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## org.apache.uima.resource.metadata
Interface SimplePrecondition

All Superinterfaces:
  Cloneable, MetaDataObject, Precondition, Serializable, XMLizable

All Known Subinterfaces:
  LanguagePrecondition, MimeTypePrecondition

    public interface SimplePrecondition

extends Precondition

`SimplePrecondition` defines a few simple conditions that can be evaluted against a `CAS`.

A value in the CAS (see below) will be compared against the precondition's `comparisonValue` property using the speicified `predicate`.

The value in the CAS is specified by providing values for `indexName`, `fsMatchConstraint`, and `featureName`. If any FeatureStructure in the specified index matches the FS match constraint and has a feature value that satisfies this precondition's precicate, the precondition will be considered satisfied. If the index name is ommitted, the default Annotation index (if present) will be used.

The possible predicates are defined by constants on this interface. The currently avaialble predicates are:

- `EQUAL` - evaluates to true if and only if the values are equal (according to the equality rules of their data type).
- `ELEMENT_OF` - the comparison value must be an array. Evaluates to true if and only if the test value is equal to one of the elements of the comparison array.
- `LANGUAGE_SUBSUMED` - the comparison value must be an array of Strings, each of which is an ISO language identifier. Evaluates to true if and only if the test value is an ISO language identifier that is subsumed by one of the values of the comparison array. (For example, "en_US" is subsumed by "en.")

As with all `MetaDataObject`s, a `SimplePrecondition` may or may not be modifiable. An application can find out by calling the `MetaDataObject.isModifiable()` method.

Field Summary
`static String` | `ELEMENT_OF` Identifies the ELEMENT_OF predicate.
`static String` | `EQUAL` Identifies the EQUAL predicate.
`static String` | `LANGUAGE_SUBSUMED` Identifies the LANGUAGE_SUBSUMED predicate.
`static String` | `PRECONDITION_TYPE` The type identifier for this class of precondition.

Method Summary
`Object` | `getComparisonValue()` Retrieves the literal value to which features' values will be compared.
`boolean` | `getDefault()` Retrieves the deafult value for this precondition.
`String` | `getFeatureName()` Gets the name of the feature to be tested.
`String` | `getFsIndexName()` Retrieves the name of the FeatureStructure index containing FeatureStructures to be tested by this precondition.
`FSMatchConstraint` | `getFsMatchConstraint()` Retrieves the FSMatchConstraint that determines which CAS feature structures will be tested by this precondition.
`String` | `getPreconditionType()` Gets the type of this precondition.
`String` | `getPredicate()` Retrieves the predicate used to compare the test value to the comparison value.
`void` | `setComparisonValue(Object aValue)` Sets the literal value to which features' values will be compared.
`void` | `setDefault(boolean aDefault)` Sets the deafult value for this precondition.
`void` | `setFeatureName(String aFeatureName)` Sets the name of the feature to be tested.
`void` | `setFsIndexName(String aIndexName)` Sets the name of the FeatureStructure index containing FeatureStructures to be tested by this precondition.
`void` | `setFsMatchConstraint(FSMatchConstraint aConstraint)` Sets the FSMatchConstraint that determines which CAS feature structures will be tested by this precondition.
`void` | `setPredicate(String aPredicate)` Sets the predicate used to compare the test value to the comparison value.

Methods inherited from interface org.apache.uima.resource.metadata.Precondition
`evaluate`

Methods inherited from interface org.apache.uima.resource.metadata.MetaDataObject
`clone, equals, getAttributeValue, getSourceUrl, getSourceUrlString, isModifiable, listAttributes, setAttributeValue, setSourceUrl`

Methods inherited from interface org.apache.uima.util.XMLizable
`buildFromXMLElement, buildFromXMLElement, toXML, toXML, toXML, toXML`

Field Detail

### PRECONDITION_TYPE

    static final String PRECONDITION_TYPE

  The type identifier for this class of precondition. This is the return value of `getPreconditionType()`.

  See Also:
    Constant Field Values

### EQUAL

    static final String EQUAL

  Identifies the EQUAL predicate. This predicate evaluates to true if and only if the test value and the comparison value are of the same data type and are equal, according to the equality rules of that data type.

