fix Object.free (#982)

* lib/std/collections: add HashMap.@each_entry()
* lib/std/json: fix Object.free() when object is a map
* lib/std/collections: fix allocator use in Object.{set,set_at,append}
* lib/std: add char.from_hex
* lib/std/collections: print arrays and objects compactly
* lib/std/io: fix Formatter.vprintf result
* lib/std/io/stream: rename module for ByteBuffer
* lib/std/io/stream: make Scanner a Stream reader
* lib/std/io: make std{in,err,out} return File* if no libc

lib/std/io/stream/bytebuffer.c3

@@ -30,9 +30,19 @@ fn ByteBuffer*! ByteBuffer.tinit(&self, usz max_read, usz initial_capacity = 16)
 	return self.init(max_read, initial_capacity, mem::temp())!;
 }
 
+/**
+ * @require buf.len > 0
+ * @require self.bytes.len == 0 "Buffer already initialized."
+ **/
+fn ByteBuffer*! ByteBuffer.init_with_buffer(&self, char[] buf)
+{
+	*self = { .stream.fns = &BYTEBUFFER_INTERFACE, .max_read = buf.len, .bytes = buf };
+	return self;
+}
+
 fn void! ByteBuffer.free(&self)
 {
-	self.allocator.free(self.bytes)!;
+	if (self.allocator) self.allocator.free(self.bytes)!;
 	*self = {};
 }
 
@@ -104,6 +114,23 @@ fn void! ByteBuffer.pushback_byte(&self)
 	self.has_last = false;
 }
 
+fn void! ByteBuffer.seek(&self, isz offset, Seek seek)
+{
+	switch (seek)
+	{
+		case SET:
+			if (offset < 0 || offset > self.write_idx) return IoError.INVALID_POSITION?;
+			self.read_idx = offset;
+		case CURSOR:
+			if ((offset < 0 && self.read_idx < -offset) ||
+				(offset > 0 && self.read_idx + offset > self.write_idx)) return IoError.INVALID_POSITION?;
+			self.read_idx += offset;
+		case END:
+			if (offset < 0 || offset > self.write_idx) return IoError.INVALID_POSITION?;
+			self.read_idx = self.write_idx - offset;
+	}
+}
+
 fn usz! ByteBuffer.available(&self) @inline
 {
 	return self.write_idx - self.read_idx;