pt-lisp/implementations/js/reader.js

import { Cons, Nil, String, Symbol, Number } from './datatypes.js';

export class ReaderMacros {
    static setMacroCharacter(macros, c, fn) {
	macros[c] = { outer: macros[c], fn };
    }

    static popMacroCharacter(macros, c) {
	macros[c] = macros[c].outer;
    }
}

export class Reader {
    static readData(data) {
	if (isNaN(data)) {
	    return new Symbol(data.toUpperCase());
	} 
	return new Number(parseFloat(data));
    }

    static read(macros, stream) {
	let data = '';
	let c = null;
	while (c = stream.peekChar()) {
	    const macro = macros[c];
	    if (macro) {
		if (data) {
		    return Reader.readData(data);
		}
		return macro.fn(stream.readChar(), stream);
	    }
	    
	    c = stream.readChar();
	    if (!c.trim()) {
		if (data.length) {
		    return Reader.readData(data);
		}
	    } else {
		data += c;
	    }
	}
	
	if (data.length) {
	    return Reader.readData(data);
	}
	
	return null;
    }
}