66 lines
1.1 KiB
Go
66 lines
1.1 KiB
Go
package ast
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import (
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"fmt"
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"strconv"
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)
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type Printer struct {
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result string
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}
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var _ ExprVisitor = new(Printer)
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func (p *Printer) VisitBinaryExpr(b *BinaryExpr) any {
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return p.Parenthesize(b.Operator.Lexeme, b.Left, b.Right)
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}
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func (p *Printer) VisitGroupingExpr(g *GroupingExpr) any {
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return p.Parenthesize("group", g.Expr)
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}
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func (p *Printer) VisitLiteralExpr(g *LiteralExpr) any {
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switch t := g.Value.(type) {
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case string:
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return t
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case bool:
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if t {
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return "true"
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}
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return "false"
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case float64:
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return strconv.FormatFloat(t, 'f', 3, 64)
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case nil:
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return "nil"
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}
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return fmt.Sprintf("%v", g.Value)
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}
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func (p *Printer) VisitUnaryExpr(g *UnaryExpr) any {
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return p.Parenthesize(g.Operator.Lexeme, g.Right)
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}
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func (p *Printer) Parenthesize(name string, expressions ...Expr) string {
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val := "(" + name
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for _, e := range expressions {
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exprStr, ok := (e.accept(p)).(string)
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if !ok {
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panic("badly implemented visitor")
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}
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val += " " + exprStr
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}
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val += ")"
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return val
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}
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func (p *Printer) Print(e Expr) string {
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str, ok := (e.accept(p)).(string)
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if !ok {
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panic("badly implemented visitor")
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}
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return str
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}
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