Merge pull request #1573 from takluyver/fix-backspace-in-output

Process backspace characters in output

notebook/static/base/js/utils.js

@@ -453,6 +453,22 @@ define([
         return txt;
     }
 
+    // Remove characters that are overridden by backspace characters
+    function fixBackspace(txt) {
+        var tmp = txt;
+        do {
+            txt = tmp;
+            // Cancel out anything-but-newline followed by backspace
+            tmp = txt.replace(/[^\n]\x08/gm, '');
+        } while (tmp.length < txt.length);
+        return txt;
+    }
+
+    // Remove characters overridden by backspace and carriage return
+    function fixOverwrittenChars(txt) {
+        return fixCarriageReturn(fixBackspace(txt));
+    }
+
     // Locate any URLs and convert them to a anchor tag
     function autoLinkUrls(txt) {
         return txt.replace(/(^|\s)(https?|ftp)(:[^'"<>\s]+)/gi,
@@ -972,6 +988,8 @@ define([
         uuid : uuid,
         fixConsole : fixConsole,
         fixCarriageReturn : fixCarriageReturn,
+        fixBackspace : fixBackspace,
+        fixOverwrittenChars: fixOverwrittenChars,
         autoLinkUrls : autoLinkUrls,
         points_to_pixels : points_to_pixels,
         get_body_data : get_body_data,

notebook/static/notebook/js/outputarea.js

@@ -504,7 +504,7 @@ define([
                     // latest output was in the same stream,
                     // so append to it instead of making a new output.
                     // escape ANSI & HTML specials:
-                    last.text = utils.fixCarriageReturn(last.text + json.text);
+                    last.text = utils.fixOverwrittenChars(last.text + json.text);
                     var pre = this.element.find('div.'+subclass).last().find('pre');
                     var html = utils.fixConsole(last.text);
                     html = utils.autoLinkUrls(html);
@@ -659,7 +659,7 @@ define([
     var append_text = function (data, md, element) {
         var type = 'text/plain';
         var toinsert = this.create_output_subarea(md, "output_text", type);
-        data = utils.fixCarriageReturn(data);
+        data = utils.fixOverwrittenChars(data);
         // escape ANSI & HTML specials in plaintext:
         data = utils.fixConsole(data);
         data = utils.autoLinkUrls(data);

notebook/static/notebook/js/pager.js

@@ -157,7 +157,7 @@ define([
          * The only user content injected with this HTML call is escaped by
          * the fixConsole() method.
          */
-        this.pager_element.find(".container").append($('<pre/>').html(utils.fixConsole(utils.fixCarriageReturn(text))));
+        this.pager_element.find(".container").append($('<pre/>').html(utils.fixConsole(utils.fixOverwrittenChars(text))));
     };
 
     Pager.prototype.append = function (htm) {

notebook/tests/base/utils.js

@@ -1,4 +1,5 @@
 casper.notebook_test(function () {
+    // Test fixConsole
     // Note, \u001b is the unicode notation of octal \033 which is not officially in js
     var input = [
         "\u001b[0m[\u001b[0minfo\u001b[0m] \u001b[0mtext\u001b[0m",
@@ -29,7 +30,25 @@ casper.notebook_test(function () {
     }, input);
 
     this.test.assertEquals(result, output, "IPython.utils.fixConsole() handles [0m correctly");
-    
+
+    // Test fixOverwrittenChars
+    var overwriting_test_cases = [
+        {input: "ABC\rDEF", result: "DEF"},
+        {input: "ABC\r\nDEF", result: "ABC\nDEF"},
+        {input: "123\b456", result: "12456"},
+        {input: "123\n\b456", result: "123\n\b456"},
+        {input: "\b456", result: "\b456"}
+    ];
+
+    var that = this;
+    overwriting_test_cases.forEach(function(testcase){
+        var result = that.evaluate(function (input) {
+            return IPython.utils.fixOverwrittenChars(input);
+        }, testcase.input);
+        that.test.assertEquals(result, testcase.result, "Overwriting characters processed");
+    });
+
+    // Test load_extensions
     this.thenEvaluate(function() {
         define('nbextensions/a', [], function() { window.a = true; });
         define('nbextensions/c', [], function() { window.c = true; });