Package com.tangosol.util.extractor

Class UniversalExtractor<T,E>

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.extractor.AbstractExtractor<T,E>
com.tangosol.util.extractor.UniversalExtractor<T,E>
Type Parameters:
T - the type of the value to extract from
E - the type of value that will be extracted
All Implemented Interfaces:
CanonicallyNamed, ExternalizableLite, PortableObject, QueryMapComparator, Remote.Function<T,E>, Remote.ToDoubleFunction<T>, Remote.ToIntFunction<T>, Remote.ToLongFunction<T>, ValueExtractor<T,E>, Serializable, Comparator, Function<T,E>, ToDoubleFunction<T>, ToIntFunction<T>, ToLongFunction<T>
public class UniversalExtractor<T,E> extends AbstractExtractor<T,E> implements ValueExtractor<T,E>, ExternalizableLite, PortableObject
Universal ValueExtractor implementation.

Either a property or method based extractor based on parameters passed to constructor UniversalExtractor(String, Object[], int). Generally, the name value passed to the UniversalExtractor constructor represents a property unless sName value ends in METHOD_SUFFIX, "()", then this instance is a reflection based method extractor. Special cases are described in the constructor documentation.

AbstractExtractor.equals(Object) and AbstractExtractor.hashCode() describe how this Extractor can be equivalent to other ValueExtractor implementations.

Since:
12.2.1.4
Author:
cp/gg 2002.11.01, ew 2007.02.01, jf 2017.11.20
See Also:

  • Field Details

    • BEAN_ACCESSOR_PREFIXES

      public static final String[] BEAN_ACCESSOR_PREFIXES
      JavaBean accessor prefixes.

    • METHOD_SUFFIX

      public static final String METHOD_SUFFIX
      If m_sName ends with this suffix, it represents a method name.
      See Also:

    • m_sName

      protected String m_sName
      A method or property name.

    • m_aoParam

      protected Object[] m_aoParam
      The parameter array. Must be null or zero length for a property based extractor.

    • m_sNameCanon

      protected transient String m_sNameCanon
      Canonical name for this extractor.

      Note: subclasses are responsible for initialization and POF and/or Lite serialization of this field.

  • Constructor Details

    • UniversalExtractor

      public UniversalExtractor()
      Default constructor (necessary for the ExternalizableLite interface).

    • UniversalExtractor

      public UniversalExtractor(String sName)
      Construct a UniversalExtractor based on syntax of sName.

      If sName does not end in METHOD_SUFFIX, "()", this extractor is a property extractor. If sName is prefixed with one of the BEAN_ACCESSOR_PREFIXES and optionally ends in the METHOD_SUFFIX, this extractor is a property extractor. Otherwise, if the sName just ends in {#link #METHOD_SUFFIX}, this extractor is considered a method extractor.

      Parameters:
      sName - a method or property name

    • UniversalExtractor

      public UniversalExtractor(String sName, Object[] aoParam)
      Construct a UniversalExtractor based on a name and optional parameters.

      If sName does not end in METHOD_SUFFIX, "()", and has no aoParams,this extractor is a property extractor. If sName is prefixed with one of the BEAN_ACCESSOR_PREFIXES, optionally ends in METHOD_SUFFIX and has no aoParams,this extractor is a property extractor. Otherwise, if the sNamejust ends in {#link #METHOD_SUFFIX}, this extractor is considered a method extractor.

      Parameters:
      sName - a method or property name
      aoParam - the array of arguments to be used in the method invocation; may be null
      Throws:
      IllegalArgumentException - when sName does not end in METHOD_SUFFIX and aoParam array length is one or more.

    • UniversalExtractor

      public UniversalExtractor(String sName, Object[] aoParam, int nTarget)
      Construct a UniversalExtractor based on a name, optional parameters and the entry extraction target.

      If sName does not end in METHOD_SUFFIX, "()", this extractor is a property extractor. If sName is prefixed with one of the BEAN_ACCESSOR_PREFIXES and optionally ends in METHOD_SUFFIX, this extractor is a property extractor. If the sName just ends in METHOD_SUFFIX, this extractor is considered a method extractor.

      Parameters:
      sName - a method or property name
      aoParam - the array of arguments to be used in the method invocation; may be null
      nTarget - one of the AbstractExtractor.VALUE or AbstractExtractor.KEY values
      Throws:
      IllegalArgumentException - when sName does not end in METHOD_SUFFIX and aoParam array length is one or more.

  • Method Details

    • extract

      public E extract(T oTarget)
      Extract from target using reflection or map access.

      If name is a property, reflection accessor method lookup on T fails and oTarget is an instance Map, use canonical name to get value from target.

      Specified by:
      extract in interface ValueExtractor<T,E>
      Overrides:
      extract in class AbstractExtractor<T,E>
      Parameters:
      oTarget - the target
      Returns:
      value extracted from target

    • getCanonicalName

      public String getCanonicalName()
      Description copied from interface: ValueExtractor
      Return the canonical name for this extractor.

      A canonical name uniquely identifies what is to be extracted, but not how it is to be extracted. Thus two different extractor implementations with the same non-null canonical name are considered to be equal, and should reflect this in their implementations of hashCode and equals.

      Canonical names for properties are designated by their property name in camel case, for instance a Java Bean with method getFooBar would have a property named fooBar, and would have fooBar as its canonical name.

