Regex PHP match character only if not preceded or followed by same character.

Question

so I am trying to match a back tick ` but only when it is not more than one in a row:

`test` // matches
``test`` // does NOT match

// does NOT match
```java
    test
```

BUT it needs to also match if is at the beginning of the string or end, so all three must match.

`matches`

Text `matches`

Text `matches`EOL

Answer 1

UPDATE 3

The regex below matches exactly as the previous one, but consumes the backtick ` avoiding that an ending backtick is considered a starting backtick when the regex engine searchs for the next one.

(?<!`)`([^`

]+)`(?!`)

The correct behaviour (extract only the text wrapped inside single backticks) is keeped using a capturing group `([^` ]+)`.

Use it with preg_match_all, try this online php demo.

Legenda:

• (?<!`)` a backtick not preceded another one
• `([^` ]+)` a capturing group that matches everything that is not a backtick or a newline (CR or LF)
• `(?!`) a backtick not followed by another one

Updated Online Demo