Parse expressions with parentheses

Author: mudge

lib/expression_parser.rb

@@ -38,6 +38,15 @@ def parse
       identifier = tokenizer.identifier
 
       Variable.new(identifier)
+    when Tokenizer::SYMBOL
+      fail 'Not an opening parenthesis' unless tokenizer.symbol == '('
+      tokenizer.advance
+
+      node = parse
+
+      fail 'Not a closing parenthesis' unless tokenizer.token_type == Tokenizer::SYMBOL && tokenizer.symbol == ')'
+
+      node
     end
 
     return left_node unless tokenizer.has_more_tokens?

spec/unit/expression_parser_spec.rb

@@ -76,6 +76,26 @@
 push constant 2
 push constant 3
 add
+add
+    VM
+  end
+
+  it 'emits VM code for compound binary expressions with parentheses' do
+    tokenizer = Tokenizer.new('(1 + 2) + 3')
+    tokenizer.advance
+
+    symbol_table = SymbolTable.new
+
+    result = ExpressionParser.new(tokenizer).parse
+    output = StringIO.new
+    vm_writer = VMWriter.new(output)
+    result.emit(vm_writer, symbol_table)
+
+    expect(output.string).to eq(<<-VM)
+push constant 1
+push constant 2
+add
+push constant 3
 add
     VM
   end