/**
* JavaScript Query Language v0.1
* Provides a query layer for interacting with the DOM
* Matt Hackett 2009 scriptnode.com
*/
JSQL = (function() {
// Constants (sort of)
var BODIES = ['body', 'document', 'document.body'],
CONDITIONAL_EQUALS = 1,
CONDITIONAL_NOT_EQUAL = 2;
// debug gets called but does nothing by default. Set with setDebug()
var debug = function() {};
/**
* Does a very basic check to see if a value is in an array (cannot use indexOf; not cross-browser yet)
* @param {Array} arr The array to look in
* @param {Mixed} val The value to check
* @return {Mixed} The index of the value or -1 on failure
* @member JSQL
* @private
*/
var inArray = function(arr, val) {
var i,
len = arr.length;
for (i = 0; i < len; i++) {
if (arr[i] === val) {
return i;
}
}
return -1;
};
/**
* Executes a JSQL query
* @param {String} qry The query to execute
* @return {Object} An object with two keys (error is true or false) which changes based on request type.
* Returns either the affected elements (count for UPDATE), number of affected elements (count for DELETE), or the requested elements themselves (elements, an array, for SELECT)
* @member JSQL
* @public
*/
var query = function(qry) {
var index = 0,
operation = {
parsedTargets : [],
targets : {},
type : '',
values : [],
where : []
},
query,
result = {
each : function(fn) {
for (var i = 0; i < this.elements.length; i++) {
fn.call(this.elements[i]);
}
return this;
},
error : false
};
/**
* Executes a DELETE query -- removes selected nodes from the DOM
* @private
*/
var execDelete = function() {
var c, el,
len = operation.parsedTargets.length;
result.count = 0;
result.elements = [];
for (c = 0; c < len; c++) {
el = operation.parsedTargets[c];
if (el && el.parentNode) {
el.parentNode.removeChild(el);
result.count++;
result.elements.push(el);
}
}
};
/**
* Executes the query based on the operation object
* @private
*/
var execQuery = function() {
if (result.error) {
return;
}
if (operation.type == 'DELETE') {
execDelete();
} else if (operation.type == 'SELECT') {
execSelect();
} else if (operation.type == 'UPDATE') {
execUpdate();
}
};
/**
* Executes a SELECT query -- returns selected nodes
* @private
*/
var execSelect = function() {
var c, el,
len = operation.parsedTargets.length;
result.count = 0;
result.elements = [];
for (c = 0; c < len; c++) {
el = operation.parsedTargets[c];
if (el) {
result.elements.push(el);
}
}
result.count = result.elements.length;
};
/**
* Executes an UPDATE query -- alters selected nodes
* @private
*/
var execUpdate = function() {
var c, el, i,
len = operation.parsedTargets.length;
result.count = 0;
result.elements = [];
for (c = 0; c < len; c++) {
el = operation.parsedTargets[c];
for (i = 0; i < operation.values.length; i++) {
if (el) {
var val = operation.values[i],
dots = val.key.split('.');
// (Half-assed) support for style., parentNode., etc attributes
if (dots.length == 2) {
debug('Setting "' + val.key + '" to "' + val.value + '"', el);
el[dots[0]][dots[1]] = val.value;
} else {
debug('Setting "' + val.key + '" to "' + val.value + '"', el);
el[val.key] = val.value;
}
result.count++;
result.elements.push(el);
}
}
}
};
/**
* Format the query into a usable format (array, split properly)
* Stores the value into query for use by other methods
* @param {String} qry The query to format
* @private
*/
var formatQuery = function(qry) {
// These split up words for easy parsing
var splits = [
' ',
'=',
','
];
var escs = ['"', "'"]; // These encapsulate strings that ignore splits
var c, cut,
esc = false,
len = qry.length,
word = '',
words = [];
for (var i = 0; i <= len; i++) {
c = qry.substr(i, 1);
cut = true;
if (esc) {
if (c == esc) {
c = '';
esc = false;
} else {
cut = false;
}
} else if (inArray(escs, c) > -1) {
if (qry.substr(i + 1, 1) == c) {
// We have an empty string '', "" (intentional)
c = false;
cut = true;
word = false;
i++;
words.push('');
} else {
cut = false;
esc = c;
c = '';
}
} else if (inArray(splits, c) > -1) {
if (c == ' ') {
c = false;
}
} else {
cut = false;
}
if (c) {
word += c;
}
if (cut) {
if (word) {
words.push(word);
}
word = '';
}
}
query = words;
};
/**
* Out of the targets in the query, find out which ones match the WHERE clause
*/
var getParsedTargets = function() {
if (result.error) {
return;
}
var c, el,
els = getTargets(),
len = els.length,
operate, w, where;
for (c = 0; c < len; c++) {
el = els[c];
