Add nu script execution capabilities

Signed-off-by: trivernis <trivernis@protonmail.com>

.gitignore

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+/target
+test.nu

Cargo.toml

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+[package]
+name = "tourmaline"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+name = "tourmaline"
+
+[[bin]]
+name = "tml"
+path = "src/main.rs"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+clap = "3.2.22"
+color-eyre = "0.6.2"
+nu-cli = "0.68.1"
+nu-command = "0.68.1"
+nu-protocol = "0.68.1"
+thiserror = "1.0.35"
+tokio = { version = "1.21.1", features = ["rt", "io-std", "io-util", "process", "time", "macros", "tracing", "fs"] }
+tracing = "0.1.36"
+tracing-subscriber = "0.3.15"

src/lib.rs

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+use scripting::executor::NuExecutor;
+
+mod scripting;
+
+pub fn test_execute(script: String) {
+    NuExecutor::new(script).execute();
+}

src/main.rs

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+use std::env::args;
+
+fn main() {
+    let script_path = args().skip(1).next().unwrap();
+    tourmaline::test_execute(script_path);
+}

src/scripting/executor.rs

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+#![allow(unused)]
+use nu_protocol::{PipelineData, Span};
+
+/// An executor for nu scripts
+pub struct NuExecutor {
+    script_path: String,
+    args: Vec<String>,
+}
+
+impl NuExecutor {
+    pub fn new(script_path: String) -> Self {
+        Self {
+            script_path,
+            args: Vec::new(),
+        }
+    }
+
+    pub fn add_arg<S: ToString>(&mut self, arg: S) -> &mut Self {
+        self.args.push(arg.to_string());
+
+        self
+    }
+
+    pub fn add_args<S: ToString, I: IntoIterator<Item = S>>(&mut self, args: I) -> &mut Self {
+        let mut args = args.into_iter().map(|a| a.to_string()).collect::<Vec<_>>();
+        self.args.append(&mut args);
+
+        self
+    }
+
+    pub fn execute(&mut self) {
+        let mut engine_state = nu_command::create_default_context();
+        let mut stack = nu_protocol::engine::Stack::new();
+        let input = PipelineData::new(Span::new(0, 0));
+        let init_cwd = nu_cli::get_init_cwd();
+        nu_cli::gather_parent_env_vars(&mut engine_state, &init_cwd);
+
+        nu_cli::evaluate_file(
+            self.script_path.clone(),
+            &self.args,
+            &mut engine_state,
+            &mut stack,
+            input,
+            false,
+        )
+        .unwrap();
+    }
+}

src/scripting/mod.rs

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+pub mod executor;
+mod loader;