Added ByteBuffer::getUnreadLength()

this provides the needed functionality to implement both missing APIs in #10.

Author: dktapps

encoding.cpp

@@ -565,6 +565,17 @@ static PHP_METHOD(ByteBuffer, rewind) {
 	object->offset = 0;
 }
 
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(ByteBuffer_getUnreadLength, 0, 0, IS_LONG, 0)
+ZEND_END_ARG_INFO()
+
+static PHP_METHOD(ByteBuffer, getUnreadLength) {
+	zend_parse_parameters_none_throw();
+
+	auto object = fetch_from_zend_object<byte_buffer_zend_object>(Z_OBJ_P(ZEND_THIS));
+
+	RETURN_LONG(object->used - object->offset);
+}
+
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(ByteBuffer___serialize, 0, 0, IS_ARRAY, 0)
 ZEND_END_ARG_INFO()
 
@@ -721,6 +732,8 @@ static zend_function_entry byte_buffer_methods[] = {
 
 	PHP_ME(ByteBuffer, rewind, ByteBuffer_rewind, ZEND_ACC_PUBLIC)
 
+	PHP_ME(ByteBuffer, getUnreadLength, ByteBuffer_getUnreadLength, ZEND_ACC_PUBLIC)
+
 	PHP_ME(ByteBuffer, __serialize, ByteBuffer___serialize, ZEND_ACC_PUBLIC)
 	PHP_ME(ByteBuffer, __unserialize, ByteBuffer___unserialize, ZEND_ACC_PUBLIC)
 	PHP_ME(ByteBuffer, __debugInfo, ByteBuffer___debugInfo, ZEND_ACC_PUBLIC)

tests/unread-length.phpt

@@ -0,0 +1,32 @@
+--TEST--
+Test that ByteBuffer::getUnreadLength() works correctly
+--FILE--
+<?php
+
+use pmmp\encoding\ByteBuffer;
+
+$buffer = new ByteBuffer("hello world");
+var_dump($buffer->getUnreadLength());
+
+$buffer = new ByteBuffer();
+var_dump($buffer->getUnreadLength());
+
+$buffer->writeByteArray("hello world");
+var_dump($buffer->getUnreadLength()); //zero, because read and write share the same offset (perhaps a bad idea?)
+
+$buffer->rewind();
+var_dump($buffer->getUnreadLength());
+
+$buffer->readByteArray(6);
+var_dump($buffer->getUnreadLength());
+
+$buffer->readByteArray($buffer->getUnreadLength());
+var_dump($buffer->getUnreadLength());
+?>
+--EXPECT--
+int(11)
+int(0)
+int(0)
+int(11)
+int(5)
+int(0)