From 9d25466b34a5f7c1c8b1c273976cf59c33961a6c Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 4 Feb 2004 16:49:51 +0000 Subject: * An attribute set update operator (//). E.g., {x=1; y=2; z=3;} // {y=4;} => {x=1; y=4; z=3;} --- src/libexpr/eval.cc | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'src/libexpr/eval.cc') diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 802b83aa160d..eaa4b4ea444c 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -134,6 +134,18 @@ ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds) } +static Expr updateAttrs(Expr e1, Expr e2) +{ + /* Note: e1 and e2 should be in normal form. */ + + ATermMap attrs; + queryAllAttrs(e1, attrs); + queryAllAttrs(e2, attrs); + + return makeAttrs(attrs); +} + + string evalString(EvalState & state, Expr e) { e = evalExpr(state, e); @@ -264,6 +276,10 @@ Expr evalExpr2(EvalState & state, Expr e) if (atMatch(m, e) >> "OpOr" >> e1 >> e2) return makeBool(evalBool(state, e1) || evalBool(state, e2)); + /* Attribut set update (//). */ + if (atMatch(m, e) >> "OpUpdate" >> e1 >> e2) + return updateAttrs(evalExpr(state, e1), evalExpr(state, e2)); + /* Barf. */ throw badTerm("invalid expression", e); } -- cgit 1.4.1