From 16808c7ff93d256806c6eb5639ac48c4bf9b9bff Mon Sep 17 00:00:00 2001
From: Pekka Laiho <pekka.i.laiho@gmail.com>
Date: Sat, 19 Dec 2020 17:45:18 +0700
Subject: [PATCH] add support for variable arguments using &

---
 src/Evaller.php   |  4 +--
 src/UserFunc.php  |  5 +---
 src/Util.php      | 16 ++++++++++++
 test/UtilTest.php | 62 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 80 insertions(+), 7 deletions(-)

diff --git a/src/Evaller.php b/src/Evaller.php
index 5bb1a8f..68b9bcb 100644
--- a/src/Evaller.php
+++ b/src/Evaller.php
@@ -241,9 +241,7 @@ class Evaller
                     $closure = function (...$args) use ($bindings, $env, $astData, $depth) {
                         $newEnv = new Env('closure', $env);
 
-                        for ($i = 0; $i < count($bindings); $i++) {
-                            $newEnv->set($bindings[$i]->getName(), $args[$i] ?? null);
-                        }
+                        Util::bindArguments($newEnv, $bindings, $args);
 
                         return $this->eval($astData[2], $newEnv, $depth + 1);
                     };
diff --git a/src/UserFunc.php b/src/UserFunc.php
index 3c1f64f..e8a93f7 100644
--- a/src/UserFunc.php
+++ b/src/UserFunc.php
@@ -38,10 +38,7 @@ class UserFunc extends Func
     {
         $newEnv = new Env('apply', $this->tempEnv);
 
-        $bindings = $this->bindings->getData();
-        for ($i = 0; $i < count($bindings); $i++) {
-            $newEnv->set($bindings[$i]->getName(), $args[$i] ?? null);
-        }
+        Util::bindArguments($newEnv, $this->bindings->getData(), $args);
 
         return $newEnv;
     }
diff --git a/src/Util.php b/src/Util.php
index 8f01e3e..416a857 100644
--- a/src/Util.php
+++ b/src/Util.php
@@ -9,6 +9,22 @@ namespace MadLisp;
 
 class Util
 {
+    public static function bindArguments(Env $env, array $bindings, array $args): void
+    {
+        for ($i = 0; $i < count($bindings); $i++) {
+            if ($bindings[$i]->getName() == '&') {
+                if ($i < count($bindings) - 1) {
+                    $env->set($bindings[$i + 1]->getName(), new Vector(array_slice($args, $i)));
+                    return;
+                } else {
+                    throw new MadLispException('no binding after &');
+                }
+            } else {
+                $env->set($bindings[$i]->getName(), $args[$i] ?? null);
+            }
+        }
+    }
+
     public static function makeHash(array $args): Hash
     {
         if (count($args) % 2 == 1) {
diff --git a/test/UtilTest.php b/test/UtilTest.php
index f87af57..3fbbeb3 100644
--- a/test/UtilTest.php
+++ b/test/UtilTest.php
@@ -7,12 +7,74 @@
 
 use PHPUnit\Framework\TestCase;
 
+use MadLisp\Env;
 use MadLisp\Hash;
 use MadLisp\MadLispException;
+use MadLisp\Symbol;
 use MadLisp\Util;
+use MadLisp\Vector;
 
 class UtilTest extends TestCase
 {
+    public function testBindArguments()
+    {
+        $env = new Env('env');
+
+        Util::bindArguments($env, [
+            new Symbol('a'),
+            new Symbol('b')
+        ], [
+            1,
+            2
+        ]);
+
+        $this->assertSame(['a' => 1, 'b' => 2], $env->getData());
+    }
+
+    public function testBindArgumentsVariable()
+    {
+        $env = new Env('env');
+
+        Util::bindArguments($env, [
+            new Symbol('a'),
+            new Symbol('b'),
+            new Symbol('&'),
+            new Symbol('c')
+        ], [
+            1,
+            2,
+            3,
+            4
+        ]);
+
+        $data = $env->getData();
+        $this->assertCount(3, $data);
+        $this->assertSame(1, $data['a']);
+        $this->assertSame(2, $data['b']);
+        $vec = $data['c'];
+        $this->assertInstanceOf(Vector::class, $vec);
+        $this->assertSame([3, 4], $vec->getData());
+    }
+
+    public function testBindArgumentsVariableInvalid()
+    {
+        $this->expectException(MadLispException::class);
+        $this->expectExceptionMessage('no binding after &');
+
+        $env = new Env('env');
+
+        Util::bindArguments($env, [
+            new Symbol('a'),
+            new Symbol('b'),
+            new Symbol('&')
+        ], [
+            1,
+            2,
+            3,
+            4
+        ]);
+    }
+
     public function testMakeHash()
     {
         $hash = Util::makeHash(['a', 1, 'b', 2]);