Syntax highlighting is done by pluggable highlighters:

• main - the base highlighter, and the only one active by default.
• brackets - matches brackets and parenthesis.
• pattern - matches user-defined patterns.
• regexp - matches user-defined regular expressions.
• cursor - matches the cursor position.
• root - highlights the whole command line if the current user is root.
• line - applied to the whole command line.

Highlighter-independent settings

By default, all command lines are highlighted. However, it is possible to prevent command lines longer than a fixed number of characters from being highlighted by setting the variable ${ZSH_HIGHLIGHT_MAXLENGTH} to the maximum length (in characters) of command lines to be highlighter. This is useful when editing very long command lines (for example, with the fned utility function). Example:

ZSH_HIGHLIGHT_MAXLENGTH=512

How to activate highlighters

To activate an highlighter, add it to the ZSH_HIGHLIGHT_HIGHLIGHTERS array in ~/.zshrc, for example:

ZSH_HIGHLIGHT_HIGHLIGHTERS=(main brackets pattern cursor)

By default, $ZSH_HIGHLIGHT_HIGHLIGHTERS is unset and only the main highlighter is active.

How to tweak highlighters

Highlighters look up styles from the ZSH_HIGHLIGHT_STYLES associative array. Navigate into the individual highlighters' documentation to see what styles (keys) each highlighter defines; the syntax for values is the same as the syntax of "types of highlighting" of the zsh builtin $zle_highlight array, which is documented in the zshzle(1) manual page.

Some highlighters support additional configuration parameters; see each highlighter's documentation for details and examples.

How to implement a new highlighter

To create your own acme highlighter:

• Create your script at highlighters/acme/acme-highlighter.zsh.

• Implement the _zsh_highlight_highlighter_acme_predicate function. This function must return 0 when the highlighter needs to be called and non-zero otherwise, for example:

  _zsh_highlight_highlighter_acme_predicate() {
    # Call this highlighter in SVN working copies
    [[ -d .svn ]]
  }
  

• Implement the _zsh_highlight_highlighter_acme_paint function. This function does the actual syntax highlighting, by calling _zsh_highlight_add_highlight with the start and end of the region to be highlighted and the ZSH_HIGHLIGHT_STYLES key to use. Define the default style for that key in the highlighter script outside of any function with : ${ZSH_HIGHLIGHT_STYLES[key]:=value}, being sure to prefix the key with your highlighter name and a colon. For example:

  : ${ZSH_HIGHLIGHT_STYLES[acme:aurora]:=fg=green}
  
  _zsh_highlight_highlighter_acme_paint() {
    # Colorize the whole buffer with the 'aurora' style
    _zsh_highlight_add_highlight 0 $#BUFFER acme:aurora
  }
  

If you need to test which options the user has set, test zsyh_user_options with a sensible default if the option is not present in supported zsh versions. For example:

```zsh
[[ ${zsyh_user_options[ignoreclosebraces]:-off} == on ]]
```

The option name must be all lowercase with no underscores and not an alias.

• Name your own functions and global variables _zsh_highlight_acme_*.

  • In zsh-syntax-highlighting 0.4.0 and earlier, the entrypoints _zsh_highlight_highlighter_acme_predicate and _zsh_highlight_highlighter_acme_paint were named _zsh_highlight_acme_highlighter_predicate and _zsh_highlight_highlighter_acme_paint respectively.

    These names are still supported for backwards compatibility; however, support for them will be removed in a future major or minor release (v0.x.0 or v1.0.0).

• Activate your highlighter in ~/.zshrc:

  ZSH_HIGHLIGHT_HIGHLIGHTERS+=(acme)
  

• Write tests.