From d3f5585d071ff86fec23cbaeb447491ba0de7fcf Mon Sep 17 00:00:00 2001
From: Jeff <dev@jeffa.io>
Date: Mon, 15 Jul 2024 16:58:54 -0400
Subject: [PATCH] Add interpreter context management

---
 dust-lang/examples/interpreter_async.rs |  5 +++--
 dust-lang/src/lib.rs                    | 26 ++++++++++++++++++++-----
 dust-shell/src/cli.rs                   |  6 +++---
 dust-shell/src/main.rs                  |  7 +++----
 4 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/dust-lang/examples/interpreter_async.rs b/dust-lang/examples/interpreter_async.rs
index 7e2432a..1b3a985 100644
--- a/dust-lang/examples/interpreter_async.rs
+++ b/dust-lang/examples/interpreter_async.rs
@@ -4,7 +4,6 @@ use std::{
     time::Duration,
 };
 
-use context::Context;
 use dust_lang::*;
 
 fn run_fibnacci(interpreter: &Interpreter, i: u8) -> Value {
@@ -30,13 +29,15 @@ fn run_fibnacci(interpreter: &Interpreter, i: u8) -> Value {
 }
 
 fn main() {
-    let interpreter = Interpreter::new(Context::new());
+    let interpreter = Interpreter::new();
     let (tx, rx) = channel();
 
     for i in 1..10 {
         let interpreter = interpreter.clone();
         let tx = tx.clone();
 
+        println!("Spawning thread for fib({})", i);
+
         thread::spawn(move || {
             let value = run_fibnacci(&interpreter, i);
 
diff --git a/dust-lang/src/lib.rs b/dust-lang/src/lib.rs
index cb0f8c7..7ecbd8b 100644
--- a/dust-lang/src/lib.rs
+++ b/dust-lang/src/lib.rs
@@ -23,6 +23,7 @@ use std::{
 };
 
 pub use abstract_tree::Type;
+use standard_library::core_context;
 pub use value::Value;
 
 use abstract_tree::AbstractTree;
@@ -33,7 +34,7 @@ use lexer::{lex, Token};
 use parser::{parse, parser};
 
 pub fn interpret(source_id: &str, source: &str) -> Result<Option<Value>, InterpreterError> {
-    let interpreter = Interpreter::new(Context::new());
+    let interpreter = Interpreter::new();
 
     interpreter.run(Arc::from(source_id), Arc::from(source))
 }
@@ -44,14 +45,14 @@ pub fn interpret(source_id: &str, source: &str) -> Result<Option<Value>, Interpr
 /// used to identify the source of errors and to provide more detailed error messages.
 #[derive(Clone, Debug)]
 pub struct Interpreter {
-    context: Context,
+    contexts: Arc<RwLock<HashMap<Arc<str>, Context>>>,
     sources: Arc<RwLock<HashMap<Arc<str>, Arc<str>>>>,
 }
 
 impl Interpreter {
-    pub fn new(context: Context) -> Self {
+    pub fn new() -> Self {
         Interpreter {
-            context,
+            contexts: Arc::new(RwLock::new(HashMap::new())),
             sources: Arc::new(RwLock::new(HashMap::new())),
         }
     }
@@ -111,8 +112,9 @@ impl Interpreter {
             source_id: source_id.clone(),
             errors,
         })?;
+        let context = self.get_or_create_context(&source_id);
         let value_option = abstract_tree
-            .run(&self.context, true)
+            .run(&context, true)
             .map_err(|errors| InterpreterError { source_id, errors })?;
 
         Ok(value_option)
@@ -121,6 +123,20 @@ impl Interpreter {
     pub fn sources(&self) -> hash_map::IntoIter<Arc<str>, Arc<str>> {
         self.sources.read().unwrap().clone().into_iter()
     }
+
+    fn get_or_create_context(&self, source_id: &Arc<str>) -> Context {
+        let mut contexts = self.contexts.write().unwrap();
+
+        if let Some(context) = contexts.get(source_id) {
+            context.clone()
+        } else {
+            let context = core_context().clone();
+
+            contexts.insert(source_id.clone(), context.clone());
+
+            context
+        }
+    }
 }
 
 #[derive(Debug, PartialEq)]
diff --git a/dust-shell/src/cli.rs b/dust-shell/src/cli.rs
index 4a10698..aa9b8ef 100644
--- a/dust-shell/src/cli.rs
+++ b/dust-shell/src/cli.rs
@@ -7,7 +7,7 @@ use std::{
 };
 
 use ariadne::sources;
-use dust_lang::{context::Context, *};
+use dust_lang::*;
 use nu_ansi_term::{Color, Style};
 use reedline::{
     default_emacs_keybindings, ColumnarMenu, DefaultHinter, EditCommand, Emacs, KeyCode,
@@ -15,8 +15,8 @@ use reedline::{
     SqliteBackedHistory,
 };
 
-pub fn run_shell(context: Context) -> Result<(), io::Error> {
-    let interpreter = Interpreter::new(context.clone());
+pub fn run_shell() -> Result<(), io::Error> {
+    let interpreter = Interpreter::new();
     let mut keybindings = default_emacs_keybindings();
 
     keybindings.add_binding(
diff --git a/dust-shell/src/main.rs b/dust-shell/src/main.rs
index 63f793e..648e850 100644
--- a/dust-shell/src/main.rs
+++ b/dust-shell/src/main.rs
@@ -14,7 +14,7 @@ use std::{
     sync::Arc,
 };
 
-use dust_lang::{context::Context, Interpreter};
+use dust_lang::Interpreter;
 
 /// Command-line arguments to be parsed.
 #[derive(Parser, Debug)]
@@ -56,8 +56,7 @@ fn main() {
         .init();
 
     let args = Args::parse();
-    let context = Context::new_with_std_core().unwrap();
-    let interpreter = Interpreter::new(context.clone());
+    let interpreter = Interpreter::new();
 
     let (source_id, source): (Arc<str>, Arc<str>) = if let Some(path) = args.path {
         let source = read_to_string(&path).unwrap();
@@ -66,7 +65,7 @@ fn main() {
     } else if let Some(command) = args.command {
         (Arc::from("command"), Arc::from(command))
     } else {
-        match run_shell(context) {
+        match run_shell() {
             Ok(_) => {}
             Err(error) => eprintln!("{error}"),
         }