alasql/src/16comments.js

AlaSQL.js - JavaScript SQL database library for relational and graph data manipulation with support of localStorage, IndexedDB, and Excel

/**
 Strip all comments.
 Based om the https://github.com/lehni/uncomment.js/blob/master/uncomment.js
 I just replaced JavaScript's '//' to SQL's '--' and remove other stuff
 TODO: Fixed [aaa/*bbb] for column names
 TODO: Bug if -- comments in the last line
 */

alasql.utils.uncomment = function uncomment(str) {
	// Add some padding so we can always look ahead and behind by two chars
	str = ('__' + str + '__').split('');
	var quote = false,
		quoteSign,
		// regularExpression = false,
		// characterClass = false,
		blockComment = false,
		lineComment = false;
		// preserveComment = false;

	for (var i = 0, l = str.length; i < l; i++) {
//		console.log(i,str[i]);
		// When checking for quote escaping, we also need to check that the
		// escape sign itself is not escaped, as otherwise '\\' would cause
		// the wrong impression of an unclosed string:
		var unescaped = str[i - 1] !== '\\' || str[i - 2] === '\\';

		if (quote) {
			if (str[i] === quoteSign && unescaped)
				quote = false;
		// } else if (regularExpression) {
			// Make sure '/'' inside character classes is not considered the end
			// of the regular expression.
			// if (str[i] === '[' && unescaped) {
			// 	characterClass = true;
			// } else if (str[i] === ']' && unescaped && characterClass) {
			// 	characterClass = false;
			// } else if (str[i] === '/' && unescaped && !characterClass) {
			// 	regularExpression = false;
			// }
		} else if (blockComment) {
			// Is the block comment closing?
			if (str[i] === '*' && str[i + 1] === '/') {
				// if (!preserveComment)
					str[i] = str[i + 1] = '';
				blockComment /* = preserveComment*/ = false;
				// Increase by 1 to skip closing '/', as it would be mistaken
				// for a regexp otherwise
				i++;
			} else { //if (!preserveComment) {
				str[i] = '';
			}
		} else if (lineComment) {
			// One-line comments end with the line-break
			if (str[i + 1] == '\n' || str[i + 1] == '\r')
				lineComment = false;
			str[i] = '';
		} else {
			if (str[i] == '"' || str[i] == "'") {
				quote = true;
				quoteSign = str[i];
			} else if (str[i] == '[' && str[i-1] != "@") {
				quote = true;
				quoteSign = ']';
			// } else if (str[i] === '-' &&  str[i + 1] === '-') {
			// 	str[i] = '';
			// 	lineComment = true;
			} else if (str[i] === '/' && str[i + 1] === '*') {
					// Do not filter out conditional comments /*@ ... */
					// and comments marked as protected /*! ... */
//					preserveComment = /[@!]/.test(str[i + 2]);
//					if (!preserveComment)
						str[i] = '';
					blockComment = true;
//					console.log('block');
				// } else if (str[i + 1] === '/') {
				// 	str[i] = '';
				// 	lineComment = true;
				// } else {
					// We need to make sure we don't count normal divisions as
					// regular expresions. Matching this properly is difficult,
					// but if we assume that normal division always have a space
					// after /, a simple check for white space or '='' (for /=)
					// is enough to distinguish divisions from regexps.
					// TODO: Develop a proper check for regexps.
					// if (!/[\s=]/.test(str[i + 1])) {
					// 	regularExpression = true;
					// }
				// }
			}
		}
	}
	// Remove padding again.
	str = str.join('').slice(2, -2);

/*
	// Strip empty lines that contain only white space and line breaks, as they
	// are left-overs from comment removal.
	str = str.replace(/^[ \t]+(\r\n|\n|\r)/gm, function(all) {
		return '';
	});
	// Replace a sequence of more than two line breaks with only two.
	str = str.replace(/(\r\n|\n|\r)(\r\n|\n|\r)+/g, function(all, lineBreak) {
		return lineBreak + lineBreak;
	});
*/
	return str;
};