Add comm utility

README.md

@@ -48,7 +48,7 @@ count below and mark it as done in this README.md. Thanks!
 GNU coreutils. They are not 100% compatiable. If you encounter different behaviors,
 compare against the true GNU coreutils version on the Linux-based tests first.
 
-## Completed (74/109) - 68% done!
+## Completed (75/109) - 69% done!
 
 |  Done   | Cmd       | Descripton                                       | Windows | 
 | :-----: | --------- | ------------------------------------------------ | ------- |
@@ -66,7 +66,7 @@ compare against the true GNU coreutils version on the Linux-based tests first.
 |         | chown     | Change file owner and group                      |         |
 |         | chroot    | Run a command with a different root directory    |         |
 | ✓ | cksum     | Print CRC checksum and byte counts               | ✓ |
-|         | comm      | Compare two sorted files line by line            | ✓ |
+| ✓ | comm      | Compare two sorted files line by line            | ✓ |
 |         | coreutils | Multi-call program                               | ✓ |
 | ✓ | cp        | Copy files and directories                       | ✓ |
 |         | csplit    | Split a file into context-determined pieces      | ✓ |

common/common.c.v

@@ -14,7 +14,7 @@ fn C.GetConsoleOutputCP() u32 // ref: <https://learn.microsoft.com/en-us/windows
 fn C.GetOEMCP() u32 // ref: <https://learn.microsoft.com/en-us/windows/win32/api/winnls/nf-winnls-getoemcp> @@ <https://archive.is/Cvtvm>
 
