1 files changed, 194 insertions, 0 deletions
diff --git a/src/builtins/mod.rs b/src/builtins/mod.rs
new file mode 100644
index 0000000..5c7d4b6
--- /dev/null
+++ b/src/builtins/mod.rs
@@ -0,0 +1,194 @@
+use std::os::unix::process::ExitStatusExt as _;
+
+pub mod command;
+pub use command::{Child, Command};
+
+type Builtin = &'static (dyn Fn(
+    &crate::parse::Exe,
+    &crate::env::Env,
+    command::Io,
+) -> anyhow::Result<command::Child>
+              + Sync
+              + Send);
+
+#[allow(clippy::as_conversions)]
+static BUILTINS: once_cell::sync::Lazy<
+    std::collections::HashMap<&'static str, Builtin>,
+> = once_cell::sync::Lazy::new(|| {
+    let mut builtins = std::collections::HashMap::new();
+    builtins.insert("cd", &cd as Builtin);
+    builtins.insert("echo", &echo);
+    builtins.insert("and", &and);
+    builtins.insert("or", &or);
+    builtins.insert("command", &command);
+    builtins.insert("builtin", &builtin);
+    builtins
+});
+
+// clippy can't tell that the type is necessary
+#[allow(clippy::unnecessary_wraps)]
+fn cd(
+    exe: &crate::parse::Exe,
+    env: &crate::env::Env,
+    io: command::Io,
+) -> anyhow::Result<command::Child> {
+    async fn async_cd(
+        exe: &crate::parse::Exe,
+        _env: &crate::env::Env,
+        io: command::Io,
+    ) -> std::process::ExitStatus {
+        let dir = exe
+            .args()
+            .into_iter()
+            .map(std::convert::AsRef::as_ref)
+            .next()
+            .unwrap_or("");
+
+        let dir = if dir.is_empty() {
+            home()
+        } else if dir.starts_with('~') {
+            let path: std::path::PathBuf = dir.into();
+            if let std::path::Component::Normal(prefix) =
+                path.components().next().unwrap()
+            {
+                if prefix.to_str() == Some("~") {
+                    home().join(path.strip_prefix(prefix).unwrap())
+                } else {
+                    // TODO
+                    io.write_stderr(b"unimplemented\n").await.unwrap();
+                    return async_std::process::ExitStatus::from_raw(1 << 8);
+                }
+            } else {
+                unreachable!()
+            }
+        } else {
+            dir.into()
+        };
+        let code = match std::env::set_current_dir(&dir) {
+            Ok(()) => 0,
+            Err(e) => {
+                io.write_stderr(
+                    format!(
+                        "{}: {}: {}\n",
+                        exe.exe(),
+                        crate::format::io_error(&e),
+                        dir.display()
+                    )
+                    .as_bytes(),
+                )
+                .await
+                .unwrap();
+                1
+            }
+        };
+        async_std::process::ExitStatus::from_raw(code << 8)
+    }
+
+    let exe = exe.clone();
+    let env = env.clone();
+    Ok(command::Child::new_fut(async move {
+        async_cd(&exe, &env, io).await
+    }))
+}
+
+// clippy can't tell that the type is necessary
+#[allow(clippy::unnecessary_wraps)]
+// mostly just for testing and ensuring that builtins work, i'll likely remove
+// this later, since the binary seems totally fine
+fn echo(
+    exe: &crate::parse::Exe,
+    env: &crate::env::Env,
+    io: command::Io,
+) -> anyhow::Result<command::Child> {
+    async fn async_echo(
+        exe: &crate::parse::Exe,
+        _env: &crate::env::Env,
+        io: command::Io,
+    ) -> std::process::ExitStatus {
+        macro_rules! write_stdout {
+            ($bytes:expr) => {
+                if let Err(e) = io.write_stdout($bytes).await {
+                    io.write_stderr(format!("echo: {}", e).as_bytes())
+                        .await
+                        .unwrap();
+                    return async_std::process::ExitStatus::from_raw(1 << 8);
+                }
+            };
+        }
+        let count = exe.args().count();
+        for (i, arg) in exe.args().enumerate() {
+            write_stdout!(arg.as_bytes());
+            if i == count - 1 {
+                write_stdout!(b"\n");
+            } else {
+                write_stdout!(b" ");
+            }
+        }
+
+        async_std::process::ExitStatus::from_raw(0)
+    }
+
+    let exe = exe.clone();
+    let env = env.clone();
+    Ok(command::Child::new_fut(async move {
+        async_echo(&exe, &env, io).await
+    }))
+}
+
+fn and(
+    exe: &crate::parse::Exe,
+    env: &crate::env::Env,
+    io: command::Io,
+) -> anyhow::Result<command::Child> {
+    let exe = exe.shift();
+    if env.latest_status().success() {
+        let mut cmd = crate::pipeline::Command::new(&exe);
+        io.setup_command(&mut cmd);
+        Ok(command::Child::new_wrapped(cmd.spawn(env)?))
+    } else {
+        let env = env.clone();
+        Ok(command::Child::new_fut(async move { *env.latest_status() }))
+    }
+}
+
+fn or(
+    exe: &crate::parse::Exe,
+    env: &crate::env::Env,
+    io: command::Io,
+) -> anyhow::Result<command::Child> {
+    let exe = exe.shift();
+    if env.latest_status().success() {
+        let env = env.clone();
+        Ok(command::Child::new_fut(async move { *env.latest_status() }))
+    } else {
+        let mut cmd = crate::pipeline::Command::new(&exe);
+        io.setup_command(&mut cmd);
+        Ok(command::Child::new_wrapped(cmd.spawn(env)?))
+    }
+}
+
+fn command(
+    exe: &crate::parse::Exe,
+    env: &crate::env::Env,
+    io: command::Io,
+) -> anyhow::Result<command::Child> {
+    let exe = exe.shift();
+    let mut cmd = crate::pipeline::Command::new_binary(&exe);
+    io.setup_command(&mut cmd);
+    Ok(command::Child::new_wrapped(cmd.spawn(env)?))
+}
+
+fn builtin(
+    exe: &crate::parse::Exe,
+    env: &crate::env::Env,
+    io: command::Io,
+) -> anyhow::Result<command::Child> {
+    let exe = exe.shift();
+    let mut cmd = crate::pipeline::Command::new_builtin(&exe);
+    io.setup_command(&mut cmd);
+    Ok(command::Child::new_wrapped(cmd.spawn(env)?))
+}
+
+fn home() -> std::path::PathBuf {
+    std::env::var_os("HOME").unwrap().into()
+}