all JME functions are random: false; implement tokenToJME for TSpreadsheet

The spreadsheet modification functions are deterministic. Marking them
as not-random means that spreadsheet variables constructed
deterministically aren't saved in the suspend data.

This commit also implements serialisation to JME for spreadsheet values,
so if they do get serialised for some reason, they can be restored.

Author: christianp

src/extension.js

@@ -263,6 +263,10 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             return sheet[ref]?.v;
         }
 
+        to_base64() {
+            const buffer = XLSX.write(this.wb, {type: 'array', bookType: 'xlsx'});
+            return encode_array(buffer);
+        }
     }
 
     const {TString, TList, TDict, THTML} = Numbas.jme.types;
@@ -277,9 +281,6 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
         TSpreadsheet,
         'spreadsheet',
         {
-            'list': function(s) {
-                // TODO
-            },
             'html': function(s) {
                 const e = document.createElement('spread-sheet');
                 e.setAttribute('disabled',true);
@@ -301,8 +302,7 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             return '\\text{Spreadsheet}';
         },
         jme: (tree,tok,bits) => {
-            // TODO
-            return 'spreadsheet()';
+            return 'spreadsheet_from_base64_file("sheet.xlsx",safe("' + Numbas.jme.escape(tok.value.to_base64())+'"))';
         }
     });
 
@@ -315,7 +315,7 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             };
             return new TSpreadsheet(new Workbook(workbook));
         },
-        { unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
 
     sheets.scope.addFunction(new jme.funcObj('spreadsheet',['list of list'],TSpreadsheet, 
@@ -327,22 +327,22 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             };
             return new TSpreadsheet(new Workbook(workbook));
         },
-        { unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
 
     sheets.scope.addFunction(new jme.funcObj('spreadsheet_from_base64_file', ['string', 'string'], TSpreadsheet,
         (filename, base64) => {
             const data = decode_array(base64);
             return new TSpreadsheet(new Workbook(XLSX.read(data, {sheetStubs: true})));
         },
-        { unwrapValues: true }
-    ))
+        { unwrapValues: true, random: false }
+    ));
 
     sheets.scope.addFunction(new jme.funcObj('update_range',[TSpreadsheet,TString,TDict], TSpreadsheet,
         (spreadsheet, range_string, changes) => {
             return new TSpreadsheet(spreadsheet.update_range(range_string, changes));
         },
-        {unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
 
     sheets.scope.addFunction(new jme.funcObj('update_range',[TSpreadsheet,'list of string',TDict], TSpreadsheet,
@@ -353,7 +353,7 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             }
             return new TSpreadsheet(wb);
         },
-        {unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
 
     sheets.scope.addFunction(new jme.funcObj('disable_cells',[TSpreadsheet,'list of string'], TSpreadsheet,
@@ -364,7 +364,7 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             }
             return new TSpreadsheet(wb);
         },
-        {unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
 
     sheets.scope.addFunction(new jme.funcObj('fill_range',[TSpreadsheet, TString, 'list of (string or number)'], TSpreadsheet,
@@ -379,13 +379,13 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             }
             return new TSpreadsheet(spreadsheet.fill_range(range,values));
         },
-        {unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
     sheets.scope.addFunction(new jme.funcObj('fill_range',[TSpreadsheet,TString,'list of list of (string or number)'], TSpreadsheet,
         (spreadsheet, range, values) => {
             return new TSpreadsheet(spreadsheet.fill_range(range,values));
         },
-        {unwrapValues: true}
+        { unwrapValues: true, random: false }
     ));
 
     /** Interpret a range string and return a list of the cells it contains.
@@ -400,12 +400,13 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
                 }
             }
             return out;
-        }
+        },
+        { random: false }
     ));
 
     sheets.scope.addFunction(new jme.funcObj('slice', [TSpreadsheet, TString], TSpreadsheet, (wb,range) => {
         return wb.slice(range);
-    }));
+    }, {random: false}));
 
     sheets.scope.addFunction(new jme.funcObj('listval', [TSpreadsheet, TString], '?', null, {
         evaluate: function(args, scope) {
@@ -446,12 +447,13 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             } else {
                 return new TString((wb.get_cell_value(sheet,ref) || '')+'');
             }
-        }
+        },
+        random: false
     }));
 
     sheets.scope.addFunction(new jme.funcObj('encode_range',['integer','integer','integer','integer'], TString, (cs,rs,ce,re) => {
         return XLSX.utils.encode_range({s:{c:cs,r:rs}, e:{c:ce,r:re}});
-    }));
+    }, {random: false}));
 
     /** 
      * Create an ArrayBuffer containing the given string.
@@ -483,21 +485,21 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
         link.innerHTML = `Download <code>${filename}</code>`;
 
         return link;
-    }));
+    }, {random: false}));
 
     function add_style_function(name,args,fn) {
         args = args.slice();
         sheets.scope.addFunction(new jme.funcObj(name, args, TDict, function(...args) {
             var style = fn(...args);
             return jme.wrapValue({style: style});
-        },{unwrapValues: true}));
+        },{unwrapValues: true, random: false}));
 
         var dargs = args.slice();
         dargs.splice(0,0,'dict');
         sheets.scope.addFunction(new jme.funcObj(name, dargs, TDict, function(pd,...args) {
             var style = fn(...args);
             return jme.wrapValue(Numbas.util.deep_extend_object(pd,{style: style}));
-        },{unwrapValues: true}));
+        },{unwrapValues: true, random: false}));
     }
 
     function css_color_to_rgba(color) {
@@ -555,7 +557,7 @@ Numbas.addExtension('sheets', ['display', 'util', 'jme','sheet-element', 'xlsx']
             'number': 'n'
         };
         return jme.wrapValue({t: types_map[type] || type});
-    },{unwrapValues: true}));
+    },{unwrapValues: true, random: false}));
 
     if(Numbas.editor?.register_variable_template_type !== undefined) {
         class SpreadsheetVariableTemplateWidget extends HTMLElement {