Changes:

- Boolean expression can now be parsed. 
- Formatting

git-svn-id: https://svn.tlawal.org/svn/monkey@32 f6afcba9-9ef1-4bdd-9b72-7484f5705bac

ast/ast.go

@@ -71,6 +71,11 @@ type InfixExpression struct {
 	Right    Expression
 }
 
+type Boolean struct {
+	Token token.Token
+	Value bool
+}
+
 // Let Statements
 func (ls *LetStatement) statement_node() {}
 
@@ -182,3 +187,8 @@ func (ie *InfixExpression) String() string {
 
 	return out.String()
 }
+
+// Booleans
+func (b *Boolean) expression_node()     {}
+func (b *Boolean) TokenLiteral() string { return b.Token.Literal }
+func (b *Boolean) String() string       { return b.Token.Literal }

parser/parser.go

@@ -96,6 +96,10 @@ func New(l_lexer *lexer.Lexer) *Parser {
 	l_parser.register_infix(token.LT, l_parser.parse_infix_expression)
 	l_parser.register_infix(token.GT, l_parser.parse_infix_expression)
 
+	// Boolean
+	l_parser.register_prefix(token.TRUE, l_parser.parse_boolean)
+	l_parser.register_prefix(token.FALSE, l_parser.parse_boolean)
+
 	return l_parser
 }
 
@@ -266,3 +270,12 @@ func (l_parser *Parser) no_prefix_parse_function_error(l_token_type token.TokenT
 	message := fmt.Sprintf("no prefix parse function for %s, found", l_token_type)
 	l_parser.errors = append(l_parser.errors, message)
 }
+
+
+func (l_parser *Parser) parse_boolean() ast.Expression {
+	defer untrace(trace("parse_boolean"))
+	return &ast.Boolean{
+		Token: l_parser.current_token,
+		Value: l_parser.current_token_is(token.TRUE),
+	}
+}

parser/parser_test.go

@@ -210,7 +210,7 @@ func TestParsingInfixExpressions(l_test *testing.T) {
 			l_test.Fatalf("program.Statements[0] is not ast.ExpressionStatement, got=%T", program.Statements[0])
 		}
 
-		if !testInfixExpression(l_test, statement.Expression, tt.left_value, tt.operator, tt.right_value){
+		if !testInfixExpression(l_test, statement.Expression, tt.left_value, tt.operator, tt.right_value) {
 			return
 		}
 	}
@@ -283,6 +283,41 @@ func TestOperatorPrecedenceParsing(l_test *testing.T) {
 	}
 }
 
+func TestBooleanExpression(l_test *testing.T) {
+	tests := []struct {
+		input            string
+		expected_boolean bool
+	}{
+		{"true;", true},
+		{"false;", false},
+	}
+
+	for _, tt := range tests {
+		l_lexer := lexer.New(tt.input)
+		l_parser := New(l_lexer)
+
+		program := l_parser.ParseProgram()
+		check_parser_errors(l_test, l_parser)
+
+		if len(program.Statements) != 1 {
+			l_test.Fatalf("program.Statements does not have enough statements, got=%d", len(program.Statements))
+		}
+
+		statement, ok := program.Statements[0].(*ast.ExpressionStatement)
+		if !ok {
+			l_test.Fatalf("program.Statements[0] is not ast.ExpressionStatement, got=%T", program.Statements[0])
+		}
+
+		boolean, ok := statement.Expression.(*ast.Boolean)
+		if !ok {
+			l_test.Fatalf("exp not *ast.Boolean, got=%T", statement.Expression)
+		}
+		if boolean.Value != tt.expected_boolean {
+			l_test.Errorf("boolean.Value not %t, got=%t", tt.expected_boolean, boolean.Value)
+		}
+	}
+}
+
 // Helpers
 
 func check_parser_errors(l_test *testing.T, l_parser *Parser) {
@@ -377,14 +412,14 @@ func testLiteralExpression(l_test *testing.T, exp ast.Expression, expected inter
 	return false
 }
 
-func testInfixExpression(l_test *testing.T, exp ast.Expression, left interface{}, operator string, right interface{}) bool{
+func testInfixExpression(l_test *testing.T, exp ast.Expression, left interface{}, operator string, right interface{}) bool {
 	operator_expression, ok := exp.(*ast.InfixExpression)
 	if !ok {
 		l_test.Errorf("exp is not ast.InfixExpression, got=%T(%s)", exp, exp)
 		return false
 	}
 
-	if !testLiteralExpression(l_test, operator_expression.Left, left){
+	if !testLiteralExpression(l_test, operator_expression.Left, left) {
 		return false
 	}
 
@@ -393,7 +428,7 @@ func testInfixExpression(l_test *testing.T, exp ast.Expression, left interface{}
 		return false
 	}
 
-	if !testLiteralExpression(l_test, operator_expression.Right, right){
+	if !testLiteralExpression(l_test, operator_expression.Right, right) {
 		return false
 	}
 	return true