Updated the way built-in commands are called/used

Previously, built-in commands were fairly primitive, merely outputting
STDOUT and STDERR with the print! macros. However, we need them to
behave like normal programs, that is:

  - Acknowledge their verse's meter (forking, piping, etc.),
  - Ability to capture STDOUT and STDERR (>, 2>),
  - and Affect the currently running environment.

For these reasons, the anthology was reworked, and now contains the
Anthology struct, which mimics both std::process::{Child, Command}.

The AnthologyStdin helper struct was also created, for built-ins to
take input on STDIN, though no built-in is currently using it.

Each built-ins' incant functions were updated to return a
std::process::Output. It contains output from STDOUT, output from
STDERR, and the exit code of the "process".

A fix was also implemented for aliases, where the STDOUT and STDERR
vectors were not being copied to the newly constructed verse.

6 files changed, 238 insertions, 63 deletions

diff --git a/src/poem/anthology/alias.rs b/src/poem/anthology/alias.rs
index 45ee7f2..0746b59 100644
--- a/src/poem/anthology/alias.rs
+++ b/src/poem/anthology/alias.rs
@@ -1,6 +1,7 @@
-use crate::poem::Verse;
 use std::collections::BTreeMap;
 use std::collections::HashMap;
+use std::os::unix::process::ExitStatusExt;
+use std::process::{ExitStatus, Output};
 
 /// alias
 ///
@@ -11,8 +12,15 @@ use std::collections::HashMap;
 /// ```sh
 /// alias vim=nvim
 /// ```
-pub fn incant(verse: &Verse, out: &mut Vec<u8>, aliases: &mut HashMap<String, String>) -> i32 {
-    match verse.clause() {
+pub fn incant(
+    clause: &Option<Vec<String>>,
+    uout: bool,
+    aliases: &mut HashMap<String, String>,
+) -> Output {
+    let status = 0;
+    let mut out: Vec<u8> = Vec::new();
+    let err: Vec<u8> = Vec::new();
+    match clause {
         Some(clause) => {
             for stanza in clause {
                 let (key, val) = match stanza.split_once("=") {
@@ -24,7 +32,7 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, aliases: &mut HashMap<String, St
         }
         None => {
             let mut lines = Vec::new();
-            let sorted: BTreeMap<_, _> = aliases.into_iter().collect();
+            let sorted: BTreeMap<_, _> = aliases.iter().collect();
             for (key, val) in sorted {
                 let line = if key.contains(' ') && val.contains(' ') {
                     format!("'{}'='{}'", key, val)
@@ -40,14 +48,19 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, aliases: &mut HashMap<String, St
                 lines.push(line);
             }
 
-            if verse.couplet > 0 {
-                *out = format!("{}\n", lines.join("\n")).as_bytes().to_vec();
+            if uout {
+                out.append(&mut format!("{}\n", lines.join("\n")).as_bytes().to_vec());
             } else {
                 println!("{}", lines.join("\n"));
             }
         }
     }
-    0
+
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
+    }
 }
 
 /// unalias
@@ -59,17 +72,34 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, aliases: &mut HashMap<String, St
 /// ```sh
 /// unalias vim
 /// ```
-pub fn unincant(verse: &Verse, aliases: &mut HashMap<String, String>) -> i32 {
-    match verse.clause() {
+pub fn unincant(
+    clause: &Option<Vec<String>>,
+    uerr: bool,
+    aliases: &mut HashMap<String, String>,
+) -> Output {
+    let out: Vec<u8> = Vec::new();
+    let mut err: Vec<u8> = Vec::new();
+
+    let status = match clause {
         Some(clause) => {
             for stanza in clause {
-                aliases.remove(&stanza);
+                aliases.remove(stanza);
             }
+            0
         }
         None => {
-            eprintln!("unalias: not enough arguments");
-            return 1;
+            if uerr {
+                err.append(&mut "unalias: not enough arguments".as_bytes().to_vec());
+            } else {
+                eprintln!("unalias: not enough arguments");
+            }
+            1
         }
+    };
+
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
     }
-    0
 }
diff --git a/src/poem/anthology/cd.rs b/src/poem/anthology/cd.rs
index 5b39359..bdf04f6 100644
--- a/src/poem/anthology/cd.rs
+++ b/src/poem/anthology/cd.rs
@@ -1,5 +1,6 @@
-use crate::poem::Verse;
 use std::env;
+use std::os::unix::process::ExitStatusExt;
+use std::process::{ExitStatus, Output};
 
