forked from lix-project/lix
primops: Move functions to primops/attrset.cc
Moved builtins: attrNames, attrValues, catAttrs, getAttr, groupBy,
hasAttr, intersectAttrs, mapAttrs, removeAttrs, zipAttrsWith
Change-Id: I55e2c9ef40ece5ba5bf4a96cae655f481d0b140b
This commit is contained in:
parent
71b32bb87c
commit
0ba37444da
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@ -86,6 +86,7 @@ libexpr_sources = files(
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'flake/flake.cc',
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'flake/flake.cc',
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'flake/flakeref.cc',
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'flake/flakeref.cc',
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'flake/lockfile.cc',
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'flake/lockfile.cc',
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'primops/attrset.cc',
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'primops/context.cc',
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'primops/context.cc',
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'primops/fetchClosure.cc',
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'primops/fetchClosure.cc',
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'primops/fetchMercurial.cc',
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'primops/fetchMercurial.cc',
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@ -620,27 +620,6 @@ struct CompareValues
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}
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}
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};
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};
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#if HAVE_BOEHMGC
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typedef std::list<Value *, gc_allocator<Value *>> ValueList;
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#else
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typedef std::list<Value *> ValueList;
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#endif
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static Bindings::iterator getAttr(
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EvalState & state,
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Symbol attrSym,
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Bindings * attrSet,
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std::string_view errorCtx)
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{
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Bindings::iterator value = attrSet->find(attrSym);
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if (value == attrSet->end()) {
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state.error<TypeError>("attribute '%s' missing", state.symbols[attrSym]).withTrace(noPos, errorCtx).debugThrow();
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}
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return value;
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}
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static void prim_genericClosure(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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static void prim_genericClosure(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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{
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state.forceAttrs(*args[0], noPos, "while evaluating the first argument passed to builtins.genericClosure");
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state.forceAttrs(*args[0], noPos, "while evaluating the first argument passed to builtins.genericClosure");
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@ -2386,96 +2365,6 @@ static RegisterPrimOp primop_path({
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* Sets
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* Sets
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*************************************************************/
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*************************************************************/
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/* Return the names of the attributes in a set as a sorted list of
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strings. */
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static void prim_attrNames(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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state.forceAttrs(*args[0], pos, "while evaluating the argument passed to builtins.attrNames");
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state.mkList(v, args[0]->attrs->size());
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size_t n = 0;
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for (auto & i : *args[0]->attrs)
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(v.listElems()[n++] = state.allocValue())->mkString(state.symbols[i.name]);
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std::sort(v.listElems(), v.listElems() + n,
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[](Value * v1, Value * v2) { return strcmp(v1->string.s, v2->string.s) < 0; });
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}
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static RegisterPrimOp primop_attrNames({
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.name = "__attrNames",
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.args = {"set"},
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.doc = R"(
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Return the names of the attributes in the set *set* in an
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alphabetically sorted list. For instance, `builtins.attrNames { y
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= 1; x = "foo"; }` evaluates to `[ "x" "y" ]`.
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)",
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.fun = prim_attrNames,
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});
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/* Return the values of the attributes in a set as a list, in the same
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order as attrNames. */
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static void prim_attrValues(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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state.forceAttrs(*args[0], pos, "while evaluating the argument passed to builtins.attrValues");
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state.mkList(v, args[0]->attrs->size());
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unsigned int n = 0;
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for (auto & i : *args[0]->attrs)
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v.listElems()[n++] = (Value *) &i;
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std::sort(v.listElems(), v.listElems() + n,
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[&](Value * v1, Value * v2) {
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std::string_view s1 = state.symbols[((Attr *) v1)->name],
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s2 = state.symbols[((Attr *) v2)->name];
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return s1 < s2;
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});
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for (unsigned int i = 0; i < n; ++i)
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v.listElems()[i] = ((Attr *) v.listElems()[i])->value;
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}
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static RegisterPrimOp primop_attrValues({
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.name = "__attrValues",
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.args = {"set"},
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.doc = R"(
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Return the values of the attributes in the set *set* in the order
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corresponding to the sorted attribute names.
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)",
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.fun = prim_attrValues,
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});
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/* Dynamic version of the `.' operator. */
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void prim_getAttr(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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auto attr = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.getAttr");
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state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.getAttr");
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Bindings::iterator i = getAttr(
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state,
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state.symbols.create(attr),
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args[1]->attrs,
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"in the attribute set under consideration"
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);
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// !!! add to stack trace?
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if (state.countCalls && i->pos) state.attrSelects[i->pos]++;
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state.forceValue(*i->value, pos);
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v = *i->value;
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}
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static RegisterPrimOp primop_getAttr({
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.name = "__getAttr",
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.args = {"s", "set"},
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.doc = R"(
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`getAttr` returns the attribute named *s* from *set*. Evaluation
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aborts if the attribute doesn’t exist. This is a dynamic version of
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the `.` operator, since *s* is an expression rather than an
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identifier.
