Basic AST to represent expressions, statement, identifiers

I now understand how it works.

git-svn-id: https://svn.tlawal.org/svn/monkey@10 f6afcba9-9ef1-4bdd-9b72-7484f5705bac

ast/ast.go

@@ -1,50 +0,0 @@
-package ast
-
-import "monkey/token"
-
-type Node interface {
-	TokenLiteral() string
-}
-
-type Statement interface {
-	Node
-	statementNode()
-}
-
-type Expression interface {
-	Node
-	expressionNode()
-}
-
-type Identifier struct {
-	Token token.Token // the token.IDENT token
-	Value string
-}
-
-type Program struct {
-	Statements []Statement
-}
-
-type LetStatement struct {
-	Token token.Token // the token.LET token
-	Name  *Identifier
-	Value Expression
-}
-
-func (ls *LetStatement) stamementNode() {}
-func (ls *LetStatement) TokenLiteral() string {
-	return ls.Token.Literal
-}
-
-func (i *Identifier) expressionNode() {}
-func (i *Identifier) TokenLiteral() string {
-	return i.Token.Literal
-}
-
-func (p *Program) TokenLiteral() string {
-	if len(p.Statements) > 0 {
-		return p.Statements[0].TokenLiteral()
-	} else {
-		return ""
-	}
-}