hlre

Interactively highlight regular expression matches.

What?

A TUI application that shows the matches of a (python-flavored) regular expression as you type it.

Why?

I really like using RegExr, but it uses the javascript regex engine and there are some subtle differences between the results there and what you get with python.

Installation

python3 -m pip install hlre

Usage

TLDR

1. Run

   hlre -f nginx.log
   

2. Type a regex and see the matches highlighted in nginx.log.

3. Press Control-C to exit.

Input Sources

You can either highlight matches with the built-in example text, a string passed on the command line, or in an external file.

• Built-in Demo Text

  hlre --demo-text
  

• String

  hlre --text 'This is the regular expression subject.'
  

• External File

  hlre --file nginx.log
  

  Reading in the whole file can slow this tool down quite a bit, so you probably want to do something like:

  hlre --file <(head -n 10 nginx.log)
  

  To look at just the first 10 lines.

Highlighting All Matches

By default, each line is treated as a seperate subject to match the regex on.

To highlight all matches in the subject, use the -a flag:

hlre --demo-text -a
# OR
hlre --file nginx.log --all

This uses re.finditer and the re.MULTILINE flag under the hood.

Customizing Highlight Styles

hlre uses prompt toolkit's HTML functionality, so any tag name that works there should work here. This tool does not currently support any custom attributes on tags (e.g style="...").

Here are some examples:

• Underline the entire match, highlight capture groups in a dark red

  hlre --demo-text --highlight-style u --group-highlight-style firebrick
  

• Highlight the entire match in green, bold the capture groups

  hlre --demo-text -s green -g b
  

• Italicize the entire match, highlight capture groups in cyan

  hlre --demo-text -s i -g cyan