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148 changes: 143 additions & 5 deletions docs/reference/analysis/tokenfilters/classic-tokenfilter.asciidoc
Original file line number Diff line number Diff line change
@@ -1,9 +1,147 @@
[[analysis-classic-tokenfilter]]
=== Classic Token Filter
=== Classic token filter
++++
<titleabbrev>Classic</titleabbrev>
++++

The `classic` token filter does optional post-processing of
terms that are generated by the <<analysis-classic-tokenizer,`classic` tokenizer>>.
Performs optional post-processing of terms generated by the
<<analysis-classic-tokenizer,`classic` tokenizer>>.

This filter removes the english possessive from the end of words, and
it removes dots from acronyms.
This filter removes the english possessive (`'s`) from the end of words and
removes dots from acronyms. It uses Lucene's
https://lucene.apache.org/core/{lucene_version_path}/analyzers-common/org/apache/lucene/analysis/standard/ClassicFilter.html[ClassicFilter].

[[analysis-classic-tokenfilter-analyze-ex]]
==== Example

The following <<indices-analyze,analyze API>> request demonstrates how the
classic token filter works.

[source,console]
--------------------------------------------------
GET /_analyze
{
"tokenizer" : "classic",
"filter" : ["classic"],
"text" : "The 2 Q.U.I.C.K. Brown-Foxes jumped over the lazy dog's bone."
}
--------------------------------------------------

The filter produces the following tokens:

[source,text]
--------------------------------------------------
[ The, 2, QUICK, Brown, Foxes, jumped, over, the, lazy, dog, bone ]
--------------------------------------------------

/////////////////////
[source,console-result]
--------------------------------------------------
{
"tokens" : [
{
"token" : "The",
"start_offset" : 0,
"end_offset" : 3,
"type" : "<ALPHANUM>",
"position" : 0
},
{
"token" : "2",
"start_offset" : 4,
"end_offset" : 5,
"type" : "<ALPHANUM>",
"position" : 1
},
{
"token" : "QUICK",
"start_offset" : 6,
"end_offset" : 16,
"type" : "<ACRONYM>",
"position" : 2
},
{
"token" : "Brown",
"start_offset" : 17,
"end_offset" : 22,
"type" : "<ALPHANUM>",
"position" : 3
},
{
"token" : "Foxes",
"start_offset" : 23,
"end_offset" : 28,
"type" : "<ALPHANUM>",
"position" : 4
},
{
"token" : "jumped",
"start_offset" : 29,
"end_offset" : 35,
"type" : "<ALPHANUM>",
"position" : 5
},
{
"token" : "over",
"start_offset" : 36,
"end_offset" : 40,
"type" : "<ALPHANUM>",
"position" : 6
},
{
"token" : "the",
"start_offset" : 41,
"end_offset" : 44,
"type" : "<ALPHANUM>",
"position" : 7
},
{
"token" : "lazy",
"start_offset" : 45,
"end_offset" : 49,
"type" : "<ALPHANUM>",
"position" : 8
},
{
"token" : "dog",
"start_offset" : 50,
"end_offset" : 55,
"type" : "<APOSTROPHE>",
"position" : 9
},
{
"token" : "bone",
"start_offset" : 56,
"end_offset" : 60,
"type" : "<ALPHANUM>",
"position" : 10
}
]
}
--------------------------------------------------
/////////////////////

[[analysis-classic-tokenfilter-analyzer-ex]]
==== Add to an analyzer

The following <<indices-create-index,create index API>> request uses the
classic token filter to configure a new
<<analysis-custom-analyzer,custom analyzer>>.

[source,console]
--------------------------------------------------
PUT /classic_example
{
"settings" : {
"analysis" : {
"analyzer" : {
"classic_analyzer" : {
"tokenizer" : "classic",
"filter" : ["classic"]
}
}
}
}
}
--------------------------------------------------