Non-greedy String Splitting (#7)

* Add non_greedy flag

* Add non-greedy tests

* Prevent printing spaces for empty fields

* Prevent filtering non-empty fields when non-greedy

2 files changed, 63 insertions, 8 deletions

diff --git a/src/choice.rs b/src/choice.rs
index 63ddb2e..941f512 100644
--- a/src/choice.rs
+++ b/src/choice.rs
@@ -29,7 +29,10 @@ impl Choice {
         config: &Config,
         handle: &mut BufWriter<WriterType>,
     ) {
-        let mut line_iter = config.separator.split(line).filter(|s| !s.is_empty());
+        let mut line_iter = config
+            .separator
+            .split(line)
+            .filter(|s| !s.is_empty() || config.opt.non_greedy);
 
         if self.is_reverse_range() && !self.has_negative_index() {
             if self.end > 0 {
@@ -101,13 +104,18 @@ impl Choice {
     }
 
     fn write_bytes<WriterType: Write>(handle: &mut BufWriter<WriterType>, b: &[u8]) {
-        match handle.write(b) {
-            Ok(_) => (),
-            Err(e) => eprintln!("Failed to write to output: {}", e),
-        }
-        match handle.write(b" ") {
-            Ok(_) => (),
-            Err(e) => eprintln!("Failed to write to output: {}", e),
+        let num_bytes_written = match handle.write(b) {
+            Ok(x) => x,
+            Err(e) => {
+                eprintln!("Failed to write to output: {}", e);
+                0
+            }
+        };
+        if num_bytes_written > 0 {
+            match handle.write(b" ") {
+                Ok(_) => (),
+                Err(e) => eprintln!("Failed to write to output: {}", e),
+            }
         }
     }
 
@@ -513,6 +521,49 @@ mod tests {
             );
             assert_eq!(String::from(""), MockStdout::str_from_buf_writer(handle));
         }
+
+        #[test]
+        fn print_0_to_2_greedy() {
+            let config = Config::from_iter(vec!["choose", "0:2", "-f", ":"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(&String::from("a:b::c:::d"), &config, &mut handle);
+            assert_eq!(
+                String::from("a b c"),
+                MockStdout::str_from_buf_writer(handle)
+            );
+        }
+
+        #[test]
+        fn print_0_to_2_non_greedy() {
+            let config = Config::from_iter(vec!["choose", "0:2", "-n", "-f", ":"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(&String::from("a:b::c:::d"), &config, &mut handle);
+            assert_eq!(String::from("a b"), MockStdout::str_from_buf_writer(handle));
+        }
+
+        #[test]
+        fn print_2_to_neg_1_non_greedy_negative() {
+            let config = Config::from_iter(vec!["choose", "2:-1", "-n", "-f", ":"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(&String::from("a:b::c:::d"), &config, &mut handle);
+            assert_eq!(String::from("c d"), MockStdout::str_from_buf_writer(handle));
+        }
+
+        #[test]
+        fn print_2_to_0_non_greedy_reversed() {
+            let config = Config::from_iter(vec!["choose", "2:0", "-n", "-f", ":"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(&String::from("a:b::c:::d"), &config, &mut handle);
+            assert_eq!(String::from("b a"), MockStdout::str_from_buf_writer(handle));
+        }
+
+        #[test]
+        fn print_neg_1_to_neg_3_non_greedy_negative_reversed() {
+            let config = Config::from_iter(vec!["choose", "-1:-3", "-n", "-f", ":"]);
+            let mut handle = BufWriter::new(MockStdout::new());
+            config.opt.choice[0].print_choice(&String::from("a:b::c:::d"), &config, &mut handle);
+            assert_eq!(String::from("d"), MockStdout::str_from_buf_writer(handle));
+        }
     }
 
     mod is_reverse_range_tests {
diff --git a/src/opt.rs b/src/opt.rs
index 77fc710..4170fb7 100644
--- a/src/opt.rs
+++ b/src/opt.rs
@@ -12,6 +12,10 @@ pub struct Opt {
     #[structopt(short, long)]
     pub field_separator: Option<String>,
 
+    /// Use non-greedy field separators
+    #[structopt(short, long)]
+    pub non_greedy: bool,
+
     /// Use exclusive ranges, similar to array indexing in many programming languages
     #[structopt(short = "x", long)]
     pub exclusive: bool,