operate;
if (el) {
operate = true;
if (operation.where) {
for (w = 0; w < operation.where.length; w++) {
where = operation.where[w];
if (where.type == CONDITIONAL_EQUALS) {
debug('Checking if (' + where.key + ' = "' + where.value + '") => ' + el[where.key], el);
if (el[where.key] != where.value) {
operate = false;
break;
}
} else if (where.type == CONDITIONAL_NOT_EQUAL) {
if (el[where.key] == where.value) {
operate = false;
break;
}
}
}
}
if (operate) {
operation.parsedTargets.push(el);
}
}
}
};
/**
* Gets the targets and their children
* @return {Array} The array of nodes within the selector
*/
var getTargets = function() {
var c, children, cLen,
els = [],
i,
len = operation.targets.length;
for (i = 0; i < len; i++) {
children = operation.targets[i].getElementsByTagName('*');
cLen = children.length;
for (c = 0; c < cLen; c++) {
els.push(children[c]);
}
}
return els;
};
/**
* Checks to see if an index exists in query before accessing its value
* @param {Number} sel The index to check
* @return {Mixed} The value of the index or false on failure
* @private
*/
var getWord = function(sel) {
if (query[sel]) {
return query[sel];
}
return false;
};
/**
* Parses the query itself, plopping the results into the operation object
* @private
*/
var parseQuery = function() {
var type = query[0].toUpperCase();
if (type == 'DELETE') {
var word = getWord(1);
if (word && (word.toUpperCase() == 'FROM')) {
operation.targets = parseTargets(2);
operation.where = parseWhere();
} else {
result.error = 'Syntax error. Expected FROM, got ' + word;
return;
}
} else if (type == 'SELECT') {
var word1 = getWord(1),
word2 = getWord(2);
if (word1 && (word1 == '*')) {
if (word2 && (word2.toUpperCase() == 'FROM')) {
operation.targets = parseTargets(3);
operation.where = parseWhere();
} else {
result.error = 'Syntax error. Expected FROM, got ' + word;
return;
}
} else {
result.error = 'Syntax error. Expected *, got ' + word;
return;
}
} else if (type == 'UPDATE') {
operation.targets = parseTargets(1);
operation.values = parseValues();
operation.where = parseWhere();
debug('Operation: ', operation);
} else {
result.error = 'Unknown command ' + getWord(0);
return;
}
operation.type = type;
};
/**
* Parse the targets out of the query (eg, UPDATE #my-form)
* @param {Number} start The index of the starting point in query
* @return {Object} The captured element
* @private
*/
var parseTargets = function(start) {
index = start;
var sel = getWord(index),
error = 'Unknown target ' + sel;
if (sel) {
var c = sel.substr(0, 1);
// By id?
if (c == '#') {
var el = document.getElementById(sel.substr(1, sel.length));
if (el) {
index++;
return [el];
}
// The entire body?
} else if (inArray(BODIES, sel) > -1) {
index++;
return [document.body];
}
}
result.error = error;
};
/**
* Parse the values of the query (eg, SET key = 'value')
* @return {Object} The values in key/value pair
*/
var parseValues = function() {
var qry = getWord(index),
values = [];
if (qry.toUpperCase() == 'SET') {
index++;
while ((index < query.length) && query[index].toUpperCase() != 'WHERE') {
var
key = query[index++],
eq = query[index++],
value = query[index++];
if (eq != '=') {
result.error = 'Expected =, got ' + eq;
return;
}
if (value === 'false') {
value = false;
} else if (value === undefined) {
value = '';
}
values.push({
key : key,
value : value
});
};
return values;
} else {
result.error = 'Expected SET, got ' + query[index];
}
};
/**
* Parses the WHERE clause of the query
* @return {Object} The key/value where object
* @private
*/
var parseWhere = function() {
if (result.error || !query[index]) {
return [];
}
if (query[index].toUpperCase() == 'WHERE') {
var where = [];
index++;
while ((index < query.length) && (query[index].toUpperCase() != 'LIMIT')) {
var key = query[index++],
cond = query[index++],
value = query[index++];
if (cond == '=') {
type = CONDITIONAL_EQUALS;
} else if (cond == '!=') {
type = CONDITIONAL_NOT_EQUAL;
} else {
result.error = 'Unknown conditional "' + eq + '"';
return;
}
where.push({
key : key,
type : type,
value : value || ''
});
};
return where;
}
};
formatQuery(qry);
parseQuery();
getParsedTargets();
execQuery();
return result;
};
/**
* Sets the private debug method to something useful
* @param {Function} The function to call to handle debug messages
* @public
*/
query.setDebug = function(fn) {
debug = fn;
};
return query;
})();
