From 4ff70466bf0fea1fa91c130e3864868459bfbe9e Mon Sep 17 00:00:00 2001
From: Timotej Lazar <timotej.lazar@fri.uni-lj.si>
Date: Wed, 18 Nov 2015 18:36:58 +0100
Subject: Editor: decrease indent with shift-tab / backspace

Backspace is "smart" - behaves normally except on the first
non-whitespace character in the current line.
---
 js/codeq/editor.js | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/js/codeq/editor.js b/js/codeq/editor.js
index d0b365e..27296d5 100644
--- a/js/codeq/editor.js
+++ b/js/codeq/editor.js
@@ -9,10 +9,26 @@ codeq.makeEditor = function (elt, options) {
             matchBrackets: true,
             extraKeys: {
                 // replace tabs with spaces
-                Tab: function (cm) {
+                'Tab': function (cm) {
                     var spaces = Array(cm.getOption("indentUnit") + 1).join(" ");
                     cm.replaceSelection(spaces);
-                }
+                },
+                // decrease indent if on first non-whitespace character in line
+                'Backspace': function (cm) {
+                    var doc = cm.getDoc(),
+                        cursor = doc.getCursor(),
+                        line = doc.getLine(cursor.line),
+                        col = cursor.ch;
+                    if (col > 0 && !/\S/.test(line.substring(0, col)) &&
+                            (col === line.length || /\S/.test(line[col]))) {
+                        // cursor on the first non-whitespace character in line
+                        cm.execCommand('indentLess');
+                    }
+                    else {
+                        cm.execCommand('delCharBefore');
+                    }
+                },
+                'Shift-Tab': 'indentLess',
             }
         }, options),
         editor = CodeMirror(elt, allOptions);
-- 
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