 /// cd
 ///
@@ -12,27 +13,57 @@ use std::env;
 /// ```sh
 /// cd ~/.config # Change into /home/<user>/.config
 /// ```
-pub fn incant(verse: &Verse) -> i32 {
-    let path = match verse.clause() {
+pub fn incant(clause: &Option<Vec<String>>, uerr: bool) -> Output {
+    let status;
+    let out: Vec<u8> = Vec::new();
+    let mut err: Vec<u8> = Vec::new();
+    let path = match clause {
         Some(path) => path[0].to_string(),
         None => match env::var("HOME") {
             Ok(val) => val,
             Err(_) => {
-                eprintln!("cd: unknown home, staying in pwd");
-                return 1;
+                status = 1;
+                if uerr {
+                    err.append(&mut "cd: unknown home, staying in pwd\n".as_bytes().to_vec());
+                } else {
+                    eprintln!("cd: unknown home, staying in pwd");
+                }
+                return Output {
+                    status: ExitStatus::from_raw(status),
+                    stdout: out,
+                    stderr: err,
+                };
             }
         },
     };
 
-    match std::env::set_current_dir(&path) {
+    status = match std::env::set_current_dir(&path) {
         Ok(_) => 0,
         Err(e) => {
-            eprintln!(
-                "cd: unable to change into {}: {}",
-                path,
-                e.to_string().to_lowercase()
-            );
+            if uerr {
+                err.append(
+                    &mut format!(
+                        "cd: unable to change into {}: {}\n",
+                        path,
+                        e.to_string().to_lowercase()
+                    )
+                    .as_bytes()
+                    .to_vec(),
+                );
+            } else {
+                eprintln!(
+                    "cd: unable to change into {}: {}",
+                    path,
+                    e.to_string().to_lowercase()
+                );
+            }
             1
         }
+    };
+
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
     }
 }
diff --git a/src/poem/anthology/exit.rs b/src/poem/anthology/exit.rs
index 46fe13c..6bbaa33 100644
--- a/src/poem/anthology/exit.rs
+++ b/src/poem/anthology/exit.rs
@@ -1,4 +1,5 @@
 use std::process::exit;
+use std::process::Output;
 
 /// exit
 ///
@@ -7,6 +8,6 @@ use std::process::exit;
 /// # Aliases
 /// * exit
 /// * quit
-pub fn incant() -> i32 {
+pub fn incant() -> Output {
     exit(0);
 }
diff --git a/src/poem/anthology/export.rs b/src/poem/anthology/export.rs
index aa5a894..35a24ae 100644
--- a/src/poem/anthology/export.rs
+++ b/src/poem/anthology/export.rs
@@ -1,6 +1,7 @@
-use crate::poem::Verse;
 use std::collections::BTreeMap;
 use std::env;
+use std::os::unix::process::ExitStatusExt;
+use std::process::{ExitStatus, Output};
 
 /// export
 ///
@@ -15,8 +16,11 @@ use std::env;
 /// ```sh
 /// export FOO=BAR
 /// ```
-pub fn incant(verse: &Verse) -> i32 {
-    match verse.clause() {
+pub fn incant(clause: &Option<Vec<String>>, uout: bool) -> Output {
+    let status = 0;
+    let mut out: Vec<u8> = Vec::new();
+    let err: Vec<u8> = Vec::new();
+    match clause {
         Some(clause) => {
             for stanza in clause {
                 let (key, val) = match stanza.split_once("=") {
@@ -27,14 +31,25 @@ pub fn incant(verse: &Verse) -> i32 {
             }
         }
         None => {
+            let mut lines = Vec::new();
             let sorted: BTreeMap<_, _> = env::vars().into_iter().collect();
             for (key, val) in sorted {
-                println!("{}={}", key, val);
+                lines.push(format!("{}={}", key, val));
+            }
+
+            if uout {
+                out.append(&mut format!("{}\n", lines.join("\n")).as_bytes().to_vec());
+            } else {
+                println!("{}", lines.join("\n"));
             }
         }
     }
 
