render-file.node.js

#!/usr/bin/env node
"use strict"

/* Compile script for ddr0.ca.
	
	Ingests .html.js files and evaluates them, outputting the last statement
	to stdout. Usually this is the results of a big ol' format string.
	
	This script can be run manually, of course, but it is primarily intended
	to be used by the makefile.
*/

const vm = require('vm')
const fs = require('fs')


const render = (filename, constants={}) => {
	const results = vm.runInContext(
		fs.readFileSync(filename, {encoding:'utf8'}), 
		vm.createContext({
			require, render,
			include: render,
			dump: (...args) => (console.error.apply(console, args), args.slice(-1)[0]),
			paste: filename => fs.readFileSync(filename, {encoding:'utf8'}),
			indent: (level, text) => 
				level > 0
					? '\t'.repeat(level)+text.trim('\n').split('\n').join('\n'+'\t'.repeat(level))
					: text.split('\n').map(line => line.slice(-level)).join('\n'),
			page: process.argv[2],
			global: constants, //Look up a constant in the script.
			...constants, //Or just reference it, which is easier but may fail if missing.
		}),
		{
			filename,
			timeout: 200,
		}
	)
	if (typeof results === 'string') {
		return results.trim('\n')
	} else {
		throw new Error(`Compilation failed, expected string got ${typeof results}.`)
	}
}

module.exports = render