Adding Color to the Console: Pygments vs. Source-highlight

The other day I write about code syntax highlighting with less and source-highlight, when someone pointed out the Pygments package, that can do the same thing. This called for

the great source-highlight vs. pygments face-off

Installation

Source-highlight is in C++ and needs the Boost regex library. About 3.5 MB together. Pygments is in Python and has no dependencies beyond that. About 2 MB installed. No problem on either side.

In Debian, the packages are source-highlight and python-pygments. Note that the Pygments command-line tool is called pygmentize.

Source-highlight is licensed under the GPL, Pygments under a BSD license.

Getting Started

pygmentize file.c

writes a colored version of file.c to the standard output. Nice.

source-highlight file.c

writes a colored version of file.c to file.c.html. As I had written before, the correct invocation for this purpose is

source-highlight -fesc -oSTDOUT file.c

That makes pygmentize slightly easier to use, I suppose.

Supported Languages

Source-highlight supports 30 languages, Pygments supports 136.

Source-highlight can produce output for DocBook, ANSI console, (X)HTML, Javadoc, LaTeX, Texinfo. Pygments can produce output for HTML, LaTeX, RTF, SVG, and several image formats.

Source-highlight supports styles, but only ships a few. Pygments supports styles and filters, and ships over a dozen styles.

So more options with Pygments here.

Also note that Pygments is a Python library that can be used, say, in web applications for syntax highlighting. This is used in Review Board, for example. Source-highlight is just a command-line tool, but it could of course also be invoked by other packages. Horde uses this, for instance.

Speed

To process all the C files in the PostgreSQL source tree (709271 lines), writing the ANSI console colored version of each file.c to file.c.txt:

source-highlight

25 seconds

pygmentize

5 minutes

So for interactive use with less, source-highlight is probably still the better option.

Robustness

pygmentize gave me a few errors of this sort during the processing of the PostgreSQL source tree:

*** Error while highlighting:
UnicodeEncodeError: 'ascii' codec can't encode character u'\xb7' in position 83: ordinal not in range(128)
  (file "/usr/lib/python2.5/site-packages/Pygments-1.0-py2.5.egg/pygments/formatters/terminal.py", line 93, in format)

*** Error while highlighting:
UnicodeDecodeError: 'utf8' codec can't decode bytes in position 196-198: invalid data
  (file "/usr/lib/python2.5/encodings/utf_8.py", line 16, in decode)

That probably shouldn't happen.

source-highlight gave no spurious errors in my limited testing.

Miscellaneous

Source-highlight can highlight its own configuration files, which are in a custom language, and Pygments' configuration files, which are in Python. Conversely, Pygments can of course highlight its own configuration files, but doesn't know what to do with those of Source-highlight.

Summary

I will stick with Source-highlight for interactive use, but Pygments is a great alternative when you need more formatting options or want to integrate the package as a library.