nixos/nix
1
1
Fork 0
mirror of https://github.com/NixOS/nix.git synced 2025-11-09 20:16:03 +01:00
Code Activity

evaluate inherit (from) exprs only once per directive

Browse source 
desugaring inherit-from to syntactic duplication of the source expr also
duplicates side effects of the source expr (such as trace calls) and
expensive computations (such as derivationStrict).
This commit is contained in:
pennae 2024-01-27 16:33:34 +01:00
parent ecf8b12d60
commit cefd0302b5
9 changed files with 109 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

44
src/libexpr/nixexpr.cc
View file

@ -80,7 +80,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
return sa < sb;
});
std::vector<Symbol> inherits;
std::map<Expr *, std::vector<Symbol>> inheritsFrom;
std::map<ExprInheritFrom *, std::vector<Symbol>> inheritsFrom;
for (auto & i : sorted) {
switch (i->second.kind) {
case AttrDef::Kind::Plain:
@ -90,7 +90,8 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
break;
case AttrDef::Kind::InheritedFrom: {
auto & select = dynamic_cast<ExprSelect &>(*i->second.e);
inheritsFrom[select.e].push_back(i->first);
auto & from = dynamic_cast<ExprInheritFrom &>(*select.e);
inheritsFrom[&from].push_back(i->first);
break;
}
}
@ -102,7 +103,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
}
for (const auto & [from, syms] : inheritsFrom) {
str << "inherit (";
from->show(symbols, str);
(*inheritFromExprs)[from->displ]->show(symbols, str);
str << ")";
for (auto sym : syms) str << " " << symbols[sym];
str << "; ";
@ -328,6 +329,12 @@ void ExprVar::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
this->level = withLevel;
}
void ExprInheritFrom::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
if (es.debugRepl)
es.exprEnvs.insert(std::make_pair(this, env));
}
void ExprSelect::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
if (es.debugRepl)
@ -351,6 +358,27 @@ void ExprOpHasAttr::bindVars(EvalState & es, const std::shared_ptr<const StaticE
i.expr->bindVars(es, env);
}
std::shared_ptr<const StaticEnv> ExprAttrs::bindInheritSources(
EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
if (!inheritFromExprs)
return nullptr;
// the inherit (from) source values are inserted into an env of its own, which
// does not introduce any variable names.
// analysis must see an empty env, or an env that contains only entries with
// otherwise unused names to not interfere with regular names. the parser
// has already filled all exprs that access this env with appropriate level
// and displacement, and nothing else is allowed to access it. ideally we'd
// not even *have* an expr that grabs anything from this env since it's fully
// invisible, but the evaluator does not allow for this yet.
auto inner = std::make_shared<StaticEnv>(nullptr, env.get(), 0);
for (auto from : *inheritFromExprs)
from->bindVars(es, env);
return inner;
}
void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
{
if (es.debugRepl)
@ -368,8 +396,9 @@ void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
// No need to sort newEnv since attrs is in sorted order.
auto inheritFromEnv = bindInheritSources(es, newEnv);
for (auto & i : attrs)
i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, newEnv));
i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, inheritFromEnv));
for (auto & i : dynamicAttrs) {
i.nameExpr->bindVars(es, newEnv);
@ -377,8 +406,10 @@ void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
}
}
else {
auto inheritFromEnv = bindInheritSources(es, env);
for (auto & i : attrs)
i.second.e->bindVars(es, i.second.chooseByKind(env, env, env));
i.second.e->bindVars(es, i.second.chooseByKind(env, env, inheritFromEnv));
for (auto & i : dynamicAttrs) {
i.nameExpr->bindVars(es, env);
@ -446,8 +477,9 @@ void ExprLet::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
// No need to sort newEnv since attrs->attrs is in sorted order.
auto inheritFromEnv = attrs->bindInheritSources(es, newEnv);
for (auto & i : attrs->attrs)
i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, newEnv));
i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, inheritFromEnv));
if (es.debugRepl)
es.exprEnvs.insert(std::make_pair(this, newEnv));