1 files changed, 138 insertions, 0 deletions
diff --git a/test/unit_tests/shared/console.hpp b/test/unit_tests/shared/console.hpp
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+++ b/test/unit_tests/shared/console.hpp
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+// Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+// This file is part of the "winapi-common" project.
+// For details, see https://github.com/egor-tensin/winapi-common.
+// Distributed under the MIT License.
+
+#pragma once
+
+#include <winapi/error.hpp>
+#include <winapi/handle.hpp>
+#include <winapi/utf8.hpp>
+
+#include <boost/algorithm/string.hpp>
+
+#include <windows.h>
+
+#include <cstddef>
+#include <cstring>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace console {
+
+class Buffer {
+public:
+    typedef CONSOLE_SCREEN_BUFFER_INFO Info;
+
+    Buffer() : m_handle{winapi::Handle::std_out()}, m_info{get_info(m_handle)} {}
+
+    Buffer(winapi::Handle&& handle) : m_handle{std::move(handle)}, m_info{get_info(m_handle)} {}
+
+    std::size_t get_columns() const { return m_info.dwSize.X; }
+
+    std::size_t get_lines() const { return m_info.dwSize.Y; }
+
+    std::size_t get_cursor_column() const { return m_info.dwCursorPosition.X; }
+
+    std::size_t get_cursor_line() const { return m_info.dwCursorPosition.Y; }
+
+    void update() { m_info = get_info(m_handle); }
+
+    /*
+     * This is a stupid little function to read the console screen buffer.
+     * It's fragile and will break whenever anything happens (like, if the
+     * console screen is resized).
+     *
+     * The screen buffer:
+     * 1) doesn't preserve line breaks,
+     * 2) pads text lines with spaces (ASCII 0x20) for storage.
+     *
+     * Hence, the "lines" read are one-dimensional arrays, right-trimmed, and
+     * there's no way to learn whether the whole line printed by the user was
+     * read back in its entirety.
+     *
+     * For example, let the console window be 80 columns wide, and the user
+     * prints 85 consecutive characters 'a' using
+     *
+     *     std::cout << std::string(85, 'a') << '\n';
+     *
+     * The following holds:
+     * 1) read_lines(-1, -1) == {"aaaaa"},
+     * 2) read_lines(-2, -2) == {std::string(80, 'a'), "aaaaa"}.
+     *
+     * I also don't know how it interacts with tab characters '\t', encodings,
+     * etc. It sucks, don't use it.
+     */
+    std::vector<std::string> read_lines(int top, int bottom) const {
+        if (top < 0) {
+            top = get_cursor_line() + top;
+        }
+        if (bottom < 0) {
+            bottom = get_cursor_line() + bottom;
+        }
+        if (top > bottom) {
+            std::swap(top, bottom);
+        }
+        int numof_lines = bottom - top + 1;
+
+        COORD buffer_size;
+        buffer_size.X = get_columns();
+        buffer_size.Y = numof_lines;
+
+        COORD buffer_coord;
+        buffer_coord.X = 0;
+        buffer_coord.Y = 0;
+
+        std::vector<CHAR_INFO> buffer;
+        buffer.resize(buffer_size.X * buffer_size.Y);
+
+        SMALL_RECT read_region;
+        read_region.Top = top;
+        read_region.Left = 0;
+        read_region.Bottom = bottom;
+        read_region.Right = buffer_size.X - 1;
+
+        if (!::ReadConsoleOutputW(
+                m_handle.get(), buffer.data(), buffer_size, buffer_coord, &read_region)) {
+            throw winapi::error::windows(GetLastError(), "ReadConsoleOutputW");
+        }
+
+        std::vector<std::string> result;
+        for (std::size_t i = 0; i < numof_lines; ++i) {
+            std::wostringstream oss;
+            for (std::size_t c = 0; c < buffer_size.X; ++c) {
+                oss << buffer[i * buffer_size.X + c].Char.UnicodeChar;
+            }
+            result.emplace_back(boost::trim_right_copy(winapi::narrow(oss.str())));
+        }
+
+        return result;
+    }
+
+    std::vector<std::string> read_last_lines(int numof_lines = 1) const {
+        return read_lines(-numof_lines, -1);
+    }
+
+    std::string read_last_line() const { return read_lines(-1, -1)[0]; }
+
+    std::string read_line(int n) const { return read_lines(n, n)[0]; }
+
+private:
+    static Info get_info(const winapi::Handle& handle) {
+        Info dest;
+        std::memset(&dest, 0, sizeof(dest));
+
+        if (!::GetConsoleScreenBufferInfo(static_cast<HANDLE>(handle), &dest)) {
+            throw winapi::error::windows(GetLastError(), "GetConsoleScreenBufferInfo");
+        }
+
+        return dest;
+    }
+
+    winapi::Handle m_handle;
+    Info m_info;
+};
+
+} // namespace console