Added the 'which' built-in command

Added a built-in which command (for MacOS and BSD), which can check
aliases, and other shell built-in commands, in addition to bins on the
$PATH.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/poem/anthology.rs b/src/poem/anthology.rs
index 7766f62..8ff70f9 100644
--- a/src/poem/anthology.rs
+++ b/src/poem/anthology.rs
@@ -3,12 +3,13 @@ mod cd;
 mod exit;
 mod export;
 mod source;
+mod which;
 use crate::compose::Environment;
 use crate::poem::Verse;
 
 /// A static list of all the built-in commands
-static INDEX: [&str; 7] = [
-    "alias", "cd", "exit", "export", "source", "unalias", "unset",
+static INDEX: [&str; 8] = [
+    "alias", "cd", "exit", "export", "source", "unalias", "unset", "which",
 ];
 
 /// Lookup the index of a built-in command
@@ -53,6 +54,7 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, index: usize, env: &mut Environm
         "source" => source::incant(verse, out, env),
         "unalias" => alias::unincant(verse, &mut env.aliases),
         "unset" => export::unincant(verse),
+        "which" => which::incant(verse, out, env),
         _ => unreachable!(),
     }
 }