Add RandomAccessBinaryReader

Author: mgenware

lib/random_access_source.dart

@@ -2,3 +2,4 @@
 library;
 
 export 'src/random_access_source_base.dart';
+export 'src/random_access_binary_reader.dart';

lib/src/random_access_binary_reader.dart

@@ -0,0 +1,82 @@
+import 'dart:typed_data';
+
+import '../random_access_source.dart';
+
+/// A class that reads binary data from a [RandomAccessSource].
+class RandomAccessBinaryReader {
+  final RandomAccessSource source;
+  Endian endian = Endian.big;
+
+  RandomAccessBinaryReader(this.source);
+
+  Future<Uint8List> readBytes(int count) async {
+    return source.read(count);
+  }
+
+  Future<Uint8List> mustReadBytes(int count) async {
+    final data = await source.read(count);
+    if (data.length != count) {
+      throw Exception(
+          'Unexpected end of file, expected $count bytes, but got ${data.length} bytes');
+    }
+    return data;
+  }
+
+  Future<double> readFloat32([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(4);
+    return ByteData.sublistView(data).getFloat32(0, ed);
+  }
+
+  Future<double> readFloat64([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(8);
+    return ByteData.sublistView(data).getFloat64(0, ed);
+  }
+
+  Future<int> readInt8() async {
+    final data = await mustReadBytes(1);
+    return ByteData.sublistView(data).getInt8(0);
+  }
+
+  Future<int> readInt16([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(2);
+    return ByteData.sublistView(data).getInt16(0, ed);
+  }
+
+  Future<int> readInt32([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(4);
+    return ByteData.sublistView(data).getInt32(0, ed);
+  }
+
+  Future<int> readInt64([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(8);
+    return ByteData.sublistView(data).getInt64(0, ed);
+  }
+
+  Future<int> readUint8() async {
+    final data = await mustReadBytes(1);
+    return ByteData.sublistView(data).getUint8(0);
+  }
+
+  Future<int> readUint16([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(2);
+    return ByteData.sublistView(data).getUint16(0, ed);
+  }
+
+  Future<int> readUint32([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(4);
+    return ByteData.sublistView(data).getUint32(0, ed);
+  }
+
+  Future<int> readUint64([Endian? endian]) async {
+    final ed = endian ?? this.endian;
+    final data = await mustReadBytes(8);
+    return ByteData.sublistView(data).getUint64(0, ed);
+  }
+}