Completed code to support Metapath array construction.

core/src/main/java/gov/nist/secauto/metaschema/core/metapath/cst/AbstractCSTVisitorBase.java

@@ -47,6 +47,7 @@
 import javax.xml.namespace.QName;
 
 import edu.umd.cs.findbugs.annotations.NonNull;
+import edu.umd.cs.findbugs.annotations.Nullable;
 
 public abstract class AbstractCSTVisitorBase
     extends AbstractAstVisitor<IExpression> {
@@ -130,6 +131,28 @@ public IExpression visit(ParseTree tree) {
     return super.visit(tree);
   }
 
+  @Nullable
+  protected <CONTEXT extends ParserRuleContext, EXPRESSION extends IExpression> IExpression
+      nAiryToCollection(
+          @NonNull CONTEXT context,
+          int startIndex,
+          int step,
+          @NonNull BiFunction<CONTEXT, Integer, EXPRESSION> parser,
+          @NonNull Function<List<EXPRESSION>, IExpression> supplier) {
+    int numChildren = context.getChildCount();
+
+    IExpression retval = null;
+    if (startIndex < numChildren) {
+      List<EXPRESSION> children = new ArrayList<>((numChildren - startIndex) / step);
+      for (int idx = startIndex; idx < numChildren; idx += step) {
+        EXPRESSION result = parser.apply(context, idx);
+        children.add(result);
+      }
+      retval = supplier.apply(children);
+    }
+    return retval;
+  }
+
   /**
    * Parse the provided context as an n-ary phrase, which will be one of the
    * following.

core/src/main/java/gov/nist/secauto/metaschema/core/metapath/cst/AbstractExpressionVisitor.java

@@ -352,4 +352,14 @@ public RESULT visitFor(For expr, CONTEXT context) {
   public RESULT visitSimpleMap(SimpleMap expr, CONTEXT context) {
     return visitChildren(expr, context);
   }
+
+  @Override
+  public RESULT visitArray(ArraySequence expr, CONTEXT context) {
+    return visitChildren(expr, context);
+  }
+
+  @Override
+  public RESULT visitArray(ArrayMembers expr, CONTEXT context) {
+    return visitChildren(expr, context);
+  }
 }

core/src/main/java/gov/nist/secauto/metaschema/core/metapath/cst/ArrayMembers.java

@@ -0,0 +1,80 @@
+/*
+ * Portions of this software was developed by employees of the National Institute
+ * of Standards and Technology (NIST), an agency of the Federal Government and is
+ * being made available as a public service. Pursuant to title 17 United States
+ * Code Section 105, works of NIST employees are not subject to copyright
+ * protection in the United States. This software may be subject to foreign
+ * copyright. Permission in the United States and in foreign countries, to the
+ * extent that NIST may hold copyright, to use, copy, modify, create derivative
+ * works, and distribute this software and its documentation without fee is hereby
+ * granted on a non-exclusive basis, provided that this notice and disclaimer
+ * of warranty appears in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
+ * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
+ * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
+ * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
+ * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
+ * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
+ * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
+ * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
+ * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
+ * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
+ * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
+ */
+
+package gov.nist.secauto.metaschema.core.metapath.cst;
+
+import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
+import gov.nist.secauto.metaschema.core.metapath.ISequence;
+import gov.nist.secauto.metaschema.core.metapath.function.library.FnData;
+import gov.nist.secauto.metaschema.core.metapath.item.IItem;
+import gov.nist.secauto.metaschema.core.metapath.item.function.IArrayItem;
+import gov.nist.secauto.metaschema.core.metapath.item.function.IArrayMember;
+
+import java.util.List;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+public class ArrayMembers implements IExpression {
+  @NonNull
+  private final List<IExpression> children;
+
+  public ArrayMembers(@NonNull List<IExpression> children) {
+    this.children = children;
+  }
+
+  @Override
+  public List<? extends IExpression> getChildren() {
+    return children;
+  }
+
+  @Override
+  public ISequence<? extends IItem> accept(DynamicContext dynamicContext, ISequence<?> focus) {
+    return ISequence.of(getChildren().stream()
+        .map(expr -> {
+          ISequence<? extends IArrayMember> result = FnData.fnData(expr.accept(dynamicContext, focus));
+
+          IArrayMember retval;
+          switch (result.size()) {
+          case 0:
+            retval = ISequence.of();
+            break;
+          case 1:
+            retval = result.iterator().next();
+            break;
+          default:
+            retval = result;
+          }
+          return retval;
+        })
+        .collect(IArrayItem.toArrayItem()));
+  }
+
+  @Override
+  public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
+    return visitor.visitArray(this, context);
+  }
+
+}

core/src/main/java/gov/nist/secauto/metaschema/core/metapath/cst/ArraySequence.java

@@ -0,0 +1,82 @@
+/*
+ * Portions of this software was developed by employees of the National Institute
+ * of Standards and Technology (NIST), an agency of the Federal Government and is
+ * being made available as a public service. Pursuant to title 17 United States
+ * Code Section 105, works of NIST employees are not subject to copyright
+ * protection in the United States. This software may be subject to foreign
+ * copyright. Permission in the United States and in foreign countries, to the
+ * extent that NIST may hold copyright, to use, copy, modify, create derivative
+ * works, and distribute this software and its documentation without fee is hereby
+ * granted on a non-exclusive basis, provided that this notice and disclaimer
+ * of warranty appears in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
+ * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
+ * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
+ * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
+ * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
+ * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
+ * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
+ * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
+ * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
+ * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
+ * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
+ */
+
+package gov.nist.secauto.metaschema.core.metapath.cst;
+
+import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
+import gov.nist.secauto.metaschema.core.metapath.ISequence;
+import gov.nist.secauto.metaschema.core.metapath.function.library.FnData;
+import gov.nist.secauto.metaschema.core.metapath.item.function.IArrayItem;
+import gov.nist.secauto.metaschema.core.metapath.item.function.IArrayMember;
+
+import java.util.List;
+
+import edu.umd.cs.findbugs.annotations.Nullable;
+
+public class ArraySequence implements IExpression {
+  @Nullable
+  private final IExpression expr;
+
+  public ArraySequence(@Nullable IExpression expr) {
+    this.expr = expr;
+  }
+
+  @SuppressWarnings("rawtypes")
+  @Override
+  public Class<IArrayItem> getBaseResultType() {
+    return IArrayItem.class;
+  }
+
+  @SuppressWarnings("rawtypes")
+  @Override
+  public Class<IArrayItem> getStaticResultType() {
+    return IArrayItem.class;
+  }
+
+  @SuppressWarnings("null")
+  @Override
+  public List<? extends IExpression> getChildren() {
+    return List.of(expr);
+  }
+
+  @Override
+  public ISequence<IArrayItem<?>> accept(DynamicContext dynamicContext, ISequence<?> focus) {
+    ISequence<IArrayItem<?>> retval;
+    if (expr != null) {
+      List<? extends IArrayMember> result = FnData.fnData(expr.accept(dynamicContext, focus));
+      IArrayItem<?> array = IArrayItem.of(result);
+      retval = ISequence.of(array);
+    } else {
+      retval = ISequence.of();
+    }
+    return retval;
+  }
+
+  @Override
+  public <RESULT, CONTEXT> RESULT accept(IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
+    return visitor.visitArray(this, context);
+  }
+}