added "export as JSON" capability

HISTORY.md

@@ -6,7 +6,8 @@
 * Store: tweaked format for serializing atomic data lists
 * Morphic: added option to include alpha in color comparison
 * Objects: fixed "set pen color (color picker)" to observe, i.e. overwrite transparency
-* Lists, Threads, Objects: added (Bernat's) JSON parser to SPLIT block 
+* Lists, Threads, Objects: added (Bernat's) JSON parser to SPLIT block
+* Lists, Objects: added "export as JSON" capability 
 
 ### 2019-01-08
 * Objects: automatically parse csv files on import, experimental "raw data" and "parse" ops

src/lists.js

@@ -443,6 +443,50 @@ List.prototype.asCSV = function () {
     return items.map(encodeCell).join(',');
 };
 
+List.prototype.asJSON = function (guessObjects) {
+    // Caution, no error catching!
+    // this method assumes that the list.canBeJSON()
+
+    function objectify(list, guessObjects) {
+        var items = list.itemsArray(),
+            obj = {};
+        if (canBeObject(items)) {
+            items.forEach(function (pair) {
+                var value = pair.length() === 2 ? pair.at(2) : undefined;
+                obj[pair.at(1)] = (value instanceof List ?
+                    objectify(value, guessObjects) : value);
+            });
+            return obj;
+        }
+        return items.map(function (element) {
+            return element instanceof List ?
+                objectify(element, guessObjects) : element;
+        });
+    }
+
+    function canBeObject(array) {
+        // try to determine whether the contents of a list
+        // might be better represented as dictionary/object
+        // than as array
+        var keys;
+        if (array.every(function (element) {
+            return element instanceof List && (element.length() < 3);
+        })) {
+            keys = array.map(function (each) {return each.at(1); });
+            return keys.every(function (each) {
+                return isString(each) &&
+                    isUniqueIn(each, keys);
+            });
+        }
+    }
+
+    function isUniqueIn(element, array) {
+        return array.indexOf(element) === array.lastIndexOf(element);
+    }
+
+    return JSON.stringify(objectify(this, guessObjects));
+};
+
 // List testing
 
 List.prototype.equalTo = function (other) {
@@ -501,6 +545,16 @@ List.prototype.canBeCSV = function () {
     });
 };
 
+List.prototype.canBeJSON = function () {
+    return this.itemsArray().every(function (value) {
+        return !isNaN(+value) ||
+            isString(value) ||
+            value === true ||
+            value === false ||
+            (value instanceof List && value.canBeJSON);
+    });
+};
+
 List.prototype.hasOnlyAtomicData = function () {
     return this.itemsArray().every(function (value) {
         return !isNaN(+value) ||

src/objects.js

@@ -9538,6 +9538,36 @@ WatcherMorph.prototype.userMenu = function () {
                 'do not attempt to\nparse or format data',
                 new Color(100, 0, 0)
             );
+            if (this.currentValue instanceof List &&
+                    this.currentValue.canBeCSV()) {
+                menu.addItem(
+                    'export as CSV...',
+                    function () {
+                        var ide = myself.parentThatIsA(IDE_Morph);
+                        ide.saveFileAs(
+                            myself.currentValue.asCSV(),
+                            'text/csv;charset=utf-8', // RFC 4180
+                            myself.getter // variable name
+                        );
+                    }
+                );
+            }
+            if (this.currentValue instanceof List &&
+                    this.currentValue.canBeJSON()) {
+                menu.addItem(
+                    'export as JSON...',
+                    function () {
+                        var ide = myself.parentThatIsA(IDE_Morph);
+                        ide.saveFileAs(
+                            myself.currentValue.asJSON(true), // guess objects
+                            'text/json;charset=utf-8',
+                            myself.getter // variable name
+                        );
+                    },
+                    null,
+                    new Color(100, 0, 0)
+                );
+            }
         }
         if (isString(this.currentValue) || !isNaN(+this.currentValue)) {
             if (shiftClicked) {