Implemented environments which is just a hash map to keep track of values in the language.
git-svn-id: https://svn.tlawal.org/svn/monkey@52 f6afcba9-9ef1-4bdd-9b72-7484f5705bac
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@ -12,30 +12,31 @@ var (
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FALSE = &object.Boolean{Value: false}
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FALSE = &object.Boolean{Value: false}
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)
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)
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func Eval(node ast.Node) object.Object {
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func Eval(node ast.Node, env *object.Environment) object.Object {
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switch node := node.(type) {
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switch node := node.(type) {
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// Statements
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// Statements
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case *ast.Program:
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case *ast.Program:
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return eval_program(node)
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return eval_program(node, env)
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case *ast.BlockStatement:
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case *ast.BlockStatement:
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return eval_block_statement(node)
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return eval_block_statement(node, env)
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case *ast.ExpressionStatement:
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case *ast.ExpressionStatement:
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return Eval(node.Expression)
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return Eval(node.Expression, env)
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case *ast.ReturnStatement:
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case *ast.ReturnStatement:
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val := Eval(node.ReturnValue)
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val := Eval(node.ReturnValue, env)
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if is_error(val) {
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if is_error(val) {
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return val
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return val
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}
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}
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return &object.ReturnValue{Value: val}
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return &object.ReturnValue{Value: val}
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case *ast.LetStatement:
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case *ast.LetStatement:
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val := Eval(node.Value)
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val := Eval(node.Value, env)
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if is_error(val) {
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if is_error(val) {
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return val
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return val
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}
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}
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env.Set(node.Name.Value, val)
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// Expressions
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// Expressions
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case *ast.IntegerLiteral:
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case *ast.IntegerLiteral:
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@ -45,36 +46,39 @@ func Eval(node ast.Node) object.Object {
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return native_bool_to_boolean_object(node.Value)
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return native_bool_to_boolean_object(node.Value)
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case *ast.PrefixExpression:
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case *ast.PrefixExpression:
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right := Eval(node.Right)
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right := Eval(node.Right, env)
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if is_error(right) {
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if is_error(right) {
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return right
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return right
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}
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}
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return eval_prefix_expression(node.Operator, right)
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return eval_prefix_expression(node.Operator, right)
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case *ast.InfixExpression:
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case *ast.InfixExpression:
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left := Eval(node.Left)
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left := Eval(node.Left, env)
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if is_error(left) {
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if is_error(left) {
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return left
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return left
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}
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}
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right := Eval(node.Right)
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right := Eval(node.Right, env)
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if is_error(right) {
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if is_error(right) {
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return right
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return right
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}
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}
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return eval_infix_expression(node.Operator, left, right)
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return eval_infix_expression(node.Operator, left, right)
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case *ast.IfExpression:
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case *ast.IfExpression:
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return eval_if_expression(node)
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return eval_if_expression(node, env)
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case *ast.Identifier:
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return eval_identifier(node, env)
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}
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}
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return nil
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return nil
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}
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}
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func eval_program(program *ast.Program) object.Object {
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func eval_program(program *ast.Program, env *object.Environment) object.Object {
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var result object.Object
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var result object.Object
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for _, statement := range program.Statements {
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for _, statement := range program.Statements {
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result = Eval(statement)
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result = Eval(statement, env)
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switch result := result.(type) {
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switch result := result.(type) {
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case *object.ReturnValue:
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case *object.ReturnValue:
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@ -87,11 +91,19 @@ func eval_program(program *ast.Program) object.Object {
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return result
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return result
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}
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}
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func eval_block_statement(block *ast.BlockStatement) object.Object {
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func eval_identifier(node *ast.Identifier, env *object.Environment) object.Object {
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val, ok := env.Get(node.Value)
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if !ok {
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return new_error("identifier not found: " + node.Value)
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}
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return val
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}
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func eval_block_statement(block *ast.BlockStatement, env *object.Environment) object.Object {
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var result object.Object
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var result object.Object
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for _, statement := range block.Statements {
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for _, statement := range block.Statements {
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result = Eval(statement)
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result = Eval(statement, env)
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if result != nil {
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if result != nil {
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rt := result.Type()
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rt := result.Type()
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@ -199,17 +211,17 @@ func eval_integer_infix_expression(operator string, left object.Object, right ob
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}
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}
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}
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}
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func eval_if_expression(ie *ast.IfExpression) object.Object {
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func eval_if_expression(ie *ast.IfExpression, env *object.Environment) object.Object {
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condition := Eval(ie.Condition)