      Canonical names for zero-arg method invocations are the method name followed by ().

      Dots in a canonical name delimit one or more property/method accesses represented by a chaining ValueExtractor such as ChainedExtractor or PofExtractor(Class, PofNavigator, String).

      There is currently no canonical name format for methods which take parameters and as such they must return a canonical name of null.

      Specified by:
      getCanonicalName in interface CanonicallyNamed
      Specified by:
      getCanonicalName in interface ValueExtractor<T,E>
      Overrides:
      getCanonicalName in class AbstractExtractor<T,E>
      Returns:
      the extractor's canonical name, or null

    • fromKey

      public ValueExtractor<T,E> fromKey()
      Description copied from interface: ValueExtractor
      Obtain a version of this ValueExtractor that targets an entry's key.
      Specified by:
      fromKey in interface ValueExtractor<T,E>
      Returns:
      a version of this ValueExtractor that targets an entry's key

    • equals

      public boolean equals(Object o)
      Compare the UniversalExtractor with another object to determine equality.

      AbstractExtractor.equals(Object) contract takes precedence when applicable, falling back to implementation specific equals.

      Two UniversalExtractor objects, re1 and re2 are considered equal if re1.extract(o) equals re2.extract(o) for all values of o.

      Specified by:
      equals in interface Comparator<T>
      Specified by:
      equals in interface ValueExtractor<T,E>
      Overrides:
      equals in class AbstractExtractor<T,E>
      Parameters:
      o - the reference object with which to compare
      Returns:
      true iff this UniversalExtractor and the passed object are equivalent

    • hashCode

      public int hashCode()
      HashCode value is hashCode of non-null canonical name; otherwise, it is the hashCode of sName passed to {#link UniversalExtractor(String)}.
      Specified by:
      hashCode in interface ValueExtractor<T,E>
      Overrides:
      hashCode in class AbstractExtractor<T,E>
      Returns:
      an integer hash value for this UniversalExtractor object

    • toString

      public String toString()
      Provide a human-readable description of this UniversalExtractor object.
      Overrides:
      toString in class Object
      Returns:
      a human-readable description of this UniversalExtractor object

    • init

      protected void init()
      Called in constructor and deserializers.

    • getMethodName

      public String getMethodName()
      Return the method name that this extractor is configured to invoke. If a reflection-based method extractor, isMethodExtractor(), return the method name to be invoked. If a property extractor, return the likely JavaBean accessor method name.
      Returns:
      method name

    • getName

      public String getName()
      Return the name passed into UniversalExtractor(String).
      Returns:
      the name of extraction attribute.

    • getPropertyName

      public String getPropertyName()
      Return the property name of this extractor.
      Returns:
      property name of this extractor; otherwise, return null.

    • isPropertyExtractor

      public boolean isPropertyExtractor()
      Return true if this is a Property extractor.
      Returns:
      true if this a property extractor.

    • isMethodExtractor

      public boolean isMethodExtractor()
      Return true if this a method extractor.
      Returns:
      true if this is a method extractor.

    • getParameters

      public Object[] getParameters()
      Return the array of arguments used to invoke the method.
      Returns:
      the array of arguments used to invoke the method

    • extractComplex

      protected E extractComplex(T oTarget) throws InvocationTargetException, IllegalAccessException
      Extract from target using reflection or map access. If name is a property, reflection accessor method lookup on T fails and T is an instance Map, use canonical name to get value from target. If successful, cache the reflection computation.
      Parameters:
      oTarget - the target
      Returns:
      value extracted from target
      Throws:
      InvocationTargetException - if reflection method lookup fails
      IllegalAccessException - if reflection method lookup fails

    • createExtractor

      public static <T, E> ValueExtractor<T,E> createExtractor(String sNames)
      Return a ValueExtractor representing dot separated list of property and/or method names.
      Type Parameters:
      T - the type of the value to extract from
      E - the type of value that will be extracted
      Parameters:
      sNames - dot-delimited property and/or methods name(s)
      Returns:
      UniversalExtractor if only one name in parameter; otherwise, return a ChainedExtractor with a UniversalExtractor for each name.

    • readExternal

      public void readExternal(DataInput in) throws IOException
      Restore the contents of this object by loading the object's state from the passed DataInput object.
      Specified by:
      readExternal in interface ExternalizableLite
      Parameters:
      in - the DataInput stream to read data from in order to restore the state of this object
      Throws:
      IOException - if an I/O exception occurs

    • writeExternal

      public void writeExternal(DataOutput out) throws IOException
      Save the contents of this object by storing the object's state into the passed DataOutput object.
      Specified by:
      writeExternal in interface ExternalizableLite
      Parameters:
      out - the DataOutput stream to write the state of this object to
      Throws:
      IOException - if an I/O exception occurs

    • readExternal

      public void readExternal(PofReader in) throws IOException
      Restore the contents of a user type instance by reading its state using the specified PofReader object.
      Specified by:
      readExternal in interface PortableObject
      Parameters:
      in - the PofReader from which to read the object's state
      Throws:
      IOException - if an I/O error occurs

    • writeExternal

      public void writeExternal(PofWriter out) throws IOException
      Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
      Specified by:
      writeExternal in interface PortableObject
      Parameters:
      out - the PofWriter to which to write the object's state
      Throws:
      IOException - if an I/O error occurs