bfilter/trunk/bfilter.js

/*
   Fast filtering function using pre-sorted list elements
   Dobrica Pavlinusic, dpavlin@rot13.org 2004-09-06
   Matko Andjelinic, matko.andjelinic@gmail.com 2004-09-09 (contributed OO implementation)
*/


function BFilter(arr) {
        this.id_cache = Array();
        // total number of hits
        this.hits = 0;

        this.results_html = null;

        // this function is called for each result
        this.result = function (arr) {
                this.results_html += '<li><a href="'+arr[1]+'">'+
                        (this.hits % 2 == 0 ? '<span style="background: #e0e0e0;">' : '') +
                        arr[0] +
                        (this.hits % 2 == 0 ? '</span>' : '') +
                        '</a></li>';
                return true;
        }

        // this function is called when updating innerHTML with results
        this.display = function () {
                if (this.results_html) {
                        return '<ul>'+this.results_html+'</ul>';
                } else {
                        return null;
                }
        }


        if (! arr) {
                this.debug("ERROR: can't search empty array");
                return;
        }

        this.arr = arr;
        this.debug("index has "+this.arr.length+" parts");

        if (! arr.min_len) {
                this.results("ERROR: index structure problem");
                return;
        } else {
                this.min_len = arr.min_len;
        }

        this.debug("index part has "+this.min_len+" parts");

        this.show_status();

}

BFilter.prototype.element_id = function (id,no_alert) {
        if (this.id_cache[id]) {
                return this.id_cache[id];
        } else {
                var el = document.getElementById(id);
                if (el) {
                        this.id_cache[id] = el;
                        return el;
                } else {
                        if (! no_alert) {
                                alert("can't find element id: "+id);
                        } else {
                                // don't look it up again
                                this.id_cache[id] = null;
                        }
                }
        }
        return null;
}


BFilter.prototype.show_status = function (status) {
        var html;
        if (this.hits > 0) {
                html = "shown "+this.hits+" entries";
        } else {
                html = "no results";
        }
        if (! status) {
                html = "Enter "+this.min_len+" letter"+(this.min_len == 1 ? '' : 's')+" to filter entries";
                status = "";
        }

        var el = this.element_id("status");
        el.innerHTML = html+status+"\n";
}

BFilter.prototype.results = function (html,clean) {

        if (! html) { html = ""; }

        // results_div.style.cursor = 'wait'; // 'auto'
        var results_div = this.element_id("results");
        if (clean) {
                results_div.innerHTML = html;
        } else {
                html = this.display();
                if (html) results_div.innerHTML += html;
        }
}


BFilter.prototype.debug = function (html) {

        //return;

        // check if debugging is on
        if (! html) { return 1; }

        var debug_div = this.element_id("debug",1);
        if (! debug_div) { return null; }

        debug_div.innerHTML += html + "<br>\n";

        return null;
}


// modified binary search to find first element with substring
BFilter.prototype.binarySearch = function (arr, find) {
        if (!arr || typeof (find) == "undefined" || !arr.length) {
                return null;
        }
        var low = 0;
        var high = arr.length - 1;
        var middlearr = parseInt(arr.length / 2);
        var lastTry;
        while (low <= high) {
                var mid = (low + high) / 2;
                var aTry = (mid < 1) ? 0 : parseInt(mid);
        
                var curr = arr[aTry][0].substr(0,find.length).toLowerCase();
                this.debug("low="+low+" high="+high+" lastTry="+lastTry+" "+aTry+": "+curr);
                if (curr < find) {
                        low = aTry + 1;
                        continue;
                }
                if (curr > find) {
                        high = aTry - 1;
                        continue;
                }
                if (curr == find) {
                        high = aTry - 1;
                        lastTry = aTry;
                        continue;
                }
                return aTry;
        }
        this.debug("lastTry="+lastTry);

        if (typeof (lastTry) != "undefined") {
                return lastTry;
        } else {
                return null;
        }
}

BFilter.prototype.filter = function (document, find) {

        this.results('',1);
        this.hits = 0;

        if (find.length < this.min_len) {
                this.show_status();
                return;
        }

        this.debug("filter: '"+find+"'");

        var find_lc = find.toLowerCase();

        var part = find_lc.substr(0,this.min_len);

        // no part found
        if (! this.arr[part]) {
                this.show_status(" for <em>"+find+"</em><br>");
                this.debug("no part "+part);
                return;
        }

