Crawler, second version

lib/storage.js

Index: lib/storage.js
===================================================================
--- a/lib/storage.js
+++ b/lib/storage.js
@@ -1,45 +1,213 @@
-Cu.import("resource://gre/modules/FileUtils.jsm");
+let {Encoding} = require( "encoding" );
+let {Logger} = require( "logger" );
 
-let outputStream;
-let converterOutputStream;
+Cu.import( "resource://gre/modules/FileUtils.jsm" );
 
-function createTemporaryFile(name)
+//-------------------------------------------------------
+// Storage_class
+//-------------------------------------------------------
+/**
+ * Base class for particular storage mechanisms. Implements all storage framework methods. Necessary methods have
+ * implementations that throw if not overridden. Optional methods have no-op implementations.
+ * @constructor
+ */
+var Storage_class = function()
 {
-  let file = FileUtils.getFile("TmpD", [name]);
-  file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, FileUtils.PERMS_FILE);
-  return file;
-}
-
-function openOutputStream(file)
-{
-  let outputStream = FileUtils.openSafeFileOutputStream(file);
-  let converterOutputStream = Cc["@mozilla.org/intl/converter-output-stream;1"]
-      .createInstance(Ci.nsIConverterOutputStream);
-  converterOutputStream.init(outputStream, "UTF-8", 0, 0);
-  return [outputStream, converterOutputStream];
-}
-
-let Storage = exports.Storage = {};
-
-Storage.init = function()
-{
-  Storage.dataFile = createTemporaryFile("crawler-data");
-  [outputStream, converterOutputStream] = openOutputStream(Storage.dataFile);
 };
 
-Storage.write = function(data)
+/**
+ * Return a string of the form "[object ...]" like the built-in types do.
+ * <p/>
+ * Mandatory framework function.
+ */
+Storage_class.prototype.toJSON = function()
 {
-  let line = JSON.stringify(data) + "\n";
-  converterOutputStream.writeString(line);
+  throw new Error( "Subclass of Storage_class did not implement 'toJSON()'." );
 };
 
-Storage.finish = function()
+/**
+ * Called when the crawl first begins, before any targets have been loaded.
+ * <p/>
+ * Mandatory framework function.
+ */
+Storage_class.prototype.write = function()
 {
-  converterOutputStream.flush();
-  FileUtils.closeSafeFileOutputStream(outputStream);
+  throw new Error( "Subclass of Storage_class did not implement 'write()'." );
 };
 
-Storage.destroy = function()
+/**
+ * Called when the crawl ends, whether normally or abnormally.
+ */
+Storage_class.prototype.close = function()
 {
-  Storage.dataFile.remove(true);
 };
+
+Storage_class.prototype.writer = function()
+{
+  return this.write.bind( this );
+};
+
+//-------------------------------------------------------
+// Storage.Local_File
+//-------------------------------------------------------
+/**
+ * Storage to the local file system.
+ * <p>
+ * This class writes directly to the given file. It does not write to a temporary file first, say, using 'createUnique',
+ * and then renaming it.
+ *
+ * @param {nsIFile} file
+ *     File object to which to write.
+ * @constructor
+ */
+var Local_File = function( file )
+{
+  /**
+   * @type {nsIFile}
+   */
+  this.file = file;
+
+  this.output = FileUtils.openSafeFileOutputStream( file );
+  this.converter_output = Cc["@mozilla.org/intl/converter-output-stream;1"]
+    .createInstance( Ci.nsIConverterOutputStream );
+  this.converter_output.init( this.output, "UTF-8", 0, 0 );
+};
+Local_File.prototype = new Storage_class();
+
+Local_File.prototype.toJSON = function()
+{
+  return "local file " + this.file.path;
+};
+
+Local_File.prototype.close = function()
+{
+  this.converter_output.flush();
+  FileUtils.closeSafeFileOutputStream( this.output );
+};
+
+Local_File.prototype.write = function( s )
+{
+  this.converter_output.writeString( s );
+};
+
+//-------------------------------------------------------
+// Storage.Bit_Bucket
+//-------------------------------------------------------
+
+var Bit_Bucket = function()
+{
+};
+Bit_Bucket.prototype = new Storage_class();
+
+/**
+ * The only way that this differs from the do-nothing base class is that we provide a name.
+ */
+Bit_Bucket.prototype.toJSON = function()
+{
+  return "bit bucket";
+};
+Bit_Bucket.prototype.write = function()
+{
+};
+
+//-------------------------------------------------------
+// Storage.Multiple
+//-------------------------------------------------------
+/**
+ * Combine one or more Storage_class objects into a single one. This is ordinarily used for logging activity to the
+ * screen during the run. It also allows enables summary statistics to be gathered simultaneously with a crawl to
+ * support filter list construction.
+ * @constructor
+ * @param {Array} stores
+ *      An array of Storage_class objects.
+ * @param {boolean} [omit_first]
+ *      Suppress first element in JSON display.
+ */
+var Multiple = function( stores, omit_first )
+{
+  this.stores = stores;
+  this.omit_first = omit_first;
+};
+Multiple.prototype = new Storage_class();
+
+/**
+ * @override
+ */
+Multiple.prototype.toJSON = function()
+{
+  if ( this.omit_first && this.stores.length == 2 )
+  {
+    /*
+     * Special case: Pretend we're not here.
+     */
+    return this.stores[ 1 ].toJSON();
+  }
+  var s = "Multiple[";
+  var first = (this.omit_first) ? 1 : 0;
+  if ( this.first < this.stores.length )
+  {
+    for ( let i = first ; i < this.stores.length ; ++i )
+    {
+      if ( i > first ) s += ",";
+      s += " " + JSON.stringify( this.stores[i] );
+    }
+    s += " ";
+  }
+  s += "]";
+  return s;
+};
+
+/**
+ * @override
+ */
+Multiple.prototype.write = function( s )
+{
+  for ( let i = 0 ; i < this.stores.length ; ++i )
+  {
+    this.stores[i].write( s );
+  }
+};
+
+//-------------------------------------------------------
+// Storage.Display_Log
+//-------------------------------------------------------
+/**
+ * A display log in the crawler UI, presumably a simple textbox. Used to monitor progress during a crawl, if desired.
+ * @constructor
+ * @param [display]
+ *      A display object from the crawler UI.
+ */
+var Display_Log = function( display )
+{
+  this.display = display;
+};
+Display_Log.prototype = new Storage_class();
+
+/**
+ * @override
+ */
+Display_Log.prototype.toJSON = function()
+{
+  return "Display_Log";
+};
+
+/**
+ * @override
+ */
+Display_Log.prototype.write = function( s )
+{
+  this.display.write( s );
+};
+
+//-------------------------------------------------------
+// Storage
+//-------------------------------------------------------
+/**
+ * Export variable for this module. There's no single class named "Storage" as such.
+ */
+exports.Storage = {
+  Local_File: Local_File,
+  Bit_Bucket: Bit_Bucket,
+  Multiple: Multiple,
+  Display_Log: Display_Log
+};