Swath is a general-purpose utility to workaround the lack of such capability
in applications.  It analyzes the given Thai text by consulting a Thai word
list for word boundaries, before outputting the same text with the predefined
word delimitors inserted.

It can read many kinds of input, including plain text and structured documents
like HTML, RTF, LaTeX and Lambda (Unicode version of LaTeX with Omega
typesetter kernel).

Homepage:
https://linux.thai.net/projects/swath
