From 4520815c0229733eb578bdd048ff698a0e393687 Mon Sep 17 00:00:00 2001
From: Jacek Caban <jacek@codeweavers.com>
Date: Fri, 9 Sep 2011 14:49:36 +0200
Subject: [PATCH] vbscript: Added null literal support.

---
 dlls/vbscript/compile.c      |  2 ++
 dlls/vbscript/interp.c       | 20 ++++++++++++++++++--
 dlls/vbscript/parse.h        |  1 +
 dlls/vbscript/parser.y       |  1 +
 dlls/vbscript/tests/lang.vbs |  1 +
 dlls/vbscript/vbscript.h     |  1 +
 6 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/dlls/vbscript/compile.c b/dlls/vbscript/compile.c
index aa9881cc9e7..181f6c1d262 100644
--- a/dlls/vbscript/compile.c
+++ b/dlls/vbscript/compile.c
@@ -204,6 +204,8 @@ static HRESULT compile_expression(compile_ctx_t *ctx, expression_t *expr)
         return compile_member_expression(ctx, (member_expression_t*)expr, TRUE);
     case EXPR_NOT:
         return compile_unary_expression(ctx, (unary_expression_t*)expr, OP_not);
+    case EXPR_NULL:
+        return push_instr(ctx, OP_null) != -1 ? S_OK : E_OUTOFMEMORY;
     case EXPR_STRING:
         return push_instr_str(ctx, OP_string, ((string_expression_t*)expr)->value);
     default:
diff --git a/dlls/vbscript/interp.c b/dlls/vbscript/interp.c
index 4e16d742602..d02516e55a2 100644
--- a/dlls/vbscript/interp.c
+++ b/dlls/vbscript/interp.c
@@ -261,6 +261,16 @@ static HRESULT interp_empty(exec_ctx_t *ctx)
     return stack_push(ctx, &v);
 }
 
+static HRESULT interp_null(exec_ctx_t *ctx)
+{
+    VARIANT v;
+
+    TRACE("\n");
+
+    V_VT(&v) = VT_NULL;
+    return stack_push(ctx, &v);
+}
+
 static HRESULT interp_not(exec_ctx_t *ctx)
 {
     variant_val_t val;
@@ -291,8 +301,14 @@ static HRESULT cmp_oper(exec_ctx_t *ctx)
         return hres;
 
     hres = stack_pop_val(ctx, &l);
-    if(SUCCEEDED(hres))
-        hres = VarCmp(l.v, r.v, ctx->script->lcid, 0);
+    if(SUCCEEDED(hres)) {
+        if(V_VT(l.v) == VT_NULL || V_VT(r.v) == VT_NULL) {
+            FIXME("comparing nulls is not implemented\n");
+            hres = E_NOTIMPL;
+        }else {
+            hres = VarCmp(l.v, r.v, ctx->script->lcid, 0);
+        }
+    }
 
     release_val(&r);
     release_val(&l);
diff --git a/dlls/vbscript/parse.h b/dlls/vbscript/parse.h
index 409e737d262..56b3e1b6be3 100644
--- a/dlls/vbscript/parse.h
+++ b/dlls/vbscript/parse.h
@@ -22,6 +22,7 @@ typedef enum {
     EXPR_EQUAL,
     EXPR_MEMBER,
     EXPR_NOT,
+    EXPR_NULL,
     EXPR_STRING
 } expression_type_t;
 
diff --git a/dlls/vbscript/parser.y b/dlls/vbscript/parser.y
index 36ebf173bda..c1c7e61f559 100644
--- a/dlls/vbscript/parser.y
+++ b/dlls/vbscript/parser.y
@@ -147,6 +147,7 @@ LiteralExpression
     | tFALSE                        { $$ = new_bool_expression(ctx, VARIANT_FALSE); CHECK_ERROR; }
     | tString                       { $$ = new_string_expression(ctx, $1); CHECK_ERROR; }
     | tEMPTY                        { $$ = new_expression(ctx, EXPR_EMPTY, 0); CHECK_ERROR; }
+    | tNULL                         { $$ = new_expression(ctx, EXPR_NULL, 0); CHECK_ERROR; }
 
 PrimaryExpression
     : '(' Expression ')'            { $$ = $2; }
diff --git a/dlls/vbscript/tests/lang.vbs b/dlls/vbscript/tests/lang.vbs
index 3614f9686cf..8a5a9c52dbf 100644
--- a/dlls/vbscript/tests/lang.vbs
+++ b/dlls/vbscript/tests/lang.vbs
@@ -37,5 +37,6 @@ Call ok(getVT(true) = "VT_BOOL", "getVT(true) is not VT_BOOL")
 Call ok(getVT("") = "VT_BSTR", "getVT("""") is not VT_BSTR")
 Call ok(getVT("test") = "VT_BSTR", "getVT(""test"") is not VT_BSTR")
 Call ok(getVT(Empty) = "VT_EMPTY", "getVT(Empty) is not VT_EMPTY")
+Call ok(getVT(null) = "VT_NULL", "getVT(null) is not VT_NULL")
 
 reportSuccess()
diff --git a/dlls/vbscript/vbscript.h b/dlls/vbscript/vbscript.h
index aa90f4c47b1..199ca70e90c 100644
--- a/dlls/vbscript/vbscript.h
+++ b/dlls/vbscript/vbscript.h
@@ -81,6 +81,7 @@ typedef enum {
     X(icall,          1, ARG_BSTR,    ARG_UINT)   \
     X(icallv,         1, ARG_BSTR,    ARG_UINT)   \
     X(not,            1, 0,           0)          \
+    X(null,           1, 0,           0)          \
     X(ret,            0, 0,           0)          \
     X(string,         1, ARG_STR,     0)