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Highlighting
============
Rich can apply styles to patterns in text which you :meth:`~rich.console.Console.print` or :meth:`~rich.console.Console.log`. With the default settings, Rich will highlight things such as numbers, strings, collections, booleans, None, and a few more exotic patterns such as file paths, URLs and UUIDs.
You can disable highlighting either by setting ``highlight=False`` on :meth:`~rich.console.Console.print` or :meth:`~rich.console.Console.log`, or by setting ``highlight=False`` on the :class:`~rich.console.Console` constructor which disables it everywhere. If you disable highlighting on the constructor, you can still selectively *enable* highlighting with ``highlight=True`` on print/log.
Custom Highlighters
-------------------
If the default highlighting doesn't fit your needs, you can define a custom highlighter. The easiest way to do this is to extend the :class:`~rich.highlighter.RegexHighlighter` class which applies a style to any text matching a list of regular expressions.
Here's an example which highlights text that looks like an email address::
from rich.console import Console
from rich.highlighter import RegexHighlighter
from rich.theme import Theme
class EmailHighlighter(RegexHighlighter):
"""Apply style to anything that looks like an email."""
base_style = "example."
highlights = [r"(?P<email>[\w-]+@([\w-]+\.)+[\w-]+)"]
theme = Theme({"example.email": "bold magenta"})
console = Console(highlighter=EmailHighlighter(), theme=theme)
console.print("Send funds to money@example.org")
The ``highlights`` class variable should contain a list of regular expressions. The group names of any matching expressions are prefixed with the ``base_style`` attribute and used as styles for matching text. In the example above, any email addresses will have the style "example.email" applied, which we've defined in a custom :ref:`Theme <themes>`.
Setting the highlighter on the Console will apply highlighting to all text you print (if enabled). You can also use a highlighter on a more granular level by using the instance as a callable and printing the result. For example, we could use the email highlighter class like this::
console = Console(theme=theme)
highlight_emails = EmailHighlighter()
console.print(highlight_emails("Send funds to money@example.org"))
While :class:`~rich.highlighter.RegexHighlighter` is quite powerful, you can also extend its base class :class:`~rich.highlighter.Highlighter` to implement a custom scheme for highlighting. It contains a single method :class:`~rich.highlighter.Highlighter.highlight` which is passed the :class:`~rich.text.Text` to highlight.
Here's a silly example that highlights every character with a different color::
from random import randint
from rich import print
from rich.highlighter import Highlighter
class RainbowHighlighter(Highlighter):
def highlight(self, text):
for index in range(len(text)):
text.stylize(f"color({randint(16, 255)})", index, index + 1)
rainbow = RainbowHighlighter()
print(rainbow("I must not fear. Fear is the mind-killer."))
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