replace tabs with spaces for indentation

Author: Dou Du

package.json

@@ -1,6 +1,6 @@
 {
   "name": "widget_code_input",
-  "version": "3.6.1",
+  "version": "3.6.2",
   "description": "A widget to allow input of a python function, with syntax highlighting.",
   "keywords": [
     "jupyter",

pyproject.toml

@@ -34,7 +34,7 @@ classifiers = [
 dependencies = [
     "ipywidgets>=7.0.0",
 ]
-version = "3.6.1"
+version = "3.6.2"
 
 [project.optional-dependencies]
 docs = [
@@ -104,7 +104,7 @@ file = [
 ]
 
 [tool.tbump.version]
-current = "3.6.1"
+current = "3.6.2"
 regex = "(?P<major>\\d+)\\.(?P<minor>\\d+)\\.(?P<patch>\\d+)((?P<channel>a|b|rc|.dev)(?P<release>\\d+))?"
 
 [tool.tbump.git]

src/widget.ts

@@ -159,10 +159,49 @@ export class WidgetCodeView extends DOMWidgetView {
           readOnly: false,
           indentUnit: 4,
           indentWithTabs: false,
+          smartIndent: true,
           gutters: ['CodeMirror-linenumbers', 'forced-indent'],
         }
       );
 
+      this.myBodyCodeMirror.setOption("extraKeys", {
+        Tab: (cm: any) => {
+          if (cm.getMode().name === 'null') {
+            cm.execCommand('insertTab');
+          } else {
+            if (cm.somethingSelected()) {
+              cm.execCommand('indentMore');
+            } else {
+              cm.execCommand('insertSoftTab');
+            }
+          }
+        },
+        Backspace: (cm: any) => {
+          if (!cm.somethingSelected()) {
+            let cursorsPos = cm.listSelections().map((selection: any) => selection.anchor);
+            let indentUnit = cm.options.indentUnit;
+            let shouldDelChar = false;
+            for (let cursorIndex in cursorsPos) {
+              let cursorPos = cursorsPos[cursorIndex];
+              let indentation = cm.getStateAfter(cursorPos.line).indented;
+              if (!(indentation !== 0 &&
+                cursorPos.ch <= indentation &&
+                cursorPos.ch % indentUnit === 0)) {
+                shouldDelChar = true;
+              }
+            }
+            if (!shouldDelChar) {
+              cm.execCommand('indentLess');
+            } else {
+              cm.execCommand('delCharBefore');
+            }
+          } else {
+            cm.execCommand('delCharBefore');
+          }
+        },
+        'Shift-Tab': (cm: any) => cm.execCommand('indentLess')
+      })
+
       // Add CSS
       this.myBodyCodeMirror.setOption('theme', this.theme);
       this.myBodyCodeMirror.display.wrapper.classList.add(

widget_code_input/_version.py

@@ -4,5 +4,5 @@
 # Copyright (c) Dou Du and Giovanni Pizzi.
 # Distributed under the terms of the Modified BSD License.
 
-version_info = (3, 5, 5)
+version_info = (3, 6, 2)
 __version__ = ".".join(map(str, version_info))