line_printer.cc

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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "line_printer.h"

#include <stdio.h>
#include <stdlib.h>
#ifdef _WIN32
#include <windows.h>
#else
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#endif

#include "util.h"

LinePrinter::LinePrinter() : have_blank_line_(true) {
#ifndef _WIN32
  const char* term = getenv("TERM");
  smart_terminal_ = isatty(1) && term && string(term) != "dumb";
#else
  // Disable output buffer.  It'd be nice to use line buffering but
  // MSDN says: "For some systems, [_IOLBF] provides line
  // buffering. However, for Win32, the behavior is the same as _IOFBF
  // - Full Buffering."
  setvbuf(stdout, NULL, _IONBF, 0);
  console_ = GetStdHandle(STD_OUTPUT_HANDLE);
  CONSOLE_SCREEN_BUFFER_INFO csbi;
  smart_terminal_ = GetConsoleScreenBufferInfo(console_, &csbi);
#endif
}

void LinePrinter::Print(string to_print, LineType type) {
#ifdef _WIN32
  CONSOLE_SCREEN_BUFFER_INFO csbi;
  GetConsoleScreenBufferInfo(console_, &csbi);
#endif

  if (smart_terminal_) {
#ifndef _WIN32
    printf("\r");  // Print over previous line, if any.
#else
    csbi.dwCursorPosition.X = 0;
    SetConsoleCursorPosition(console_, csbi.dwCursorPosition);
#endif
  }

  if (smart_terminal_ && type == ELIDE) {
#ifdef _WIN32
    // Don't use the full width or console will move to next line.
    size_t width = static_cast<size_t>(csbi.dwSize.X) - 1;
    to_print = ElideMiddle(to_print, width);
    // We don't want to have the cursor spamming back and forth, so
    // use WriteConsoleOutput instead which updates the contents of
    // the buffer, but doesn't move the cursor position.
    GetConsoleScreenBufferInfo(console_, &csbi);
    COORD buf_size = { csbi.dwSize.X, 1 };
    COORD zero_zero = { 0, 0 };
    SMALL_RECT target = {
      csbi.dwCursorPosition.X, csbi.dwCursorPosition.Y,
      static_cast<SHORT>(csbi.dwCursorPosition.X + csbi.dwSize.X - 1),
      csbi.dwCursorPosition.Y
    };
    CHAR_INFO* char_data = new CHAR_INFO[csbi.dwSize.X];
    memset(char_data, 0, sizeof(CHAR_INFO) * csbi.dwSize.X);
    for (int i = 0; i < csbi.dwSize.X; ++i) {
      char_data[i].Char.AsciiChar = ' ';
      char_data[i].Attributes = csbi.wAttributes;
    }
    for (size_t i = 0; i < to_print.size(); ++i)
      char_data[i].Char.AsciiChar = to_print[i];
    WriteConsoleOutput(console_, char_data, buf_size, zero_zero, &target);
    delete[] char_data;
#else
    // Limit output to width of the terminal if provided so we don't cause
    // line-wrapping.
    winsize size;
    if ((ioctl(0, TIOCGWINSZ, &size) == 0) && size.ws_col) {
      to_print = ElideMiddle(to_print, size.ws_col);
    }
    printf("%s", to_print.c_str());
    printf("\x1B[K");  // Clear to end of line.
    fflush(stdout);
#endif

    have_blank_line_ = false;
  } else {
    printf("%s\n", to_print.c_str());
  }
}

void LinePrinter::PrintOnNewLine(const string& to_print) {
  if (!have_blank_line_)
    printf("\n");
  printf("%s", to_print.c_str());
  have_blank_line_ = to_print.empty() || *to_print.rbegin() == '\n';
}