Bitshift

code/code.go

@@ -33,6 +33,8 @@ const (
 	OpBitwiseXOR
 	OpBitwiseAND
 	OpBitwiseNOT
+	OpLeftShift
+	OpRightShift
 	OpTrue
 	OpFalse
 	OpEqual
@@ -84,6 +86,8 @@ var definitions = map[Opcode]*Definition{
 	OpBitwiseXOR:       {"OpBitwiseXOR", []int{}},
 	OpBitwiseAND:       {"OpBitwiseAND", []int{}},
 	OpBitwiseNOT:       {"OpBitwiseNOT", []int{}},
+	OpLeftShift:        {"OpLeftShift", []int{}},
+	OpRightShift:       {"OpRightShift", []int{}},
 	OpTrue:             {"OpTrue", []int{}},
 	OpFalse:            {"OpFalse", []int{}},
 	OpEqual:            {"OpEqual", []int{}},

compiler/compiler.go

@@ -148,6 +148,10 @@ func (c *Compiler) Compile(node ast.Node) error {
 			c.emit(code.OpBitwiseXOR)
 		case "&":
 			c.emit(code.OpBitwiseAND)
+		case "<<":
+			c.emit(code.OpLeftShift)
+		case ">>":
+			c.emit(code.OpRightShift)
 		case "||":
 			c.emit(code.OpOr)
 		case "&&":

compiler/compiler_test.go

@@ -87,6 +87,26 @@ func TestIntegerArithmetic(t *testing.T) {
 				code.Make(code.OpPop),
 			},
 		},
+		{
+			input:             "1 << 2",
+			expectedConstants: []interface{}{1, 2},
+			expectedInstructions: []code.Instructions{
+				code.Make(code.OpConstant, 0),
+				code.Make(code.OpConstant, 1),
+				code.Make(code.OpLeftShift),
+				code.Make(code.OpPop),
+			},
+		},
+		{
+			input:             "4 >> 2",
+			expectedConstants: []interface{}{4, 2},
+			expectedInstructions: []code.Instructions{
+				code.Make(code.OpConstant, 0),
+				code.Make(code.OpConstant, 1),
+				code.Make(code.OpRightShift),
+				code.Make(code.OpPop),
+			},
+		},
 		{
 			input:             "-1",
 			expectedConstants: []interface{}{1},

evaluator/evaluator.go

@@ -434,6 +434,10 @@ func evalIntegerInfixExpression(operator string, left, right object.Object) obje
 		return &object.Integer{Value: leftVal ^ rightVal}
 	case "&":
 		return &object.Integer{Value: leftVal & rightVal}
+	case "<<":
+		return &object.Integer{Value: leftVal << uint64(rightVal)}
+	case ">>":
+		return &object.Integer{Value: leftVal >> uint64(rightVal)}
 	case "<":
 		return nativeBoolToBooleanObject(leftVal < rightVal)
 	case "<=":

evaluator/evaluator_test.go

@@ -38,6 +38,8 @@ func TestEvalExpressions(t *testing.T) {
 		{"3 & 6", 2},
 		{`" " * 4`, "    "},
 		{`4 * " "`, "    "},
+		{"1 << 2", 4},
+		{"4 >> 2", 1},
 	}
 
 	for _, tt := range tests {

lexer/lexer.go

@@ -116,6 +116,11 @@ func (l *Lexer) NextToken() token.Token {
 			l.readChar()
 			tok = newToken(token.LTE, l.ch)
 			tok.Literal = "<="
+		} else if l.peekChar() == '<' {
+			ch := l.ch
+			l.readChar()
+			literal := string(ch) + string(l.ch)
+			tok = token.Token{Type: token.LEFT_SHIFT, Literal: literal}
 		} else {
 			tok = newToken(token.LT, l.ch)
 		}
@@ -124,6 +129,11 @@ func (l *Lexer) NextToken() token.Token {
 			l.readChar()
 			tok = newToken(token.GTE, l.ch)
 			tok.Literal = ">="
+		} else if l.peekChar() == '>' {
+			ch := l.ch
+			l.readChar()
+			literal := string(ch) + string(l.ch)
+			tok = token.Token{Type: token.RIGHT_SHIFT, Literal: literal}
 		} else {
 			tok = newToken(token.GT, l.ch)
 		}

lexer/lexer_test.go

@@ -35,6 +35,7 @@ func TestNextToken(t *testing.T) {
 				d.foo
 				&|^~
 				!&&||
+				<<>>
 			`
 