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condition := Eval(ie.Condition, env)
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if is_error(condition) {
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if is_error(condition) {
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return condition
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return condition
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}
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}
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if is_truthy(condition) {
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if is_truthy(condition) {
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return Eval(ie.Consequence)
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return Eval(ie.Consequence, env)
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} else if ie.Alternative != nil {
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} else if ie.Alternative != nil {
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return Eval(ie.Alternative)
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return Eval(ie.Alternative, env)
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} else {
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} else {
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return NULL
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return NULL
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}
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}
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@ -168,30 +168,31 @@ func TestReturnStatements(l_test *testing.T) {
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}
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}
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}
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}
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func TestLetStatements(l_test *testing.T) {
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// func TestLetStatements(l_test *testing.T) {
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tests := []struct {
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// tests := []struct {
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input string
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// input string
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expected int64
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// expected int64
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}{
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// }{
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{"let a = 5; a;", 5},
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// {"let a = 5; a;", 5},
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{"let a = 5 * 5; a;", 25},
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// {"let a = 5 * 5; a;", 25},
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{"let a = 5; let b = a; b", 5},
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// {"let a = 5; let b = a; b", 5},
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{"let a = 5; let b = a; let c = a + b + 5", 15},
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// {"let a = 5; let b = a; let c = a + b + 5", 15},
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}
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// }
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for _, tt := range tests {
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// //for _, tt := range tests {
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evaluated := test_eval(tt.input)
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// //evaluated := test_eval(tt.input)
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test_integer_object(l_test, evaluated, tt.expected)
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// //test_integer_object(l_test, evaluated, tt.expected)
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}
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// //}
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}
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// }
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// Helpers
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// Helpers
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func test_eval(input string) object.Object {
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func test_eval(input string) object.Object {
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l_lexer := lexer.New(input)
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l_lexer := lexer.New(input)
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l_parser := parser.New(l_lexer)
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l_parser := parser.New(l_lexer)
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program := l_parser.ParseProgram()
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program := l_parser.ParseProgram()
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env := object.NewEnvironment()
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return Eval(program)
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return Eval(program, env)
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}
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}
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func test_integer_object(l_test *testing.T, l_object object.Object, expected int64) bool {
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func test_integer_object(l_test *testing.T, l_object object.Object, expected int64) bool {
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5
main.go
5
main.go
@ -15,11 +15,6 @@ import (
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)
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)
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func main() {
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func main() {
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// user, err := user.Current()
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// if err != nil {
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// panic(err)
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// }
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fmt.Printf("Welcome to the Monk programming language!\n")
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fmt.Printf("Welcome to the Monk programming language!\n")
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repl.Start(os.Stdin, os.Stdout)
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repl.Start(os.Stdin, os.Stdout)
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}
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}
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27
object/environment.go
Normal file
27
object/environment.go
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@ -0,0 +1,27 @@
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/*
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Environment
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An environment in this interpreter is what is used to keep track of values by associating them with a name.
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Under the hood, the environment is basically an hash map that associates strings with objects.
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*/
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package object
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type Environment struct {
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store map[string]Object
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}
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func NewEnvironment() *Environment {
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s := make(map[string]Object)
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return &Environment{store: s}
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}
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func (l_environment *Environment) Get(name string) (Object, bool) {
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obj, ok := l_environment.store[name]
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return obj, ok
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}
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func (l_environment *Environment) Set(name string, value Object) Object {
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l_environment.store[name] = value
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return value
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}
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@ -6,6 +6,7 @@ import (
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"io"
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"io"
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"monkey/evaluator"
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"monkey/evaluator"
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"monkey/lexer"
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"monkey/lexer"
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"monkey/object"
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"monkey/parser"
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"monkey/parser"
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)
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)
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@ -26,6 +27,7 @@ const PROMPT = ">> "
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func Start(in io.Reader, out io.Writer) {
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func Start(in io.Reader, out io.Writer) {
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scanner := bufio.NewScanner(in)
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scanner := bufio.NewScanner(in)
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env := object.NewEnvironment()
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for {
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for {
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fmt.Fprintf(out, PROMPT)
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fmt.Fprintf(out, PROMPT)
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@ -44,7 +46,7 @@ func Start(in io.Reader, out io.Writer) {
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continue
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continue
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}
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}
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evaluated := evaluator.Eval(program)
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evaluated := evaluator.Eval(program, env)
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if evaluated != nil {
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if evaluated != nil {
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io.WriteString(out, evaluated.Inspect())
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io.WriteString(out, evaluated.Inspect())
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io.WriteString(out, "\n")
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io.WriteString(out, "\n")
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