php8.1: added intersection types support (#29)

pkg/visitor/printer/printer.go

@@ -180,6 +180,10 @@ func (p *printer) Union(n *ast.Union) {
 	p.printSeparatedList(n.Types, n.SeparatorTkns, []byte("|"))
 }
 
+func (p *printer) Intersection(n *ast.Intersection) {
+	p.printSeparatedList(n.Types, n.SeparatorTkns, []byte("&"))
+}
+
 func (p *printer) Attribute(n *ast.Attribute) {
 	p.printNode(n.Name)
 	p.printToken(n.OpenParenthesisTkn, p.ifNodeList(n.Args, []byte("(")))

pkg/visitor/printer/printer_php8_1_test.go

@@ -104,3 +104,13 @@ $foo = $closure->__invoke(...);
 // new Foo(...); // not working
 `)
 }
+
+func TestIntersectionTypesSyntaxPHP81(t *testing.T) {
+	tester.NewParserPrintTestSuite(t).UsePHP8().Run(`<?php
+class Test {
+    public A&B $prop;
+}
+
+function test(A&B $a): A&B {}
+`)
+}