 	tests := []struct {
@@ -146,6 +147,8 @@ func TestNextToken(t *testing.T) {
 		{token.NOT, "!"},
 		{token.AND, "&&"},
 		{token.OR, "||"},
+		{token.LEFT_SHIFT, "<<"},
+		{token.RIGHT_SHIFT, ">>"},
 		{token.EOF, ""},
 	}
 

parser/parser.go

@@ -14,17 +14,18 @@ const (
 	OR
 	AND
 	NOT
-	ASSIGN      // := or =
-	EQUALS      // ==
-	LESSGREATER // > or <
-	BITWISE_OR  // |
-	BITWISE_XOR // ^
-	BITWISE_AND // &
-	SUM         // + or -
-	PRODUCT     // * or / or %
-	PREFIX      // -X or !X
-	CALL        // myFunction(X)
-	INDEX       // array[index]
+	ASSIGN        // := or =
+	EQUALS        // ==
+	LESSGREATER   // > or <
+	BITWISE_OR    // |
+	BITWISE_XOR   // ^
+	BITWISE_AND   // &
+	BITWISE_SHIFT // << or >>
+	SUM           // + or -
+	PRODUCT       // * or / or %
+	PREFIX        // -X or !X
+	CALL          // myFunction(X)
+	INDEX         // array[index]
 )
 
 var precedences = map[token.TokenType]int{
@@ -42,6 +43,8 @@ var precedences = map[token.TokenType]int{
 	token.BITWISE_OR:  BITWISE_OR,
 	token.BITWISE_XOR: BITWISE_XOR,
 	token.BITWISE_AND: BITWISE_AND,
+	token.LEFT_SHIFT:  BITWISE_SHIFT,
+	token.RIGHT_SHIFT: BITWISE_SHIFT,
 	token.PLUS:        SUM,
 	token.MINUS:       SUM,
 	token.DIVIDE:      PRODUCT,
@@ -112,6 +115,9 @@ func New(l *lexer.Lexer) *Parser {
 	p.registerInfix(token.BITWISE_XOR, p.parseInfixExpression)
 	p.registerInfix(token.BITWISE_AND, p.parseInfixExpression)
 
+	p.registerInfix(token.LEFT_SHIFT, p.parseInfixExpression)
+	p.registerInfix(token.RIGHT_SHIFT, p.parseInfixExpression)
+
 	p.registerPrefix(token.NOT, p.parsePrefixExpression)
 	p.registerInfix(token.OR, p.parseInfixExpression)
 	p.registerInfix(token.AND, p.parseInfixExpression)

token/token.go

@@ -38,6 +38,10 @@ const (
 	BITWISE_XOR = "^"
 	// BITWISE_NOT NOT
 	BITWISE_NOT = "~"
+	// LeftShift
+	LEFT_SHIFT = "<<"
+	// RightShift
+	RIGHT_SHIFT = ">>"
 
 	//
 	// Comparision operators

vm/vm.go

@@ -114,7 +114,8 @@ func (vm *VM) Run() error {
 			}
 
 		case code.OpAdd, code.OpSub, code.OpMul, code.OpDiv, code.OpMod, code.OpOr,
-			code.OpAnd, code.OpBitwiseOR, code.OpBitwiseXOR, code.OpBitwiseAND:
+			code.OpAnd, code.OpBitwiseOR, code.OpBitwiseXOR, code.OpBitwiseAND,
+			code.OpLeftShift, code.OpRightShift:
 			err := vm.executeBinaryOperation(op)
 			if err != nil {
 				return err
@@ -631,6 +632,10 @@ func (vm *VM) executeBinaryIntegerOperation(op code.Opcode, left, right object.O
 		result = leftValue ^ rightValue
 	case code.OpBitwiseAND:
 		result = leftValue & rightValue
+	case code.OpLeftShift:
+		result = leftValue << uint64(rightValue)
+	case code.OpRightShift:
+		result = leftValue >> uint64(rightValue)
 
 	default:
 		return fmt.Errorf("unknown integer operator: %d", op)

vm/vm_test.go

@@ -230,6 +230,8 @@ func TestIntegerArithmetic(t *testing.T) {
 		{"1 | 2", 3},
 		{"2 ^ 4", 6},
 		{"3 & 6", 2},
+		{"1 << 2", 4},
+		{"4 >> 2", 1},
 	}
 
 	runVmTests(t, tests)