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* delete asciidoc files
* add migrated files
* fix errors
* Disable docs tests
* Clarify release notes page titles
* Revert "Clarify release notes page titles"
This reverts commit 8be688648d.
* Comment out edternal URI images
* Clean up query languages landing pages, link to conceptual docs
* Add .md to url
* Fixes inference processor nesting.
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Co-authored-by: Liam Thompson <32779855+leemthompo@users.noreply.github.com>
Co-authored-by: Liam Thompson <leemthompo@gmail.com>
Co-authored-by: Martijn Laarman <Mpdreamz@gmail.com>
Co-authored-by: István Zoltán Szabó <szabosteve@gmail.com>
34 lines
1.3 KiB
Markdown
34 lines
1.3 KiB
Markdown
---
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mapped_pages:
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- https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-regexes.html
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---
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# Regexes [painless-regexes]
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Regular expression constants are directly supported. To ensure fast performance, this is the only mechanism for creating patterns. Regular expressions are always constants and compiled efficiently a single time.
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```painless
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Pattern p = /[aeiou]/
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```
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::::{warning}
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A poorly written regular expression can significantly slow performance. If possible, avoid using regular expressions, particularly in frequently run scripts.
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::::
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## Pattern flags [pattern-flags]
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You can define flags on patterns in Painless by adding characters after the trailing `/` like `/foo/i` or `/foo \w #comment/iUx`. Painless exposes all of the flags from Java’s [ Pattern class](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.md) using these characters:
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| Character | Java Constant | Example |
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| --- | --- | --- |
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| `c` | CANON_EQ | `'å' ==~ /å/c` (open in hex editor to see) |
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| `i` | CASE_INSENSITIVE | `'A' ==~ /a/i` |
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| `l` | LITERAL | `'[a]' ==~ /[a]/l` |
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| `m` | MULTILINE | `'a\nb\nc' =~ /^b$/m` |
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| `s` | DOTALL (aka single line) | `'a\nb\nc' =~ /.b./s` |
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| `U` | UNICODE_CHARACTER_CLASS | `'Ɛ' ==~ /\\w/U` |
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| `u` | UNICODE_CASE | `'Ɛ' ==~ /ɛ/iu` |
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| `x` | COMMENTS (aka extended) | `'a' ==~ /a #comment/x` |
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