 fn init() {
-	C.setlocale(C.LC_ALL, ''.str)
+	C.setlocale(C.LC_ALL, c'')
 }
 
 // is_utf8 returns whether the locale supports UTF-8 or not

src/comm/comm.v

@@ -0,0 +1,205 @@
+module main
+
+import os
+import io
+import common
+
+struct Settings {
+	suppress_col1    bool
+	suppress_col2    bool
+	suppress_col3    bool
+	check_order      bool
+	nocheck_order    bool
+	output_delimiter string
+	zero_terminated  bool
+	show_total       bool
+}
+
+fn main() {
+	mut fp := common.flag_parser(os.args)
+	fp.application('comm')
+	fp.description('Compare two sorted files line by line')
+	fp.version(common.coreutils_version())
+
+	suppress_col1 := fp.bool('', `1`, false, 'suppress column 1 (lines unique to FILE1)')
+	suppress_col2 := fp.bool('', `2`, false, 'suppress column 2 (lines unique to FILE2)')
+	suppress_col3 := fp.bool('', `3`, false, 'suppress column 3 (lines that appear in both files)')
+	check_order := fp.bool('check-order', 0, false, 'check that the input is correctly sorted, even if all input lines are pairable')
+	nocheck_order := fp.bool('nocheck-order', 0, false, 'do not check that the input is correctly sorted')
+	output_delimiter := fp.string('output-delimiter', 0, '\t', 'separate columns with STRING')
+	zero_terminated := fp.bool('zero-terminated', `z`, false, 'line delimiter is NUL, not newline')
+	total := fp.bool('total', 0, false, 'output a summary')
+
+	positional_args := fp.finalize() or {
+		eprintln(err)
+		println(fp.usage())
+		exit(1)
+	}
+
+	if positional_args.len != 2 {
+		eprintln('comm: missing operand')
+		eprintln("Try 'comm --help' for more information.")
+		exit(1)
+	}
+
+	settings := Settings{
+		suppress_col1:    suppress_col1
+		suppress_col2:    suppress_col2
+		suppress_col3:    suppress_col3
+		check_order:      check_order
+		nocheck_order:    nocheck_order
+		output_delimiter: output_delimiter
+		zero_terminated:  zero_terminated
+		show_total:       total
+	}
+
+	run(settings, positional_args[0], positional_args[1])
+}
+
+fn run(settings Settings, file1_path string, file2_path string) {
+	mut file1 := open_file_or_stdin(file1_path) or {
+		common.exit_with_error_message('comm', '${err}')
+	}
+	defer {
+		file1.close()
+	}
+
+	mut file2 := open_file_or_stdin(file2_path) or {
+		common.exit_with_error_message('comm', '${err}')
+	}
+	defer {
+		file2.close()
+	}
+
+	mut reader1 := io.new_buffered_reader(reader: file1)
+	mut reader2 := io.new_buffered_reader(reader: file2)
+
+	delimiter := if settings.zero_terminated { `\0` } else { `\n` }
+
+	mut line1 := read_line(mut reader1, delimiter) or { '' }
+	mut line2 := read_line(mut reader2, delimiter) or { '' }
+	mut prev_line1 := ''
+	mut prev_line2 := ''
+
+	mut col1_count := 0
+	mut col2_count := 0
+	mut col3_count := 0
+
+	check_order := !settings.nocheck_order && settings.check_order
+
+	for {
+		// Check sort order if needed
+		if check_order {
+			if line1 != '' && prev_line1 != '' && line1 < prev_line1 {
+				eprintln('comm: file 1 is not in sorted order')
+				exit(1)
+			}
+			if line2 != '' && prev_line2 != '' && line2 < prev_line2 {
+				eprintln('comm: file 2 is not in sorted order')
+				exit(1)
+			}
+		}
+
+		// Both files exhausted
+		if line1 == '' && line2 == '' {
+			break
+		}
+
+		// File 2 exhausted or line1 comes before line2
+		if line2 == '' || (line1 != '' && line1 < line2) {
+			if !settings.suppress_col1 {
+				print_column(1, line1, settings)
+			}
+			col1_count++
+			prev_line1 = line1
+			line1 = read_line(mut reader1, delimiter) or { '' }
+		}
+		// File 1 exhausted or line2 comes before line1
+		else if line1 == '' || line2 < line1 {
+			if !settings.suppress_col2 {
+				print_column(2, line2, settings)
+			}
+			col2_count++
+			prev_line2 = line2
+			line2 = read_line(mut reader2, delimiter) or { '' }
+		}
+		// Lines are equal
+		else {
+			if !settings.suppress_col3 {
+				print_column(3, line1, settings)
+			}
+			col3_count++
+			prev_line1 = line1
+			prev_line2 = line2
+			line1 = read_line(mut reader1, delimiter) or { '' }
+			line2 = read_line(mut reader2, delimiter) or { '' }
+		}
+	}
+
+	if settings.show_total {
+		if !settings.suppress_col1 {
+			print('${col1_count}')
+		}
+		if !settings.suppress_col2 {
+			if !settings.suppress_col1 {
+				print(settings.output_delimiter)
+			}
+			print('${col2_count}')
+		}
+		if !settings.suppress_col3 {
+			if !settings.suppress_col1 || !settings.suppress_col2 {
+				print(settings.output_delimiter)
+			}
+			print('${col3_count}')
+		}
+		print('\ttotal\n')
+	}
+}
+
+fn open_file_or_stdin(path string) !os.File {
+	if path == '-' {
+		return os.stdin()
+	}
+	return os.open(path)!
+}
+
+fn read_line(mut reader io.BufferedReader, delimiter u8) !string {
+	line := reader.read_line(delim: delimiter)!
+	if line.len > 0 && line[line.len - 1] == delimiter {
+		return line[..line.len - 1]
+	}
+	return line
+}
+
+fn print_column(column int, text string, settings Settings) {
+	mut prefix := ''
+
+	// Add tabs based on which columns are being printed
+	match column {
+		1 {
+			// Column 1 has no prefix
+		}
+		2 {
+			// Column 2 has one tab if column 1 is being printed
+			if !settings.suppress_col1 {
+				prefix = settings.output_delimiter
+			}
+		}
+		3 {
+			// Column 3 has tabs for each unsuppressed column before it
+			if !settings.suppress_col1 {
+				prefix += settings.output_delimiter
+			}
+			if !settings.suppress_col2 {
+				prefix += settings.output_delimiter
+			}
+		}
+		else {}
+	}
+
+	if settings.zero_terminated {
+		print('${prefix}${text}\0')
+	} else {
+		println('${prefix}${text}')
+	}
+}