Added title iterator as preparation for infix search.

www/js/lib/archive.js

@@ -29,6 +29,7 @@ define(function(require) {
     var util = require('util');
     var geometry = require('geometry');
     var jQuery = require('jquery');
+    var titleIterators = require('titleIterators');
     
     // Declare the webworker that can uncompress with bzip2 algorithm
     var webworkerBzip2 = new Worker("js/lib/webworker_bzip2.js");
@@ -303,114 +304,30 @@ define(function(require) {
         });
     };
 
-    /**
-     * This function is recursively called after each asynchronous read, so that
-     * to find the closest index in titleFile to the given prefix
-     * When found, call the callbackFunction with the index
-     * 
-     * @param reader
-     * @param normalizedPrefix
-     * @param lo
-     * @param hi
-     * @param callbackFunction
-     */
-    LocalArchive.prototype.recursivePrefixSearch = function(reader, normalizedPrefix, lo, hi, callbackFunction) {
-        if (lo < hi - 1) {
-            var mid = Math.floor((lo + hi) / 2);
-            var blob = this.titleFile.slice(mid, mid + MAX_TITLE_LENGTH);
-            var currentLocalArchiveInstance = this;
-            reader.onload = function(e) {
-                var binaryTitleFile = e.target.result;
-                var byteArray = new Uint8Array(binaryTitleFile);
-                // Look for the index of the next NewLine
-                var newLineIndex = 0;
-                while (newLineIndex < byteArray.length && byteArray[newLineIndex] !== 10) {
-                    newLineIndex++;
-                }
-                var startIndex = 0;
-                if (mid > 0) {
-                    startIndex = newLineIndex + 16;
-                    newLineIndex = startIndex;
-                    // Look for the index of the next NewLine	
-                    while (newLineIndex < byteArray.length && byteArray[newLineIndex] !== 10) {
-                        newLineIndex++;
-                    }
-                }
-                if (newLineIndex === startIndex) {
-                    // End of file reached
-                    hi = mid;
-                }
-                else {
-                    var normalizedTitle = currentLocalArchiveInstance.normalizeStringIfCompatibleArchive(
-                            utf8.parse(byteArray.subarray(startIndex, newLineIndex)));
-                    if (normalizedTitle < normalizedPrefix) {
-                        lo = mid + newLineIndex - 1;
-                    }
-                    else {
-                        hi = mid;
-                    }
-                }
-                currentLocalArchiveInstance.recursivePrefixSearch(reader, normalizedPrefix, lo, hi, callbackFunction);
-            };
-            // Read the file as a binary string
-            reader.readAsArrayBuffer(blob);
-        }
-        else {
-            if (lo > 0) {
-                // Let lo point to the start of an entry
-                lo++;
-                lo++;
-            }
-            // We found the closest title at index lo
-            callbackFunction(lo);
-        }
-    };
-
     /**
      * Read the titles in the title file starting at the given offset (maximum titleCount), and call the callbackFunction with this list of Title instances
-     * @param titleOffset
+     * @param titleOffset offset into the title file - it has to point excatly
+     *                    to the start of a title entry
      * @param titleCount maximum number of titles to retrieve
      * @param callbackFunction
      */
     LocalArchive.prototype.getTitlesStartingAtOffset = function(titleOffset, titleCount, callbackFunction) {
-        var reader = new FileReader();
-        reader.onerror = errorHandler;
-        reader.onabort = function(e) {
-            alert('Title file read cancelled');
-        };
-
-        var currentLocalArchiveInstance = this;
-        reader.onload = function(e) {
-            var binaryTitleFile = e.target.result;
-            var byteArray = new Uint8Array(binaryTitleFile);
-            var i = 0;
-            var newLineIndex = 0;
-            var titleNumber = 0;
-            var titleList = new Array();
-            while (i < byteArray.length && titleNumber < titleCount) {
-                // Look for the index of the next NewLine
-                newLineIndex += 15;
-                while (newLineIndex < byteArray.length && byteArray[newLineIndex] != 10) {
-                    newLineIndex++;
+        var titles = [];
+        jQuery.when().then(function() {
+            var iterator = new titleIterators.SequentialTitleIterator(this, titleOffset);
+            function addNext() {
+                if (titles.length >= titleCount) {
+                    return titles;
                 }
-
-                // Copy the encodedTitle in a new Array
-                var encodedTitle = new Uint8Array(newLineIndex - i);
-                for (var j = 0; j < newLineIndex - i; j++) {
-                    encodedTitle[j] = byteArray[i + j];
-                }
-
-                var title = evopediaTitle.Title.parseTitle(encodedTitle, currentLocalArchiveInstance, i);
-
-                titleList[titleNumber] = title;
-                titleNumber++;
-                i = newLineIndex + 1;
+                return iterator.advance().then(function(title) {
+                    if (title == null)
+                        return titles;
+                    titles.push(title);
+                    return addNext();
+                });
             }
-            callbackFunction(titleList);
-        };
-        var blob = this.titleFile.slice(titleOffset, titleOffset + titleCount * MAX_TITLE_LENGTH);
-        // Read in the file as a binary string
-        reader.readAsArrayBuffer(blob);
+            return addNext();
+        }).then(callbackFunction, errorHandler);
     };
 
