Add Reverse Text Block (#1998)

Co-authored-by: Evan W. Patton <ewpatton@mit.edu>

appinventor/blocklyeditor/src/blocks/text.js

@@ -497,3 +497,18 @@ Blockly.Blocks['text_is_string'] = {
   },
   typeblock: [{translatedName: Blockly.Msg.LANG_TEXT_TEXT_IS_STRING_TITLE}]
 };
+
+Blockly.Blocks['text_reverse'] = {
+  // String reverse.
+  category: 'Text',
+  helpUrl: Blockly.Msg.LANG_TEXT_REVERSE_HELPURL,
+  init: function () {
+    this.setColour(Blockly.TEXT_CATEGORY_HUE);
+    this.setOutput(true, Blockly.Blocks.Utilities.YailTypeToBlocklyType("text", Blockly.Blocks.Utilities.OUTPUT));
+    this.appendValueInput('VALUE')
+        .setCheck(Blockly.Blocks.Utilities.YailTypeToBlocklyType("text", Blockly.Blocks.Utilities.INPUT))
+        .appendField(Blockly.Msg.LANG_TEXT_REVERSE_INPUT);
+    this.setTooltip(Blockly.Msg.LANG_TEXT_REVERSE_TOOLTIP);
+  },
+  typeblock: [{translatedName: Blockly.Msg.LANG_TEXT_REVERSE_INPUT}]
+};

appinventor/blocklyeditor/src/generators/yail/text.js

@@ -318,3 +318,19 @@ Blockly.Yail['text_is_string'] = function() {
   code = code + Blockly.Yail.YAIL_DOUBLE_QUOTE + "is a string?" + Blockly.Yail.YAIL_DOUBLE_QUOTE + Blockly.Yail.YAIL_CLOSE_COMBINATION;
   return [ code, Blockly.Yail.ORDER_ATOMIC ];
 };
+
+Blockly.Yail['text_reverse'] = function() {
+  // String reverse.
+  var argument = Blockly.Yail.valueToCode(this, 'VALUE', Blockly.Yail.ORDER_NONE) || "\"\"";
+  var code = Blockly.Yail.YAIL_CALL_YAIL_PRIMITIVE + "string-reverse"
+      + Blockly.Yail.YAIL_SPACER;
+  code = code + Blockly.Yail.YAIL_OPEN_COMBINATION
+      + Blockly.Yail.YAIL_LIST_CONSTRUCTOR + Blockly.Yail.YAIL_SPACER
+      + argument + Blockly.Yail.YAIL_CLOSE_COMBINATION;
+  code = code + Blockly.Yail.YAIL_SPACER + Blockly.Yail.YAIL_QUOTE
+      + Blockly.Yail.YAIL_OPEN_COMBINATION + "text"
+      + Blockly.Yail.YAIL_CLOSE_COMBINATION + Blockly.Yail.YAIL_SPACER;
+  code = code + Blockly.Yail.YAIL_DOUBLE_QUOTE + "reverse"
+      + Blockly.Yail.YAIL_DOUBLE_QUOTE + Blockly.Yail.YAIL_CLOSE_COMBINATION;
+  return [ code, Blockly.Yail.ORDER_ATOMIC ];
+};

appinventor/blocklyeditor/src/msg/en/_messages.js

@@ -758,6 +758,10 @@ Blockly.Msg.en.switch_language_to_english = {
     Blockly.Msg.LANG_TEXT_TEXT_IS_STRING_INPUT_THING = 'thing';
     Blockly.Msg.LANG_TEXT_TEXT_IS_STRING_TOOLTIP = 'Returns true if <code>thing</code> is a string.';
 
+    Blockly.Msg.LANG_TEXT_REVERSE_HELPURL = '/reference/blocks/text.html#reverse';
+    Blockly.Msg.LANG_TEXT_REVERSE_INPUT = 'reverse';
+    Blockly.Msg.LANG_TEXT_REVERSE_TOOLTIP = 'Reverse the given text.';
+
 // Lists Blocks.
     Blockly.Msg.LANG_CATEGORY_LISTS = 'Lists';
 //Blockly.Msg.LANG_LISTS_CREATE_EMPTY_HELPURL = 'http://en.wikipedia.org/wiki/Linked_list.html#Empty_lists';

appinventor/blocklyeditor/src/versioning.js

@@ -1813,7 +1813,10 @@ Blockly.Versioning.AllUpgradeMaps =
     28: "noUpgrade",
 
     // AI2: Added "for each in dictionary" block.
-    29: "noUpgrade"
+    29: "noUpgrade",
+
+    // AI2: In BLOCKS_LANGUAGE_VERSION 30, The Reverse Text block was added
+    30: "noUpgrade"
 
   }, // End Language upgraders
 

appinventor/buildserver/src/com/google/appinventor/buildserver/resources/runtime.scm

