICE) {
+            ret = def;
+        } else {
+            ret = xmlRelaxNGNewDefine(ctxt, node);
+            if (ret == NULL)
+                return (NULL);
+            ret->parent = def;
+            ret->type = XML_RELAXNG_CHOICE;
+        }
 
         if (node->children == NULL) {
             xmlRngPErr(ctxt, node, XML_RNGP_CHOICE_EMPTY,
@@ -5379,7 +5383,7 @@ xmlRelaxNGParseNameClass(xmlRelaxNGParserCtxtPtr ctxt, xmlNodePtr node,
                 tmp = xmlRelaxNGParseNameClass(ctxt, child, ret);
                 if (tmp != NULL) {
                     if (last == NULL) {
-                        last = ret->nameClass = tmp;
+                        last = tmp;
                     } else {
                         last->next = tmp;
                         last = tmp;