diff options
| author | Eelco Dolstra <e.dolstra@tudelft.nl> | 2005-07-19 11:48:05 +0000 |
|---|---|---|
| committer | Eelco Dolstra <e.dolstra@tudelft.nl> | 2005-07-19 11:48:05 +0000 |
| commit | 0f827cc6076ae3c395537a0c9bd806b0d42947c2 (patch) | |
| tree | 13c7e2090562d1e2cb02aade854a7599f4072275 /src | |
| parent | 2135e7c0417b366b4161d01ebf794d25e96b61ba (diff) | |
* Prevent repeated wrapping of closed terms
(closed(closed(closed(...)))) since this reduces performance by
producing bigger terms and killing caching (which incidentally also
prevents useful infinite recursion detection).
Diffstat (limited to 'src')
| -rw-r--r-- | src/libexpr/nixexpr.cc | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc index 5c67b74ca..289e923c3 100644 --- a/src/libexpr/nixexpr.cc +++ b/src/libexpr/nixexpr.cc @@ -233,7 +233,12 @@ Expr substitute(const ATermMap & subs, Expr e) if (matchVar(e, name)) { Expr sub = subs.get(name); - return sub ? makeClosed(sub) : e; + Expr wrapped; + /* Add a "closed" wrapper around terms that aren't already + closed. The check is necessary to prevent repeated + wrapping, e.g., closed(closed(closed(...))), which kills + caching. */ + return sub ? (matchClosed(sub, wrapped) ? sub : makeClosed(sub)) : e; } /* In case of a function, filter out all variables bound by this |