RSP Text Preprocessor

• RSP Preprocessor

Short for REBOL Server Pages.  Originally an all-in-one REBOL CGI framework, this iteration abstracts only the text pre-processor.  This closely resembles RSP as used in QuarterMaster.

RSP Basics

There are three forms of markup associated with RSP.  First there is the output directive:

<%= title %>

This replaces the mark with the value of ‘title.  Then the flow directive:

<% loop 3 [ %>Ha! <% ] %>

There is no output from a flow block, and REBOL block types do not have to be terminated in the same flow block (though they still have to be terminated).

And finally, the build-tag directive.

<%: a href http://www.rebol.com/ %>

Put it all together and you can start to build some interesting pages:

<ul><%
    sites: [
        "Yahoo" http://yahoo.com
        "Google" http://google.com
        "Apple" http://apple.com
    ]

    foreach [site link] sites [
%><li><%: a href (link) %><%= site %></a></li><%
    ]
%></ul>

Additionally, you can comment your code like so:

<%; This is a comment %>

(note that in QM, ‘build-tag has different syntax - see QM documentation)

Script Usage

do http://reb4.me/r/rsp

There are three functions included in this module: ‘load-rsp, ‘render and ‘render-each

‘load-rsp

This is the low-level parser that turns the RSP string into a function:

build-page: load-rsp {<h1><%= title %></h1>}

page1: build-page context [title: "Title 1"]
page2: build-page context [title: "Title 2"]

‘render

This function is a simple wrapper for ‘load-rsp:

render {<%= 1 + 1 %>}
render/with {<%= title %>} context [title: "Jaws"]

‘render-each

Works much like ‘foreach and produces a single string output:

render-each [term definition] dictionary {
    <dt><%= term %></dt>
    <dd><%= definition %></dd>
}

Both ‘render and ‘render-each take file! and url! arguments in addition to string!

Binding Local Values

When loading an RSP string, it is loaded into the global namespace.  You need to explicitly pass a set of local words or an object to avoid having to work globally.  With ‘render and ‘render-each, this can be passed using the /with refinement.