diff options
| -rw-r--r-- | src/libexpr/eval.cc | 11 | ||||
| -rw-r--r-- | src/libexpr/nixexpr-ast.def | 1 | ||||
| -rw-r--r-- | src/libexpr/nixexpr.cc | 34 | ||||
| -rw-r--r-- | src/libexpr/nixexpr.hh | 27 |
4 files changed, 54 insertions, 19 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 384d87a26..1ee9da3b9 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -71,7 +71,7 @@ static Expr substArgs(Expr body, ATermList formals, Expr arg) throw Error(format("required function argument `%1%' missing") % aterm2String(*i)); - return substitute(subs, body); + return substitute(Substitution(0, &subs), body); } @@ -97,11 +97,13 @@ ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds) subs.set(name, e2); } + Substitution subs_(0, &subs); + /* Create the non-recursive set. */ ATermMap as; for (ATermIterator i(rbnds); i; ++i) { if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */ - as.set(name, makeAttrRHS(substitute(subs, e2), pos)); + as.set(name, makeAttrRHS(substitute(subs_, e2), pos)); } /* Copy the non-recursive bindings. !!! inefficient */ @@ -344,7 +346,7 @@ Expr evalExpr2(EvalState & state, Expr e) try { ATermMap subs; subs.set(name, e2); - return evalExpr(state, substitute(subs, e4)); + return evalExpr(state, substitute(Substitution(0, &subs), e4)); } catch (Error & e) { e.addPrefix(format("while evaluating the function at %1%:\n") % showPos(pos)); @@ -402,7 +404,7 @@ Expr evalExpr2(EvalState & state, Expr e) throw; } try { - e2 = substitute(attrs, e2); + e2 = substitute(Substitution(0, &attrs), e2); checkVarDefs(state.primOps, e2); return evalExpr(state, e2); } catch (Error & e) { @@ -534,4 +536,5 @@ void printEvalStats(EvalState & state) % state.nrEvaluated % state.nrCached % ((float) state.nrCached / (float) state.nrEvaluated * 100) % AT_calcAllocatedSize()); + sleep(100); } diff --git a/src/libexpr/nixexpr-ast.def b/src/libexpr/nixexpr-ast.def index 3f6473e94..a4565ab1f 100644 --- a/src/libexpr/nixexpr-ast.def +++ b/src/libexpr/nixexpr-ast.def @@ -30,6 +30,7 @@ Uri | string | Expr | List | ATermList | Expr | BlackHole | | Expr | Undefined | | Expr | +Removed | | Expr | PrimOp | int ATermBlob ATermList | Expr | Attrs | ATermList | Expr | Closed | Expr | Expr | diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc index 3adba1e2e..bfa7a9ed7 100644 --- a/src/libexpr/nixexpr.cc +++ b/src/libexpr/nixexpr.cc @@ -222,7 +222,7 @@ Expr makeAttrs(const ATermMap & attrs) } -Expr substitute(const ATermMap & subs, Expr e) +Expr substitute(const Substitution & subs, Expr e) { checkInterrupt(); @@ -235,7 +235,8 @@ Expr substitute(const ATermMap & subs, Expr e) if (matchClosed(e, e2)) return e; if (matchVar(e, name)) { - Expr sub = subs.get(name); + Expr sub = subs.lookup(name); + if (sub == makeRemoved()) sub = 0; Expr wrapped; /* Add a "closed" wrapper around terms that aren't already closed. The check is necessary to prevent repeated @@ -249,36 +250,37 @@ Expr substitute(const ATermMap & subs, Expr e) ATermList formals; ATerm body, def; if (matchFunction(e, formals, body, pos)) { - ATermMap subs2(subs); + ATermMap map; for (ATermIterator i(formals); i; ++i) { if (!matchNoDefFormal(*i, name) && !matchDefFormal(*i, name, def)) abort(); - subs2.remove(name); + map.set(name, makeRemoved()); } + Substitution subs2(&subs, &map); return makeFunction( (ATermList) substitute(subs2, (ATerm) formals), substitute(subs2, body), pos); } if (matchFunction1(e, name, body, pos)) { - ATermMap subs2(subs); - subs2.remove(name); - return makeFunction1(name, substitute(subs2, body), pos); + ATermMap map; + map.set(name, makeRemoved()); + return makeFunction1(name, substitute(Substitution(&subs, &map), body), pos); } /* Idem for a mutually recursive attribute set. */ ATermList rbnds, nrbnds; if (matchRec(e, rbnds, nrbnds)) { - ATermMap subs2(subs); + ATermMap map; for (ATermIterator i(rbnds); i; ++i) - if (matchBind(*i, name, e2, pos)) subs2.remove(name); + if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved()); else abort(); /* can't happen */ for (ATermIterator i(nrbnds); i; ++i) - if (matchBind(*i, name, e2, pos)) subs2.remove(name); + if (matchBind(*i, name, e2, pos)) map.set(name, makeRemoved()); else abort(); /* can't happen */ return makeRec( - (ATermList) substitute(subs2, (ATerm) rbnds), + (ATermList) substitute(Substitution(&subs, &map), (ATerm) rbnds), (ATermList) substitute(subs, (ATerm) nrbnds)); } @@ -286,11 +288,15 @@ Expr substitute(const ATermMap & subs, Expr e) AFun fun = ATgetAFun(e); int arity = ATgetArity(fun); ATerm args[arity]; + bool changed = false; - for (int i = 0; i < arity; ++i) - args[i] = substitute(subs, ATgetArgument(e, i)); + for (int i = 0; i < arity; ++i) { + ATerm arg = ATgetArgument(e, i); + args[i] = substitute(subs, arg); + if (args[i] != arg) changed = true; + } - return (ATerm) ATmakeApplArray(fun, args); + return changed ? (ATerm) ATmakeApplArray(fun, args) : e; } if (ATgetType(e) == AT_LIST) { diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh index d66b0819f..298a9f0b9 100644 --- a/src/libexpr/nixexpr.hh +++ b/src/libexpr/nixexpr.hh @@ -60,6 +60,31 @@ private: typedef vector<ATerm> ATermVector; +/* A substitution is a linked list of ATermMaps that map names to + identifiers. We use a list of ATermMaps rather than a single to + make it easy to grow or shrink a substitution when entering a + scope. */ +struct Substitution +{ + ATermMap * map; + const Substitution * prev; + + Substitution(const Substitution * prev, ATermMap * map) + { + this->prev = prev; + this->map = map; + } + + Expr lookup(Expr name) const + { + Expr x; + for (const Substitution * s(this); s; s = s->prev) + if (x = s->map->get(name)) return x; + return 0; + } +}; + + /* Show a position. */ string showPos(ATerm pos); @@ -85,7 +110,7 @@ Expr queryAttr(Expr e, const string & name, ATerm & pos); Expr makeAttrs(const ATermMap & attrs); /* Perform a set of substitutions on an expression. */ -Expr substitute(const ATermMap & subs, Expr e); +Expr substitute(const Substitution & subs, Expr e); /* Check whether all variables are defined in the given expression. Throw an exception if this isn't the case. */ |