Added the fn:name Metapath function.

core/src/main/java/gov/nist/secauto/metaschema/core/metapath/function/library/FnName.java

@@ -0,0 +1,109 @@
+/*
+ * SPDX-FileCopyrightText: none
+ * SPDX-License-Identifier: CC0-1.0
+ */
+
+package gov.nist.secauto.metaschema.core.metapath.function.library;
+
+import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
+import gov.nist.secauto.metaschema.core.metapath.MetapathConstants;
+import gov.nist.secauto.metaschema.core.metapath.StaticContext;
+import gov.nist.secauto.metaschema.core.metapath.function.FunctionUtils;
+import gov.nist.secauto.metaschema.core.metapath.function.IArgument;
+import gov.nist.secauto.metaschema.core.metapath.function.IFunction;
+import gov.nist.secauto.metaschema.core.metapath.item.IItem;
+import gov.nist.secauto.metaschema.core.metapath.item.ISequence;
+import gov.nist.secauto.metaschema.core.metapath.item.atomic.IStringItem;
+import gov.nist.secauto.metaschema.core.metapath.item.node.IDefinitionNodeItem;
+import gov.nist.secauto.metaschema.core.metapath.item.node.INodeItem;
+import gov.nist.secauto.metaschema.core.util.ObjectUtils;
+
+import java.util.List;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * /** Implements
+ * <a href= "https://www.w3.org/TR/xpath-functions-31/#func-name">fn:name</a>
+ * functions.
+ */
+public final class FnName {
+  @NonNull
+  private static final String NAME = "name";
+  @NonNull
+  static final IFunction SIGNATURE_NO_ARG = IFunction.builder()
+      .name(NAME)
+      .namespace(MetapathConstants.NS_METAPATH_FUNCTIONS)
+      .deterministic()
+      .contextDependent()
+      .focusDependent()
+      .returnType(IStringItem.type())
+      .returnOne()
+      .functionHandler(FnName::executeNoArg)
+      .build();
+  @NonNull
+  static final IFunction SIGNATURE_ONE_ARG = IFunction.builder()
+      .name(NAME)
+      .namespace(MetapathConstants.NS_METAPATH_FUNCTIONS)
+      .deterministic()
+      .contextIndependent()
+      .focusDependent()
+      .argument(IArgument.builder()
+          .name("arg")
+          .type(INodeItem.type())
+          .zeroOrOne()
+          .build())
+      .returnType(IStringItem.type())
+      .returnOne()
+      .functionHandler(FnName::executeOneArg)
+      .build();
+
+  @SuppressWarnings("unused")
+  @NonNull
+  private static ISequence<IStringItem> executeNoArg(@NonNull IFunction function,
+      @NonNull List<ISequence<?>> arguments,
+      @NonNull DynamicContext dynamicContext,
+      IItem focus) {
+
+    INodeItem arg = FunctionUtils.asType(ObjectUtils.requireNonNull(focus));
+
+    return ISequence.of(
+        IStringItem.valueOf(fnName(arg, dynamicContext.getStaticContext())));
+  }
+
+  @SuppressWarnings("unused")
+  @NonNull
+  private static ISequence<IStringItem> executeOneArg(@NonNull IFunction function,
+      @NonNull List<ISequence<?>> arguments,
+      @NonNull DynamicContext dynamicContext,
+      IItem focus) {
+    INodeItem arg = FunctionUtils.asTypeOrNull(ObjectUtils.requireNonNull(arguments.get(0)).getFirstItem(true));
+
+    return ISequence.of(
+        IStringItem.valueOf(arg == null ? "" : fnName(arg, dynamicContext.getStaticContext())));
+  }
+
+  /**
+   * Get the name of the provided node item.
+   * <p>
+   * Based on the XPath 3.1
+   * <a href= "https://www.w3.org/TR/xpath-functions-31/#func-name">fn:name</a>
+   * function.
+   *
+   * @param arg
+   *          the node item to get the name for
+   * @param staticContext
+   *          the static context used to resolve the namespace prefix
+   * @return the name of the node if it has one, or an empty string otherwise
+   */
+  @NonNull
+  public static String fnName(@NonNull INodeItem arg, @NonNull StaticContext staticContext) {
+    return arg instanceof IDefinitionNodeItem
+        ? ((IDefinitionNodeItem<?, ?>) arg).getQName().toEQName(staticContext)
+        : "";
+  }
+
+  private FnName() {
+    // disable construction
+  }
+}