136 lines
2.2 KiB
Go
136 lines
2.2 KiB
Go
package main
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import (
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"fmt"
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"strings"
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)
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type Visitor interface {
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visitBinary(b *Binary)
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visitLiteral(l *Literal)
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visitGrouping(g *Grouping)
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visitUnary(u *Unary)
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}
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type Expr interface {
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expr()
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accept(v Visitor)
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}
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type Binary struct {
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left Expr
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op Token
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right Expr
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}
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type Unary struct {
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op Token
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right Expr
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}
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type Grouping struct {
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expression Expr
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}
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type Literal struct {
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value any
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}
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func (u *Unary) expr() {}
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func (g *Grouping) expr() {}
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func (l *Literal) expr() {}
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func (b *Binary) expr() {}
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func (u *Unary) accept(v Visitor) {
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v.visitUnary(u)
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}
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func (g *Grouping) accept(v Visitor) {
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v.visitGrouping(g)
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}
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func (l *Literal) accept(v Visitor) {
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v.visitLiteral(l)
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}
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func (b *Binary) accept(v Visitor) {
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v.visitBinary(b)
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}
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type AstStringer struct {
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str strings.Builder
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}
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func (as AstStringer) String(expr Expr) string {
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if expr == nil {
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return ""
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}
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expr.accept(&as)
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return as.str.String()
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}
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func (as *AstStringer) visitBinary(b *Binary) {
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as.str.WriteString("(")
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as.str.WriteString(b.op.lexeme)
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as.str.WriteString(" ")
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b.left.accept(as)
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as.str.WriteString(" ")
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b.right.accept(as)
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as.str.WriteString(")")
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}
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func (as *AstStringer) visitLiteral(l *Literal) {
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as.str.WriteString(fmt.Sprintf("%v", l.value))
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}
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func (as *AstStringer) visitGrouping(g *Grouping) {
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as.str.WriteString("(group ")
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g.expression.accept(as)
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as.str.WriteString(")")
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}
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func (as *AstStringer) visitUnary(u *Unary) {
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as.str.WriteString(fmt.Sprintf("(%s ", u.op.lexeme))
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u.right.accept(as)
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as.str.WriteString(")")
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}
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type AstToRPN struct {
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str strings.Builder
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}
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func (as AstToRPN) String(expr Expr) string {
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if expr == nil {
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return ""
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}
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expr.accept(&as)
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return as.str.String()
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}
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func (as *AstToRPN) visitBinary(b *Binary) {
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b.left.accept(as)
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as.str.WriteString(" ")
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b.right.accept(as)
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as.str.WriteString(" ")
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as.str.WriteString(b.op.lexeme)
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}
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func (as *AstToRPN) visitLiteral(l *Literal) {
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as.str.WriteString(fmt.Sprintf("%v", l.value))
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}
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func (as *AstToRPN) visitGrouping(g *Grouping) {
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g.expression.accept(as)
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as.str.WriteString(" group")
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}
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func (as *AstToRPN) visitUnary(u *Unary) {
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u.right.accept(as)
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as.str.WriteString(fmt.Sprintf(" %s", u.op.lexeme))
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}
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