Examples of org.apache.commons.collections4.sequence.CommandVisitor

Package org.apache.commons.collections4.sequence

Examples of org.apache.commons.collections4.sequence.CommandVisitor

org.apache.commons.collections4.FunctorException

This interface should be implemented by user object to walk through {@link EditScript EditScript} objects.

Users should implement this interface in order to walk through the {@link EditScript EditScript} object created by the comparisonof two sequences. This is a direct application of the visitor design pattern. The {@link EditScript#visit EditScript.visit}method takes an object implementing this interface as an argument, it will perform the loop over all commands in the script and the proper methods of the user class will be called as the commands are encountered.

The implementation of the user visitor class will depend on the need. Here are two examples.

The first example is a visitor that build the longest common subsequence:

 import org.apache.commons.collections4.comparators.sequence.CommandVisitor; import java.util.ArrayList; public class LongestCommonSubSequence implements CommandVisitor { public LongestCommonSubSequence() { a = new ArrayList(); } public void visitInsertCommand(Object object) { } public void visitKeepCommand(Object object) { a.add(object); } public void visitDeleteCommand(Object object) { } public Object[] getSubSequence() { return a.toArray(); } private ArrayList a; }

The second example is a visitor that shows the commands and the way they transform the first sequence into the second one:

 import org.apache.commons.collections4.comparators.sequence.CommandVisitor; import java.util.Arrays; import java.util.ArrayList; import java.util.Iterator; public class ShowVisitor implements CommandVisitor { public ShowVisitor(Object[] sequence1) { v = new ArrayList(); v.addAll(Arrays.asList(sequence1)); index = 0; } public void visitInsertCommand(Object object) { v.insertElementAt(object, index++); display("insert", object); } public void visitKeepCommand(Object object) { ++index; display("keep  ", object); } public void visitDeleteCommand(Object object) { v.remove(index); display("delete", object); } private void display(String commandName, Object object) { System.out.println(commandName + " " + object + " ->" + this); } public String toString() { StringBuffer buffer = new StringBuffer(); for (Iterator iter = v.iterator(); iter.hasNext();) { buffer.append(' ').append(iter.next()); } return buffer.toString(); } private ArrayList v; private int index; }

@since 4.0 @version $Id: CommandVisitor.java 1477760 2013-04-30 18:34:03Z tn $

  }


  //loads the files and removes words which occur less than 5 tims
  public void loadProgram() throws FileNotFoundException
  {
    Bag wordBag = new HashBag();


    //Load all the medical files in the directory
    File[] fileList = new File(recordsDir).listFiles();
    for (int i = 0; i<fileList.length; i++) {
      loadFile(fileList[i].toString(), wordBag);
    }


    //dump bag into frequent who appear in 5 or more medical records
    for (Object obj : wordBag.uniqueSet()) {
      if (wordBag.getCount(obj) > 4){
        frequent.add((String)obj);
      }
    }


  }

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     * @param object  the input object
     * @return never
     * @throws FunctorException always
     */
    public boolean evaluate(final T object) {
        throw new FunctorException("ExceptionPredicate invoked");
    }

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     *
     * @return never
     * @throws FunctorException always
     */
    public T create() {
        throw new FunctorException("ExceptionFactory invoked");
    }

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        public T create() {
            try {
                return clazz.newInstance();
            } catch (final Exception ex) {
                throw new FunctorException("Cannot instantiate class: " + clazz, ex);
            }
        }

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        try {
            final Class<?> cls = input.getClass();
            final Method method = cls.getMethod(iMethodName, iParamTypes);
            return (O) method.invoke(input, iArgs);
        } catch (final NoSuchMethodException ex) {
            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
                                       input.getClass() + "' does not exist");
        } catch (final IllegalAccessException ex) {
            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
                                       input.getClass() + "' cannot be accessed");
        } catch (final InvocationTargetException ex) {
            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
                                       input.getClass() + "' threw an exception", ex);
        }
    }

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     * @param input  the input object to transform
     * @return never
     * @throws FunctorException always
     */
    public O transform(final I input) {
        throw new FunctorException("ExceptionTransformer invoked");
    }

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     *
     * @param input  the input object
     * @throws FunctorException always
     */
    public void execute(final E input) {
        throw new FunctorException("ExceptionClosure invoked");
    }

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     * @return true if decorated predicate returns true
     * @throws FunctorException if input is null
     */
    public boolean evaluate(final T object) {
        if (object == null) {
            throw new FunctorException("Input Object must not be null");
        }
        return iPredicate.evaluate(object);
    }

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     * @return the transformed result
     */
    public T transform(final Class<? extends T> input) {
        try {
            if (input == null) {
                throw new FunctorException(
                    "InstantiateTransformer: Input object was not an instanceof Class, it was a null object");
            }
            final Constructor<? extends T> con = input.getConstructor(iParamTypes);
            return con.newInstance(iArgs);
        } catch (final NoSuchMethodException ex) {
            throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");
        } catch (final InstantiationException ex) {
            throw new FunctorException("InstantiateTransformer: InstantiationException", ex);
        } catch (final IllegalAccessException ex) {
            throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);
        } catch (final InvocationTargetException ex) {
            throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);
        }
    }

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        }


        try {
            return iConstructor.newInstance(iArgs);
        } catch (final InstantiationException ex) {
            throw new FunctorException("InstantiateFactory: InstantiationException", ex);
        } catch (final IllegalAccessException ex) {
            throw new FunctorException("InstantiateFactory: Constructor must be public", ex);
        } catch (final InvocationTargetException ex) {
            throw new FunctorException("InstantiateFactory: Constructor threw an exception", ex);
        }
    }

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Related Classes of org.apache.commons.collections4.sequence.CommandVisitor

junit.framework.TestSuite

org.apache.commons.collections4.comparators.BooleanComparator

org.apache.commons.collections4.comparators.BooleanComparatorTest

org.apache.commons.collections4.functors.CatchAndRethrowClosure

org.apache.commons.collections4.functors.ExceptionClosure

org.apache.commons.collections4.functors.ExceptionFactory

org.apache.commons.collections4.functors.ExceptionPredicate

org.apache.commons.collections4.functors.ExceptionTransformer

org.apache.commons.collections4.functors.InstantiateFactory

org.apache.commons.collections4.functors.InstantiateTransformer

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