        // start anim icon
        //results("<img  src=\"pie.gif\">&nbsp;Please wait, filtering...\n",1);

        var i;

        // full part? (optimization)
        if (find.length == this.min_len) {
                for (i = 0; i < this.arr[part].length; i++) {
                        this.result(this.arr[part][i]);
                        this.hits++;
                }
                this.results();
        } else {

                var from = this.binarySearch(this.arr[part], find_lc);

                if (from != null) {
                
                        this.debug("loop "+from+" ... "+this.arr[part].length);

                        for(i = from ; i < this.arr[part].length ; i++) {
                                if (this.arr[part][i][0].substring(0,find.length).toLowerCase() != find_lc) {
                                        this.debug("loop exit at "+i);
                                        break;
                                }
                                this.result(this.arr[part][i]);
                                this.hits++;
                        }

                        this.results();
                }

        }

        this.show_status(" for <em>"+find+"</em>");

}

1	dpavlin	1	/*
2			Fast filtering function using pre-sorted list elements
3			Dobrica Pavlinusic, dpavlin@rot13.org 2004-09-06
4	dpavlin	10	Matko Andjelinic, matko.andjelinic@gmail.com 2004-09-09 (contributed OO implementation)
5	dpavlin	1	*/
6
7	dpavlin	2
8	dpavlin	10	function BFilter(arr) {
9			this.id_cache = Array();
10			// total number of hits
11			this.hits = 0;
12	dpavlin	1
13	dpavlin	28	this.results_html = null;
14
15	dpavlin	25	// this function is called for each result
16			this.result = function (arr) {
17	dpavlin	28	this.results_html += '<li><a href="'+arr[1]+'">'+
18	dpavlin	25	(this.hits % 2 == 0 ? '<span style="background: #e0e0e0;">' : '') +
19			arr[0] +
20			(this.hits % 2 == 0 ? '</span>' : '') +
21			'</a></li>';
22	dpavlin	28	return true;
23	dpavlin	25	}
24
25			// this function is called when updating innerHTML with results
26	dpavlin	28	this.display = function () {
27			if (this.results_html) {
28			return '<ul>'+this.results_html+'</ul>';
29			} else {
30			return null;
31			}
32	dpavlin	25	}
33
34
35	dpavlin	10	if (! arr) {
36			this.debug("ERROR: can't search empty array");
37			return;
38			}
39	dpavlin	1
40	dpavlin	10	this.arr = arr;
41			this.debug("index has "+this.arr.length+" parts");
42
43			if (! arr.min_len) {
44			this.results("ERROR: index structure problem");
45			return;
46	dpavlin	1	} else {
47	dpavlin	10	this.min_len = arr.min_len;
48			}
49
50			this.debug("index part has "+this.min_len+" parts");
51
52			this.show_status();
53
54			}
55
56			BFilter.prototype.element_id = function (id,no_alert) {
57			if (this.id_cache[id]) {
58			return this.id_cache[id];
59			} else {
60	dpavlin	1	var el = document.getElementById(id);
61			if (el) {
62	dpavlin	10	this.id_cache[id] = el;
63	dpavlin	1	return el;
64			} else {
65	dpavlin	10	if (! no_alert) {
66			alert("can't find element id: "+id);
67			} else {
68			// don't look it up again
69			this.id_cache[id] = null;
70			}
71	dpavlin	1	}
72			}
73	dpavlin	22	return null;
74	dpavlin	1	}
75
76
77	dpavlin	10	BFilter.prototype.show_status = function (status) {
78	dpavlin	1	var html;
79	dpavlin	10	if (this.hits > 0) {
80			html = "shown "+this.hits+" entries";
81	dpavlin	1	} else {
82			html = "no results";
83			}
84			if (! status) {
85	dpavlin	10	html = "Enter "+this.min_len+" letter"+(this.min_len == 1 ? '' : 's')+" to filter entries";
86	dpavlin	1	status = "";
87			}
88
89	dpavlin	10	var el = this.element_id("status");
90	dpavlin	1	el.innerHTML = html+status+"\n";
