Add overwrite method to ConsoleOutput class

lib/Cake/Console/ConsoleOutput.php

@@ -79,6 +79,14 @@ class ConsoleOutput {
  */
 	protected $_output;
 
+/**
+ * The number of bytes last written to the output stream
+ * used when overwriting the previous message.
+ *
+ * @var int
+ */
+    protected $_lastWritten = 0;
+
 /**
  * The current output type. Manipulated with ConsoleOutput::outputAs();
  *
@@ -184,6 +192,36 @@ public function write($message, $newlines = 1) {
 		return $this->_write($this->styleText($message . str_repeat(static::LF, $newlines)));
 	}
 
+/**
+ * Overwrite some already output text.
+ *
+ * Useful for building progress bars, or when you want to replace
+ * text already output to the screen with new text.
+ *
+ * **Warning** You cannot overwrite text that contains newlines.
+ *
+ * @param array|string $message The message to output.
+ * @param int $newlines Number of newlines to append.
+ * @param int $size The number of bytes to overwrite. Defaults to the
+ *    length of the last message output.
+ * @return void
+ */
+    public function overwrite($message, $newlines = 1, $size = null)
+    {
+        $size = $size ?: $this->_lastWritten;
+        // Output backspaces.
+        $this->write(str_repeat("\x08", $size), 0);
+        $newBytes = $this->write($message, 0);
+        // Fill any remaining bytes with spaces.
+        $fill = $size - $newBytes;
+        if ($fill > 0) {
+            $this->write(str_repeat(' ', $fill), 0);
+        }
+        if ($newlines) {
+            $this->write("", $newlines);
+        }
+    }
+
 /**
  * Apply styling to text.
  *
@@ -238,7 +276,8 @@ protected function _replaceTags($matches) {
  * @return bool success
  */
 	protected function _write($message) {
-		return fwrite($this->_output, $message);
+		$this->_lastWritten = fwrite($this->_output, $message);
+        return $this->_lastWritten;
 	}
 
 /**

lib/Cake/Test/Case/Console/ConsoleOutputTest.php

@@ -94,6 +94,27 @@ public function testWriteArray() {
 		$this->output->write(array('Line', 'Line', 'Line'));
 	}
 
+/**
+ * test writing an array of messages.
+ *
+ * @return void
+ */
+    public function testOverwrite() {
+        $testString = "Text";
+
+        $this->output->expects($this->at(0))->method('_write')
+            ->with($testString);
+
+        $this->output->expects($this->at(1))->method('_write')
+            ->with("");
+
+        $this->output->expects($this->at(2))->method('_write')
+            ->with("Overwriting text");
+
+        $this->output->write($testString, 0);
+        $this->output->overwrite("Overwriting text");
+    }
+
 /**
  * test getting a style.
  *