From 201ec4375413fbabccf476b8ec6277fe44e6fd7e Mon Sep 17 00:00:00 2001
From: morpheuschoo <morpheuschoo@gmail.com>
Date: Mon, 12 May 2025 02:47:48 +0800
Subject: [PATCH] feat: added static type casting

---
 .../parser/c-ast/expression/unaryExpression.ts | 13 ++++++++++---
 ctowasm/src/parser/peggyjs/parser.pegjs        | 18 +++++++++++++++++-
 ctowasm/src/processor/processExpression.ts     | 18 ++++++++++++++++++
 ctowasm/src/translator/translateExpression.ts  |  8 ++++++++
 4 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/ctowasm/src/parser/c-ast/expression/unaryExpression.ts b/ctowasm/src/parser/c-ast/expression/unaryExpression.ts
index 1e08529..e8d2428 100644
--- a/ctowasm/src/parser/c-ast/expression/unaryExpression.ts
+++ b/ctowasm/src/parser/c-ast/expression/unaryExpression.ts
@@ -2,9 +2,9 @@
  * Definition for unary expression nodes.
  */
 
-import { PostfixOperator, PrefixOperator } from "~src/common/types";
+import { PostfixOperator, PrefixOperator, ScalarCDataType } from "~src/common/types";
 import { CNodeBase, Expression } from "~src/parser/c-ast/core";
-import { DataType } from "~src/parser/c-ast/dataTypes";
+import { DataType, PrimaryDataType } from "~src/parser/c-ast/dataTypes";
 
 type UnaryExpression =
   | PostfixExpression
@@ -13,7 +13,8 @@ type UnaryExpression =
   | StructMemberAccess
   | PointerDereference
   | AddressOfExpression
-  | SizeOfExpression;
+  | SizeOfExpression
+  | TypeCastingExpression;
 
 export default UnaryExpression;
 // All unary expressions should inherit this (like function calls)
@@ -27,6 +28,12 @@ export interface PostfixExpression extends UnaryExpressionBase {
   operator: PostfixOperator;
 }
 
+export interface TypeCastingExpression extends UnaryExpressionBase {
+  type: "TypeCastingExpression";
+  expr: Expression;
+  targetDataType: PrimaryDataType;
+}
+
 export interface PrefixExpression extends UnaryExpressionBase {
   type: "PrefixExpression";
   operator: PrefixOperator;
diff --git a/ctowasm/src/parser/peggyjs/parser.pegjs b/ctowasm/src/parser/peggyjs/parser.pegjs
index 96fbe72..40c7186 100644
--- a/ctowasm/src/parser/peggyjs/parser.pegjs
+++ b/ctowasm/src/parser/peggyjs/parser.pegjs
@@ -18,6 +18,21 @@
   /**
    * Helper function to create and return a Node with position and type information
    */
+  function createTypeCastNode(type, expr) {
+    // Perform type checking for the cast
+    if (type.primaryDataType === "void") {
+      error("Cannot cast to void type");
+    }
+    if (expr.type === "StructMemberAccess" || expr.type === "StructPointerMemberAccess") {
+      error("Cannot cast struct or struct pointer types");
+    }
+
+    return generateNode("TypeCastingExpression", {
+      expr: expr,
+      targetDataType: type,
+    });
+  }
+
   function generateNode(type, data) {
     return {
       type: type,
@@ -1938,7 +1953,8 @@ multiply_divide_expression
   / unary_expression // as the last binary expression (highest precedence), this rule is needed
 
 unary_expression 
-  = operations:(@prefix_operation _)+ firstExpr:postfix_expression { return createPrefixExpressionNode(firstExpr, operations); }
+  = "(" _ type:type_name _ ")" _ expr:unary_expression { return createTypeCastNode(type, expr); }
+  / operations:(@prefix_operation _)+ firstExpr:postfix_expression { return createPrefixExpressionNode(firstExpr, operations); }
   / postfix_expression
 
 prefix_operation
diff --git a/ctowasm/src/processor/processExpression.ts b/ctowasm/src/processor/processExpression.ts
index cdaf706..36c94b5 100644
--- a/ctowasm/src/processor/processExpression.ts
+++ b/ctowasm/src/processor/processExpression.ts
@@ -270,6 +270,24 @@ export default function processExpression(
           ...returnObjectMemoryLoads.slice(1),
         ],
       };
+    } else if (expr.type === "TypeCastingExpression") {
+      // type casting is just a way to tell the compiler to treat an expression as another type
+      // no actual conversion is done here
+      const processedExpr = processExpression(expr.expr, symbolTable);
+      const targetDataType = expr.targetDataType;
+
+      return {
+        originalDataType: targetDataType,
+        exprs: [
+          {
+            type: "PreStatementExpression",
+            statements: [],
+            expr: processedExpr.exprs[0],
+            dataType: processedExpr.exprs[0].dataType,
+          },
+          ...processedExpr.exprs.slice(1),
+        ],
+      };
     } else if (expr.type === "PrefixExpression") {
       return processPrefixExpression(expr, symbolTable);
     } else if (expr.type === "PostfixExpression") {
diff --git a/ctowasm/src/translator/translateExpression.ts b/ctowasm/src/translator/translateExpression.ts
index a5bcab2..b15a7a1 100644
--- a/ctowasm/src/translator/translateExpression.ts
+++ b/ctowasm/src/translator/translateExpression.ts
@@ -42,6 +42,14 @@ export default function translateExpression(
     ) {
       return convertConstantToWasmConst(expr);
     } else if (expr.type === "PreStatementExpression") {
+      const translatedStatements = expr.statements.map((statement) =>
+        translateStatement(statement, enclosingLoopDetails),
+      );
+      const translatedExpr = translateExpression(
+        expr.expr,
+        expr.expr.dataType,
+        enclosingLoopDetails,
+      );
       return {
         type: "PreStatementExpression",
         statements: expr.statements.map((statement) =>