- Some minor formatting.
- Parser can now handle return statements. git-svn-id: https://svn.tlawal.org/svn/monkey@21 f6afcba9-9ef1-4bdd-9b72-7484f5705bac
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58f6bab88f
commit
fdf6a8a552
13
ast/ast.go
13
ast/ast.go
@ -26,11 +26,16 @@ type Identifier struct {
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}
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}
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type LetStatement struct {
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type LetStatement struct {
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Token token.Token // the token.LET token
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Token token.Token // token.LET token
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Name *Identifier
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Name *Identifier
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Value Expression
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Value Expression
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}
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}
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type ReturnStatement struct {
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Token token.Token // token.RETURN token
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ReturnValue Expression
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}
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func (ls *LetStatement) statement_node() {}
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func (ls *LetStatement) statement_node() {}
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func (ls *LetStatement) TokenLiteral() string {
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func (ls *LetStatement) TokenLiteral() string {
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@ -50,3 +55,9 @@ func (p *Program) TokenLiteral() string {
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return ""
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return ""
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}
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}
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}
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}
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func (rs *ReturnStatement) statement_node() {}
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func (rs *ReturnStatement) TokenLiteral() string {
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return rs.Token.Literal
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}
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@ -33,7 +33,7 @@ func (l_parser *Parser) ParseProgram() *ast.Program {
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program := &ast.Program{}
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program := &ast.Program{}
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program.Statements = []ast.Statement{}
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program.Statements = []ast.Statement{}
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for !l_parser.current_token_is(token.EOF){
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for !l_parser.current_token_is(token.EOF) {
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statement := l_parser.parse_statement()
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statement := l_parser.parse_statement()
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if statement != nil {
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if statement != nil {
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program.Statements = append(program.Statements, statement)
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program.Statements = append(program.Statements, statement)
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@ -52,6 +52,8 @@ func (l_parser *Parser) parse_statement() ast.Statement {
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switch l_parser.current_token.Type {
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switch l_parser.current_token.Type {
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case token.LET:
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case token.LET:
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return l_parser.parse_let_statement()
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return l_parser.parse_let_statement()
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case token.RETURN:
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return l_parser.parse_return_statement()
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default:
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default:
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return nil
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return nil
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}
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}
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@ -75,6 +77,17 @@ func (l_parser *Parser) parse_let_statement() *ast.LetStatement {
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return statement
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return statement
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}
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}
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func (l_parser *Parser) parse_return_statement() *ast.ReturnStatement {
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statement := &ast.ReturnStatement{Token: l_parser.current_token}
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l_parser.next_token()
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// TODO(tijani): Skipping the expression until there is semicolon
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for !l_parser.current_token_is(token.SEMICOLON) {
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l_parser.next_token()
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}
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return statement
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}
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func (l_parser *Parser) expect_peek(l_token token.TokenType) bool {
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func (l_parser *Parser) expect_peek(l_token token.TokenType) bool {
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if l_parser.peek_token_is(l_token) {
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if l_parser.peek_token_is(l_token) {
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l_parser.next_token()
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l_parser.next_token()
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@ -6,6 +6,20 @@ import (
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"testing"
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"testing"
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)
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)
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func check_parser_errors(l_test *testing.T, l_parser *Parser) {
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errors := l_parser.Errors()
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if len(errors) == 0 {
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return
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}
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l_test.Errorf("parser has %d errors", len(errors))
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for _, message := range errors {
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l_test.Errorf("parser error: %q", message)
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}
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l_test.FailNow()
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}
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func TestLetStatement(l_test *testing.T) {
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func TestLetStatement(l_test *testing.T) {
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input := `
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input := `
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let x = 4;
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let x = 4;
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@ -68,16 +82,33 @@ func testLetStatement(l_test *testing.T, statement ast.Statement, name string) b
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return true
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return true
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}
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}
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func check_parser_errors(l_test *testing.T, l_parser *Parser) {
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func TestReturnStatement(l_test *testing.T) {
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errors := l_parser.Errors()
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input := `
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if len(errors) == 0 {
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return 6;
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return
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return 10;
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return 8419849;
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`
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l_lexer := lexer.New(input)
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l_parser := New(l_lexer)
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program := l_parser.ParseProgram()
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check_parser_errors(l_test, l_parser)
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if len(program.Statements) != 3 {
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l_test.Fatalf("program.Statements does not contain 3 statements, got=%d", len(program.Statements))
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}
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}
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l_test.Errorf("parser has %d errors", len(errors))
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for _, statement := range program.Statements {
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return_statement, ok := statement.(*ast.ReturnStatement)
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for _, message := range errors {
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if !ok {
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l_test.Errorf("parser error: %q", message)
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l_test.Errorf("statment not *ast.ReturnStatement, got =%T", statement)
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continue
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}
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if return_statement.TokenLiteral() != "return" {
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l_test.Errorf("return_statement.TokenLiteral() not 'return', got %q", return_statement.TokenLiteral())
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}
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}
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}
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l_test.FailNow()
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}
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}
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