-    0
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
+    }
 }
 
 /// unset
@@ -47,17 +62,29 @@ pub fn incant(verse: &Verse) -> i32 {
 /// ```sh
 /// unset FOO
 /// ```
-pub fn unincant(verse: &Verse) -> i32 {
-    match verse.clause() {
+pub fn unincant(clause: &Option<Vec<String>>, uerr: bool) -> Output {
+    let mut status = 0;
+    let out: Vec<u8> = Vec::new();
+    let mut err: Vec<u8> = Vec::new();
+    match clause {
         Some(clause) => {
             for stanza in clause {
                 env::remove_var(stanza);
             }
         }
         None => {
-            eprintln!("unset: not enough arguments");
-            return 1;
+            status = 1;
+            if uerr {
+                err.append(&mut "unset: not enough arguments\n".as_bytes().to_vec());
+            } else {
+                eprintln!("unset: not enough arguments");
+            }
         }
     }
-    0
+
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
+    }
 }
diff --git a/src/poem/anthology/source.rs b/src/poem/anthology/source.rs
index 3c81110..0ed759c 100644
--- a/src/poem/anthology/source.rs
+++ b/src/poem/anthology/source.rs
@@ -1,7 +1,8 @@
 use crate::compose::Environment;
-use crate::poem::Verse;
 use crate::poem::{read::Readable, recite::Reciteable, Poem};
 use std::fs;
+use std::os::unix::process::ExitStatusExt;
+use std::process::{ExitStatus, Output};
 
 /// source
 ///
@@ -12,12 +13,29 @@ use std::fs;
 /// ```sh
 /// source ~/.dwvshrc
 /// ```
-pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &mut Environment) -> i32 {
-    let files = match verse.clause() {
+pub fn incant(
+    clause: &Option<Vec<String>>,
+    uout: bool,
+    uerr: bool,
+    env: &mut Environment,
+) -> Output {
+    let mut status = 0;
+    let mut out: Vec<u8> = Vec::new();
+    let mut err: Vec<u8> = Vec::new();
+    let files = match clause {
         Some(clause) => clause,
         None => {
-            eprintln!("source: not enough arguments");
-            return 1;
+            status = 1;
+            if uerr {
+                err.append(&mut "source: not enough arguments\n".as_bytes().to_vec());
+            } else {
+                eprintln!("source: not enough arguments");
+            }
+            return Output {
+                status: ExitStatus::from_raw(status),
+                stdout: out,
+                stderr: err,
+            };
         }
     };
 
@@ -25,31 +43,77 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &mut Environment) -> i32 {
         let poetry = match fs::read_to_string(&file) {
             Ok(poetry) => poetry,
             Err(e) => {
-                eprintln!(
-                    "source: could not load {}: {}",
-                    file,
-                    e.to_string().to_lowercase()
-                );
-                return 127;
+                status = 127;
+                if uerr {
+                    err.append(
+                        &mut format!(
+                            "source: could not load {}: {}\n",
+                            file,
+                            e.to_string().to_lowercase()
+                        )
+                        .as_bytes()
+                        .to_vec(),
+                    );
+                } else {
+                    eprintln!(
+                        "source: could not load {}: {}",
+                        file,
+                        e.to_string().to_lowercase()
+                    );
+                }
+                return Output {
+                    status: ExitStatus::from_raw(status),
+                    stdout: out,
+                    stderr: err,
+                };
             }
         };
 
         let poem = match Poem::read(poetry, env) {
             Ok(poem) => poem,
             Err(e) => {
-                eprintln!("dwvsh: {}", e.to_string().to_lowercase());
+                if uerr {
+                    err.append(
+                        &mut format!("dwvsh: {}", e.to_string().to_lowercase())
+                            .as_bytes()
+                            .to_vec(),
+                    );
+                } else {
+                    eprintln!("dwvsh: {}", e.to_string().to_lowercase());
+                }
                 continue;
             }
         };
 
