org.apache.lucene.search.suggest.analyzing

## Class BlendedInfixSuggester

- java.lang.Object
- - org.apache.lucene.search.suggest.Lookup
  - - org.apache.lucene.search.suggest.analyzing.AnalyzingInfixSuggester
    - - org.apache.lucene.search.suggest.analyzing.BlendedInfixSuggester

- All Implemented Interfaces:
    Closeable, AutoCloseable, Accountable

      public class BlendedInfixSuggester
      extends AnalyzingInfixSuggester

  Extension of the AnalyzingInfixSuggester which transforms the weight after search to take into account the position of the searched term into the indexed text. Please note that it increases the number of elements searched and applies the ponderation after. It might be costly for long suggestions.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `BlendedInfixSuggester.BlenderType` The different types of blender.

    - ### Nested classes/interfaces inherited from class org.apache.lucene.search.suggest.Lookup

      `Lookup.LookupPriorityQueue, Lookup.LookupResult`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `DEFAULT_NUM_FACTOR` Default factor
    `protected static double` | `LINEAR_COEF` Coefficient used for linear blending

    - ### Fields inherited from class org.apache.lucene.search.suggest.analyzing.AnalyzingInfixSuggester

      `CONTEXTS_FIELD_NAME, DEFAULT_ALL_TERMS_REQUIRED, DEFAULT_CLOSE_INDEXWRITER_ON_BUILD, DEFAULT_HIGHLIGHT, DEFAULT_MIN_PREFIX_CHARS, EXACT_TEXT_FIELD_NAME, indexAnalyzer, queryAnalyzer, searcherMgr, searcherMgrLock, TEXT_FIELD_NAME, TEXTGRAMS_FIELD_NAME, writer`

    - ### Fields inherited from class org.apache.lucene.search.suggest.Lookup

      `CHARSEQUENCE_COMPARATOR`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `BlendedInfixSuggester(Directory dir, Analyzer analyzer)` Create a new instance, loading from a previously built directory, if it exists.
    `BlendedInfixSuggester(Directory dir, Analyzer indexAnalyzer, Analyzer queryAnalyzer, int minPrefixChars, BlendedInfixSuggester.BlenderType blenderType, int numFactor, boolean commitOnBuild)` Create a new instance, loading from a previously built directory, if it exists.
    `BlendedInfixSuggester(Directory dir, Analyzer indexAnalyzer, Analyzer queryAnalyzer, int minPrefixChars, BlendedInfixSuggester.BlenderType blenderType, int numFactor, Double exponent, boolean commitOnBuild, boolean allTermsRequired, boolean highlight)` Create a new instance, loading from a previously built directory, if it exists.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected double` | `calculateCoefficient(int position)` Calculate the weight coefficient based on the position of the first matching word.
    `protected List<Lookup.LookupResult>` | `createResults(IndexSearcher searcher, TopFieldDocs hits, int num, CharSequence key, boolean doHighlight, Set<String> matchedTokens, String prefixToken)` Create the results based on the search hits.
    `protected FieldType` | `getTextFieldType()` Subclass can override this method to change the field type of the text field e.g.
    `List<Lookup.LookupResult>` | `lookup(CharSequence key, BooleanQuery contextQuery, int num, boolean allTermsRequired, boolean doHighlight)` This is an advanced method providing the capability to send down to the suggester any arbitrary lucene query to be used to filter the result of the suggester
    `List<Lookup.LookupResult>` | `lookup(CharSequence key, Map<BytesRef,BooleanClause.Occur> contextInfo, int num, boolean allTermsRequired, boolean doHighlight)` Retrieve suggestions, specifying whether all terms must match (`allTermsRequired`) and whether the hits should be highlighted (`doHighlight`).
    `List<Lookup.LookupResult>` | `lookup(CharSequence key, Set<BytesRef> contexts, boolean onlyMorePopular, int num)` Look up a key and return possible completion for this key.
    `List<Lookup.LookupResult>` | `lookup(CharSequence key, Set<BytesRef> contexts, int num, boolean allTermsRequired, boolean doHighlight)` Lookup, with context but without booleans.

    - ### Methods inherited from class org.apache.lucene.search.suggest.analyzing.AnalyzingInfixSuggester

      `add, addContextToQuery, addNonMatch, addPrefixMatch, addWholeMatch, build, close, commit, finishQuery, getChildResources, getCount, getDirectory, getIndexWriterConfig, getLastTokenQuery, highlight, load, lookup, ramBytesUsed, refresh, store, update`

    - ### Methods inherited from class org.apache.lucene.search.suggest.Lookup

      `build, load, lookup, store`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### LINEAR_COEF

          protected static double LINEAR_COEF

      Coefficient used for linear blending

    - #### DEFAULT_NUM_FACTOR

          public static int DEFAULT_NUM_FACTOR

      Default factor

  - ### Constructor Detail

    - #### BlendedInfixSuggester

          public BlendedInfixSuggester(Directory dir,
                                       Analyzer analyzer)
                                throws IOException

      Create a new instance, loading from a previously built directory, if it exists.
      Throws:
        `IOException`

    - #### BlendedInfixSuggester

          public BlendedInfixSuggester(Directory dir,
                                       Analyzer indexAnalyzer,
                                       Analyzer queryAnalyzer,
                                       int minPrefixChars,
                                       BlendedInfixSuggester.BlenderType blenderType,
                                       int numFactor,
                                       boolean commitOnBuild)
                                throws IOException

      Create a new instance, loading from a previously built directory, if it exists.
      Parameters:
        `blenderType` - Type of blending strategy, see BlenderType for more precisions
        `numFactor` - Factor to multiply the number of searched elements before ponderate
        `commitOnBuild` - Call commit after the index has finished building. This would persist the suggester index to disk and future instances of this suggester can use this pre-built dictionary.
      Throws:
        `IOException` - If there are problems opening the underlying Lucene index.

