Extend Name::slice() to support negative length+offset

Author: nikic

lib/PhpParser/Node/Name.php

@@ -165,17 +165,31 @@ public function setLast($name) {
      * If the slice is empty, a Name with an empty parts array is returned. While this is
      * meaningless in itself, it works correctly in conjunction with concat().
      *
-     * @param int $offset Offset to start the slice at
+     * Offset and length have the same meaning as in array_slice().
+     *
+     * @param int      $offset Offset to start the slice at (may be negative)
+     * @param int|null $length Length of the slice (may be negative)
      *
      * @return static Sliced name
      */
-    public function slice($offset) {
-        // TODO negative offset and length
-        if ($offset < 0 || $offset > count($this->parts)) {
+    public function slice($offset, $length = null) {
+        $numParts = count($this->parts);
+
+        $realOffset = $offset < 0 ? $offset + $numParts : $offset;
+        if ($realOffset < 0 || $realOffset > $numParts) {
             throw new \OutOfBoundsException(sprintf('Offset %d is out of bounds', $offset));
         }
 
-        return new static(array_slice($this->parts, $offset), $this->attributes);
+        if (null === $length) {
+            $realLength = $numParts - $realOffset;
+        } else {
+            $realLength = $length < 0 ? $length + $numParts - $realOffset : $length;
+            if ($realLength < 0 || $realLength > $numParts) {
+                throw new \OutOfBoundsException(sprintf('Length %d is out of bounds', $length));
+            }
+        }
+
+        return new static(array_slice($this->parts, $realOffset, $realLength), $this->attributes);
     }
 
     /**

test/PhpParser/Node/NameTest.php

@@ -96,20 +96,53 @@ public function testPrepend() {
     }
 
     public function testSlice() {
-        $name = new Name('foo\bar');
-        $this->assertEquals(new Name('foo\bar'), $name->slice(0));
-        $this->assertEquals(new Name('bar'), $name->slice(1));
-        $this->assertEquals(new Name([]), $name->slice(2));
+        $name = new Name('foo\bar\baz');
+        $this->assertEquals(new Name('foo\bar\baz'), $name->slice(0));
+        $this->assertEquals(new Name('bar\baz'), $name->slice(1));
+        $this->assertEquals(new Name([]), $name->slice(3));
+        $this->assertEquals(new Name('foo\bar\baz'), $name->slice(-3));
+        $this->assertEquals(new Name('bar\baz'), $name->slice(-2));
+        $this->assertEquals(new Name('foo\bar'), $name->slice(0, -1));
+        $this->assertEquals(new Name([]), $name->slice(0, -3));
+        $this->assertEquals(new Name('bar'), $name->slice(1, -1));
+        $this->assertEquals(new Name([]), $name->slice(1, -2));
+        $this->assertEquals(new Name('bar'), $name->slice(-2, 1));
+        $this->assertEquals(new Name('bar'), $name->slice(-2, -1));
+        $this->assertEquals(new Name([]), $name->slice(-2, -2));
     }
 
     /**
      * @expectedException \OutOfBoundsException
      * @expectedExceptionMessage Offset 4 is out of bounds
      */
-    public function testSliceException() {
+    public function testSliceOffsetTooLarge() {
         (new Name('foo\bar\baz'))->slice(4);
     }
 
+    /**
+     * @expectedException \OutOfBoundsException
+     * @expectedExceptionMessage Offset -4 is out of bounds
+     */
+    public function testSliceOffsetTooSmall() {
+        (new Name('foo\bar\baz'))->slice(-4);
+    }
+
+    /**
+     * @expectedException \OutOfBoundsException
+     * @expectedExceptionMessage Length 4 is out of bounds
+     */
+    public function testSliceLengthTooLarge() {
+        (new Name('foo\bar\baz'))->slice(0, 4);
+    }
+
+    /**
+     * @expectedException \OutOfBoundsException
+     * @expectedExceptionMessage Length -4 is out of bounds
+     */
+    public function testSliceLengthTooSmall() {
+        (new Name('foo\bar\baz'))->slice(0, -4);
+    }
+
     public function testConcat() {
         $this->assertEquals(new Name('foo\bar\baz'), Name::concat('foo', 'bar\baz'));
         $this->assertEquals(