Add support for inline environment variables

This patch adds the 'Notes' rune (`=`), which allows for passing
environment variables, inline, to a binary, like so:

  EDITOR=vim sudo visudo

Signed-off-by: Rory Dudley <rory@netc.lu>

1 files changed, 15 insertions, 1 deletions

diff --git a/src/poem/read.rs b/src/poem/read.rs
index 99e9aa6..baf6a1d 100644
--- a/src/poem/read.rs
+++ b/src/poem/read.rs
@@ -246,6 +246,7 @@ impl Readable for Poem {
                 '#' => Rune::Remark,
                 '\'' | '"' => Rune::String,
                 '`' => Rune::Poem,
+                '=' => Rune::Notes,
                 '<' => Rune::Read,
                 '>' => next(&mut chars, &mut i, Rune::Write, vec![(">", Rune::Addendum)]),
                 '1' => next(
@@ -352,7 +353,11 @@ impl Readable for Poem {
             match rune {
                 // Indicates the end of a word (space dilineated)
                 Rune::Pause => {
+                    if word.contains(&'=') && verse.is_empty() {
+                        channel = Some(Rune::Notes);
+                    }
                     verse.add(&mut word, channel);
+                    channel = Some(rune);
                 }
 
                 Rune::Special => {
@@ -378,6 +383,15 @@ impl Readable for Poem {
                     poem!(chars, j, i, c, verse, word, env);
                 }
 
+                // Indicates an environment variable to fork with,
+                // if the verse's stanza is empty so far
+                // Rune::Environment => {
+                //     word.push(c);
+                //     if verse.is_empty() {
+                //         channel = Some(rune);
+                //     }
+                // }
+
                 // Indicates a file operation (<, >, or >>)
                 Rune::Read
                 | Rune::Write
@@ -388,7 +402,7 @@ impl Readable for Poem {
                 | Rune::AddendumAll => {
                     channel = Some(rune);
                     verse.add(&mut word, channel);
-                    channel = Some(rune);
+                    // channel = Some(rune);
                     verse.io.push(rune);
                 }