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Change the comparison algorithm of titles when searching through the index.

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We use a comparison of byte arrays instead of String comparison.
This commit is contained in:
mossroy 2013-07-08 13:56:58 +02:00
parent 8cedce59aa
commit 7eeafe4d84
1 changed files with 61 additions and 28 deletions
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87
js/lib/evopedia.js
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@ -21,30 +21,30 @@ define(function(require) {
return byteArray[firstIndex] + byteArray[firstIndex + 1] * 256;
}
/**
* Converts a UTF-8 byte array to JavaScript's 16-bit Unicode.
* @param {Array.<number>} bytes UTF-8 byte array.
* @return {string} 16-bit Unicode string.
* Copied from http://closure-library.googlecode.com/svn/docs/closure_goog_crypt.js.source.html (Apache License 2.0)
*/
function utf8ByteArrayToString(bytes, startIndex, endIndex) {
var out = [], pos = startIndex, c = 0;
while (pos < bytes.length && pos < endIndex) {
var c1 = bytes[pos++];
if (c1 < 128) {
out[c++] = String.fromCharCode(c1);
} else if (c1 > 191 && c1 < 224) {
var c2 = bytes[pos++];
out[c++] = String.fromCharCode((c1 & 31) << 6 | c2 & 63);
} else {
var c2 = bytes[pos++];
var c3 = bytes[pos++];
out[c++] = String.fromCharCode(
(c1 & 15) << 12 | (c2 & 63) << 6 | c3 & 63);
}
}
return out.join('');
var utf8 = {}
utf8.toByteArray = function(str) {
var byteArray = [];
for (var i = 0; i < str.length; i++)
if (str.charCodeAt(i) <= 0x7F)
byteArray.push(str.charCodeAt(i));
else {
var h = encodeURIComponent(str.charAt(i)).substr(1).split('%');
for (var j = 0; j < h.length; j++)
byteArray.push(parseInt(h[j], 16));
}
return byteArray;
};
utf8.parse = function(byteArray) {
var str = '';
for (var i = 0; i < byteArray.length; i++)
str += byteArray[i] <= 0x7F ?
byteArray[i] === 0x25 ? "%25" : // %
String.fromCharCode(byteArray[i]) :
"%" + byteArray[i].toString(16).toUpperCase();
return decodeURIComponent(str);
};
/**
* Convert a Uint8Array to a lowercase hex string.
@ -218,8 +218,13 @@ define(function(require) {
hi = mid;
}
else {
var normalizedTitle = remove_diacritics.normalizeString(utf8ByteArrayToString(byteArray, startIndex, newLineIndex));
if (normalizedTitle < normalizedPrefix) {
var normalizedTitle =
remove_diacritics.normalizeString(utf8.parse(byteArray.subarray(startIndex,
newLineIndex)));
var comparison =
arrayCompare(utf8.toByteArray(normalizedTitle),
utf8.toByteArray(normalizedPrefix));
if (comparison < 0) {
lo = mid + newLineIndex - 1;
}
else {
@ -242,6 +247,34 @@ define(function(require) {
}
};
function arrayCompare(array1, array2) {
if (array1 == undefined || array1.length == 0) {
if (array2 == undefined || array2.length == 0) {
return 0;
}
else {
return -1;
}
}
if (array2 == undefined || array2.length == 0) {
return 1;
}
for (var i = 0; i < array1.length; i++) {
if (i > array2.length) {
return 1;
}
else {
if (array1[i] < array2[i]) {
return -1;
}
if (array1[i] > array2[i]) {
return 1;
}
}
}
return 0;
}
/**
* Look for a title in the title file at the given offset, and call the callbackFunction with this Title
* @param titleOffset
@ -686,7 +719,7 @@ define(function(require) {
if (len > 15 && encodedTitle[len - 1] == '\n') {
len--;
}
return utf8ByteArrayToString(encodedTitle, 15, len);
return utf8.parse(encodedTitle.subarray(15, len));
};
/**
@ -746,7 +779,7 @@ define(function(require) {
*/
return {
readIntegerFrom4Bytes: readIntegerFrom4Bytes,
utf8ByteArrayToString: utf8ByteArrayToString,
utf8: utf8,
LocalArchive: LocalArchive,
Title: Title
};