XSB-JS-Interface

Similar to the XSB C Interface, but for JS!

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Summary

The XSB-JS-Interface library is a Web Assembly port of the XSB C Interface. The XSB-JS-Interface library also provides high-level methods to add a layer of abstraction between you and XSB. Emscripten was used to port the XSB-JS-Interface library and is required to edit the source code. The XSB JS Interface can be broken in to 2 parts: the C component, and the JS component. The C component of this library inside ./src/xsbInterface.c contains all the wrapper functions that the JS component of this library uses to add a layer of abstraction. Additionally, all code in pre.js is executed before the Emscripten Runtime is, and all code in post.js is executed after the Emscripten Runtime has finished initializing. pre.js mainly contains definitions for callback functions such as onOutput() whereas post.js contains the rest of the XSB class.

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How to rebuild this library

1. Make changes to code as nessasary

2. Inside the top-level directory for this project, run make build

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How to setup this library

1. Copy all files inside ./out into your project's directory

2. Inside your webpage, import xsbInterface.js

<script src="xsbInterface.js"></script>

3. Thats it! It's that easy! 🕶✌

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Getting started

To get started with this library, experiment with the code below!

// Initialize XSB
XSB.init()

// It is possible to override how XSB handles printing.
// In this case, if XSB prints an error message, console.err() will be invoked
// else the command is printed with console.log()
XSB.Events.onOutput = function(output, isError)
{
  if(isError)
    console.err(output)
  else
    console.log(output)
}

// Tell XSB to execute "X is 6, Y is 6, X == Y."
// XSB.execute returns a structure containing return values resulting from the xsb query:
// XSB.execute("X is 6, Y is 6, X == Y.") should return the following
//	{
//		var:	[
//				["6"],
//				["6"]
//			],
//		isTrue:
//			true
//	}
//
// In general, XSB.execute() returns the following:
//{
//	var: [
//		["val1 from var0 query", ..], // Array containing query results of var1. The Nth result maps to the N-1th index
//		["val2 from var1 query", ..]  // Array containing query results of var2. The Nth result maps to the N-1th index
		..			      // Variables are ordered in the same way that they are ordered in the query. 
		..			      // For example, in the query "X is 5, Y is 6.", 'var' would be [["5"], ["6"]]
//	],
//	isTrue: Boolean // Returns 'true' for any query where XSB would return 'yes.', else returns false
//}
result = XSB.execute("X is 6, Y is 6, X == Y.")
console.log("Values of X: " + result.var[0].toString())
console.log("Values of Y: " + result.var[1].toString())
if(result.isTrue)
	console.log("The query returned true.")
else
	console.log("The query returned false.")

// Print "Hello world" using a low-level method ported directly from the C Interface
// Other directly-ported methods from the XSB C Interface reside inside the 'LowLevel' section of the XSB-JS-Interface library as well.
XSB.LowLevel.xsb_command_string("writeln('Hello world').")

// Get the latest status code from XSB
// Returns the latest status code from the latest XSB function call
// For example, if xsb_command_string() returned XSB_SUCCESS, then XSB.LowLevel.status() would return 0 until the next function call
XSB.LowLevel.status()

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Please note that

• Not all methods from the XSB-C-Interface have been ported to this library yet.
• To execute make build, you must have Emscripten 1.38.30 installed.
• This library does not currently does support Microsoft Edge due to Edge's lack of support for the TextEncoder class