regrex package
https://golang.org/pkg/regexp/
On-line Regular Expression
Meta Characters
Metacharacters are characters that are interpreted in a special way by a RegEx engine. Here’s a list of metacharacters:
[] . ^ $ * + ? {} () \ |
[] – Square brackets
Square brackets specifies a set of characters you wish to match.
. – Period
A period matches any single character (except newline '\n').
– Caret
The caret symbol ^ is used to check if a string starts with a certain character.
$ – Dollar
The dollar symbol $ is used to check if a string ends with a certain character.
* – Star
The star symbol * matches zero or more occurrences of the pattern left to it.
+ – Plus
The plus symbol + matches one or more occurrences of the pattern left to it.
? – Question Mark
The question mark symbol ? matches zero or one occurrence of the pattern left to it.
{} – Braces
Consider this code: {n,m}. This means at least n, and at most m repetitions of the pattern left to it.
| – Alternation
Vertical bar | is used for alternation (or operator).
() – Group
Parentheses () is used to group sub-patterns.
\ – Backslash
Backlash \ is used to escape various characters including all metacharacters.
Special Sequences
Special sequences make commonly used patterns easier to write.