[feature] Add fn:collation-key signature and errors.

Author: chris-evolvedbinary

exist-core/src/main/java/org/exist/xquery/functions/fn/FnModule.java

@@ -53,6 +53,7 @@ public class FnModule extends AbstractInternalModule {
         new FunctionDef(FunCodepointEqual.signature, FunCodepointEqual.class),
         new FunctionDef(FunCodepointsToString.signature, FunCodepointsToString.class),
         new FunctionDef(FunCollationKey.FS_COLLATION_KEY_SIGNATURES[0], FunCollationKey.class),
+        new FunctionDef(FunCollationKey.FS_COLLATION_KEY_SIGNATURES[1], FunCollationKey.class),
         new FunctionDef(FunCompare.signatures[0], FunCompare.class),
         new FunctionDef(FunCompare.signatures[1], FunCompare.class),
         new FunctionDef(FunConcat.signature, FunConcat.class),

exist-core/src/main/java/org/exist/xquery/functions/fn/FunCollationKey.java

@@ -30,6 +30,8 @@
 
 import com.ibm.icu.text.Collator;
 
+import java.nio.charset.StandardCharsets;
+
 public class FunCollationKey extends BasicFunction {
 
     private static final QName FN_NAME = new QName("collation-key", Function.BUILTIN_FUNCTION_NS, FnModule.PREFIX);
@@ -44,14 +46,18 @@ public class FunCollationKey extends BasicFunction {
     );
 
     public static final FunctionSignature[] FS_COLLATION_KEY_SIGNATURES = {
+            new FunctionSignature(FunCollationKey.FN_NAME, FunCollationKey.FN_DESCRIPTION,
+                    new SequenceType[] {
+                            new FunctionParameterSequenceType("value-string", Type.STRING,
+                                    Cardinality.ZERO_OR_ONE, "The value string")
+                    }, FN_RETURN),
             new FunctionSignature(FunCollationKey.FN_NAME, FunCollationKey.FN_DESCRIPTION,
                     new SequenceType[] {
                             new FunctionParameterSequenceType("value-string", Type.STRING,
                                     Cardinality.ZERO_OR_ONE, "The value string"),
                             new FunctionParameterSequenceType("collection-string", Type.STRING,
                                     Cardinality.ZERO_OR_ONE, "The collation string")
                     }, FN_RETURN)
-
     };
 
     public FunCollationKey(final XQueryContext context, final FunctionSignature signature) {
@@ -61,7 +67,18 @@ public FunCollationKey(final XQueryContext context, final FunctionSignature sign
     public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
         final BinaryValue result;
         final String source = (args.length >= 1) ? args[0].toString() : "";
-        final Collator collator = (args.length >= 2) ? Collations.getCollationFromURI(args[1].toString()) : context.getDefaultCollator();
+        final Collator collator;
+        if (args.length >= 2) {
+            collator = Collations.getCollationFromURI(args[1].toString());
+            if (collator == null) {
+                throw new XPathException(ErrorCodes.FOCH0002, "Unsupported collation: " + args[1]);
+            }
+        } else {
+            collator = context.getDefaultCollator();
+            if (collator == null) {
+                throw new XPathException(ErrorCodes.FOCH0002, "Could not get default collator.");
+            }
+        }
         result = new BinaryValueFromBinaryString(new Base64BinaryValueType(), Base64.encodeBase64String(collator.getCollationKey(source).toByteArray()));
         return result;
     }