ExpressionStatement in the AST to represent the typse of expressions that is supported in monkey.
Hand written test in the AST to test the String() function for accuracy git-svn-id: https://svn.tlawal.org/svn/monkey@22 f6afcba9-9ef1-4bdd-9b72-7484f5705bac
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parent
fdf6a8a552
commit
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64
ast/ast.go
64
ast/ast.go
@ -1,9 +1,13 @@
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package ast
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import "monkey/token"
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import (
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"bytes"
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"monkey/token"
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)
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type Node interface {
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TokenLiteral() string
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String() string
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}
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type Statement interface {
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@ -16,6 +20,14 @@ type Expression interface {
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expression_node()
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}
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func (l_program *Program) String() string {
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var out bytes.Buffer
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for _, s := range l_program.Statements {
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out.WriteString(s.String())
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}
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return out.String()
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}
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type Program struct {
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Statements []Statement
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}
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@ -36,18 +48,43 @@ type ReturnStatement struct {
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ReturnValue Expression
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}
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type ExpressionStatement struct {
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Token token.Token // the first token in the expression
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Expression Expression
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}
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// Let Statements
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func (ls *LetStatement) statement_node() {}
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func (ls *LetStatement) TokenLiteral() string {
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return ls.Token.Literal
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}
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func (ls *LetStatement) String() string {
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var out bytes.Buffer
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out.WriteString(ls.TokenLiteral() + " ")
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out.WriteString(ls.Name.String())
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out.WriteString(" = ")
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if ls.Value != nil {
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out.WriteString(ls.Value.String())
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}
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out.WriteString(";")
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return out.String()
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}
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// Identifier
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func (i *Identifier) expression_node() {}
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func (i *Identifier) TokenLiteral() string {
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return i.Token.Literal
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}
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func (i *Identifier) String() string {
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return i.Value
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}
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// Program
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func (p *Program) TokenLiteral() string {
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if len(p.Statements) > 0 {
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return p.Statements[0].TokenLiteral()
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@ -56,8 +93,33 @@ func (p *Program) TokenLiteral() string {
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}
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}
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// Return Statements
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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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func (rs *ReturnStatement) String() string {
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var out bytes.Buffer
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out.WriteString(rs.TokenLiteral() + " ")
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if rs.ReturnValue != nil {
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out.WriteString(rs.ReturnValue.String())
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}
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out.WriteString(";")
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return out.String()
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}
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// Expression Statement
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func (es *ExpressionStatement) statement_node() {}
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func (es *ExpressionStatement) TokenLiteral() string {
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return es.Token.Literal
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}
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func (es *ExpressionStatement) String() string {
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if es.Expression != nil {
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return es.Expression.String()
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}
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return ""
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}
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28
ast/ast_test.go
Normal file
28
ast/ast_test.go
Normal file
@ -0,0 +1,28 @@
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package ast
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import (
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"monkey/token"
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"testing"
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)
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func TestString(l_test *testing.T) {
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program := &Program{
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Statements: []Statement{
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&LetStatement{
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Token: token.Token{Type: token.LET, Literal: "let"},
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Name: &Identifier{
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Token: token.Token{Type: token.IDENT, Literal: "my_var"},
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Value: "my_var",
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},
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Value: &Identifier{
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Token: token.Token{Type: token.IDENT, Literal: "another_var"},
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Value: "another_var",
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},
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},
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},
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}
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if program.String() != "let my_var = another_var;" {
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l_test.Errorf("program.String() wrong, got=%q", program.String())
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}
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}
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