Add negative choice and parsing tests

Allow negative ranges as long as they aren't reversed too

Allow reversed negative ranges iff both indices are negative

src/choice.rs

@@ -1,15 +1,26 @@
+use std::convert::TryInto;
+
 use crate::config::Config;
 use crate::io::{BufWriter, Write};
 
 #[derive(Debug)]
 pub struct Choice {
-    pub start: usize,
-    pub end: usize,
+    pub start: isize,
+    pub end: isize,
+    negative_index: bool,
+    reversed: bool,
 }
 
 impl Choice {
-    pub fn new(start: usize, end: usize) -> Self {
-        Choice { start, end }
+    pub fn new(start: isize, end: isize) -> Self {
+        let negative_index = start < 0 || end < 0;
+        let reversed = end < start;
+        Choice {
+            start,
+            end,
+            negative_index,
+            reversed,
+        }
     }
 
     pub fn print_choice<WriterType: Write>(
@@ -20,9 +31,9 @@ impl Choice {
     ) {
         let mut line_iter = config.separator.split(line).filter(|s| !s.is_empty());
 
-        if self.is_reverse_range() {
+        if self.is_reverse_range() && !self.has_negative_index() {
             if self.end > 0 {
-                line_iter.nth(self.end - 1);
+                line_iter.nth((self.end - 1).try_into().unwrap());
             }
 
             let mut stack = Vec::new();
@@ -43,9 +54,37 @@ impl Choice {
                     None => break,
                 }
             }
+        } else if self.has_negative_index() {
+            let vec = line_iter.collect::<Vec<&str>>();
+
+            let start = if self.start >= 0 {
+                self.start.try_into().unwrap()
+            } else {
+                vec.len()
+                    .checked_sub(self.start.abs().try_into().unwrap())
+                    .unwrap()
+            };
+
+            let end = if self.end >= 0 {
+                self.end.try_into().unwrap()
+            } else {
+                vec.len()
+                    .checked_sub(self.end.abs().try_into().unwrap())
+                    .unwrap()
+            };
+
+            if end > start {
+                for word in vec[start..=std::cmp::min(end, vec.len() - 1)].iter() {
+                    Choice::write_bytes(handle, word.as_bytes());
+                }
+            } else if self.start < 0 {
+                for word in vec[end..=std::cmp::min(start, vec.len() - 1)].iter().rev() {
+                    Choice::write_bytes(handle, word.as_bytes());
+                }
+            }
         } else {
             if self.start > 0 {
-                line_iter.nth(self.start - 1);
+                line_iter.nth((self.start - 1).try_into().unwrap());
             }
 
             for i in 0..=(self.end - self.start) {
@@ -73,7 +112,11 @@ impl Choice {
     }
 
     pub fn is_reverse_range(&self) -> bool {
-        self.end < self.start
+        self.reversed
+    }
+
+    pub fn has_negative_index(&self) -> bool {
+        self.negative_index
     }
 }
 
@@ -383,6 +426,93 @@ mod tests {
                 MockStdout::str_from_buf_writer(handle)
             );
         }
+
+        #[test]
+        fn print_neg3_to_neg1() {
+            let config = Config::from_iter(vec!["choose", "-3:-1"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(
+                &String::from("rust lang is pretty darn cool"),
+                &config,
+                &mut handle,
+            );
+            assert_eq!(
+                String::from("pretty darn cool"),
+                MockStdout::str_from_buf_writer(handle)
+            );
+        }
+
+        #[test]
+        fn print_neg1_to_neg3() {
+            let config = Config::from_iter(vec!["choose", "-1:-3"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(
+                &String::from("rust lang is pretty darn cool"),
+                &config,
+                &mut handle,
+            );
+            assert_eq!(
+                String::from("cool darn pretty"),
+                MockStdout::str_from_buf_writer(handle)
+            );
+        }
+
+        #[test]
+        fn print_neg2_to_end() {
+            let config = Config::from_iter(vec!["choose", "-2:"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(
+                &String::from("rust lang is pretty darn cool"),
+                &config,
+                &mut handle,
+            );
+            assert_eq!(
+                String::from("darn cool"),
+                MockStdout::str_from_buf_writer(handle)
+            );
+        }
+
+        #[test]
+        fn print_start_to_neg3() {
+            let config = Config::from_iter(vec!["choose", ":-3"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(
+                &String::from("rust lang is pretty darn cool"),
+                &config,
+                &mut handle,
+            );
+            assert_eq!(
+                String::from("rust lang is pretty"),
+                MockStdout::str_from_buf_writer(handle)
+            );
+        }
+
+        #[test]
+        fn print_1_to_neg3() {
+            let config = Config::from_iter(vec!["choose", "1:-3"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(
+                &String::from("rust lang is pretty darn cool"),
+                &config,
+                &mut handle,
+            );
+            assert_eq!(
+                String::from("lang is pretty"),
+                MockStdout::str_from_buf_writer(handle)
+            );
+        }
+
+        #[test]
+        fn print_5_to_neg3_empty() {
+            let config = Config::from_iter(vec!["choose", "5:-3"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(
+                &String::from("rust lang is pretty darn cool"),
+                &config,
+                &mut handle,
+            );
+            assert_eq!(String::from(""), MockStdout::str_from_buf_writer(handle));
+        }
     }
 
