experimental "column _ of _" reporter relabelling option for "item _ of _"

HISTORY.md

@@ -5,6 +5,7 @@
 * **Notable Changes:**
     * hyperized image attribute reporter primitive (monadic)
     * when constructing a costume from a pixel list handle single values as greyscale
+    * experimental "column _ of _" reporter relabelling option for "item _ of _"
 * **Notable Fixes:**
     * fixed a glitch in the animation library's "sine in-out" easing function 
     * fixed a postMessage glitch in the API, thanks, Bernat!
@@ -13,6 +14,7 @@
 
 ### 2021-01-26
 * threads: handle single values as greyscale when constructing a costume from a pixel list
+* threads, objects experimental "column _ of _" reporter relabelling option for "item _ of _"
 
 ### 2021-01-25
 * threads: hyperized image attribute reporter primitive (monadic)

snap.html

@@ -10,7 +10,7 @@
         <script src="src/widgets.js?version=2021-01-05"></script>
         <script src="src/blocks.js?version=2020-12-22"></script>
         <script src="src/threads.js?version=2021-01-26"></script>
-        <script src="src/objects.js?version=2021-01-05"></script>
+        <script src="src/objects.js?version=2021-01-26"></script>
         <script src="src/gui.js?version=2021-01-21"></script>
         <script src="src/paint.js?version=2020-05-17"></script>
         <script src="src/lists.js?version=2020-12-01"></script>

src/objects.js

@@ -84,7 +84,7 @@ BlockEditorMorph, BlockDialogMorph, PrototypeHatBlockMorph,  BooleanSlotMorph,
 localize, TableMorph, TableFrameMorph, normalizeCanvas, VectorPaintEditorMorph,
 AlignmentMorph, Process, WorldMap, copyCanvas, useBlurredShadows*/
 
-modules.objects = '2021-January-05';
+modules.objects = '2021-January-26';
 
 var SpriteMorph;
 var StageMorph;
@@ -1318,6 +1318,12 @@ SpriteMorph.prototype.initBlocks = function () {
             spec: 'item %idx of %l',
             defaults: [1]
         },
+        reportTableColumn: {
+            type: 'reporter',
+            category: 'lists',
+            spec: 'column %idx of %l',
+            defaults: [1]
+        },
         reportCDR: {
             type: 'reporter',
             category: 'lists',
@@ -1710,7 +1716,11 @@ SpriteMorph.prototype.blockAlternatives = {
     doShowVar: ['doHideVar'],
     doHideVar: ['doShowVar'],
 
-    // lists - HOFs
+    // lists
+    reportListItem: ['reportTableColumn'],
+    reportTableColumn: ['reportListItem'],
+
+    // HOFs
     reportMap: ['reportKeep', 'reportFindFirst'],
     reportKeep: ['reportFindFirst', 'reportMap'],
     reportFindFirst: ['reportKeep', 'reportMap'],

src/threads.js

@@ -2008,6 +2008,35 @@ Process.prototype.reportItems = function (indices, list) {
 
 // Process - other basic list accessors
 
+Process.prototype.reportTableColumn = function (index, list) {
+    // experimental and probably controversial as a primitive,
+    // because it's so nice and easy to write in Snap!
+    var col;
+
+    function columns() {
+        return Math.max(...list.itemsArray().map(row =>
+            row instanceof List ? row.length() : 0)
+        );
+    }
+
+    if (!this.isMatrix(list)) {
+        throw new Error(
+            'expecting ' + 'table' + ' but getting ' + this.reportTypeOf(list)
+        );
+    }
+    if (index === '') {
+        return new List(new Array(list.length()));
+    }
+    if (this.inputOption(index) === 'any') {
+        col = this.reportBasicRandom(1, columns());
+        return list.map(row => row.at(col));
+    }
+    if (this.inputOption(index) === 'last') {
+        return list.map(row => row.at(columns()));
+    }
+    return list.map(row => row.at(index));
+};
+
 Process.prototype.reportListLength = function (list) {
     this.assertType(list, 'list');
     return list.length();