Add the 'alias' built-in command

The shell now has support for aliases (via alias foo=bar). The 'unalias'
command is also available to remove aliases. Finally,
Environment::aliases was changed to be a HashMap<String, String>,
instead of a Vec<String>.

Since the verse's verb might change (for instance, it is an environment
variable, or an alias), add another check in Poem::recite, which simply
continues, instead of running the spellchecker, if the verb is empty.

1 files changed, 8 insertions, 5 deletions

diff --git a/src/poem/anthology.rs b/src/poem/anthology.rs
index 7d97ab7..94b5f6b 100644
--- a/src/poem/anthology.rs
+++ b/src/poem/anthology.rs
@@ -1,12 +1,13 @@
-pub mod cd;
-pub mod exit;
-pub mod export;
-pub mod source;
+mod alias;
+mod cd;
+mod exit;
+mod export;
+mod source;
 use crate::compose::Environment;
 use crate::poem::Verse;
 
 /// A static list of all the built-in commands
-static INDEX: [&str; 4] = ["cd", "exit", "export", "source"];
+static INDEX: [&str; 6] = ["alias", "cd", "exit", "export", "source", "unalias"];
 
 /// Lookup the index of a built-in command
 ///
@@ -23,10 +24,12 @@ pub fn lookup(verb: &str) -> Option<usize> {
 pub fn incant(verse: &Verse, index: usize, env: &mut Environment) -> i32 {
     let verb = INDEX[index];
     match verb {
+        "alias" => alias::incant(verse, &mut env.aliases),
         "cd" => cd::incant(verse),
         "exit" => exit::incant(),
         "export" => export::incant(verse),
         "source" => source::incant(verse, env),
+        "unalias" => alias::unincant(verse, &mut env.aliases),
         _ => unreachable!(),
     }
 }