    - #### BlendedInfixSuggester

          public BlendedInfixSuggester(Directory dir,
                                       Analyzer indexAnalyzer,
                                       Analyzer queryAnalyzer,
                                       int minPrefixChars,
                                       BlendedInfixSuggester.BlenderType blenderType,
                                       int numFactor,
                                       Double exponent,
                                       boolean commitOnBuild,
                                       boolean allTermsRequired,
                                       boolean highlight)
                                throws IOException

      Create a new instance, loading from a previously built directory, if it exists.
      Parameters:
        `blenderType` - Type of blending strategy, see BlenderType for more precisions
        `numFactor` - Factor to multiply the number of searched elements before ponderate
        `exponent` - exponent used only when blenderType is BlenderType.POSITION_EXPONENTIAL_RECIPROCAL
        `commitOnBuild` - Call commit after the index has finished building. This would persist the suggester index to disk and future instances of this suggester can use this pre-built dictionary.
        `allTermsRequired` - All terms in the suggest query must be matched.
        `highlight` - Highlight suggest query in suggestions.
      Throws:
        `IOException` - If there are problems opening the underlying Lucene index.

  - ### Method Detail

    - #### lookup

          public List<Lookup.LookupResult> lookup(CharSequence key,
                                                  Set<BytesRef> contexts,
                                                  boolean onlyMorePopular,
                                                  int num)
                                           throws IOException

      Description copied from class: `Lookup`
      Look up a key and return possible completion for this key.
      Overrides:
        `lookup` in class `AnalyzingInfixSuggester`
      Parameters:
        `key` - lookup key. Depending on the implementation this may be a prefix, misspelling, or even infix.
        `contexts` - contexts to filter the lookup by, or null if all contexts are allowed; if the suggestion contains any of the contexts, it's a match
        `onlyMorePopular` - return only more popular results
        `num` - maximum number of results to return
      Returns:
        a list of possible completions, with their relative weight (e.g. popularity)
      Throws:
        `IOException`

    - #### lookup

          public List<Lookup.LookupResult> lookup(CharSequence key,
                                                  Set<BytesRef> contexts,
                                                  int num,
                                                  boolean allTermsRequired,
                                                  boolean doHighlight)
                                           throws IOException

      Description copied from class: `AnalyzingInfixSuggester`
      Lookup, with context but without booleans. Context booleans default to SHOULD, so each suggestion must have at least one of the contexts.
      Overrides:
        `lookup` in class `AnalyzingInfixSuggester`
      Throws:
        `IOException`

    - #### lookup

          public List<Lookup.LookupResult> lookup(CharSequence key,
                                                  Map<BytesRef,BooleanClause.Occur> contextInfo,
                                                  int num,
                                                  boolean allTermsRequired,
                                                  boolean doHighlight)
                                           throws IOException

      Description copied from class: `AnalyzingInfixSuggester`
      Retrieve suggestions, specifying whether all terms must match (`allTermsRequired`) and whether the hits should be highlighted (`doHighlight`).
      Overrides:
        `lookup` in class `AnalyzingInfixSuggester`
      Throws:
        `IOException`

    - #### lookup

          public List<Lookup.LookupResult> lookup(CharSequence key,
                                                  BooleanQuery contextQuery,
                                                  int num,
                                                  boolean allTermsRequired,
                                                  boolean doHighlight)
                                           throws IOException

      Description copied from class: `AnalyzingInfixSuggester`
      This is an advanced method providing the capability to send down to the suggester any arbitrary lucene query to be used to filter the result of the suggester
      Overrides:
        `lookup` in class `AnalyzingInfixSuggester`
      Parameters:
        `key` - the keyword being looked for
        `contextQuery` - an arbitrary Lucene query to be used to filter the result of the suggester. `AnalyzingInfixSuggester.addContextToQuery(org.apache.lucene.search.BooleanQuery.Builder, org.apache.lucene.util.BytesRef, org.apache.lucene.search.BooleanClause.Occur)` could be used to build this contextQuery.
        `num` - number of items to return
        `allTermsRequired` - all searched terms must match or not
        `doHighlight` - if true, the matching term will be highlighted in the search result
      Returns:
        the result of the suggester
      Throws:
        `IOException` - f the is IO exception while reading data from the index

    - #### getTextFieldType

          protected FieldType getTextFieldType()

      Description copied from class: `AnalyzingInfixSuggester`
      Subclass can override this method to change the field type of the text field e.g. to change the index options
      Overrides:
        `getTextFieldType` in class `AnalyzingInfixSuggester`

    - #### createResults

          protected List<Lookup.LookupResult> createResults(IndexSearcher searcher,
                                                            TopFieldDocs hits,
                                                            int num,
                                                            CharSequence key,
                                                            boolean doHighlight,
                                                            Set<String> matchedTokens,
                                                            String prefixToken)
                                                     throws IOException

      Description copied from class: `AnalyzingInfixSuggester`
      Create the results based on the search hits. Can be overridden by subclass to add particular behavior (e.g. weight transformation). Note that there is no prefix toke (the `prefixToken` argument will be null) whenever the final token in the incoming request was in fact finished (had trailing characters, such as white-space).
      Overrides:
        `createResults` in class `AnalyzingInfixSuggester`
      Throws:
        `IOException` - If there are problems reading fields from the underlying Lucene index.

    - #### calculateCoefficient

          protected double calculateCoefficient(int position)

      Calculate the weight coefficient based on the position of the first matching word. Subclass should override it to adapt it to particular needs
      Parameters:
        `position` - of the first matching word in text
      Returns:
        the coefficient

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