POC https://wiki.php.net/rfc/function-composition

Author: sgolemon

Zend/tests/composed_callable_001.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Composed callable using direct object methods.
+--FILE--
+<?php
+
+$cb = new \ComposedCallable(strtolower(...));
+var_dump($cb("Hello"));
+$cb->prepend(fn($x) => "$x World");
+var_dump($cb("Hello"));
+$cb->append('strrev');
+var_dump($cb("Hello"));
+$cb->insert(ucfirst(...), 2);
+var_dump($cb("Hello"));
+--EXPECT--
+string(5) "hello"
+string(11) "hello world"
+string(11) "dlrow olleh"
+string(11) "dlrow olleH"

Zend/tests/composed_callable_002.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Composed callable using composition.
+--FILE--
+<?php
+
+$cb1 = new \ComposedCallable([strtolower(...)]);
+$cb2 = $cb1 + strrev(...);
+var_dump($cb1("Hello World"));
+var_dump($cb2("Hello World"));
+--EXPECT--
+string(11) "hello world"
+string(11) "dlrow olleh"

Zend/tests/composed_callable_003.phpt

@@ -0,0 +1,9 @@
+--TEST--
+Composed callable using composition and auto-promotion
+--FILE--
+<?php
+
+$cb = strtolower(...) + str_rot13(...) + (fn($x) => "<$x>");
+var_dump($cb("Hello World"));
+--EXPECT--
+string(13) "<uryyb jbeyq>"

Zend/zend_closures.c

@@ -21,6 +21,7 @@
 #include "zend.h"
 #include "zend_API.h"
 #include "zend_closures.h"
+#include "zend_composed_callable.h"
 #include "zend_exceptions.h"
 #include "zend_interfaces.h"
 #include "zend_objects.h"
@@ -705,6 +706,14 @@ ZEND_COLD ZEND_METHOD(Closure, __construct)
 }
 /* }}} */
 
+static zend_result zend_closure_do_operation(uint8_t opcode, zval *result, zval *op1, zval *op2) {
+	if (opcode != ZEND_ADD) {
+		return FAILURE;
+	}
+
+	return zend_composed_callable_new_from_pair(result, op1, op2);
+}
+
 void zend_register_closure_ce(void) /* {{{ */
 {
 	zend_ce_closure = register_class_Closure();
@@ -720,6 +729,7 @@ void zend_register_closure_ce(void) /* {{{ */
 	closure_handlers.get_debug_info = zend_closure_get_debug_info;
 	closure_handlers.get_closure = zend_closure_get_closure;
 	closure_handlers.get_gc = zend_closure_get_gc;
+	closure_handlers.do_operation = zend_closure_do_operation;
 }
 /* }}} */