     /**
@@ -420,30 +337,23 @@ define(function(require) {
      * @param callbackFunction
      */
     LocalArchive.prototype.getTitleByName = function(titleName, callbackFunction) {
-        var titleFileSize = this.titleFile.size;
-        var reader = new FileReader();
-        reader.onerror = errorHandler;
-        reader.onabort = function(e) {
-            alert('Title file read cancelled');
-        };
-        var currentLocalArchiveInstance = this;
-        var normalizedTitleName = currentLocalArchiveInstance.normalizeStringIfCompatibleArchive(titleName);
-        this.recursivePrefixSearch(reader, normalizedTitleName, 0, titleFileSize, function(titleOffset) {
-            currentLocalArchiveInstance.getTitlesStartingAtOffset(titleOffset, MAX_TITLES_WITH_SAME_NORMALIZED_NAME, function(titleList) {
-                if (titleList !== null && titleList.length>0) {
-                    for (var i=0; i<titleList.length; i++) {
-                        var title = titleList[i];
-                        if (title.name === titleName) {
-                            // The title has been found
-                            callbackFunction(title);
-                            return;
-                        }
-                    }
+        var that = this;
+        var normalize = this.getNormalizeFunction();
+        var normalizedTitleName = normalize(titleName);
+
+        titleIterators.FindPrefixOffset(this.titleFile, titleName, normalize).then(function(offset) {
+            var iterator = new titleIterators.SequentialTitleIterator(that, offset);
+            function check(title) {
+                if (title == null || normalize(title.name) !== normalizedTitleName) {
+                    return null;
+                } else if (title.name === titleName) {
+                    return title;
+                } else {
+                    return iterator.advance().then(check);
                 }
-                // The title has not been found
-                callbackFunction(null);
-            });
-        });
+            }
+            return iterator.advance().then(check);
+        }).then(callbackFunction, errorHandler);
     };
 
     /**
@@ -461,32 +371,30 @@ define(function(require) {
      * @param callbackFunction
      */
     LocalArchive.prototype.findTitlesWithPrefix = function(prefix, maxSize, callbackFunction) {
-        var titleFileSize = this.titleFile.size;
-        if (prefix) {
-            prefix = this.normalizeStringIfCompatibleArchive(prefix);
-        }
+        var that = this;
+        var titles = [];
+        var normalize = this.getNormalizeFunction();
+        prefix = normalize(prefix);
 
