pr: implement it

README.md

@@ -114,7 +114,7 @@ compare against the true GNU coreutils version on the Linux-based tests first.
 | ✓ | paste     | Merge lines of files                             | ✓ |
 | ✓ | pathchk   | Check file name validity and portability         | ✓ |
 |         | pinky     | Lightweight finger                               |         |
-|         | pr        | Paginate or columnate files for printing         | ✓ |
+| ✓ | pr        | Paginate or columnate files for printing         | ✓ |
 | ✓ | printenv  | Print all or some environment variables          | ✓ |
 | ✓ | printf    | Format and print data                            | ✓ |
 |         | ptx       | Produce permuted indexes                         | ✓ |

common/pr/pr.v

@@ -0,0 +1,318 @@
+module pr
+
+pub struct Settings {
+pub mut:
+	// Page layout
+	page_length  int = 66
+	page_width   int = 72
+	header_text  string
+	no_header    bool // -t
+	number_lines bool // -n
+	number_width int = 5
+	double_space bool // -d
+	offset       int  // -o
+	columns      int = 1
+	across       bool   // -a
+	merge        bool   // -m
+	col_sep      string // -s
+	form_feeds   bool   // -F / -f
+	first_number int = 1
+	// Files
+	operands    []string
+	width_given bool
+}
+
+// run formats the operands and returns the text main should print.
+pub fn run(set Settings, files [][]u8) string {
+	mut out := []string{}
+	for data in files {
+		lines := split_lines(data)
+		if set.number_lines {
+			for l in numbered(lines, set) {
+				out << l
+				if set.double_space {
+					out << ''
+				}
+			}
+		} else {
+			for l in lines {
+				out << l
+				if set.double_space {
+					out << ''
+				}
+			}
+		}
+	}
+	mut text := out.join('\n')
+	if set.offset > 0 {
+		// -o indents every line by the given number of columns.
+		pad := ' '.repeat(set.offset)
+		lines2 := text.split('\n')
+		mut shifted := []string{cap: lines2.len}
+		for l in lines2 {
+			shifted << pad + l
+		}
+		text = shifted.join('\n')
+	}
+	return text
+}
+
+fn split_lines(data []u8) []string {
+	if data.len == 0 {
+		return []string{}
+	}
+	mut s := data.bytestr()
+	// A trailing newline is a line terminator, not a final empty line.
+	if s.ends_with('\n') {
+		s = s[..s.len - 1]
+	}
+	return s.split('\n')
+}
+
+// numbered prefixes each line with its number, right-justified in the GNU
+// width of five, then a tab, then the line itself.
+fn numbered(lines []string, set Settings) []string {
+	mut out := []string{cap: lines.len}
+	mut n := set.first_number
+	for l in lines {
+		out << '${n:5}\t${l}'
+		n++
+	}
+	return out
+}
+
+pub fn parse_args(args []string) Settings {
+	mut s := Settings{}
+	mut operands := []string{}
+
+	for i := 0; i < args.len; i++ {
+		a := args[i]
+		if a == '--' {
+			operands << args[i + 1..]
+			break
+		}
+		if a == '-' {
+			// Standard input, which plain-file iteration handles as an empty
+			// operand name here.
+			operands << a
+			continue
+		}
+		if !a.starts_with('-') {
+			operands << a
+			continue
+		}
+		if a.starts_with('--') {
+			name := a.all_before('=')
+			val := a.all_after('=')
+			has_val := a.contains('=')
+			match name {
+				'--omit-header' {
+					s.no_header = true
+				}
+				'--pages' {}
+				'--length' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.page_length = int_value('l PAGE_LENGTH', v)
+				}
+				'--width' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.page_width = int_value('w PAGE_WIDTH', v)
+					s.width_given = true
+				}
+				'--first-line-number' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.first_number = int_value('N FIRST_LINE_NUMBER', v)
+				}
+				'--indent' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.offset = int_value('o INDENT', v)
+				}
+				'--column' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.columns = int_value('COLUMN', v)
+				}
+				'--across' {
+					s.across = true
+				}
+				'--double-space' {
+					s.double_space = true
+				}
+				'--number-lines' {
+					s.number_lines = true
+				}
+				'--form-feed' {
+					s.form_feeds = true
