From e00d9afc7b7459d0421d3ff40a299f1c08b201f4 Mon Sep 17 00:00:00 2001
From: sofia <sofia@teascade.net>
Date: Wed, 21 Aug 2024 23:07:04 +0300
Subject: [PATCH] Add Scope

---
 examples/reid/easy.reid |  7 ++++-
 src/codegen/llvm.rs     |  3 +-
 src/codegen/mod.rs      | 68 +++++++++++++++++++++++++++++++++--------
 3 files changed, 63 insertions(+), 15 deletions(-)

diff --git a/examples/reid/easy.reid b/examples/reid/easy.reid
index 2dc010c..87362f3 100644
--- a/examples/reid/easy.reid
+++ b/examples/reid/easy.reid
@@ -1,5 +1,10 @@
 // Arithmetic, function calls and imports!
 
 fn main() {
-    return 5;
+    let test = 9;
+    let simpleAdd = 2 + 2;
+    let simpleMult = 7 * 2;
+    let arithmetic = 3 + 2 * 5 + 1 * 2;
+
+    return arithmetic + simpleMult * arithmetic;
 }
\ No newline at end of file
diff --git a/src/codegen/llvm.rs b/src/codegen/llvm.rs
index 04dd0c8..1252e13 100644
--- a/src/codegen/llvm.rs
+++ b/src/codegen/llvm.rs
@@ -71,6 +71,7 @@ impl<'a> Drop for IRModule<'a> {
     }
 }
 
+#[derive(Clone)]
 pub enum IRType {
     I32,
 }
@@ -86,7 +87,6 @@ impl IRType {
     }
 }
 
-#[must_use = "asd"]
 pub struct IRFunction<'a, 'b> {
     module: &'b mut IRModule<'a>,
     /// The actual function
@@ -151,6 +151,7 @@ impl<'a, 'b, 'c> Drop for IRBlock<'a, 'b, 'c> {
     }
 }
 
+#[derive(Clone)]
 pub struct IRValue {
     pub ir_type: IRType,
     ir_value: *mut LLVMValue,
diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
index c47a190..51ab6ef 100644
--- a/src/codegen/mod.rs
+++ b/src/codegen/mod.rs
@@ -1,5 +1,7 @@
 mod llvm;
 
+use std::collections::HashMap;
+
 use llvm::{IRBlock, IRContext, IRFunction, IRModule, IRValue};
 
 use crate::{
@@ -19,49 +21,89 @@ pub fn from_statements(
     statements: Vec<TopLevelStatement>,
 ) -> Result<IRModule, Error> {
     let mut module = context.module("testmod".to_owned());
+    let mut scope = ScopeData::new();
     for statement in statements {
-        statement.codegen(&mut module);
+        statement.codegen(&mut scope, &mut module);
     }
 
     Ok(module)
 }
 
 impl TopLevelStatement {
-    fn codegen(&self, module: &mut IRModule) {
+    fn codegen(&self, scope: &mut ScopeData, module: &mut IRModule) {
         match self {
-            Self::FunctionDefinition(func) => func.codegen(module),
+            Self::FunctionDefinition(func) => func.codegen(scope, module),
             Self::Import(_) => panic!("not implemented"),
         }
     }
 }
 
 impl FunctionDefinition {
-    fn codegen(&self, module: &mut IRModule) {
+    fn codegen(&self, scope: &mut ScopeData, module: &mut IRModule) {
         let FunctionDefinition(signature, block, _) = self;
-        let mut function = IRFunction::new(&signature.name, module);
-        block.codegen(&mut function)
+        let mut ir_function = IRFunction::new(&signature.name, module);
+        let ir_block = IRBlock::new(&mut ir_function);
+        block.codegen(scope.with_block(ir_block));
     }
 }
 
 impl Block {
-    fn codegen(&self, function: &mut IRFunction) {
-        let mut block = IRBlock::new(function);
-
+    fn codegen(&self, mut scope: Scope) {
         if let Some((_, return_exp)) = &self.1 {
-            let value = return_exp.codegen(&mut block);
-            block.add_return(Some(value))
+            let value = return_exp.codegen(&mut scope);
+            scope.block.add_return(Some(value));
         }
     }
 }
 
 impl Expression {
-    fn codegen(&self, block: &mut IRBlock) -> IRValue {
+    fn codegen(&self, scope: &mut Scope) -> IRValue {
         let Expression(kind, _) = self;
 
         use ExpressionKind::*;
         match kind {
-            Literal(lit) => IRValue::from_literal(lit, block),
+            Literal(lit) => IRValue::from_literal(lit, &mut scope.block),
+            VariableName(v) => scope.data.fetch(v),
             _ => panic!("expression type not supported"),
         }
     }
 }
+
+#[derive(Clone)]
+struct ScopeData {
+    vars: HashMap<String, IRValue>,
+}
+
+impl ScopeData {
+    fn new() -> ScopeData {
+        ScopeData {
+            vars: HashMap::new(),
+        }
+    }
+
+    fn with_block<'a, 'b, 'c>(&self, block: IRBlock<'a, 'b, 'c>) -> Scope<'a, 'b, 'c> {
+        Scope {
+            data: self.clone(),
+            block,
+        }
+    }
+
+    fn fetch(&self, name: &String) -> IRValue {
+        match self.vars.get(name) {
+            Some(val) => val.clone(),
+            _ => panic!("No such variable in scope: {}", name),
+        }
+    }
+
+    fn insert(&mut self, name: &String, value: IRValue) {
+        match self.vars.insert(name.clone(), value) {
+            Some(_) => panic!("{} was already defined in scope", name),
+            _ => {}
+        }
+    }
+}
+
+struct Scope<'a, 'b, 'c> {
+    data: ScopeData,
+    block: IRBlock<'a, 'b, 'c>,
+}