Add missing array syntax

corpus/expressions.txt

@@ -149,6 +149,7 @@ echo ${a[@]}
 echo ${#b[@]}
 
 a[$i]=50
+a+=(foo "bar" $(baz))
 
 ---
 
@@ -159,4 +160,10 @@ a[$i]=50
   (command (command_name (word)) (expansion (variable_name)))
   (environment_variable_assignment
     (subscript (variable_name) (simple_expansion (variable_name)))
-    (word)))
+    (word))
+  (environment_variable_assignment
+    (variable_name)
+    (array
+      (word)
+      (string)
+      (command_substitution (command (command_name (word)))))))

grammar.js

@@ -182,7 +182,10 @@ module.exports = grammar({
         $.variable_name,
         $.subscript
       ),
+      choice(
         '=',
+        '+='
+      ),
       choice(
         $._expression,
         $.array,
@@ -271,7 +274,7 @@ module.exports = grammar({
 
     array: $ => seq(
       '(',
-      repeat($.word),
+      repeat($._expression),
       ')'
     ),
 

src/grammar.json

@@ -601,10 +601,19 @@
             }
           ]
         },
+        {
+          "type": "CHOICE",
+          "members": [
             {
               "type": "STRING",
               "value": "="
             },
+            {
+              "type": "STRING",
+              "value": "+="
+            }
+          ]
+        },
         {
           "type": "CHOICE",
           "members": [
@@ -939,7 +948,7 @@
           "type": "REPEAT",
           "content": {
             "type": "SYMBOL",
-            "name": "word"
+            "name": "_expression"
           }
         },
         {

src/scanner.cc

@@ -170,14 +170,27 @@ struct Scanner {
         }
       }
 
-      if (is_number && valid_symbols[FILE_DESCRIPTOR] && (lexer->lookahead == '>' || lexer->lookahead == '<')) {
+      if (is_number &&
+          valid_symbols[FILE_DESCRIPTOR] &&
+          (lexer->lookahead == '>' || lexer->lookahead == '<')) {
         lexer->result_symbol = FILE_DESCRIPTOR;
         return true;
       }
 
-      if (valid_symbols[VARIABLE_NAME] && (lexer->lookahead == '=' || lexer->lookahead == '[')) {
+      if (valid_symbols[VARIABLE_NAME]) {
+        if (lexer->lookahead == '+') {
+          lexer->mark_end(lexer);
+          advance(lexer);
+          if (lexer->lookahead == '=') {
             lexer->result_symbol = VARIABLE_NAME;
             return true;
+          } else {
+            return false;
+          }
+        } else if (lexer->lookahead == '=' || lexer->lookahead == '[') {
+          lexer->result_symbol = VARIABLE_NAME;
+          return true;
+        }
       }
 
       return false;