Add elision token filter docs #7981

_analyzers/token-filters/elision.md

@@ -0,0 +1,124 @@
+---
+layout: default
+title: Elision
+parent: Token filters
+nav_order: 130
+---
+
+# Elision token filter
+
+The `elision` token filter is used to remove elided characters from words in certain languages. Elision typically occurs in languages such as French, in which words are often contracted and combined with the following word, typically by omitting a vowel and replacing it with an apostrophe. 
+
+The `elision` token filter is already preconfigured in the following [language analyzers]({{site.url}}{{site.baseurl}}/analyzers/language-analyzers/): `catalan`, `french`, `irish`, and `italian`.
+{: .note}
+
+## Parameters
+
+The custom `elision` token filter can be configured with the following parameters.
+
+Parameter | Required/Optional | Data type | Description
+:--- | :--- | :--- | :--- 
+`articles` | Required if `articles_path` is not configured | Array of strings | Defines which articles or short words should be removed when they appear as part of an elision.
+`articles_path` | Required if `articles` is not configured | String | Specifies the path to a custom list of articles that should be removed during the analysis process. 
+`articles_case` | Optional | Boolean | Specifies whether the filter is case sensitive when matching elisions. Default is `false`.
+
+## Example
+
+The default set of French elisions is `l'`, `m'`, `t'`, `qu'`, `n'`, `s'`, `j'`, `d'`, `c'`, `jusqu'`, `quoiqu'`, `lorsqu'`, and `puisqu'`. You can update this by configuring the `french_elision` token filter. The following example request creates a new index named `french_texts` and configures an analyzer with the `french_elision` filter:
+
+```json
+PUT /french_texts
+{
+  "settings": {
+    "analysis": {
+      "filter": {
+        "french_elision": {
+          "type": "elision",
+          "articles": [ "l", "t", "m", "d", "n", "s", "j" ]
+        }
+      },
+      "analyzer": {
+        "french_analyzer": {
+          "type": "custom",
+          "tokenizer": "standard",
+          "filter": ["lowercase", "french_elision"]
+        }
+      }
+    }
+  },
+  "mappings": {
+    "properties": {
+      "text": {
+        "type": "text",
+        "analyzer": "french_analyzer"
+      }
+    }
+  }
+}
+
+```
+{% include copy-curl.html %}
+
+## Generated tokens
+
+Use the following request to examine the tokens generated using the analyzer:
+
+```json
+POST /french_texts/_analyze
+{
+  "analyzer": "french_analyzer",
+  "text": "L'étudiant aime l'école et le travail."
+}
+```
+{% include copy-curl.html %}
+
+The response contains the generated tokens:
+
+```json
+{
+  "tokens": [
+    {
+      "token": "étudiant",
+      "start_offset": 0,
+      "end_offset": 10,
+      "type": "<ALPHANUM>",
+      "position": 0
+    },
+    {
+      "token": "aime",
+      "start_offset": 11,
+      "end_offset": 15,
+      "type": "<ALPHANUM>",
+      "position": 1
+    },
+    {
+      "token": "école",
+      "start_offset": 16,
+      "end_offset": 23,
+      "type": "<ALPHANUM>",
+      "position": 2
+    },
+    {
+      "token": "et",
+      "start_offset": 24,
+      "end_offset": 26,
+      "type": "<ALPHANUM>",
+      "position": 3
+    },
+    {
+      "token": "le",
+      "start_offset": 27,
+      "end_offset": 29,
+      "type": "<ALPHANUM>",
+      "position": 4
+    },
+    {
+      "token": "travail",
+      "start_offset": 30,
+      "end_offset": 37,
+      "type": "<ALPHANUM>",
+      "position": 5
+    }
+  ]
+}
+```

_analyzers/token-filters/index.md

@@ -27,7 +27,7 @@ Token filter | Underlying Lucene token filter|  Description
 [`delimited_term_freq`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/delimited-term-frequency/) | [DelimitedTermFrequencyTokenFilter](https://lucene.apache.org/core/9_7_0/analysis/common/org/apache/lucene/analysis/miscellaneous/DelimitedTermFrequencyTokenFilter.html) | Separates a token stream into tokens with corresponding term frequencies, based on a provided delimiter. A token consists of all characters before the delimiter, and a term frequency is the integer after the delimiter. For example, if the delimiter is `|`, then for the string `foo|5`, `foo` is the token and `5` is the term frequency.
 [`dictionary_decompounder`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/dictionary-decompounder/) | [DictionaryCompoundWordTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/compound/DictionaryCompoundWordTokenFilter.html) | Decomposes compound words found in many Germanic languages.
 [`edge_ngram`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/edge-ngram/) | [EdgeNGramTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ngram/EdgeNGramTokenFilter.html) | Tokenizes the given token into edge n-grams (n-grams that start at the beginning of the token) of lengths between `min_gram` and `max_gram`. Optionally, keeps the original token.
-`elision` | [ElisionFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/util/ElisionFilter.html) | Removes the specified [elisions](https://en.wikipedia.org/wiki/Elision) from the beginning of tokens. For example, changes `l'avion` (the plane) to `avion` (plane).
+[`elision`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/elision/) | [ElisionFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/util/ElisionFilter.html) | Removes the specified [elisions](https://en.wikipedia.org/wiki/Elision) from the beginning of tokens. For example, changes `l'avion` (the plane) to `avion` (plane).
 [`fingerprint`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/fingerprint/) | [FingerprintFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/FingerprintFilter.html) | Sorts and deduplicates the token list and concatenates tokens into a single token.
 `flatten_graph` | [FlattenGraphFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/FlattenGraphFilter.html) | Flattens a token graph produced by a graph token filter, such as `synonym_graph` or `word_delimiter_graph`, making the graph suitable for indexing.
 `hunspell` | [HunspellStemFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/hunspell/HunspellStemFilter.html) | Uses [Hunspell](https://en.wikipedia.org/wiki/Hunspell) rules to stem tokens. Because Hunspell supports a word having multiple stems, this filter can emit multiple tokens for each consumed token. Requires you to configure one or more language-specific Hunspell dictionaries.