From 48cb618d5afcd082d25fcce981d22bcbd0a8b473 Mon Sep 17 00:00:00 2001
From: 0x4261756D <–38735823+0x4261756D@users.noreply.github.com>
Date: Wed, 14 Dec 2022 09:34:41 +0100
Subject: [PATCH] Add interpreter

---
 src/main.rs | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 1 deletion(-)

diff --git a/src/main.rs b/src/main.rs
index da0decf..cbac1ef 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -74,11 +74,13 @@ fn main()
 		usage()
 	}
 	let mut debug = false;
+	let mut interpret = false;
 	for arg in &args[3..]
 	{
 		match arg.as_str()
 		{
 			"-d" | "--debug" => debug = true,
+			"-i" | "--interpret" => interpret = true,
 			_ => panic!("Unknown option {}", arg),
 		}
 	}
@@ -97,11 +99,96 @@ fn main()
 			println!("---Done validating function calls---");
 			typecheck(&operations, &functions, &intrinsics, debug);
 			println!("---Done typechecking---");
+			if interpret
+			{
+				println!("---Starting to interpret the program---\n\n");
+				interpret_program(&operations, &mut Vec::new(), &functions, &intrinsics, debug);
+			}
 		}
 		_ => panic!("Unknown option {}", args[1])
 	}
 }
 
+fn interpret_program(operations: &Vec<Operation>, queue: &mut Vec<String>, functions: &Vec<Function>, intrinsics: &HashMap<&str, (Vec<Datatype>, Vec<Datatype>)>, debug: bool)
+{
+	for operation in operations
+	{
+		if debug
+		{
+			println!("before: {:?}: {:?}", operation, queue);
+		}
+		match operation
+		{
+			Operation::Dequeue(_, _) =>
+			{
+				queue.remove(0);
+			}
+			Operation::Enqueue(_, value, _, _) =>
+			{
+				queue.push(value.clone());
+			}
+			Operation::Requeue(_, _) =>
+			{
+				let val = queue.remove(0);
+				queue.push(val);
+			}
+			Operation::FunctionCall(function_name, _, _) =>
+			{
+				interpret_program(&functions.iter().find(|x| &x.name == function_name).unwrap().content, queue, functions, intrinsics, debug);
+			}
+			Operation::If(if_block, maybe_else_block, _, _) =>
+			{
+				let val = queue.remove(0);
+				// TODO: Add bool type
+				if val == "0"
+				{
+					interpret_program(if_block, queue, functions, intrinsics, debug);
+				}
+				else if let Some(else_block) = maybe_else_block
+				{
+					interpret_program(else_block, queue, functions, intrinsics, debug);
+				}
+			}
+			Operation::Intrinsic(intrinsic_name, line, col) =>
+			{
+				match intrinsic_name.as_str()
+				{
+					"print" =>
+					{
+						print!("{}", queue.remove(0));
+					}
+					"-" =>
+					{
+						let minuend = queue.remove(0).parse::<i64>().unwrap();
+						let subtrahend = queue.remove(0).parse::<i64>().unwrap();
+						queue.push((minuend - subtrahend).to_string());
+					}
+					_ =>
+					{
+						panic!("Unexpected intrinsic '{}' at {}:{}", intrinsic_name, line, col);
+					}
+				}
+			}
+			Operation::While(while_block, _, _) =>
+			{
+				loop
+				{
+					let val = queue.get(0).unwrap();
+					if val == "0"
+					{
+						break;
+					}
+					interpret_program(while_block, queue, functions, intrinsics, debug);
+				}
+			}
+		}
+		if debug
+		{
+			println!("after: {:?}: {:?}", operation, queue);
+		}
+	}
+}
+
 fn typecheck(operations: &Vec<Operation>, functions: &Vec<Function>, intrinsics: &HashMap<&str, (Vec<Datatype>, Vec<Datatype>)>, debug: bool)
 {
 	for function in functions
@@ -403,13 +490,17 @@ fn extract_functions(tokens: &mut Vec<Token>, intrinsics: &HashMap<&str, (Vec<Da
 										"any" => outs.push(Datatype::Any),
 										"str" => outs.push(Datatype::String),
 										"int" => outs.push(Datatype::Int),
-										"{" | "}" => panic!("Expected function name but got {} at {}:{}", word, line, col),
+										"{" | "}" | "deq" | "req" => panic!("Expected function name but got {} at {}:{}", word, line, col),
 										_ =>
 										{
 											if functions.iter().any(|x| &x.name == word)
 											{
 												panic!("Redeclaration of function '{}' at {}:{}", word, line, col);
 											}
+											if intrinsics.contains_key(word.as_str())
+											{
+												panic!("Function name {} at {}:{} is already an intrinsic", word, line, col);
+											}
 											if debug
 											{
 												println!("outs: {:?}", outs);