fix: improve prefixing for inline preview

src/autocomplete.js

@@ -197,7 +197,14 @@ class Autocomplete {
     }
 
     $updateGhostText(completion) {
-        var prefix = util.getCompletionPrefix(this.editor);
+        // Ghost text can include characters normally not part of the prefix (e.g. whitespace).
+        // When typing ahead with ghost text however, we want to simply prefix with respect to the
+        // base of the completion.
+        var row = this.base.row;
+        var column = this.base.column;
+        var cursorColumn = this.editor.getCursorPosition().column;
+        var prefix = this.editor.session.getLine(row).slice(column, cursorColumn);
+
         if (!this.inlineRenderer.show(this.editor, completion, prefix)) {
             this.inlineRenderer.hide();
         } else {

src/autocomplete_test.js

@@ -5,7 +5,7 @@
 "use strict";
 
 var sendKey = require("./test/user").type;
 var {buildDom} = require("./lib/dom");
 var ace = require("./ace");
 var assert = require("./test/assertions");
 var user = require("./test/user");
@@ -1383,6 +1383,51 @@
                 assert.strictEqual(inline.isOpen(), true);
                 assert.strictEqual(editor.renderer.$ghostText.text, "n\nthat does something\ncool");
 
+                done();
+            }, 100);
+        }, 100);
+    },
+    "test: should keep showing ghost text when typing ahead with whitespace": function(done) {
+        var editor = initEditor("");
+
+        editor.completers = [
+            {
+                getCompletions: function (editor, session, pos, prefix, callback) {
+                    var completions = [
+                        {
+                            value: "function that does something cool"
+                        }
+                    ];
+                    callback(null, completions);
+                }
+            }
+        ];
+
+        var completer = Autocomplete.for(editor);
+        completer.inlineEnabled = true;
+
+        user.type("f");
+        var inline = completer.inlineRenderer;
+
+        // Popup should be open, with inline text renderered.
+        assert.equal(completer.popup.isOpen, true);  
+        assert.equal(completer.popup.getRow(), 0);
+        assert.strictEqual(inline.isOpen(), true);
+        assert.strictEqual(editor.renderer.$ghostText.text, "unction that does something cool");
+
+        // when you keep typing, the ghost text should update accordingly
+        user.type("unction th");
+
+        setTimeout(() => {
+            assert.strictEqual(inline.isOpen(), true);
+            assert.strictEqual(editor.renderer.$ghostText.text, "at does something cool");
+
+            user.type("at do");
+
+            setTimeout(() => {
+                assert.strictEqual(inline.isOpen(), true);
+                assert.strictEqual(editor.renderer.$ghostText.text, "es something cool");
+
                 done();
             }, 100);
         }, 100);