Added a new structure expansion token <STRUCTURE_FIRST_UNIQUE_KEY>.

Author: SteveIves

CodeGenEngine/TokenExpanders/TokenExpanderStructure.dbl

@@ -87,6 +87,7 @@ namespace CodeGen.Engine
             structureTokenExpanders.Add("STRUCTURE_DESC", expandStructureDesc)
             structureTokenExpanders.Add("STRUCTURE_FIELDS", expandStructureFields)
             structureTokenExpanders.Add("STRUCTURE_FILES", expandStructureFiles)
+            structureTokenExpanders.Add("STRUCTURE_FIRST_UNIQUE_KEY", expandStructureFirstUniqueKey)
             structureTokenExpanders.Add("STRUCTURE_KEYS", expandStructureKeys)
             structureTokenExpanders.Add("STRUCTURE_LDESC", expandStructureLongDescription)
             structureTokenExpanders.Add("STRUCTURE_NAME", expandStructureName)
@@ -667,6 +668,23 @@ namespace CodeGen.Engine
             mreturn ExpandStructureToken(tkn, template, loops, doExpand)
         endmethod
 
+        private static method expandStructureFirstUniqueKey, string
+            tkn, @Token 
+            template, @FileNode 
+            loops, @IEnumerable<LoopNode> 
+            endparams
+        proc
+            lambda doExpand(str)
+            begin
+                data thekey, @RpsKey, str.Keys.FirstOrDefault(lambda (k) {k.Duplicates == RpsKeyDuplicates.NoDuplicates})
+                if (thekey == ^null) then
+                    mreturn ""
+                else
+                    mreturn thekey.KeyOfReference.ToString()
+            end
+            mreturn ExpandStructureToken(tkn, template, loops, doExpand)
+        endmethod
+
         private static method expandStructureKeys, string
             tkn, @Token 
             template, @FileNode 

CodeGenEngine/Tokenizer.dbl

@@ -261,6 +261,7 @@ namespace CodeGen.Engine
             &    { new TokenMeta() {Name = "STRUCTURE_DESC", TypeOfToken = TokenType.StructureInfo, IsPaired = false, Validity = TokenValidity.Anywhere, RequiresRepository = true} }, 
             &    { new TokenMeta() {Name = "STRUCTURE_FIELDS", TypeOfToken = TokenType.StructureInfo, IsPaired = false, Validity = TokenValidity.Anywhere, RequiresRepository = true} }, 
             &    { new TokenMeta() {Name = "STRUCTURE_FILES", TypeOfToken = TokenType.StructureInfo, IsPaired = false, Validity = TokenValidity.Anywhere, RequiresRepository = true} }, 
+            &    { new TokenMeta() {Name = "STRUCTURE_FIRST_UNIQUE_KEY", TypeOfToken = TokenType.StructureInfo, IsPaired = false, Validity = TokenValidity.Anywhere, RequiresRepository = true} }, 
             &    { new TokenMeta() {Name = "STRUCTURE_KEYS", TypeOfToken = TokenType.StructureInfo, IsPaired = false, Validity = TokenValidity.Anywhere, RequiresRepository = true} }, 
             &    { new TokenMeta() {Name = "STRUCTURE_LDESC", TypeOfToken = TokenType.StructureInfo, IsPaired = false, Validity = TokenValidity.Anywhere, RequiresRepository = true} }, 
             &    { makeTokenMeta_AllVariants("STRUCTURE_NAME", TokenType.StructureInfo, TokenValidity.Anywhere, true) },