Ruth

logo by Silvia Polverini

© 2002–2022 Reuben Thomas [email protected]
https://github.com/rrthomas/ruth

Ruth is a simple XQuery-based XML templating system, based on the plain text-oriented Nancy. Ruth reads a file or directory into an XML document; XML files become subdocuments. It then produces a copy of the original file or directory, executing embedded XQuery queries against the constructed XML document. Custom XQuery functions and external programs can be used.

Ruth is free software, licensed under the GNU GPL version 3 (or, at your option, any later version), and written in TypeScript.

Ruth uses fontoxpath as its XQuery implementation. fontoxpath implements a subset of XQuery 3.1.

See the Cookbook for examples.

Please send questions, comments, and bug reports to the maintainer, or report them on the project’s web page (see above for addresses).

Installation

Install Ruth with npm (part of Node):

$ npm install -g @sc3d/ruth

API documentation

Ruth is mostly used via the ruth command, not least because of a limitation of fontoxpath, which cannot easily be run more than once in the same process. Nonetheless, Ruth provides some APIs which are documented in docs/index.html.

Invocation

{/bin/sh,-c,./bin/run.js --help | sed -e 's/usage: run.js/ruth/' -e 's/^   //g'}

Operation

Ruth starts by combining the list of directories given as its input path. If the same file or directory exists in more than one of the directories on the input path, the left-most takes precedence. The result is called the “input tree”, and all paths are relative to it.

Ruth then creates the output directory if it does not already exist.

Next, Ruth traverses the input tree, or the subtree given by the --path argument, if any, in breadth-first order.

For each file, Ruth looks at its name, and:

• If the name contains the suffix .ruth, optionally followed by decimal digits, the file is added to the list of files to process. The decimal digits are the phase number, which defaults to zero. The files are processed in phase order: any phase 0 files first, then phase 1, and so on.
• If the name contains the suffix .in, the file is skipped. (It may be used by macros in other files.)
• Otherwise, the file is added to the list of files to process in phase 0.

The list of files to process is then processed, in order. For each file:

• If the name contains the suffix .ruth, the file’s contents is expanded (see below), and if the name does not contain the suffix .in the result is then written to a file of the same name, but with the .ruth suffix removed, in the corresponding place in the output directory. The working XML document is also updated with the result.
• Otherwise, the file is copied verbatim to the corresponding place in the output directory.

The special suffixes need not end the file name; they can be used as infixes before the file type suffix.

Template expansion

Ruth expands a template file as follows by executing it as an XQuery expression.

The use of XQuery is beyond the scope of this manual; see the XQuery specification and fontoxpath documentation for more details.

Ruth provides some built-in global variables:

• $ruth:root: the INPUT-PATH argument.
• $ruth_path: the relative path from $ruth:root to the file currently being expanded.
• $ruth_element: the element in Ruth's working XML document corresponding to the file currently being expanded.

Ruth provides the following built-in custom functions:

• ruth:eval($query as xs:string) as node()*: evaluates the XQuery expression $query, and returns the first matching node, or, if there is none, raises an error.
• ruth:real-path($relPath as xs:string) as xs:string returns the file system path of the file given by $relPath. If $relPath does not correspond to a file, an error is raised. Note in particular that a directory does not necessarily correspond to a single file system path.

Ruth also supplies a version of the FunctX function library, without the functions that fontoxpath does not support.

Ruth also loads other XQuery functions from lib/ruth.xq. See that file for documentation.

See the website example in the Cookbook for a worked example of using Ruth to template a website.

Running other programs

An executable file in the input is turned into a pair of XQuery functions in the ruth namespace. Any .in suffix is stripped out. So for example, foo.in becomes a function ruth:foo(). The functions have the following signature:

ruth:foo($args as xs:string*) as xs:string
ruth:foo($args as xs:string*, $input as xs:string) as xs:string

The sequence $args is passed to the program as its command-line arguments. The string $input is fed to the program's standard input.

Development

Check out the git repository and download dependencies with:

git clone https://github.com/rrthomas/ruth
npm install

To run the tests:

npm test