From ac4d39f9db28743b6c1e9def7a61241a50b02335 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Sun, 28 Mar 2004 21:15:01 +0000
Subject: * Added an operator `?' to test for attribute existence, e.g.,  
 `attrs ? x' yields true iff `attrs' has an attribute named `x'.

---
 src/libexpr/eval.cc | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'src/libexpr/eval.cc')

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2281ee7212..0623e49532 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -288,10 +288,17 @@ Expr evalExpr2(EvalState & state, Expr e)
     if (atMatch(m, e) >> "OpOr" >> e1 >> e2)
         return makeBool(evalBool(state, e1) || evalBool(state, e2));
 
-    /* Attribut set update (//). */
+    /* Attribute set update (//). */
     if (atMatch(m, e) >> "OpUpdate" >> e1 >> e2)
         return updateAttrs(evalExpr(state, e1), evalExpr(state, e2));
 
+    /* Attribute existence test (?). */
+    if (atMatch(m, e) >> "OpHasAttr" >> e1 >> name) {
+        ATermMap attrs;
+        queryAllAttrs(evalExpr(state, e1), attrs);
+        return makeBool(attrs.get(name) != 0);
+    }
+
     /* Barf. */
     throw badTerm("invalid expression", e);
 }
-- 
cgit 1.4.1