JavaScript file I/O

http://www.tiddlywiki.com/

function saveFile(fileUrl, content) {
    var r = null;
    if ((r == null) || (r == false)) r = mozillaSaveFile(fileUrl, content);
    if ((r == null) || (r == false)) r = ieSaveFile(fileUrl, content);
    if ((r == null) || (r == false)) r = javaSaveFile(fileUrl, content);
    return (r);
}
function loadFile(fileUrl) {
    var r = null;
    if ((r == null) || (r == false)) r = mozillaLoadFile(fileUrl);
    if ((r == null) || (r == false)) r = ieLoadFile(fileUrl);
    if ((r == null) || (r == false)) r = javaLoadFile(fileUrl);
    return (r);
} // Returns null if it can't do it, false if there's an error, true if it saved OK
function ieSaveFile(filePath, content) {
    try {
        var fso = new ActiveXObject("Scripting.FileSystemObject");
    } catch(e) { //alert("Exception while attempting to save\n\n" + e.toString());
        return (null);
    }
    var file = fso.OpenTextFile(filePath, 2, -1, 0);
    file.Write(content);
    file.Close();
    return (true);
} // Returns null if it can't do it, false if there's an error, or a string of the content if successful
function ieLoadFile(filePath) {
    try {
        var fso = new ActiveXObject("Scripting.FileSystemObject");
        var file = fso.OpenTextFile(filePath, 1);
        var content = file.ReadAll();
        file.Close();
    } catch(e) { //alert("Exception while attempting to load\n\n" + e.toString());
        return (null);
    }
    return (content);
} // Returns null if it can't do it, false if there's an error, true if it saved OK
function mozillaSaveFile(filePath, content) {
    if (window.Components) try {
        netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
        var file = Components.classes["@mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
        file.initWithPath(filePath);
        if (!file.exists()) file.create(0, 0664);
        var out = Components.classes["@mozilla.org/network/file-output-stream;1"].createInstance(Components.interfaces.nsIFileOutputStream);
        out.init(file, 0x20 | 0x02, 00004, null);
        out.write(content, content.length);
        out.flush();
        out.close();
        return (true);
    } catch(e) { //alert("Exception while attempting to save\n\n" + e);
        return (false);
    }
    return (null);
} // Returns null if it can't do it, false if there's an error, or a string of the content if successful
function mozillaLoadFile(filePath) {
    if (window.Components) try {
        netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
        var file = Components.classes["@mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
        file.initWithPath(filePath);
        if (!file.exists()) return (null);
        var inputStream = Components.classes["@mozilla.org/network/file-input-stream;1"].createInstance(Components.interfaces.nsIFileInputStream);
        inputStream.init(file, 0x01, 00004, null);
        var sInputStream = Components.classes["@mozilla.org/scriptableinputstream;1"].createInstance(Components.interfaces.nsIScriptableInputStream);
        sInputStream.init(inputStream);
        return (sInputStream.read(sInputStream.available()));
    } catch(e) { //alert("Exception while attempting to load\n\n" + e);
        return (false);
    }
    return (null);
}
function javaUrlToFilename(url) {
    var f = "//localhost";
    if (url.indexOf(f) == 0) return url.substring(f.length);
    var i = url.indexOf(":");
    if (i & gt; 0) return url.substring(i - 1);
    return url;
}
function javaSaveFile(filePath, content) {
    try {
        if (document.applets["TiddlySaver"]) return document.applets["TiddlySaver"].saveFile(javaUrlToFilename(filePath), "UTF-8", content);
    } catch(e) {}
    try {
        var s = new java.io.PrintStream(new java.io.FileOutputStream(javaUrlToFilename(filePath)));
        s.print(content);
        s.close();
    } catch(e) {
        return null;
    }
    return true;
}
function javaLoadFile(filePath) {
    try {
        if (document.applets["TiddlySaver"]) return String(document.applets["TiddlySaver"].loadFile(javaUrlToFilename(filePath), "UTF-8"));
    } catch(e) {}
    var content = [];
    try {
        var r = new java.io.BufferedReader(new java.io.FileReader(javaUrlToFilename(filePath)));
        var line;
        while ((lie = r.readLine()) != null) content.push(new String(line));
        r.close();
    } catch(e) {
        return null;
    }
    return content.join("\n");
} // UTF-8 encoding rules:
// 0x0000 - 0x007F: 0xxxxxxx
// 0x0080 - 0x07FF: 110xxxxx 10xxxxxx
// 0x0800 - 0xFFFF: 1110xxxx 10xxxxxx 10xxxxxx
function convertUTF8ToUnicode(u) {
    if (window.netscape == undefined) return manualConvertUTF8ToUnicode(u);
    else return mozConvertUTF8ToUnicode(u);
}
function manualConvertUTF8ToUnicode(utf) {
    var uni = utf;
    var src = 0;
    var dst = 0;
    var b1, b2, b3;
    var c;
    while (src & lt; utf.length) {
        b1 = utf.charCodeAt(src++);
        if (b1 & lt; 0x80) dst++;
        else if (b1 & lt; 0xE0) {
            b2 = utf.charCodeAt(src++);
            c = String.fromCharCode(((b1 & amp; 0x1F) & lt; & lt; 6) | (b2 & amp; 0x3F));
            uni = uni.substring(0, dst++).concat(c, utf.substr(src));
        } else {
            b2 = utf.charCodeAt(src++);
            b3 = utf.charCodeAt(src++);
            c = String.fromCharCode(((b1 & amp; 0xF) & lt; & lt; 12) | ((b2 & amp; 0x3F) & lt; & lt; 6) | (b3 & amp; 0x3F));
            uni = uni.substring(0, dst++).concat(c, utf.substr(src));
        }
    }
    return (uni);
}
function manualConvertUTF8ToUnicode(u) {
    try {
        netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
        var converter = Components.classes["@mozilla.org/intl/scriptableunicodeconverter"].createInstance(Components.interfaces.nsIScriptableUnicodeConverter);
        converter.charset = "UTF-8";
    } catch(e) {
        return manualConvertUTF8ToUnicode(u);
    } // fallback
    var s = converter.ConvertToUnicode(u);
    var fin = converter.Finish();
    return (fin.length & gt; 0) ? s + fin: s;
}
function convertUnicodeToUTF8(s) {
    if (window.netscape == undefined) return manualConvertUnicodeToUTF8(s);
    else return mozConvertUnicodeToUTF8(s);
}
function manualConvertUnicodeToUTF8(s) {
    var re = /[^\u0000-\u007F]/g;
    return s.replace(re,
    function($0) {
        return ("&#" + $0.charCodeAt(0).toString() + ";");
    })
}
function mozConvertUnicodeToUTF8(s) {
    try {
        netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
        var converter = Components.classes["@mozilla.org/intl/scriptableunicodeconverter"].createInstance(Components.interfaces.nsIScriptableUnicodeConverter);
        converter.charset = "UTF-8";
    } catch(e) {
        return manualConvertUnicodeToUTF8(s);
    } // fallback
    var u = converter.ConvertFromUnicode(s);
    var fin = converter.Finish();
    if (fin.length & gt; 0) return u + fin;
    else return u;
}