Initial commit

engines/ags/shared/util/text_stream_reader.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "ags/shared/util/math.h"
+#include "ags/shared/util/stream.h"
+#include "ags/shared/util/text_stream_reader.h"
+
+namespace AGS3 {
+namespace AGS {
+namespace Shared {
+
+TextStreamReader::TextStreamReader(Stream *stream)
+	: _stream(stream) {
+}
+
+TextStreamReader::~TextStreamReader() {
+	// TODO: use shared ptr
+	delete _stream;
+}
+
+bool TextStreamReader::IsValid() const {
+	return _stream && _stream->CanRead();
+}
+
+const Stream *TextStreamReader::GetStream() const {
+	return _stream;
+}
+
+void TextStreamReader::ReleaseStream() {
+	_stream = nullptr;
+}
+
+bool TextStreamReader::EOS() const {
+	return _stream ? _stream->EOS() : true;
+}
+
+char TextStreamReader::ReadChar() {
+	return _stream->ReadInt8();
+}
+
+String TextStreamReader::ReadString(size_t length) {
+	// TODO: remove carriage-return characters
+	return String::FromStreamCount(_stream, length);
+}
+
+String TextStreamReader::ReadLine() {
+	// TODO
+	// Probably it is possible to group Stream::ReadString with this,
+	// both use similar algorythm, difference is only in terminator chars
+
+	String str;
+	int chars_read_last = 0;
+	int line_break_position = -1;
+	// Read a chunk of memory to buffer and seek for null-terminator,
+	// if not found, repeat until EOS
+	const int single_chunk_length = 3000;
+	const int max_chars = 5000000;
+	char char_buffer[single_chunk_length + 1];
+	do {
+		chars_read_last = _stream->Read(char_buffer, single_chunk_length);
+		char *seek_ptr = char_buffer;
+		int c;
+		for (c = 0; c < chars_read_last && *seek_ptr != '\n'; ++c, ++seek_ptr);
+
+		int append_length = 0;
+		int str_len = str.GetLength();
+		if (c < chars_read_last && *seek_ptr == '\n') {
+			line_break_position = seek_ptr - char_buffer;
+			if (str_len < max_chars) {
+				append_length = MIN(line_break_position, max_chars - str_len);
+			}
+		} else {
+			append_length = MIN(chars_read_last, max_chars - str_len);
+		}
+
+		if (append_length > 0) {
+			char_buffer[append_length] = '\0';
+			str.Append(char_buffer);
+		}
+	} while (!EOS() && line_break_position < 0);
+
+	// If null-terminator was found make sure stream is positioned at the next
+	// byte after line end
+	if (line_break_position >= 0) {
+		// CHECKME: what if stream does not support seek? need an algorythm fork for that
+		// the seek offset should be negative
+		_stream->Seek(line_break_position - chars_read_last + 1 /* beyond line feed */);
+	}
+
+	str.TrimRight('\r'); // skip carriage-return, if any
+	return str;
+}
+
+String TextStreamReader::ReadAll() {
+	size_t len = Math::InRangeOrDef<size_t>((size_t)(_stream->GetLength() - _stream->GetPosition()), SIZE_MAX);
+	return ReadString(len);
+}
+
+} // namespace Shared
+} // namespace AGS
+} // namespace AGS3