ast + basic printer

ast.go

@@ -0,0 +1,53 @@
+package main
+
+// todo: find something better than any here
+// we can't use generics on either the visitor itself or
+// each individual method because the adding it to the
+// visitor itself infects every expr you use with it
+// and methods cannot have generic parameters
+
+type exprVisitor interface {
+	visitBinaryExpr(b *binaryExpr) any
+	visitGroupingExpr(g *groupingExpr) any
+	visitLiteralExpr(g *literalExpr) any
+	visitUnaryExpr(g *unaryExpr) any
+}
+
+type expr interface {
+	accept(v exprVisitor) any
+}
+
+type binaryExpr struct {
+	Left     expr
+	Operator *token
+	Right    expr
+}
+
+func (b *binaryExpr) accept(v exprVisitor) any {
+	return v.visitBinaryExpr(b)
+}
+
+type groupingExpr struct {
+	Expr expr
+}
+
+func (g *groupingExpr) accept(v exprVisitor) any {
+	return v.visitGroupingExpr(g)
+}
+
+type literalExpr struct {
+	Value any
+}
+
+func (l *literalExpr) accept(v exprVisitor) any {
+	return v.visitLiteralExpr(l)
+}
+
+type unaryExpr struct {
+	Operator *token
+	Right    expr
+}
+
+func (u *unaryExpr) accept(v exprVisitor) any {
+	return v.visitUnaryExpr(u)
+}