package ast

import "code.osinet.fr/fgm/waiig15/token"

// Every node in the AST implements Node.
type Node interface {
	// TokenLiteral returns the literal value of the token it's associated to.
	TokenLiteral() string
}

type Statement interface {
	// Expression extends Node.
	Node
	statementNode()
}

type Expression interface {
	// Expression extends Node.
	Node
	expressionNode()
}

type Program struct {
	Statements []Statement
}

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

type LetStatement struct {
	Token token.Token // the token.LET token. Why do we need it ?
	Name  *Identifier
	Value Expression
}

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

type Identifier struct {
	Token token.Token // the token.IDENT token. Why do we need it ?
	Value string      // The identifier string.
}

func (i *Identifier) expressionNode() {}
func (i *Identifier) TokenLiteral() string {
	return i.Token.Literal
}