fix: allow completers to trigger on newline characters (#5519)

* fix: allow completers to trigger on newline characters

ace.d.ts

@@ -622,6 +622,7 @@ export namespace Ace {
     documentToScreenColumn(row: number, docColumn: number): number;
     documentToScreenRow(docRow: number, docColumn: number): number;
     getScreenLength(): number;
+    getPrecedingCharacter(): string;
     toJSON(): Object;
     destroy(): void;
   }

src/autocomplete/util.js

@@ -1,5 +1,9 @@
 "use strict";
 
+/**
+ * @typedef {import("../editor").Editor} Editor
+ */
+
 exports.parForEach = function(array, fn, callback) {
     var completed = 0;
     var arLength = array.length;
@@ -59,14 +63,18 @@ exports.getCompletionPrefix = function (editor) {
     return prefix || this.retrievePrecedingIdentifier(line, pos.column);
 };
 
-exports.triggerAutocomplete = function (editor) {
-    var pos = editor.getCursorPosition();
-    var line = editor.session.getLine(pos.row);
-    var column = (pos.column === 0) ? 0 : pos.column - 1;
-    var previousChar = line[column];
-    return editor.completers.some((el) => {
-        if (el.triggerCharacters && Array.isArray(el.triggerCharacters)) {
-            return el.triggerCharacters.includes(previousChar);
+/**
+ * @param {Editor} editor
+ * @param {string} [previousChar] if not provided, it falls back to the preceding character in the editor
+ * @returns {boolean} whether autocomplete should be triggered
+ */
+exports.triggerAutocomplete = function (editor, previousChar) {
+    var previousChar = previousChar == null
+        ? editor.session.getPrecedingCharacter()
+        : previousChar;
+    return editor.completers.some((completer) => {
+        if (completer.triggerCharacters && Array.isArray(completer.triggerCharacters)) {
+            return completer.triggerCharacters.includes(previousChar);
         }
     });
 };

src/autocomplete_test.js

@@ -403,6 +403,7 @@ module.exports = {
     },
     "test: trigger autocomplete for specific characters": function (done) {
         var editor = initEditor("document");
+        var newLineCharacter = editor.session.doc.getNewLineCharacter();
 
         editor.completers = [
             {
@@ -418,18 +419,27 @@ module.exports = {
                     ];
                     callback(null, completions);
                 },
-                triggerCharacters: ["."]
+                triggerCharacters: [".", newLineCharacter]
             }
         ];
-        
+
         editor.moveCursorTo(0, 8);
-        sendKey(".");
+        user.type(".");
         var popup = editor.completer.popup;
         check(function () {
             assert.equal(popup.data.length, 2);
-            editor.onCommandKey(null, 0, 13);
+            user.type("Return");  // Accept suggestion
             assert.equal(editor.getValue(), "document.all");
-            done();
+
+            user.type(Array(4).fill("Backspace"));  // Delete '.all'
+            user.type("Return");  // Enter new line
+
+            check(function() {
+                assert.equal(popup.data.length, 2);
+                user.type("Return");  // Accept suggestion
+                assert.equal(editor.getValue(), `document${newLineCharacter}all`);
+                done();
+            });
         });
 
         function check(callback) {

src/edit_session.js

@@ -2366,6 +2366,20 @@ class EditSession {
         };
     }
 
+    /**
+     * @returns {string} the last character preceding the cursor in the editor
+     */
+    getPrecedingCharacter() {
+        var pos = this.selection.getCursor();
+
+        if (pos.column === 0) {
+            return pos.row === 0 ? "" : this.doc.getNewLineCharacter();
+        }
+
+        var currentLine = this.getLine(pos.row);
+        return currentLine[pos.column - 1];
+    }
+
     destroy() {
         if (!this.destroyed) {
             this.bgTokenizer.setDocument(null);

src/ext/language_tools.js

@@ -162,7 +162,8 @@ var showLiveAutocomplete = function(e) {
     var editor = e.editor;
     var prefix = util.getCompletionPrefix(editor);
     // Only autocomplete if there's a prefix that can be matched or previous char is trigger character 
-    var triggerAutocomplete = util.triggerAutocomplete(editor);
+    var previousChar = e.args;
+    var triggerAutocomplete = util.triggerAutocomplete(editor, previousChar);
     if (prefix && prefix.length >= editor.$liveAutocompletionThreshold || triggerAutocomplete) {
         var completer = Autocomplete.for(editor);
         // Set a flag for auto shown