Monkey/ast/ast.go

package ast

import "github/runnignwater/monkey/token"

/**
 * @Author: simon
 * @Author: ynwdlxm@163.com
 * @Date: 2022/10/2 下午8:58
 * @Desc:
 */
type Node interface {
	TokenLiteral() string
}

// expressions produce values, statements don't
type Statement interface {
	Node
	statementNode()
}
type Expression interface {
	Node
	expressionNode()
}

// ---------------------implementation of Node----------------------------------BEGIN-----------------------------------
// Root Node of our parser produces.
type Program struct {
	Statements []Statement
}

func (p *Program) TokenLiteral() string {
	if len(p.Statements) > 0 {
		return p.Statements[0].TokenLiteral()
	} else {
		return ""
	}
}

//---------------------implementation of Node-----------------------------------END-------------------------------------

// let <identifier> = <expression>;
//
//      let x = 5 AST
//  |-------------------|
//  |  *ast.Program     |
//  |-------------------|
//  |  Statements       |
//  |-------------------|
//         ↓
//  |-------------------|
//  | *ast.LetStatement |
//  |-------------------|
//  |     Name          |
//  |-------------------|
//  |     Value         |
//  |-------------------|
//
//  *ast.Identifier              *ast.Expression
//
type LetStatement struct {
	Token token.Token // the token.LET token
	Name  *Identifier
	Value Expression
}

func (ls *LetStatement) TokenLiteral() string {
	return ls.Token.Literal
}

func (ls *LetStatement) statementNode() {
	panic("implement me")
}

type Identifier struct {
	Token token.Token // the token.IDENT token
	Value string
}

func (i *Identifier) expressionNode() {
	panic("implement me")
}
func (i *Identifier) TokenLiteral() string {
	return i.Token.Literal
}