  See Also:
    Constant Field Values

### ELEMENT_OF

    static final String ELEMENT_OF

  Identifies the ELEMENT_OF predicate. For this predicate, the comparison value must be an array. ELEMENT_OF evaluates to true if and only if the test value is equal to one of the elements of the array. (If the comparison value is not an array, ELEMENT_OF always evaluates to false.)

  See Also:
    Constant Field Values

### LANGUAGE_SUBSUMED

    static final String LANGUAGE_SUBSUMED

  Identifies the LANGUAGE_SUBSUMED predicate. For this predicate, the comparison value must be an array of ISO language identifiers. LANGUAGE_SUBSUMED evaluates to true if and only if the test value is an ISO language identifier that is subsumed by one of the values of the comparison array. (For example, "en_US" is subsumed by "en.")

  See Also:
    Constant Field Values

Method Detail

### getPreconditionType

    String getPreconditionType()

  Gets the type of this precondition. Each sub-interface of `Precondition` has its own standard type identifier String. These identifier Strings are used instead of Java class names in order to ease portability of metadata to other languages.

  Specified by:
    `getPreconditionType` in interface `Precondition`
  Returns:
    `PRECONDITION_TYPE`

### getFsIndexName

    String getFsIndexName()

  Retrieves the name of the FeatureStructure index containing FeatureStructures to be tested by this precondition.

  Returns:
    the name of the FS index, `null` if the default annotation index should be used

### setFsIndexName

    void setFsIndexName(String aIndexName)

  Sets the name of the FeatureStructure index containing FeatureStructures to be tested by this precondition.

  Parameters:
    `aIndexName` - the name of the FS index, `null` if the default annotation index should be used
  Throws:
    `UIMA_UnsupportedOperationException` - if this `MetaDataObject` is not modifiable.

### getFsMatchConstraint

    FSMatchConstraint getFsMatchConstraint()

  Retrieves the FSMatchConstraint that determines which CAS feature structures will be tested by this precondition.

  Returns:
    the FS match constraint, `null` if none

### setFsMatchConstraint

    void setFsMatchConstraint(FSMatchConstraint aConstraint)

  Sets the FSMatchConstraint that determines which CAS feature structures will be tested by this precondition.

  Parameters:
    `aConstraint` - the FS match constraint, `null` if none
  Throws:
    `UIMA_UnsupportedOperationException` - if this `MetaDataObject` is not modifiable.

### getFeatureName

    String getFeatureName()

  Gets the name of the feature to be tested.

  Returns:
    the feature name, `null` if none

### setFeatureName

    void setFeatureName(String aFeatureName)

  Sets the name of the feature to be tested.

  Parameters:
    `aFeatureName` - the feature name, `null` if none
  Throws:
    `UIMA_UnsupportedOperationException` - if this `MetaDataObject` is not modifiable.

### getComparisonValue

    Object getComparisonValue()

  Retrieves the literal value to which features' values will be compared.

  Returns:
    the value, which must be a String, Integer, Float, Boolean or an array of one of those four types.

### setComparisonValue

    void setComparisonValue(Object aValue)

  Sets the literal value to which features' values will be compared.

  Parameters:
    `aValue` - the comparison value, which must be a String, Integer, Float, Boolean, or an array of one of those four types.
  Throws:
    `UIMA_UnsupportedOperationException` - if this `MetaDataObject` is not modifiable.

### getPredicate

    String getPredicate()

  Retrieves the predicate used to compare the test value to the comparison value.

  Returns:
    a String that identifies the predicate used. This will always match one of the constants defined on this interface.

### setPredicate

    void setPredicate(String aPredicate)

  Sets the predicate used to compare the test value to the comparison value.

  Parameters:
    `aPredicate` - a String that identifies the predicate used. This must match one of the constants defined on this interface.
  Throws:
    `UIMA_UnsupportedOperationException` - if this `MetaDataObject` is not modifiable.
    `UIMA_IllegalArgumentException` - if the given value is not appropriate for the given attribute.

### getDefault

    boolean getDefault()

  Retrieves the deafult value for this precondition. This is the value returned if there is no applicable test value in the CAS.

  Returns:
    the default value

### setDefault

    void setDefault(boolean aDefault)

  Sets the deafult value for this precondition. This is the value returned if there is no applicable test value in the CAS.

  Parameters:
    `aDefault` - the default value
  Throws:
    `UIMA_UnsupportedOperationException` - if this `MetaDataObject` is not modifiable.

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Copyright © 2008 The Apache Software Foundation. All Rights Reserved.