implement replaceAlias() function, #287

docs/sources/reference/functions.md

@@ -158,3 +158,35 @@ Examples:
 ```
 setAlias(Zabbix busy [a-zA-Z]+)
 ```
+
+### replaceAlias
+```
+replaceAlias(pattern, newAlias)
+```
+
+Replace metric name using pattern. Pattern is regex or regular string. If regex is used, following special replacement patterns are supported:
+
+|Pattern	| Inserts|
+----------|---------
+|$$	| Inserts a "$". |
+|$&	| Inserts the matched substring. |
+|$`	| Inserts the portion of the string that precedes the matched substring. |
+|$'	| Inserts the portion of the string that follows the matched substring. |
+|$n	| Where n is a non-negative integer less than 100, inserts the nth parenthesized submatch string, provided the first argument was a RegExp object. |
+
+For more detais see [String.prototype.replace()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace) function.
+
+Examples:
+```
+CPU system time
+replaceAlias(/CPU (.*) time/, $1) -> system
+
+backend01: CPU system time
+replaceAlias(/CPU (.*) time/, $1) -> backend01: system
+
+backend01: CPU system time
+replaceAlias(/.*CPU (.*) time/, $1) -> system
+
+backend01: CPU system time
+replaceAlias(/(.*): CPU (.*) time/, $1 - $2) -> backend01 - system
+```