feat: Special trigger characters to start autocomplete (#5147)

* implement special trigger characters to forcely start autocomplete

Author: mkslanc

ace.d.ts

@@ -1008,6 +1008,7 @@ export namespace Ace {
       callback: CompleterCallback): void;
     getDocTooltip?(item: Completion): undefined | string | Completion;
     id?: string;
+    triggerCharacters?: string[]
   }
 
   export class AceInline {

src/autocomplete/util.js

@@ -54,3 +54,15 @@ exports.getCompletionPrefix = function (editor) {
     }.bind(this));
     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);
+        }
+    });
+};

src/autocomplete_test.js

@@ -249,6 +249,45 @@ module.exports = {
             done();
         }, 10);
     },
+    "test: trigger autocomplete for specific characters": function (done) {
+        var editor = initEditor("document");
+
+        editor.completers = [
+            {
+                getCompletions: function (editor, session, pos, prefix, callback) {
+                    var completions = [
+                        {
+                            caption: "append",
+                            value: "append"
+                        }, {
+                            caption: "all",
+                            value: "all"
+                        }
+                    ];
+                    callback(null, completions);
+                },
+                triggerCharacters: ["."]
+            }
+        ];
+        
+        editor.moveCursorTo(0, 8);
+        sendKey(".");
+        var popup = editor.completer.popup;
+        check(function () {
+            assert.equal(popup.data.length, 2);
+            editor.onCommandKey(null, 0, 13);
+            assert.equal(editor.getValue(), "document.all");
+            done();
+        });
+
+        function check(callback) {
+            popup = editor.completer.popup;
+            popup.renderer.on("afterRender", function wait() {
+                popup.renderer.off("afterRender", wait);
+                callback();
+            });
+        }
+    },
     "test: empty message if no suggestions available": function(done) {
         var editor = initEditor("");
         var emptyMessageText = "No suggestions.";

src/ext/language_tools.js

@@ -143,8 +143,9 @@ var doLiveAutocomplete = function(e) {
     }
     else if (e.command.name === "insertstring") {
         var prefix = util.getCompletionPrefix(editor);
-        // Only autocomplete if there's a prefix that can be matched
-        if (prefix && !hasCompleter) {
+        // Only autocomplete if there's a prefix that can be matched or previous char is trigger character 
+        var triggerAutocomplete = util.triggerAutocomplete(editor);
+        if ((prefix || triggerAutocomplete) && !hasCompleter) {
             var completer = Autocomplete.for(editor);
             // Set a flag for auto shown
             completer.autoShown = true;