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.

2 files changed, 65 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!(),
     }
 }
diff --git a/src/poem/anthology/which.rs b/src/poem/anthology/which.rs
new file mode 100644
index 0000000..515b52e
--- /dev/null
+++ b/src/poem/anthology/which.rs
@@ -0,0 +1,61 @@
+use crate::compose::Environment;
+use crate::poem::Verse;
+
+pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &Environment) -> i32 {
+    let mut status = 0;
+    match verse.clause() {
+        Some(clause) => {
+            let mut output: String;
+            for word in clause {
+                // Check if it's an alias
+                if env.aliases.contains_key(&word) {
+                    output = format!("{}: aliased to {}\n", word, env.aliases.get(&word).unwrap());
+                    if verse.couplet > 0 {
+                        out.append(&mut output.as_bytes().to_vec());
+                    } else {
+                        print!("{}", output);
+                    }
+                    continue;
+                }
+
+                // Check if it's a built-in
+                match super::lookup(&word) {
+                    Some(_) => {
+                        output = format!("{}: shell built-in command\n", word);
+                        if verse.couplet > 0 {
+                            out.append(&mut output.as_bytes().to_vec());
+                        } else {
+                            print!("{}", output);
+                        }
+                        continue;
+                    }
+                    None => {}
+                }
+
+                // Manually check the path
+                let mut verb = Verse::new();
+                verb.push(word.clone());
+                match verb.spellcheck(&env.bins) {
+                    Some(i) => {
+                        output = format!("{}\n", env.bins[i]);
+                        if verse.couplet > 0 {
+                            out.append(&mut output.as_bytes().to_vec());
+                        } else {
+                            print!("{}", output);
+                        }
+                    }
+                    None => {
+                        output = format!("{} not found\n", word);
+                        status = 1;
+                        eprint!("{}", output);
+                    }
+                }
+            }
+        }
+        None => {
+            eprintln!("which: not enough arguments");
+            return 1;
+        }
+    }
+    status
+}