plain_text_delimiters.js

module.exports = () => {
	const self = {
		fieldDelimiter: ':',
		commandDelimiter: '\n',
		commentToken: '#'
	};

	// Takes a { op: "NAME", args: [ "ARG_1", ... ]} and 
	// returns the formatted command suitable to write to a log file
	self.stringFromCommand = ({ op, args }) => {
		return [op].concat(args).join(self.fieldDelimiter) + self.commandDelimiter;
	};

	// Takes a formatted command from the log file (i.e. `stringFromCommand`) 
	// and returns { op: "OP_NAME", args: ["ARG_1", "ARG_2", "ARG_3"]} 
	self.commandFromString = (string) => {
		const parts = [];
		var acc = '';
		var matchingQuote = null;

		for (var i = 0; i < string.length; i++) {
			if (string[i] === '"' || string[i] === "'") {
				acc += string[i];
				
				if (!matchingQuote) {
					matchingQuote = string[i];
				} else if (matchingQuote === string[i]) {
					matchingQuote = null;
				}
			} else if (string[i] === self.fieldDelimiter && !matchingQuote) {
				parts.push(acc);
				acc = '';
			} else {
				acc += string[i];
			}
		}

		if (acc) {
			parts.push(acc);
		}

		const command = {};
		command.op = parts[0];
		command.args = parts.slice(1);

		if (!command.op || !command.args) return;
		if (command.op[0] === self.commentToken) return;
		return command;
	};

	self.statements = (string) => {
		return string.split(self.commandDelimiter).filter(c => !!c);
	};

	self.command = (line) => {
		return self.commandFromString(line);
	};

	return self;
}