Add snippet support for LaTeX and custom macro completer.

The snippets are copied from the snippets for TeX.
The current keywordCompleter for LaTeX is unused because the highlight rules
do not give a list of keywords, but color every LaTeX macro, so the completer
cannot use the rules to provide completion. This macro completer is inspired
from the text completer, but complete only macros (the current text completer
do not consider \ to be a part of a word).

Author: JeanCASPAR

src/mode/latex.js

@@ -1,5 +1,6 @@
 "use strict";
 
+const { triggerAutocomplete } = require("../autocomplete/util");
 var oop = require("../lib/oop");
 var TextMode = require("./text").Mode;
 var LatexHighlightRules = require("./latex_highlight_rules").LatexHighlightRules;
@@ -19,6 +20,8 @@ oop.inherits(Mode, TextMode);
     this.lineCommentStart = "%";
 
     this.$id = "ace/mode/latex";
+
+    this.snippetFileId = "ace/snippets/latex";
 
     this.getMatching = function(session, row, column) {
         if (row == undefined)
@@ -35,6 +38,49 @@ oop.inherits(Mode, TextMode);
             return this.foldingRules.latexBlock(session, row, column, true);
         }
     };
+
+    function wordDistances(doc, pos) {
+        var macroName = /\\[a-zA-Z0-9]+/g;
+
+        var textBefore = doc.getTextRange(Range.fromPoints({
+            row: 0,
+            column: 0
+        }, pos));
+        var prefixPos = [...textBefore.matchAll(macroName)].length - 1;
+
+        var words = [...doc.getValue().matchAll(macroName)];
+        var wordScores = Object.create(null);
+
+        var currentWord = words[prefixPos];
+
+        words.forEach(function (word, idx) {
+            if (!word || word === currentWord) return;
+
+            var distance = Math.abs(prefixPos - idx);
+            var score = words.length - distance;
+            wordScores[word] = Math.max(score, wordScores[word] ?? 0);
+        });
+        return wordScores;
+    }
+
+    this.completer = {
+        getCompletions: (editor, session, pos, prefix, callback) => {
+            var wordScores = wordDistances(session, pos);
+            var wordList = Object.keys(wordScores);
+            callback(null, wordList.map(function (word) {
+                return {
+                    caption: word,
+                    value: word,
+                    score: wordScores[word],
+                    meta: "macro",
+                    completer: this,
+                    completerId: this.id,
+                };
+            }, this));
+        },
+        triggerCharacters: ["\\"],
+        id: "latexMacroCompleter",
+    };
 }).call(Mode.prototype);
 
 exports.Mode = Mode;

src/snippets/latex.js

@@ -0,0 +1,4 @@
+"use strict";
+
+exports.snippetText = require("./latex.snippets");
+exports.scope = "latex";

src/snippets/latex.snippets.js

@@ -0,0 +1 @@
+module.exports = require("./tex.snippets");