From f93f7b75be7851affd1288dc36d6d4c4f0d43743 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 30 Aug 2006 13:10:04 +0000 Subject: * Okay, that's a bit harder than expected. --- src/libexpr/eval.cc | 21 ++++++++++++++------- src/libexpr/eval.hh | 7 +++++-- 2 files changed, 19 insertions(+), 9 deletions(-) (limited to 'src') diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index e49dc0a3b966..aacdc1c8ebf1 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -466,11 +466,15 @@ Expr evalExpr2(EvalState & state, Expr e) } } - /* Generic equality. */ + /* Generic equality/inequality. Note that the behaviour on + composite data (lists, attribute sets) and functions is + undefined, since the subterms of those terms are not evaluated. + However, we don't want to make (==) strict, because that would + make operations like `big_derivation == null' very slow (unless + we were to evaluate them side-by-side). */ if (matchOpEq(e, e1, e2)) return makeBool(evalExpr(state, e1) == evalExpr(state, e2)); - /* Generic inequality. */ if (matchOpNEq(e, e1, e2)) return makeBool(evalExpr(state, e1) != evalExpr(state, e2)); @@ -594,7 +598,7 @@ Expr evalFile(EvalState & state, const Path & path) } -Expr strictEvalExpr(EvalState & state, Expr e) +Expr strictEvalExpr(EvalState & state, Expr e, bool canonicalise) { e = evalExpr(state, e); @@ -604,8 +608,10 @@ Expr strictEvalExpr(EvalState & state, Expr e) for (ATermIterator i(as); i; ++i) { ATerm name; Expr e; ATerm pos; if (!matchBind(*i, name, e, pos)) abort(); /* can't happen */ - as2 = ATinsert(as2, makeBind(name, strictEvalExpr(state, e), pos)); + as2 = ATinsert(as2, makeBind(name, strictEvalExpr(state, e, canonicalise), + canonicalise ? makeNoPos() : pos)); } + /* !!! sort attributes if canonicalise == true */ return makeAttrs(ATreverse(as2)); } @@ -613,7 +619,7 @@ Expr strictEvalExpr(EvalState & state, Expr e) if (matchList(e, es)) { ATermList es2 = ATempty; for (ATermIterator i(es); i; ++i) - es2 = ATinsert(es2, strictEvalExpr(state, *i)); + es2 = ATinsert(es2, strictEvalExpr(state, *i, canonicalise)); return makeList(ATreverse(es2)); } @@ -630,13 +636,14 @@ Expr strictEvalExpr(EvalState & state, Expr e) if (matchValidValues(valids, valids2)) { ATermList valids3 = ATempty; for (ATermIterator j(valids2); j; ++j) - valids3 = ATinsert(valids3, strictEvalExpr(state, *j)); + valids3 = ATinsert(valids3, strictEvalExpr(state, *j, canonicalise)); valids = makeValidValues(ATreverse(valids3)); } formals2 = ATinsert(formals2, makeFormal(name, valids, dummy)); } - return makeFunction(ATreverse(formals2), body, pos); + return makeFunction(ATreverse(formals2), body, + canonicalise ? makeNoPos() : pos); } return e; diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh index 58e6b40d7780..c95a309359af 100644 --- a/src/libexpr/eval.hh +++ b/src/libexpr/eval.hh @@ -48,8 +48,11 @@ Expr evalExpr(EvalState & state, Expr e); Expr evalFile(EvalState & state, const Path & path); /* Evaluate an expression, and recursively evaluate list elements and - attributes. */ -Expr strictEvalExpr(EvalState & state, Expr e); + attributes. If `canonicalise' is true, we remove things like + position information and make sure that attribute sets are in + sorded order. */ +Expr strictEvalExpr(EvalState & state, Expr e, + bool canonicalise = false); /* Specific results. */ string evalString(EvalState & state, Expr e); -- cgit 1.4.1