-        var reader = new FileReader();
-        reader.onerror = errorHandler;
-        reader.onabort = function(e) {
-            alert('Title file read cancelled');
-        };
-        var currentLocalArchiveInstance = this;
-        var normalizedPrefix = this.normalizeStringIfCompatibleArchive(prefix);
-        this.recursivePrefixSearch(reader, normalizedPrefix, 0, titleFileSize, function(titleOffset) {
-            currentLocalArchiveInstance.getTitlesStartingAtOffset(titleOffset, maxSize, function(titleList) {
-                // Keep only the titles with names starting with the prefix
-                var i = 0;
-                for (i = 0; i < titleList.length; i++) {
-                    var titleName = titleList[i].name;
-                    var normalizedTitleName = currentLocalArchiveInstance.normalizeStringIfCompatibleArchive(titleName);
-                    if (normalizedTitleName.length < normalizedPrefix.length || normalizedTitleName.substring(0, normalizedPrefix.length) !== normalizedPrefix) {
-                        break;
-                    }
+        titleIterators.FindPrefixOffset(this.titleFile, prefix, normalize).then(function(offset) {
+            var iterator = new titleIterators.SequentialTitleIterator(that, offset);
+            function addNext() {
+                if (titles.length >= maxSize) {
+                    return titles;
                 }
-                callbackFunction(titleList.slice(0, i));
-            });
-        });
+                return iterator.advance().then(function(title) {
+                    if (title == null)
+                        return titles;
+                    // check whether this title really starts with the prefix
+                    var name = normalize(title.name);
+                    if (name.length < prefix.length || name.substring(0, prefix.length) != prefix)
+                        return titles;
+                    titles.push(title);
+                    return addNext();
+                });
+            }
+            return addNext();
+        }).then(callbackFunction, errorHandler);
     };
 
 
@@ -950,6 +858,18 @@ define(function(require) {
         }
     };
     
+    /**
+     * Returns a function that normalizes strings if the current archive is compatible.
+     * If it is not, returns the identity function.
+     */
+    LocalArchive.prototype.getNormalizeFunction = function() {
+        if (this.normalizedTitles === true) {
+            return normalize_string.normalizeString;
+        } else {
+            return function(string) { return string; }
+        }
+    };
+    
     /**
      * ErrorHandler for FileReader
      * @param {type} evt

www/js/lib/title.js

@@ -147,4 +147,4 @@ define(function(require) {
     return {
         Title: Title
     };
-});
+});

