cat function Null safety
Concatenates files in paths
to stdout or File.
output
should be an IOSink like stdout or a File.input
can be stdin.log
is used for debugging/testing purposes.
The remaining optional parameters are similar to the GNU cat utility.
Implementation
Future<CatResult> cat(List<String> paths, Object output,
{Stream<List<int>>? input,
List<String>? log,
bool showEnds = false,
bool numberNonBlank = false,
bool showLineNumbers = false,
bool showTabs = false,
bool squeezeBlank = false,
bool showNonPrinting = false}) async {
var result = CatResult();
var lineNumber = 1;
log?.clear();
if (paths.isEmpty) {
if (input != null) {
final lines = await _readStream(input);
try {
await _writeLines(
lines,
lineNumber,
output,
log,
showEnds,
showLineNumbers,
numberNonBlank,
showTabs,
squeezeBlank,
showNonPrinting);
} catch (e) {
result.addMessage(exitFailure, '$e');
}
}
} else {
for (final path in paths) {
try {
final Stream<String> lines;
if (path == '-' && input != null) {
lines = await _readStream(input);
} else {
lines = utf8.decoder
.bind(File(path).openRead())
.transform(const LineSplitter());
}
lineNumber = await _writeLines(
lines,
lineNumber,
output,
log,
showEnds,
showLineNumbers,
numberNonBlank,
showTabs,
squeezeBlank,
showNonPrinting);
} on FileSystemException catch (e) {
final String? osMessage = e.osError?.message;
final String message;
if (osMessage != null && osMessage.isNotEmpty) {
message = osMessage;
} else {
message = e.message;
}
result.addMessage(exitFailure, message, path: path);
} on FormatException {
result.addMessage(exitFailure, 'Binary file not supported.',
path: path);
} catch (e) {
result.addMessage(exitFailure, '$e', path: path);
}
}
}
return result;
}