     mod is_reverse_range_tests {

src/config.rs

@@ -6,7 +6,7 @@ use crate::choice::Choice;
 use crate::opt::Opt;
 
 lazy_static! {
-    static ref PARSE_CHOICE_RE: Regex = Regex::new(r"^(\d*):(\d*)$").unwrap();
+    static ref PARSE_CHOICE_RE: Regex = Regex::new(r"^(-?\d*):(-?\d*)$").unwrap();
 }
 
 pub struct Config {
@@ -66,7 +66,7 @@ impl Config {
         };
 
         let start = if cap[1].is_empty() {
-            usize::min_value()
+            0
         } else {
             match cap[1].parse() {
                 Ok(x) => x,
@@ -78,7 +78,7 @@ impl Config {
         };
 
         let end = if cap[2].is_empty() {
-            usize::max_value()
+            isize::max_value()
         } else {
             match cap[2].parse() {
                 Ok(x) => x,
@@ -115,28 +115,55 @@ mod tests {
         #[test]
         fn parse_none_started_range() {
             let result = Config::parse_choice(":5").unwrap();
-            assert_eq!((usize::min_value(), 5), (result.start, result.end))
+            assert_eq!((0, 5), (result.start, result.end))
         }
 
         #[test]
         fn parse_none_terminated_range() {
             let result = Config::parse_choice("5:").unwrap();
-            assert_eq!((5, usize::max_value()), (result.start, result.end))
+            assert_eq!((5, isize::max_value()), (result.start, result.end))
         }
 
         #[test]
-        fn parse_full_range() {
+        fn parse_full_range_pos_pos() {
             let result = Config::parse_choice("5:7").unwrap();
             assert_eq!((5, 7), (result.start, result.end))
         }
 
+        #[test]
+        fn parse_full_range_neg_neg() {
+            let result = Config::parse_choice("-3:-1").unwrap();
+            assert_eq!((-3, -1), (result.start, result.end))
+        }
+
+        #[test]
+        fn parse_neg_started_none_ended() {
+            let result = Config::parse_choice("-3:").unwrap();
+            assert_eq!((-3, isize::max_value()), (result.start, result.end))
+        }
+
+        #[test]
+        fn parse_none_started_neg_ended() {
+            let result = Config::parse_choice(":-1").unwrap();
+            assert_eq!((0, -1), (result.start, result.end))
+        }
+
+        #[test]
+        fn parse_full_range_pos_neg() {
+            let result = Config::parse_choice("5:-3").unwrap();
+            assert_eq!((5, -3), (result.start, result.end))
+        }
+
+        #[test]
+        fn parse_full_range_neg_pos() {
+            let result = Config::parse_choice("-3:5").unwrap();
+            assert_eq!((-3, 5), (result.start, result.end))
+        }
+
         #[test]
         fn parse_beginning_to_end_range() {
             let result = Config::parse_choice(":").unwrap();
-            assert_eq!(
-                (usize::min_value(), usize::max_value()),
-                (result.start, result.end)
-            )
+            assert_eq!((0, isize::max_value()), (result.start, result.end))
         }
 
         #[test]

src/opt.rs

@@ -6,6 +6,7 @@ use crate::config::Config;
 
 #[derive(Debug, StructOpt)]
 #[structopt(name = "choose", about = "`choose` sections from each line of files")]
+#[structopt(setting = structopt::clap::AppSettings::AllowLeadingHyphen)]
 pub struct Opt {
     /// Specify field separator other than whitespace
     #[structopt(short, long)]

test/choose_-4:-2.txt

@@ -0,0 +1,6 @@
+sed do eiusmod
+ad minim veniam,
+ex ea commodo
+esse cillum dolore
+non proident, sunt
+anim id est

test/e2e_test.sh

@@ -13,6 +13,7 @@ diff -w <(cargo run -- 9 3 -i ${test_dir}/lorem.txt 2>/dev/null) <(cat "${test_d
 diff -w <(cargo run -- 9 -i ${test_dir}/lorem.txt 2>/dev/null) <(cat "${test_dir}/choose_9.txt")
 diff -w <(cargo run -- 12 -i ${test_dir}/lorem.txt 2>/dev/null) <(cat "${test_dir}/choose_12.txt")
 diff -w <(cargo run -- 4:2 -i ${test_dir}/lorem.txt 2>/dev/null) <(cat "${test_dir}/choose_4:2.txt")
+diff -w <(cargo run -- -4:-2 -i ${test_dir}/lorem.txt 2>/dev/null) <(cat "${test_dir}/choose_-4:-2.txt")
 # add tests for different delimiters
 # add tests using piping