@@ -1872,6 +1872,21 @@
 (define (string-to-lower-case s)
   (String:toLowerCase (s:toString)))
 
+(define (unicode-string->list str :: <string>) :: <list>
+  (let loop ((result :: <list> '()) (i :: <int> (string-length str)))
+    (set! i (- i 1))
+    (if (< i 0) result
+        (if (and (>= i 1)
+              (let ((c (string-ref str i))
+                    (c1 (string-ref str (- i 1))))
+                (and (char>=? c #\xD800) (char<=? c #\xDFFF)
+                     (char>=? c1 #\xD800) (char<=? c1 #\xDFFF))))
+            (loop (make <pair> (string-ref str i) (make <pair> (string-ref str (- i 1)) result)) (- i 1))
+          (loop (make <pair> (string-ref str i) result) i)))))
+
+(define (string-reverse s)
+  (list->string (reverse (unicode-string->list s))))
+
 ;;; returns a string that is the number formatted with a
 ;;; specified number of decimal places
 (define (format-as-decimal number places)

appinventor/buildserver/tests/com/google/appinventor/buildserver/YailEvalTest.java

@@ -77,6 +77,12 @@ public class YailEvalTest extends TestCase {
                  scheme.eval(thunkify(schemeString)).toString());
   }
 
+  public void testStringReverse() throws Throwable {
+    assertEquals("raboof", (scheme.eval("(string-reverse \"foobar\")")).toString());
+    assertEquals("\uD83D\uDE43\uD83D\uDE0F\uD83E\uDD29\uD83D\uDE02\uD83D\uDC4F\uD83D\uDE03\uD83D\uDC4D\uD83D\uDE18",
+        (scheme.eval("(string-reverse \"\uD83D\uDE18\uD83D\uDC4D\uD83D\uDE03\uD83D\uDC4F\uD83D\uDE02\uD83E\uDD29\uD83D\uDE0F\uD83D\uDE43\")")).toString());
+  }
+
   /**
    * This is mostly here as a workaround for some strange behavior with top-level try-catch
    * expressions in Kawa.

appinventor/components/src/com/google/appinventor/components/common/YaVersion.java

@@ -499,8 +499,10 @@ public class YaVersion {
   // - FORM_COMPONENT_VERSION was incremented to 27.
   // For YOUNG_ANDROID_VERSION 201:
   // - CANVAS_COMPONENT_VERSION was incremented to 13
+  // For YOUNG_ANDROID_VERSION 202:
+  // - BLOCKS_LANGUAGE_VERSION was incremented to 30
 
-  public static final int YOUNG_ANDROID_VERSION = 201;
+  public static final int YOUNG_ANDROID_VERSION = 202;
 
   // ............................... Blocks Language Version Number ...............................
 
@@ -576,8 +578,10 @@ public class YaVersion {
   // - The dictionaries blocks were added.
   // For BLOCKS_LANGUAGE_VERSION 29
   // - The for-each-in-dictionary block was added.
+  // For BLOCKS_LANGUAGE_VERSION 30:
+  // - The Reverse Text block was added
 
-  public static final int BLOCKS_LANGUAGE_VERSION = 29;
+  public static final int BLOCKS_LANGUAGE_VERSION = 30;
 
   // ................................. Target SDK Version Number ..................................
 

appinventor/docs/html/reference/blocks/text.html

@@ -145,6 +145,7 @@
   <li><a href="#replaceall">replace all</a></li>
   <li><a href="#obfuscatetext">obfuscated text</a></li>
   <li><a href="#isstring">is a string?</a></li>
+  <li><a href="#reverse">reverse</a></li>
 </ul>
 
 <h3 id="string">” “ (string block)</h3>
@@ -273,6 +274,12 @@
 
 <p>Returns true if <em>thing</em> is a text object, otherwise false.</p>
 
+<h3 id="reverse">reverse</h3>
+
+<p><img src="images/text/text_reverse.png" alt="" /></p>
+
+<p>Reverse the given text. For example, “reverse” would become “esrever”.</p>
+
 </article>
 <script>
   // Handle redirection to documentation based on locale query parameter (if specified)

appinventor/docs/markdown/reference/blocks/text.md

@@ -22,6 +22,7 @@ layout: documentation
 * [replace all](#replaceall)
 * [obfuscated text](#obfuscatetext)
 * [is a string?](#isstring)
+* [reverse](#reverse)
 
 ### " " (string block)   {#string}
 
@@ -148,3 +149,9 @@ Produces text, like a text block.  The difference is that th etext is not easily
 ![](images/text/isstring.png)
 
 Returns true if *thing* is a text object, otherwise false.
+
+### reverse   {#reverse}
+
+![](images/text/text_reverse.png)
+
+Reverse the given text. For example, "reverse" would become "esrever".