PHP8 attributes support

[thekid]

See https://wiki.php.net/rfc/shorter_attribute_syntax

use unittest\Test;

class DemoTest {

  @@Test
  public function can_create() {
    new Demo();
  }
}

• Types
• Properties
• Methods
• Parameters
• Constants
• Anonymous class instances
• Functions
• Closure and lambda expressions

[thekid]

This should be re-considered - and maybe moved to either emitter or to XP Framework...

[thekid]

We could change annotation layout from an optional value to a list arguments, giving us:

// No argument / without value
@@Test #[@test]
$arguments= [];

// Single argument / with value
@@Author('Timm') #[@author('Timm')]
$arguments= ['Timm'];

// Single array argument / array value
@@Values(['a', 'b', 'c']) #[@values(['a', 'b', 'c')]
$arguments= [['a', 'b', 'c']];

// Multiple arguments - not supported by XP annotations!
@@Values('a', 'b', 'c')
$arguments= ['a', 'b', 'c']

This would create a BC break for this library

[thekid]

Conflict between PHP attributes, which have 0..n arguments versus XP annotations, which have an optional value.

// No argument / without value
@@Test
#[@test]

// Single argument / with value
@@Author('Timm')
#[@author('Timm')]

// Single array argument / array value
@@Values(['a', 'b', 'c'])
#[@values(['a', 'b', 'c')]

// Multiple arguments - not supported by XP annotations!
@@Values('a', 'b', 'c')
...

Should @@Values('a', 'b', 'c') simply yield the same as @@Values(['a', 'b', 'c']) (thus making the first three forms equivalent) OR should PHP 8 attributes always yield arrays as value (thus requiring quite a bit of change in code processing both annotations and attributes)?

[thekid]

With this patch to the XP compiler, backwards- and forwards compatibility can be ensured:

$ git diff
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
index 980d247..0b19ca8 100755
--- a/src/main/php/lang/ast/emit/PHP.class.php
+++ b/src/main/php/lang/ast/emit/PHP.class.php
@@ -285,13 +285,24 @@ abstract class PHP extends Emitter {
   }

   protected function emitAnnotations($result, $annotations) {
-    foreach ($annotations as $name => $annotation) {
+    foreach ($annotations as $name => $arguments) {
       $result->out->write("'".$name."' => ");
-      if ($annotation) {
-        $this->emitOne($result, $annotation);
+
+      if (empty($arguments)) {
+        $result->out->write('null,');
+      } else if ($arguments instanceof Node) {
+        $this->emitOne($result, $arguments);
+        $result->out->write(',');
+      } else if (1 === sizeof($arguments)) {
+        $this->emitOne($result, $arguments[0]);
         $result->out->write(',');
       } else {
-        $result->out->write('null,');
+        $result->out->write('[');
+        foreach ($arguments as $argument) {
+          $this->emitOne($result, $argument);
+          $result->out->write(',');
+        }
+        $result->out->write('],');
       }
     }
   }

However, in the long run it might be more elegant to always emit DETAIL_ANNOTATIONS as an array and change the XP Framework itself. Hrm...