Merge pull request #1873 from jqnatividad/1871-select-underscore-last…

…-column

`select`: use underscore char (_) to indicate last column, replacing 9999 sentinel value

src/cmd/select.rs

@@ -21,11 +21,11 @@ selected using regular expressions.
  Select the third column named 'Foo':
  $ qsv select 'Foo[2]'
 
- Select the first and last columns, 9999 is a special index for the last column:
- $ qsv select 1,9999
+ Select the first and last columns, _ is a special character for the last column:
+ $ qsv select 1,_
 
  Reverse the order of columns:
- $ qsv select 9999-1
+ $ qsv select _-1
 
  Sort the columns lexicographically. Note that you must provide a dummy selector:
  $ qsv select 1 --sort

src/select.rs

@@ -157,6 +157,10 @@ impl SelectorParser {
  self.bump();
  self.parse_quoted_name()?
  } else {
+ if self.cur() == Some('_') {
+ self.bump();
+ return Ok(OneSelector::End);
+ }
  self.parse_name()
  };
  Ok(if self.cur() == Some('[') {
@@ -318,14 +322,10 @@ impl OneSelector {
  } else {
  first_record.len() - 1
  }),
- OneSelector::Index(mut i) => {
+ OneSelector::Index(i) => {
  if first_record.is_empty() {
  return fail!("Input is empty.");
  }
- // 9999 is a sentinel value that means "last column".
- if i == 9999 {
- i = first_record.len();
- }
  if i < 1 || i > first_record.len() {
  fail_format!(
  "Selector index {i} is out of bounds. Index must be >= 1 and <= {}.",

tests/test_select.rs

@@ -180,7 +180,7 @@ select_test!(
 
 select_test!(
  select_reverse_sentinel,
- r#"9999-1"#,
+ r#"_-1"#,
  "5-1",
  ["h1", "h4", "h[]3", "h2", "h1"],
  ["e", "d", "c", "b", "a"]