Package com.yahoo.prelude.query

Class Item

java.lang.Object
com.yahoo.prelude.query.Item
All Implemented Interfaces:
Cloneable
Direct Known Subclasses:
CompositeItem, FalseItem, NullItem, PureWeightedItem, SimpleTaggableItem, TrueItem
public abstract class Item extends Object implements Cloneable
An item in the tree which defines which documents will match a query. Item subclasses can be composed freely to create arbitrary complex matching trees. Items are in general mutable and not thread safe. They can be deeply cloned by calling clone(). Their identity is defined by their content (i.e. the field value of two items decide if they are equal).
Author:
bratseth, havardpe

  • Field Details

    • DEFAULT_WEIGHT

      public static final int DEFAULT_WEIGHT
      See Also:

    • uniqueID

      protected int uniqueID
      Unique identifier to address the item for external annotation

    • connectedItem

      protected Item connectedItem
      Items for explicit connectivity

    • connectivity

      protected double connectivity

    • significance

      protected double significance
      Explicit term significance

    • explicitSignificance

      protected boolean explicitSignificance

  • Constructor Details

    • Item

      public Item()

  • Method Details

    • setIndexName

      public abstract void setIndexName(String index)
      Sets the index name of this item

    • getCode

      public final int getCode()
      Returns the int code of this item

    • getItemType

      public abstract Item.ItemType getItemType()
      Return the enumerated type of this item.

    • getName

      public abstract String getName()
      Returns the name of this item

    • setFilter

      public void setFilter(boolean filter)
      Sets whether this is a filter term. This indicates that the term origins from the filter parameter in the search API. The search backend does not handle filter terms any different than non-filter terms.

    • isFilter

      public boolean isFilter()
      Returns whether this is a filter term

    • getCreator

      public Item.ItemCreator getCreator()
      Returns the item creator value.

    • setCreator

      public void setCreator(Item.ItemCreator creator)
      Sets the item creator value.

    • setWeight

      public void setWeight(int w)
      Sets the relative importance of this term

    • getWeight

      public int getWeight()
      Returns the relative importance of this term. Default is 100.

    • addAnnotation

      public void addAnnotation(String key, Object value)
      Annotate this item
      Parameters:
      key - the annotation key
      value - the value, or null to set a valueless annotation

    • getAnnotation

      public Object getAnnotation(String annotation)
      Returns an annotation on this item, or null if the annotation is not set

    • hasAnnotation

      public boolean hasAnnotation(String annotation)
      Returns whether this has an annotation

    • setProtected

      public void setProtected(boolean isProtected)
      Set whether this should be protected from change/remove by query rewriters

    • isProtected

      public boolean isProtected()
      Returns whether this is to be protected from change/remove by query rewriters. default is false

    • setParent

      public void setParent(CompositeItem parent)
      Sets the parent in the tree. Do not use: Only to be called from CompositeItem/QueryTree

    • getParent

      public CompositeItem getParent()
      Returns the parent in the query tree, or null if this node has no parent

    • encode

      public abstract int encode(ByteBuffer buffer)

    • encodeThis

      protected void encodeThis(ByteBuffer buffer)

    • getBytes

      protected static byte[] getBytes(String string)
      Utility method for turning a string into utf-8 bytes

    • putString

      public static void putString(String s, ByteBuffer buffer)

    • putBytes

      public static void putBytes(byte[] bytes, ByteBuffer buffer)

    • getTermCount

      public abstract int getTermCount()

    • toString

      public String toString()
      Returns the canonical query language string of this item. The canonical language represent an item by the string 
       ([itemName] [body])
      where the body may recursively be other items.
      Overrides:
      toString in class Object

    • shouldParenthesize

      protected boolean shouldParenthesize()
      Returns whether this item should be parenthesized when printed. Default is false - no parentheses

    • appendHeadingString

      protected void appendHeadingString(StringBuilder buffer)
      Appends the heading of this string. As default getName() followed by a space.

    • appendBodyString

      protected abstract void appendBodyString(StringBuilder buffer)
      Override to append the item body in the canonical query language of this item. An item is usually represented by the string 
       ([itemName] [body])
      The body must be appended appended by this method.

    • clone

      public Item clone()
      Returns a deep copy of this item
      Overrides:
      clone in class Object

    • equals

      public boolean equals(Object o)
      Returns whether this item is of the same class and contains the same state as the given item.
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • hasUniqueID

      protected boolean hasUniqueID()

    • setHasUniqueID

      protected void setHasUniqueID(boolean hasUniqueID)

    • setLabel

      public void setLabel(String label)
      Label this item with a symbolic name which can later be used by the back-end to identify specific items for ranking purposes.
      Parameters:
      label - label for this item

    • getLabel

      public String getLabel()
      Returns the label for this item. This method will return null if no label has been set.

    • setRanked

      public void setRanked(boolean isRanked)
      Sets whether this term item should affect ranking. If set to false this term is not exposed to the ranking framework in the search backend.

    • isRanked

      public boolean isRanked()
      Returns whether or not this item should affect ranking.

    • setPositionData

      public void setPositionData(boolean usePositionData)
      Sets whether position data should be used when ranking this term item. If set to false the search backend uses fast bit vector data structures when matching on this term and only a few simple ranking features will be available when ranking this term. Note that setting this to false also saves a lot of CPU during matching as bit vector data structures are used.

    • usePositionData

      public boolean usePositionData()
      Returns whether position data should be used when ranking this item

    • disclose

      public void disclose(Discloser discloser)

    • isFromSpecialToken

      public boolean isFromSpecialToken()

    • setFromSpecialToken

      public void setFromSpecialToken(boolean fromSpecialToken)

    • getLanguage

      public com.yahoo.language.Language getLanguage()
      Returns the language of any natural language text below this item, or Language.UNKNOWN if not set.

    • setLanguage

      public void setLanguage(com.yahoo.language.Language language)
      Sets the language of any natural language text below this item. This cannot be set to null but can be set to Language.UNKNOWN

    • hasConnectivityBackLink

      public boolean hasConnectivityBackLink()
      DO NOT USE

    • isRoot

      public boolean isRoot()
      Returns true if this is the root item - that is if the parent is the QueryTree (or null for legacy reasons)