From bfd7d85d9c5570b8085d62297669e7526a4cc9bc Mon Sep 17 00:00:00 2001
From: MilkeeyCat <milkeeycat@gmail.com>
Date: Mon, 3 Jun 2024 13:31:56 +0300
Subject: [PATCH] feat(type): `castable` method

---
 src/parser/expr/expr.rs | 12 +++++++++---
 src/parser/type_.rs     | 10 ++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/parser/expr/expr.rs b/src/parser/expr/expr.rs
index 65e2553..8eafde4 100644
--- a/src/parser/expr/expr.rs
+++ b/src/parser/expr/expr.rs
@@ -90,7 +90,7 @@ impl Expr {
             {
                 Symbol::GlobalVar(global_var) => Ok(global_var.type_.clone()),
             },
-            Self::Cast(cast) => Ok(cast.type_()),
+            Self::Cast(cast) => cast.type_(symtable),
         }
     }
 }
@@ -170,7 +170,13 @@ impl ExprCast {
         Self { type_, expr }
     }
 
-    pub fn type_(&self) -> Type {
-        self.type_.to_owned()
+    pub fn type_(&self, symbtable: &SymbolTable) -> Result<Type, TypeError> {
+        let expr_type = self.expr.type_(symbtable)?;
+
+        if expr_type.castable(&self.type_) {
+            Ok(self.type_.clone())
+        } else {
+            Err(TypeError::Cast(expr_type, self.type_.clone()))
+        }
     }
 }
diff --git a/src/parser/type_.rs b/src/parser/type_.rs
index 7e3fcf6..372d100 100644
--- a/src/parser/type_.rs
+++ b/src/parser/type_.rs
@@ -4,6 +4,7 @@ use std::fmt::Display;
 pub enum TypeError {
     Promotion(Type, Type),
     IdentNotFound(String),
+    Cast(Type, Type),
 }
 
 impl Display for TypeError {
@@ -13,6 +14,7 @@ impl Display for TypeError {
             Self::Promotion(lhs, rhs) => {
                 write!(f, "Operation between {} and {} are not allowed", lhs, rhs)
             }
+            Self::Cast(from, to) => write!(f, "Cant cast {} into {}", from, to),
         }
     }
 }
@@ -94,4 +96,12 @@ impl Type {
 
         false
     }
+
+    pub fn castable(&self, type_: &Self) -> bool {
+        if self.int() && type_.int() {
+            return true;
+        }
+
+        false
+    }
 }