add way to create a new search term from JS

mailnews/base/search/public/nsIMsgFilter.idl

@@ -38,7 +38,6 @@ interface nsIMsgFilter : nsISupports {
 
     readonly attribute nsIMsgFilterList filterList; // owning filter list
     
-    readonly attribute long numTerms;
     void AddTerm(in nsMsgSearchAttribValue attrib,
                  in nsMsgSearchOpValue op,
                  in nsIMsgSearchValue value,
@@ -54,6 +53,7 @@ interface nsIMsgFilter : nsISupports {
 
     void appendTerm(in nsIMsgSearchTerm term);
 
+    nsIMsgSearchTerm createTerm();
 
     // this is the actual array of search terms, and is thus modifyable
     readonly attribute nsISupportsArray searchTerms;

mailnews/base/search/src/nsMsgFilter.cpp

@@ -59,23 +59,7 @@ nsMsgFilter::~nsMsgFilter()
 {
 }
 
-NS_IMPL_ADDREF(nsMsgFilter)
-NS_IMPL_RELEASE(nsMsgFilter)
-
-NS_IMETHODIMP nsMsgFilter::QueryInterface(REFNSIID aIID, void** aResult)
-{   
-    if (aResult == NULL)  
-        return NS_ERROR_NULL_POINTER;  
-
-    if (aIID.Equals(NS_GET_IID(nsIMsgFilter)) ||
-        aIID.Equals(NS_GET_IID(nsISupports)))
-	{
-        *aResult = NS_STATIC_CAST(nsMsgFilter*, this);   
-        NS_ADDREF_THIS();
-        return NS_OK;
-    }
-    return NS_NOINTERFACE;
-}   
+NS_IMPL_ISUPPORTS1(nsMsgFilter, nsIMsgFilter)
 
 NS_IMETHODIMP nsMsgFilter::GetFilterType(nsMsgFilterTypeType *aResult)
 {
@@ -148,18 +132,17 @@ NS_IMETHODIMP nsMsgFilter::AppendTerm(nsIMsgSearchTerm * aTerm)
     return m_termList->AppendElement(aTerm);
 }
 
-NS_IMETHODIMP nsMsgFilter::GetNumTerms(PRInt32 *aResult)
+NS_IMETHODIMP
+nsMsgFilter::CreateTerm(nsIMsgSearchTerm **aResult)
 {
-	if (aResult == NULL)  
-        return NS_ERROR_NULL_POINTER;  
-
-    PRUint32 count;
-    m_termList->Count(&count);
-    *aResult = count;
-	return NS_OK;
+    nsMsgSearchTerm *term = new nsMsgSearchTerm;
+    NS_ENSURE_TRUE(term, NS_ERROR_OUT_OF_MEMORY);
+    
+    *aResult = NS_STATIC_CAST(nsIMsgSearchTerm*,term);
+    NS_ADDREF(*aResult);
+    return NS_OK;
 }
 
-
 NS_IMETHODIMP nsMsgFilter::GetTerm(PRInt32 termIndex, 
 	nsMsgSearchAttribValue *attrib,    /* attribute for this term          */
 	nsMsgSearchOpValue *op,         /* operator e.g. opContains           */