FunctionLibrary.java

/*
 * 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.function;

import gov.nist.secauto.metaschema.core.metapath.IExpression;
import gov.nist.secauto.metaschema.core.util.ObjectUtils;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Stream;

import javax.xml.namespace.QName;

import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;

public class FunctionLibrary implements IFunctionLibrary {

  @NonNull
  private final Map<QName, NamedFunctionSet> libraryByQName = new HashMap<>(); // NOPMD - intentional
  @NonNull
  private final Map<String, NamedFunctionSet> libraryByName = new HashMap<>(); // NOPMD - intentional

  /**
   * Register the provided function signature.
   *
   * @param function
   *          the function signature to register
   * @throws IllegalArgumentException
   *           if the provided function has the same arity as a previously
   *           registered function with the same name
   */
  public void registerFunction(@NonNull IFunction function) {
    registerFunctionByQName(function);
    registerFunctionByName(function);
  }

  protected void registerFunctionByQName(@NonNull IFunction function) {
    QName qname = function.getQName();
    IFunction duplicate;
    synchronized (this) {
      NamedFunctionSet functions = libraryByQName.get(qname);
      if (functions == null) {
        functions = new NamedFunctionSet();
        libraryByQName.put(qname, functions);
      }
      duplicate = functions.addFunction(function);
    }
    if (duplicate != null) {
      throw new IllegalArgumentException(String.format("Duplicate functions with same arity: %s shadows %s",
          duplicate.toSignature(), function.toSignature()));
    }
  }

  protected void registerFunctionByName(@NonNull IFunction function) {
    String name = function.getName();
    synchronized (this) {
      NamedFunctionSet functions = libraryByName.get(name);
      if (functions == null) {
        functions = new NamedFunctionSet();
        libraryByName.put(name, functions);
      }
      // replace duplicates
      functions.addFunction(function);
    }
  }

  @Override
  public Stream<IFunction> getFunctionsAsStream() {
    synchronized (this) {
      return ObjectUtils.notNull(
          libraryByQName.values().stream().flatMap(set -> {
            return set.getFunctionsAsStream();
          }));
    }
  }

  @Override
  public IFunction getFunction(@NonNull String name, @NonNull List<IExpression> args) {
    IFunction retval;
    synchronized (this) {
      NamedFunctionSet functions = libraryByName.get(name);
      retval = functions == null ? null : functions.getFunctionWithArity(args.size());
    }
    return retval;
  }

  @Override
  public IFunction getFunction(@NonNull QName name, @NonNull List<IExpression> args) {
    IFunction retval;
    synchronized (this) {
      NamedFunctionSet functions = libraryByQName.get(name);
      retval = functions == null ? null : functions.getFunctionWithArity(args.size());
    }
    return retval;
  }

  private static class NamedFunctionSet {
    private final Map<Integer, IFunction> arityToFunctionMap;

    public NamedFunctionSet() {
      this.arityToFunctionMap = new HashMap<>();
    }

    @SuppressWarnings("null")
    @NonNull
    public Stream<IFunction> getFunctionsAsStream() {
      return arityToFunctionMap.values().stream();
    }

    @Nullable
    public IFunction getFunctionWithArity(int arity) {
      return arityToFunctionMap.get(arity);
    }

    @Nullable
    public IFunction addFunction(@NonNull IFunction function) {
      return arityToFunctionMap.put(function.arity(), function);
    }
  }
}