Add encodebase64/decodebase64 operators

Proposed by @ericshulman

core/modules/filters/encodings.js

@@ -16,6 +16,22 @@ Filter operator for applying decodeURIComponent() to each item.
 Export our filter functions
 */
 
+exports.decodebase64 = function(source,operator,options) {
+	var results = [];
+	source(function(tiddler,title) {
+		results.push($tw.utils.base64Decode(title));
+	});
+	return results;
+};
+
+exports.encodebase64 = function(source,operator,options) {
+	var results = [];
+	source(function(tiddler,title) {
+		results.push($tw.utils.base64Encode(title));
+	});
+	return results;
+};
+
 exports.decodeuricomponent = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

editions/test/tiddlers/tests/data/filters/Base64.tid

@@ -0,0 +1,19 @@
+title: Filters/Base64
+description: Test {encode|decode}base64 operators
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+(<$text text={{{ [[Jeremy1234]encodebase64[]] }}}/>)
+(<$text text={{{ [[]encodebase64[]] }}}/>)
+(<$text text={{{ [[SmVyZW15MTIzNA==]decodebase64[]] }}}/>)
+(<$text text={{{ [[]decodebase64[]] }}}/>)
++
+title: ExpectedResult
+
+<p>(SmVyZW15MTIzNA==)
+()
+(Jeremy1234)
+()</p>

editions/tw5.com/tiddlers/filters/decodebase64 Operator.tid

@@ -0,0 +1,16 @@
+caption: decodebase64
+op-input: a [[selection of titles|Title Selection]]
+op-output: the input with base 64 decoding applied
+op-parameter: 
+op-parameter-name: 
+op-purpose: apply base 64 decoding to a string
+tags: [[Filter Operators]] [[String Operators]]
+title: decodebase64 Operator
+type: text/vnd.tiddlywiki
+from-version: 5.2.6
+
+See Mozilla Developer Network for details of [[base 64 encoding|https://developer.mozilla.org/en-US/docs/Glossary/Base64]]. TiddlyWiki uses [[library code from @nijikokun|https://gist.github.com/Nijikokun/5192472]] to handle the conversion.
+
+The input strings must be base64 encoded. The output strings are binary data.
+
+<<.operator-examples "decodebase64">>

editions/tw5.com/tiddlers/filters/encodebase64 Operator.tid

@@ -0,0 +1,16 @@
+caption: encodebase64
+op-input: a [[selection of titles|Title Selection]]
+op-output: the input with base 64 encoding applied
+op-parameter: 
+op-parameter-name: 
+op-purpose: apply base 64 encoding to a string
+tags: [[Filter Operators]] [[String Operators]]
+title: encodebase64 Operator
+type: text/vnd.tiddlywiki
+from-version: 5.2.6
+
+See Mozilla Developer Network for details of [[base 64 encoding|https://developer.mozilla.org/en-US/docs/Glossary/Base64]]. TiddlyWiki uses [[library code from @nijikokun|https://gist.github.com/Nijikokun/5192472]] to handle the conversion.
+
+The input strings are interpreted as binary data. The output strings are base64 encoded.
+
+<<.operator-examples "encodebase64">>