91			}
92
93	dpavlin	10	BFilter.prototype.results = function (html,clean) {
94	dpavlin	1
95			if (! html) { html = ""; }
96
97			// results_div.style.cursor = 'wait'; // 'auto'
98	dpavlin	10	var results_div = this.element_id("results");
99	dpavlin	1	if (clean) {
100	dpavlin	25	results_div.innerHTML = html;
101	dpavlin	1	} else {
102	dpavlin	28	html = this.display();
103			if (html) results_div.innerHTML += html;
104	dpavlin	1	}
105			}
106
107	dpavlin	10
108			BFilter.prototype.debug = function (html) {
109
110			//return;
111
112			// check if debugging is on
113			if (! html) { return 1; }
114
115			var debug_div = this.element_id("debug",1);
116	dpavlin	22	if (! debug_div) { return null; }
117	dpavlin	10
118	dpavlin	12	debug_div.innerHTML += html + "<br>\n";
119	dpavlin	22
120			return null;
121	dpavlin	10	}
122
123
124	dpavlin	2	// modified binary search to find first element with substring
125	dpavlin	10	BFilter.prototype.binarySearch = function (arr, find) {
126	dpavlin	6	if (!arr \|\| typeof (find) == "undefined" \|\| !arr.length) {
127	dpavlin	2	return null;
128			}
129			var low = 0;
130			var high = arr.length - 1;
131			var middlearr = parseInt(arr.length / 2);
132			var lastTry;
133			while (low <= high) {
134			var mid = (low + high) / 2;
135			var aTry = (mid < 1) ? 0 : parseInt(mid);
136
137	dpavlin	25	var curr = arr[aTry][0].substr(0,find.length).toLowerCase();
138	dpavlin	12	this.debug("low="+low+" high="+high+" lastTry="+lastTry+" "+aTry+": "+curr);
139	dpavlin	2	if (curr < find) {
140			low = aTry + 1;
141			continue;
142			}
143			if (curr > find) {
144			high = aTry - 1;
145			continue;
146			}
147			if (curr == find) {
148			high = aTry - 1;
149			lastTry = aTry;
150			continue;
151			}
152			return aTry;
153			}
154	dpavlin	12	this.debug("lastTry="+lastTry);
155	dpavlin	1
156	dpavlin	2	if (typeof (lastTry) != "undefined") {
157			return lastTry;
158			} else {
159			return null;
160			}
161			}
162
163	dpavlin	10	BFilter.prototype.filter = function (document, find) {
164	dpavlin	1
165	dpavlin	10	this.results('',1);
166			this.hits = 0;
167	dpavlin	1
168	dpavlin	10	if (find.length < this.min_len) {
169			this.show_status();
170	dpavlin	1	return;
171			}
172
173	dpavlin	12	this.debug("filter: '"+find+"'");
174	dpavlin	1
175			var find_lc = find.toLowerCase();
176
177	dpavlin	10	var part = find_lc.substr(0,this.min_len);
178	dpavlin	1
179			// no part found
180	dpavlin	10	if (! this.arr[part]) {
181			this.show_status(" for <em>"+find+"</em><br>");
182			this.debug("no part "+part);
183	dpavlin	1	return;
184			}
185
186			// start anim icon
187			//results("<img src=\"pie.gif\"> Please wait, filtering...\n",1);
188
189	dpavlin	22	var i;
190
191	dpavlin	1	// full part? (optimization)
192	dpavlin	10	if (find.length == this.min_len) {
193	dpavlin	22	for (i = 0; i < this.arr[part].length; i++) {
194	dpavlin	28	this.result(this.arr[part][i]);
195	dpavlin	10	this.hits++;
196	dpavlin	1	}
197	dpavlin	28	this.results();
198	dpavlin	1	} else {
199
200	dpavlin	10	var from = this.binarySearch(this.arr[part], find_lc);
201	dpavlin	1
202	dpavlin	2	if (from != null) {
203
204	dpavlin	12	this.debug("loop "+from+" ... "+this.arr[part].length);
205	dpavlin	5
206	dpavlin	22	for(i = from ; i < this.arr[part].length ; i++) {
207	dpavlin	25	if (this.arr[part][i][0].substring(0,find.length).toLowerCase() != find_lc) {
208	dpavlin	10	this.debug("loop exit at "+i);
209	dpavlin	2	break;
210			}
211	dpavlin	28	this.result(this.arr[part][i]);
212	dpavlin	10	this.hits++;
213	dpavlin	1	}
214	dpavlin	5
215	dpavlin	28	this.results();
216	dpavlin	1	}
217
218			}
219
220	dpavlin	10	this.show_status(" for <em>"+find+"</em>");
221	dpavlin	1
222			}
223