-        *out = match poem.recite(env) {
-            Ok(out) => out,
+        status = match poem.recite(env) {
+            Ok(mut sout) => {
+                if uout {
+                    out.append(&mut sout);
+                } else {
+                    if !sout.is_empty() {
+                        println!("{}", String::from_utf8_lossy(&sout));
+                    }
+                }
+                0
+            }
             Err(e) => {
-                eprintln!("dwvsh: {}", e.to_string().to_lowercase());
-                continue;
+                if uerr {
+                    err.append(
+                        &mut format!("dwvsh: {}", e.to_string().to_lowercase())
+                            .as_bytes()
+                            .to_vec(),
+                    );
+                } else {
+                    eprintln!("dwvsh: {}", e.to_string().to_lowercase());
+                }
+                1
             }
         };
     }
 
-    0
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
+    }
 }
diff --git a/src/poem/anthology/which.rs b/src/poem/anthology/which.rs
index 515b52e..6fe709c 100644
--- a/src/poem/anthology/which.rs
+++ b/src/poem/anthology/which.rs
@@ -1,16 +1,20 @@
 use crate::compose::Environment;
 use crate::poem::Verse;
+use std::os::unix::process::ExitStatusExt;
+use std::process::{ExitStatus, Output};
 
-pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &Environment) -> i32 {
+pub fn incant(clause: &Option<Vec<String>>, uout: bool, uerr: bool, env: &Environment) -> Output {
     let mut status = 0;
-    match verse.clause() {
+    let mut out: Vec<u8> = Vec::new();
+    let mut err: Vec<u8> = Vec::new();
+    match 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 {
+                if env.aliases.contains_key(word) {
+                    output = format!("{}: aliased to {}\n", word, env.aliases.get(word).unwrap());
+                    if uout {
                         out.append(&mut output.as_bytes().to_vec());
                     } else {
                         print!("{}", output);
@@ -22,7 +26,7 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &Environment) -> i32 {
                 match super::lookup(&word) {
                     Some(_) => {
                         output = format!("{}: shell built-in command\n", word);
-                        if verse.couplet > 0 {
+                        if uout {
                             out.append(&mut output.as_bytes().to_vec());
                         } else {
                             print!("{}", output);
@@ -38,7 +42,7 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &Environment) -> i32 {
                 match verb.spellcheck(&env.bins) {
                     Some(i) => {
                         output = format!("{}\n", env.bins[i]);
-                        if verse.couplet > 0 {
+                        if uout {
                             out.append(&mut output.as_bytes().to_vec());
                         } else {
                             print!("{}", output);
@@ -47,15 +51,33 @@ pub fn incant(verse: &Verse, out: &mut Vec<u8>, env: &Environment) -> i32 {
                     None => {
                         output = format!("{} not found\n", word);
                         status = 1;
-                        eprint!("{}", output);
+                        if uerr {
+                            err.append(&mut output.as_bytes().to_vec());
+                        } else {
+                            eprint!("{}", output);
+                        }
                     }
                 }
             }
         }
         None => {
-            eprintln!("which: not enough arguments");
-            return 1;
+            status = 1;
+            if uerr {
+                err.append(&mut "which: not enough arguments".as_bytes().to_vec());
+            } else {
+                eprintln!("which: not enough arguments");
+            }
+            return Output {
+                status: ExitStatus::from_raw(status),
+                stdout: out,
+                stderr: err,
+            };
         }
     }
-    status
+
+    Output {
+        status: ExitStatus::from_raw(status),
+        stdout: out,
+        stderr: err,
+    }
 }