Refactor: Extract seeking to Streams class

Author: thekid

src/main/php/io/Blob.class.php

@@ -1,8 +1,8 @@
 <?php namespace io;
 
 use IteratorAggregate, Traversable;
-use io\streams\{InputStream, IterableInputStream, Seekable};
-use lang\{Value, IllegalArgumentException, IllegalStateException};
+use io\streams\{InputStream, IterableInputStream, Streams};
+use lang\{Value, IllegalArgumentException};
 use util\{Bytes, Objects};
 
 /** @test io.unittest.BlobTest */
@@ -22,15 +22,7 @@ public function __construct($parts= []) {
         static $started= false;
 
         return (function() use(&$started) {
-          if ($started) {
-            if ($this->parts instanceof Seekable) {
-              $this->parts->seek(0);
-            } else {
-              throw new IllegalStateException('Cannot seek '.Objects::stringOf($this->parts));
-            }
-          }
-
-          $started= true;
+          $started ? Streams::seek($this->parts, 0) : $started= true;
           while ($this->parts->available()) {
             yield $this->parts->read();
           }

src/main/php/io/streams/Streams.class.php

@@ -1,7 +1,6 @@
 <?php namespace io\streams;
 
-use io\FileNotFoundException;
-use io\IOException;
+use io\{FileNotFoundException, OperationNotSupportedException, IOException};
 
 /**
  * Wraps I/O streams into PHP streams
@@ -134,6 +133,23 @@ public static function readAll(InputStream $s) {
     return $r;
   }
 
+  /**
+   * Read an IOElements' contents completely into a buffer in a single call.
+   *
+   * @param   io.streams.InputStream $s
+   * @param   int $offset
+   * @param   int $whence default SEEK_SET (one of SEEK_[SET|CUR|END])
+   * @return  void
+   * @throws  io.IOException
+   */
+  public static function seek($s, $offset, $whence= SEEK_SET) {
+    if ($s instanceof Seekable) {
+      $s->seek($offset, $whence);
+    } else {
+      throw new OperationNotSupportedException('Cannot seek instances of '.nameof($s));
+    }
+  }
+
   /**
    * Callback for fopen
    *

src/test/php/io/unittest/BlobTest.class.php

@@ -1,9 +1,9 @@
 <?php namespace io\unittest;
 
 use ArrayObject;
-use io\Blob;
 use io\streams\{MemoryInputStream, InputStream};
-use lang\{IllegalArgumentException, IllegalStateException};
+use io\{Blob, OperationNotSupportedException};
+use lang\IllegalArgumentException;
 use test\{Assert, Expect, Test, Values};
 use util\Bytes;
 
@@ -85,6 +85,6 @@ public function close() { $this->input= []; }
     });
     iterator_to_array($fixture->slices());
 
-    Assert::throws(IllegalStateException::class, fn() => iterator_to_array($fixture->slices()));
+    Assert::throws(OperationNotSupportedException::class, fn() => iterator_to_array($fixture->slices()));
   }
 }