makeCSVReader.js

function makeCSVReader(records, opts) {
	'use strict';
	function noop() {}

	function createRecordConstructor(fields) {
		var src = '';
		for (var i = 0; i < fields.length; i++) {
			src += 'this[' + JSON.stringify(fields[i]) + '] = fields[' + i + '];\n';
		}

		// EVAL, EVAL, EVAL
		return new Function('fields', src);
	}
	
	var state = 1;
	var fields = [];
	var Record = null;
	var field = [];
	var onClose = opts.onClose || noop;
	opts = opts || {};

	function terminateField() {
		fields[fields.length] = field.join('');
		field = [];
	}
	
	function terminateRecordWithHeader() {
		terminateField();
		if (Record == null) {
			Record = createRecordConstructor(fields);
		} else {
			records.push(new Record(fields));
		}
		fields = [];
	}

	function terminateRecordWithoutHeader() {
		terminateField();
		records.push(fields);
		fields = [];
	}

	var terminateRecord = opts.header ?
				terminateRecordWithHeader :
				terminateRecordWithoutHeader;
	
	var COMMA = ',';
	var CR = '\r';
	var LF = '\n';
	var DOUBLE_QUOTE = '"';

	var CTX_FIELD_START = 1;
	var CTX_IN_FIELD = 2;
	var CTX_IN_QUOTED_FIELD = 3;
	var CTX_ON_QUOTE = 4;
	var CTX_ON_CR = 5;

	var EXPECTED_LINE_FEED = -1;
	var EXPECTED_FIELD_TERMINATOR = -2;

	return function readString(str) {
		if (str == null) {
			terminateRecord();
			onClose();
			return 0;
		}

		for (var i = 0; i < str.length; i++) {
			var char = str[i];

			switch (state) {
				case CTX_FIELD_START:
					if (char === DOUBLE_QUOTE) {
						state = CTX_IN_QUOTED_FIELD;
					} else {
						field = [char];
						state = CTX_IN_FIELD;
					}
					break;

				case CTX_IN_FIELD:
					if (char === CR) {
						terminateRecord();
						state = CTX_ON_CR;
					} else if (char === LF) {
						terminateRecord();
						state = CTX_FIELD_START;
					} else if (char === COMMA) {
						terminateField();
						state = CTX_FIELD_START;
					} else {
						field[field.length] = char;
					}
					break;

				case CTX_IN_QUOTED_FIELD:
					if (char === DOUBLE_QUOTE) {
						state = CTX_ON_QUOTE;
					} else {
						field[field.length] = char;
					}
					break;

				case CTX_ON_QUOTE:
					if (char === DOUBLE_QUOTE) {
						field[field.length] = char;
						state = CTX_IN_QUOTED_FIELD;
					}	else if (char === COMMA) {
						terminateField();
						state = CTX_FIELD_START;
					} else if (char === CR) {
						terminateRecord();
						state = CTX_ON_CR;
					} else {
						return EXPECTED_FIELD_TERMINATOR;
					}
					break;

				case CTX_ON_CR:
					if (char !== LF) {
						return EXPECTED_LINE_FEED;
					}
					state = CTX_FIELD_START;
					break;
			}
		}

		return str.length;
	};
}