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## org.apache.lucene.search.suggest.tst
Class TSTAutocomplete

    java.lang.Object
      org.apache.lucene.search.suggest.tst.TSTAutocomplete

    public class TSTAutocomplete

extends Object

Ternary Search Trie implementation.

See Also:
  `TernaryTreeNode`

Method Summary
`void` | `balancedTree(Object[] tokens, Object[] vals, int lo, int hi, TernaryTreeNode root)` Inserting keys in TST in the order middle,small,big (lexicographic measure) recursively creates a balanced tree which reduces insertion and search times significantly.
`TernaryTreeNode` | `insert(TernaryTreeNode currentNode, CharSequence s, Object val, int x)` Inserts a key in TST creating a series of Binary Search Trees at each node.
`ArrayList<TernaryTreeNode>` | `prefixCompletion(TernaryTreeNode root, CharSequence s, int x)` Auto-completes a given prefix query using Depth-First Search with the end of prefix as source node each time finding a new leaf to get a complete key to be added in the suggest list.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Method Detail

### balancedTree

    public void balancedTree(Object[] tokens,
                             Object[] vals,
                             int lo,
                             int hi,
                             TernaryTreeNode root)

  Inserting keys in TST in the order middle,small,big (lexicographic measure) recursively creates a balanced tree which reduces insertion and search times significantly.

  Parameters:
    `tokens` - Sorted list of keys to be inserted in TST.
    `lo` - stores the lower index of current list.
    `hi` - stores the higher index of current list.
    `root` - a reference object to root of TST.

### insert

    public TernaryTreeNode insert(TernaryTreeNode currentNode,
                                  CharSequence s,
                                  Object val,
                                  int x)

  Inserts a key in TST creating a series of Binary Search Trees at each node. The key is actually stored across the eqKid of each node in a successive manner.

  Parameters:
    `currentNode` - a reference node where the insertion will take currently.
    `s` - key to be inserted in TST.
    `x` - index of character in key to be inserted currently.
  Returns:
    currentNode The new reference to root node of TST

### prefixCompletion

    public ArrayList<TernaryTreeNode> prefixCompletion(TernaryTreeNode root,
                                                       CharSequence s,
                                                       int x)

  Auto-completes a given prefix query using Depth-First Search with the end of prefix as source node each time finding a new leaf to get a complete key to be added in the suggest list.

  Parameters:
    `root` - a reference to root node of TST.
    `s` - prefix query to be auto-completed.
    `x` - index of current character to be searched while traversing through the prefix in TST.
  Returns:
    suggest list of auto-completed keys for the given prefix query.

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