Utilities/cat: Add -b to number non-blank lines

Base/usr/share/man/man1/cat.md

@@ -5,13 +5,18 @@ cat - concatenate files to stdout
 ## Synopsis
 
 ```**sh
-$ cat [file...]
+$ cat [options...] [files...]
 ```
 
 ## Description
 
 This program passes contents of specified `files` to standard output, in the specified order. If no `file` is specified, or it is `-`, it defaults to standard input.
 
+## Options
+
+* `-n`, `--number`: Number all output lines
+* `-b`, `--number-non-blank`: Number non-blank output lines
+
 ## Arguments
 
 * `file`: Files to print

Tests/Utilities/CMakeLists.txt

@@ -2,6 +2,7 @@ set(TEST_SOURCES
  TestSed.cpp
  TestPatch.cpp
  TestUniq.cpp
+ TestCat.cpp
 )
 
 foreach(source IN LISTS TEST_SOURCES)

Tests/Utilities/TestCat.cpp

@@ -0,0 +1,45 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/ScopeGuard.h>
+#include <AK/StringView.h>
+#include <LibCore/Command.h>
+#include <LibCore/File.h>
+#include <LibTest/Macros.h>
+#include <LibTest/TestCase.h>
+
+static void run_cat(Vector<char const*>&& arguments, StringView standard_input, StringView expected_stdout)
+{
+ MUST(arguments.try_insert(0, "cat"));
+ MUST(arguments.try_append(nullptr));
+ auto cat = MUST(Core::Command::create("cat"sv, arguments.data()));
+ MUST(cat->write(standard_input));
+ auto [stdout, stderr] = MUST(cat->read_all());
+ auto status = MUST(cat->status());
+ if (status != Core::Command::ProcessResult::DoneWithZeroExitCode) {
+ FAIL(ByteString::formatted("cat didn't exit cleanly: status: {}, stdout:{}, stderr: {}", static_cast<int>(status), StringView { stdout.bytes() }, StringView { stderr.bytes() }));
+ }
+
+ EXPECT_EQ(StringView { expected_stdout.bytes() }, StringView { stdout.bytes() });
+}
+
+TEST_CASE(show_lines)
+{
+ run_cat({ "-n" }, "hello"sv, " 1\thello"sv);
+ run_cat({ "-n" }, "hello\nworld"sv, " 1\thello\n 2\tworld"sv);
+ run_cat({ "-n" }, "hello\n\nworld"sv, " 1\thello\n 2\t\n 3\tworld"sv);
+ run_cat({ "-n" }, "\nhello"sv, " 1\t\n 2\thello"sv);
+ run_cat({ "-n" }, "hello\n"sv, " 1\thello\n"sv);
+ run_cat({ "-n" }, "hello\n\n"sv, " 1\thello\n 2\t\n"sv);
+}
+
+TEST_CASE(show_only_non_blank_lines)
+{
+ run_cat({ "-b" }, "hello"sv, " 1\thello"sv);
+ run_cat({ "-b" }, "hello\nworld"sv, " 1\thello\n 2\tworld"sv);
+ run_cat({ "-b" }, "hello\n\nworld"sv, " 1\thello\n\n 2\tworld"sv);
+ run_cat({ "-b" }, "\nhello"sv, "\n 1\thello"sv);
+ run_cat({ "-b" }, "hello\n"sv, " 1\thello\n"sv);
+ run_cat({ "-b" }, "hello\n\n"sv, " 1\thello\n\n"sv);
+}

Userland/Utilities/cat.cpp

@@ -13,20 +13,36 @@
 
 struct LineTracker {
  size_t line_count = 1;
- bool display_line_number = true;
+ enum state : u8 {
+ LINE,
+ NEWLINES,
+ } state = NEWLINES;
 };
 
-static void output_buffer_with_line_numbers(LineTracker& line_tracker, ReadonlyBytes buffer_span)
+static void output_buffer_with_line_numbers(LineTracker& line_tracker, ReadonlyBytes buffer_span, bool show_lines = true)
 {
- for (auto const curr_value : buffer_span) {
- if (line_tracker.display_line_number) {
- out("{: >6}\t", line_tracker.line_count);
- line_tracker.line_count++;
- line_tracker.display_line_number = false;
+ for (size_t i = 0; i < buffer_span.size(); i++) {
+ if (line_tracker.state == LineTracker::state::LINE) {
+ if (buffer_span[i] == '\n') {
+ out("{:c}", buffer_span[i]);
+ line_tracker.state = LineTracker::state::NEWLINES;
+ } else {
+ out("{:c}", buffer_span[i]);
+ }
+ } else if (line_tracker.state == LineTracker::state::NEWLINES) {
+ if (buffer_span[i] == '\n') {
+ if (show_lines) {
+ out("{: >6}\t", line_tracker.line_count);
+ line_tracker.line_count++;
+ }
+ out("{:c}", buffer_span[i]);
+ } else {
+ out("{: >6}\t", line_tracker.line_count);
+ line_tracker.line_count++;
+ out("{:c}", buffer_span[i]);
+ line_tracker.state = LineTracker::state::LINE;
+ }
  }
- if (curr_value == '\n')
- line_tracker.display_line_number = true;
- out("{:c}", curr_value);
  }
 }
 
@@ -36,11 +52,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
  Vector<StringView> paths;
  bool show_lines = false;
+ bool show_only_blank_lines = false;
 
  Core::ArgsParser args_parser;
  args_parser.set_general_help("Concatenate files or pipes to stdout.");
  args_parser.add_positional_argument(paths, "File path", "path", Core::ArgsParser::Required::No);
  args_parser.add_option(show_lines, "Number all output lines", "number", 'n');
+ args_parser.add_option(show_only_blank_lines, "Number all non-blank output lines", "number-non-blank", 'b');
  args_parser.parse(arguments);
 
  if (paths.is_empty())
@@ -58,15 +76,15 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
  TRY(Core::System::pledge("stdio"));
 
- // used only if we are using the -n option
+ // used only if we are using the -n or -b option
  LineTracker line_tracker;
 
  Array<u8, 32768> buffer;
  for (auto const& file : files) {
  while (!file->is_eof()) {
  auto const buffer_span = TRY(file->read_some(buffer));
- if (show_lines) {
- output_buffer_with_line_numbers(line_tracker, buffer_span);
+ if (show_lines || show_only_blank_lines) {
+ output_buffer_with_line_numbers(line_tracker, buffer_span, show_lines);
  } else {
  out("{:s}", buffer_span);
  }