www/js/lib/titleIterators.js

@@ -0,0 +1,121 @@
+/**
+ * titleIterators.js : Various classes to iterate over titles, for example as a
+ * result of searching.
+ * 
+ * Copyright 2014 Evopedia developers
+ * License GPL v3:
+ * 
+ * This file is part of Evopedia.
+ * 
+ * Evopedia is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * Evopedia is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with Evopedia (file LICENSE-GPLv3.txt).  If not, see <http://www.gnu.org/licenses/>
+ */
+define(['utf8', 'title', 'util', 'jquery'], function(utf8, evopediaTitle, util, jQuery) {
+    // Maximum length of a title
+    // 300 bytes is arbitrary : we actually do not really know how long the titles will be
+    // But mediawiki titles seem to be limited to ~200 bytes, so 300 should be more than enough
+    var MAX_TITLE_LENGTH = 300;
+
+    /**
+     * Iterates over all titles starting at the given offset.
+     * The asynchronous method advance has to be called before this.title is
+     * valid.
+     */
+    function SequentialTitleIterator(archive, offset) {
+        this._titleFile = archive.titleFile;
+        this._archive = archive;
+        this._offset = offset;
+        this.title = null;
+    }
+    /**
+     * Advances to the next title (or the first), if possible.
+     * @returns jQuery promise containing the next title or null if there is no
+     * next title
+     */
+    SequentialTitleIterator.prototype.advance = function() {
+        if (this._offset >= this._titleFile.size) {
+            this.title = null;
+            return jQuery.when(this.title);
+        }
+        var that = this;
+        return util.readFileSlice(this._titleFile, this._offset,
+                                  this._offset + MAX_TITLE_LENGTH).then(function(byteArray) {
+            var newLineIndex = 15;
+            while (newLineIndex < byteArray.length && byteArray[newLineIndex] != 10) {
+                newLineIndex++;
+            }
+            var encodedTitle = byteArray.subarray(0, newLineIndex);
+            that._title = evopediaTitle.Title.parseTitle(encodedTitle, that._archive, that._offset);
+            that._offset += newLineIndex + 1;
+            return that._title;
+        });
+    }
+
+    /**
+     * Searches for the offset into the given title file where the first title
+     * with the given prefix (or lexicographically larger) is located.
+     * The given function normalize is applied to every title before comparison.
+     * @returns jQuery promise giving the offset
+     */
+    function FindPrefixOffset(titleFile, prefix, normalize) {
+        prefix = normalize(prefix);
+        var lo = 0;
+        var hi = titleFile.size;
+        var iterate = function() {
+            if (lo >= hi) {
+                if (lo > 0)
+                    lo += 2; // Let lo point to the start of an entry
+                return jQuery.when(lo);
+            } else {
+                var mid = Math.floor((lo + hi) / 2);
+                return util.readFileSlice(titleFile, mid, mid + MAX_TITLE_LENGTH).then(function(byteArray) {
+                    // Look for the index of the next NewLine
+                    var newLineIndex = 0;
+                    while (newLineIndex < byteArray.length && byteArray[newLineIndex] !== 10) {
+                        newLineIndex++;
+                    }
+                    var startIndex = 0;
+                    if (mid > 0) {
+                        startIndex = newLineIndex + 16;
+                        newLineIndex = startIndex;
+                        // Look for the index of the next NewLine	
+                        while (newLineIndex < byteArray.length && byteArray[newLineIndex] !== 10) {
+                            newLineIndex++;
+                        }
+                    }
+                    if (newLineIndex === startIndex) {
+                        // End of file reached
+                        hi = mid;
+                    } else {
+                        var normalizedTitle = normalize(utf8.parse(byteArray.subarray(startIndex, newLineIndex)));
+                        if (normalizedTitle < prefix) {
+                            lo = mid + newLineIndex - 1;
+                        } else {
+                            hi = mid;
+                        }
+                    }
+                    return iterate();
+                });
+            }
+        }
+        return iterate();
+    }
+
+    /**
+     * Functions and classes exposed by this module
+     */
+    return {
+        SequentialTitleIterator : SequentialTitleIterator,
+        FindPrefixOffset : FindPrefixOffset
+    };
+});

www/js/lib/util.js

@@ -20,6 +20,7 @@
  * along with Evopedia (file LICENSE-GPLv3.txt).  If not, see <http://www.gnu.org/licenses/>
  */
 define(function(require) {
+    var jQuery = require('jquery');
 
     /**
      * Utility function : return true if the given string ends with the suffix
@@ -112,6 +113,25 @@ define(function(require) {
 
         return (r > 0 ? enc.slice(0, r - 3) : enc) + '==='.slice(r || 3);
     }
+
+    /**
+     * Reads a Uint8Array from the given file starting at byte offset begin and
+     * not including byte offset end.
+     * @returns jQuery promise
+     */
+    function readFileSlice(file, begin, end) {
+        var deferred = jQuery.Deferred();
+        var reader = new FileReader();
+        reader.onload = function(e) {
+            deferred.resolve(new Uint8Array(e.target.result));
+        }
+        reader.onerror = reader.onabort = function(e) {
+            deferred.reject(e);
+        }
+        reader.readAsArrayBuffer(file.slice(begin, end));
+        return deferred.promise();
+    }
+
     
     /**
      * Functions and classes exposed by this module
@@ -122,6 +142,7 @@ define(function(require) {
         readIntegerFrom2Bytes : readIntegerFrom2Bytes,
         readFloatFrom4Bytes : readFloatFrom4Bytes,
         uint8ArrayToHex : uint8ArrayToHex,
-        uint8ArrayToBase64 : uint8ArrayToBase64
+        uint8ArrayToBase64 : uint8ArrayToBase64,
+        readFileSlice : readFileSlice
     };
-});
+});