From 5fc3a4c6aa6cd5378d417f98b66f76529c4341e4 Mon Sep 17 00:00:00 2001
From: chiba <chiba@30ef5769-5b8d-40dd-aea6-55b5d6557bb3>
Date: Fri, 16 May 2003 17:07:03 +0000
Subject: [PATCH] modified the semantics of ($r).

git-svn-id: http://anonsvn.jboss.org/repos/javassist/trunk@16 30ef5769-5b8d-40dd-aea6-55b5d6557bb3
---
 src/main/javassist/compiler/CodeGen.java     | 24 +++++++++++++
 src/main/javassist/compiler/JvstCodeGen.java | 37 ++++++++++++++------
 tutorial/tutorial2.html                      | 19 ++++++++--
 3 files changed, 66 insertions(+), 14 deletions(-)

diff --git a/src/main/javassist/compiler/CodeGen.java b/src/main/javassist/compiler/CodeGen.java
index 60170dbb..e0b2dfa4 100644
--- a/src/main/javassist/compiler/CodeGen.java
+++ b/src/main/javassist/compiler/CodeGen.java
@@ -192,6 +192,30 @@ public abstract class CodeGen extends Visitor implements Opcode, TokenId {
         return sbuf.toString();
     }
 
+    protected static int jvmTypeNameToExprType(char type) {
+        switch(type) {
+        case 'Z' :
+            return BOOLEAN;
+        case 'B' :
+            return BYTE;
+        case 'C' :
+            return CHAR;
+        case 'S' :
+            return SHORT;
+        case 'I' :
+            return INT;
+        case 'J' :
+            return LONG;
+        case 'F' :
+            return FLOAT;
+        case 'D' :
+            return DOUBLE;
+        case 'V' :
+            return VOID;
+        default :
+            return CLASS;
+        }
+    }
 
     public void atASTList(ASTList n) throws CompileError { fatal(); }
     
diff --git a/src/main/javassist/compiler/JvstCodeGen.java b/src/main/javassist/compiler/JvstCodeGen.java
index 0090f851..40d39a11 100644
--- a/src/main/javassist/compiler/JvstCodeGen.java
+++ b/src/main/javassist/compiler/JvstCodeGen.java
@@ -184,10 +184,18 @@ public class JvstCodeGen extends MemberCodeGen {
      */
     protected void atCastToRtype(CastExpr expr) throws CompileError {
         expr.getOprand().accept(this);
-        if (!isRefType(exprType) || arrayDim > 0)
-            throw new CompileError("invalid type for " + returnCastName);
-
-        compileUnwrapValue(returnType, bytecode);
+        if (exprType == VOID || isRefType(exprType) || arrayDim > 0)
+            compileUnwrapValue(returnType, bytecode);
+        else if (returnType instanceof CtPrimitiveType) {
+            CtPrimitiveType pt = (CtPrimitiveType)returnType;
+            int destType = jvmTypeNameToExprType(pt.getDescriptor());
+            atNumCastExpr(exprType, destType);
+            exprType = destType;
+            arrayDim = 0;
+            className = null;
+        }
+        else
+            throw new CompileError("invalid cast");
     }
 
     protected void atCastToWrapper(CastExpr expr) throws CompileError {
@@ -583,15 +591,22 @@ public class JvstCodeGen extends MemberCodeGen {
     protected void compileUnwrapValue(CtClass type, Bytecode code)
         throws CompileError
     {
+        if (type == CtClass.voidType) {
+            addNullIfVoid();
+            return;
+        }
+
+        if (exprType == VOID)
+            throw new CompileError("invalid type for " + returnCastName);
+
         if (type instanceof CtPrimitiveType) {
             CtPrimitiveType pt = (CtPrimitiveType)type;
-            if (pt != CtClass.voidType) {
-                String wrapper = pt.getWrapperName();
-                code.addCheckcast(wrapper);
-                code.addInvokevirtual(wrapper, pt.getGetMethodName(),
-                                      pt.getGetMethodDescriptor());
-                setType(type);
-            }
+            // pt is not voidType.
+            String wrapper = pt.getWrapperName();
+            code.addCheckcast(wrapper);
+            code.addInvokevirtual(wrapper, pt.getGetMethodName(),
+                                  pt.getGetMethodDescriptor());
+            setType(type);
         }
         else {
             code.addCheckcast(type);
diff --git a/tutorial/tutorial2.html b/tutorial/tutorial2.html
index 62c26a94..b9ca5bed 100644
--- a/tutorial/tutorial2.html
+++ b/tutorial/tutorial2.html
@@ -350,15 +350,28 @@ For example, this is a typical use:
 $_ = ($r)result;</pre></ul>
 
 <p>If the result type is a primitive type, then <code>($r)</code>
-converts from the wrapper type to the primitive type.
+follows special semantics.  First, if the operand type of the cast
+expression is a primitive type, <code>($r)</code> works as a normal
+cast operator to the result type.
+On the other hand, if the operand type is a wrapper type,
+<code>($r)</code> converts from the wrapper type to the result type.
 For example, if the result type is <code>int</code>, then
 <code>($r)</code> converts from <code>java.lang.Integer</code> to
 <code>int</code>.
 
 <p>If the result type is <code>void</code>, then
 <code>($r)</code> does not convert a type; it does nothing.
-Moreover, the soruce text can include a <code>return</code>
-statement with a resulting value:
+However, if the operand is a call to a <code>void</code> method,
+then <code>($r)</code> results in <code>null</code>.  For example,
+
+<ul><pre>$_ = ($r)foo();</pre></ul>
+
+<p>is a valid statement if the result type is <code>void</code>.
+Here, <code>foo()</code> is a <code>void</code> method.
+
+<p>The cast operator <code>($r)</code> is also useful in a
+<code>return</code> statement.  Even if the result type is
+<code>void</code>, the following <code>return</code> statement is valid:
 
 <ul><pre>return ($r)result;</pre></ul>
 
-- 
2.39.5