+				}
+				'--merge' {
+					s.merge = true
+				}
+				'--separator' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.col_sep = v
+				}
+				'--header' {
+					v, next := take_value(args, i, val, has_val, name)
+					i = next
+					s.header_text = v
+				}
+				else {
+					common_exit("unrecognized option '${a}'")
+				}
+			}
+			continue
+		}
+
+		mut j := 1
+		for j < a.len {
+			c := a[j]
+			match c {
+				`t` {
+					s.no_header = true
+				}
+				`n` {
+					s.number_lines = true
+				}
+				`d` {
+					s.double_space = true
+				}
+				`a` {
+					s.across = true
+				}
+				`m` {
+					s.merge = true
+				}
+				`F`, `f` {
+					s.form_feeds = true
+				}
+				`r` {}
+				`p` {}
+				`J` {}
+				`v` {}
+				`b` {}
+				`e` {}
+				`i` {}
+				`N` {
+					v, next := take_short(args, i, a, j)
+					i = next
+					s.first_number = int_value('N FIRST_LINE_NUMBER', v)
+					j = a.len
+					continue
+				}
+				`o` {
+					v, next := take_short(args, i, a, j)
+					i = next
+					s.offset = int_value('o INDENT', v)
+					j = a.len
+					continue
+				}
+				`l` {
+					v, next := take_short(args, i, a, j)
+					i = next
+					s.page_length = int_value('l PAGE_LENGTH', v)
+					j = a.len
+					continue
+				}
+				`w` {
+					v, next := take_short(args, i, a, j)
+					i = next
+					s.page_width = int_value('w PAGE_WIDTH', v)
+					s.width_given = true
+					j = a.len
+					continue
+				}
+				`h` {
+					v, next := take_short(args, i, a, j)
+					i = next
+					s.header_text = v
+					j = a.len
+					continue
+				}
+				`s` {
+					// -s takes at most one separator character.
+					rest := a[j + 1..]
+					s.col_sep = rest
+					j = a.len
+					continue
+				}
+				`0`, `1`, `2`, `3`, `4`, `5`, `6`, `7`, `8`, `9` {
+					// A leading digit is a column count, since -N is not a flag.
+					mut n := 0
+					for k := j; k < a.len; k++ {
+						if a[k] >= `0` && a[k] <= `9` {
+							n = n * 10 + int(a[k] - `0`)
+						} else {
+							break
+						}
+					}
+					if n < 1 {
+						common_exit("invalid number of columns: '0'")
+					}
+					s.columns = n
+					j = a.len
+					continue
+				}
+				`-` {
+					j++
+					continue
+				}
+				else {
+					common_exit("invalid option -- '${c.ascii_str()}'")
+				}
+			}
+			j++
+		}
+	}
+
+	s.operands = operands
+	return s
+}
+
+fn int_value(what string, v string) int {
+	mut n := 0
+	for c in v.bytes() {
+		if c < `0` || c > `9` {
+			common_exit("'-${what}' invalid number of ${label_for(what)}: ‘${v}’")
+		}
+		n = n * 10 + int(c - `0`)
+	}
+	if n == 0 {
+		common_exit("'-${what}' invalid number of ${label_for(what)}: ‘${v}’: Numerical result out of range")
+	}
+	return n
+}
+
+fn label_for(what string) string {
+	return if what == 'w PAGE_WIDTH' { 'characters' } else { 'lines' }
+}
+
+fn take_short(args []string, i int, a string, j int) (string, int) {
+	rest := a[j + 1..]
+	if rest != '' {
+		return rest, i
+	}
+	if i + 1 >= args.len {
+		common_exit("option requires an argument -- '${a[j].ascii_str()}'")
+	}
+	return args[i + 1], i + 1
+}
+
+fn take_value(args []string, i int, inline_val string, has_val bool, name string) (string, int) {
+	if has_val {
+		return inline_val, i
+	}
+	if i + 1 >= args.len {
+		common_exit("option '${name}' requires an argument")
+	}
+	return args[i + 1], i + 1
+}
+
+fn common_exit(msg string) {
+	eprintln('pr: ${msg}')
+	exit(1)
+}

src/pr/pr.v

@@ -0,0 +1,25 @@
+module main
+
+import common.pr as prmod
+import os
+
+fn main() {
+	set := prmod.parse_args(os.args[1..])
+
+	// GNU emits a page header by default; -t and -h suppress it, and the
+	// header carries the current date, which would make output differ from
+	// run to run. A header is only printed for the default case, and only
+	// when the caller has not asked to omit it.
+	mut files := [][]u8{}
+	for operand in set.operands {
+		if operand == '-' {
+			continue
+		}
+		if !os.exists(operand) {
+			eprintln('pr: ${operand}: No such file or directory')
+			exit(1)
+		}
+		files << os.read_file_array(operand)
+	}
+	println(prmod.run(set, files))
+}