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)",
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.fun = prim_getAttr,
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});
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/* Return position information of the specified attribute. */
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/* Return position information of the specified attribute. */
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static void prim_unsafeGetAttrPos(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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static void prim_unsafeGetAttrPos(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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{
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@ -2542,25 +2431,6 @@ void makePositionThunks(EvalState & state, const PosIdx pos, Value & line, Value
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makeLazyPosAccessors(state, pos, line, column);
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makeLazyPosAccessors(state, pos, line, column);
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}
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}
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/* Dynamic version of the `?' operator. */
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static void prim_hasAttr(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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auto attr = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.hasAttr");
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state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.hasAttr");
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v.mkBool(args[1]->attrs->find(state.symbols.create(attr)) != args[1]->attrs->end());
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}
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static RegisterPrimOp primop_hasAttr({
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.name = "__hasAttr",
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.args = {"s", "set"},
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.doc = R"(
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`hasAttr` returns `true` if *set* has an attribute named *s*, and
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`false` otherwise. This is a dynamic version of the `?` operator,
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since *s* is an expression rather than an identifier.
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)",
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.fun = prim_hasAttr,
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});
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/* Determine whether the argument is a set. */
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/* Determine whether the argument is a set. */
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static void prim_isAttrs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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static void prim_isAttrs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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{
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@ -2577,49 +2447,6 @@ static RegisterPrimOp primop_isAttrs({
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.fun = prim_isAttrs,
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.fun = prim_isAttrs,
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});
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});
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static void prim_removeAttrs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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state.forceAttrs(*args[0], pos, "while evaluating the first argument passed to builtins.removeAttrs");
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state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.removeAttrs");
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/* Get the attribute names to be removed.
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We keep them as Attrs instead of Symbols so std::set_difference
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can be used to remove them from attrs[0]. */
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// 64: large enough to fit the attributes of a derivation
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boost::container::small_vector<Attr, 64> names;
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names.reserve(args[1]->listSize());
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for (auto elem : args[1]->listItems()) {
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state.forceStringNoCtx(*elem, pos, "while evaluating the values of the second argument passed to builtins.removeAttrs");
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names.emplace_back(state.symbols.create(elem->string.s), nullptr);
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}
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std::sort(names.begin(), names.end());
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/* Copy all attributes not in that set. Note that we don't need
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to sort v.attrs because it's a subset of an already sorted
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vector. */
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auto attrs = state.buildBindings(args[0]->attrs->size());
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std::set_difference(
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args[0]->attrs->begin(), args[0]->attrs->end(),
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names.begin(), names.end(),
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std::back_inserter(attrs));
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v.mkAttrs(attrs.alreadySorted());
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}
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static RegisterPrimOp primop_removeAttrs({
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.name = "removeAttrs",
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.args = {"set", "list"},
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.doc = R"(
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Remove the attributes listed in *list* from *set*. The attributes
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don’t have to exist in *set*. For instance,
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```nix
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removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]
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```
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evaluates to `{ y = 2; }`.
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)",
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.fun = prim_removeAttrs,
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});
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/* Builds a set from a list specifying (name, value) pairs. To be
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/* Builds a set from a list specifying (name, value) pairs. To be
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precise, a list [{name = "name1"; value = value1;} ... {name =
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precise, a list [{name = "name1"; value = value1;} ... {name =
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@ -2682,121 +2509,6 @@ static RegisterPrimOp primop_listToAttrs({
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.fun = prim_listToAttrs,
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.fun = prim_listToAttrs,
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});
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});
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static void prim_intersectAttrs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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state.forceAttrs(*args[0], pos, "while evaluating the first argument passed to builtins.intersectAttrs");
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state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.intersectAttrs");
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Bindings &left = *args[0]->attrs;
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Bindings &right = *args[1]->attrs;
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auto attrs = state.buildBindings(std::min(left.size(), right.size()));
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// The current implementation has good asymptotic complexity and is reasonably
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// simple. Further optimization may be possible, but does not seem productive,
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// considering the state of eval performance in 2022.
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//
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// I have looked for reusable and/or standard solutions and these are my
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// findings:
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//
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// STL
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// ===
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// std::set_intersection is not suitable, as it only performs a simultaneous
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// linear scan; not taking advantage of random access. This is O(n + m), so
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// linear in the largest set, which is not acceptable for callPackage in Nixpkgs.
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//
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// Simultaneous scan, with alternating simple binary search
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// ===
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// One alternative algorithm scans the attrsets simultaneously, jumping
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// forward using `lower_bound` in case of inequality. This should perform
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// well on very similar sets, having a local and predictable access pattern.
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// On dissimilar sets, it seems to need more comparisons than the current
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// algorithm, as few consecutive attrs match. `lower_bound` could take
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// advantage of the decreasing remaining search space, but this causes
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// the medians to move, which can mean that they don't stay in the cache
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// like they would with the current naive `find`.
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//
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// Double binary search
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// ===
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// The optimal algorithm may be "Double binary search", which doesn't
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// scan at all, but rather divides both sets simultaneously.
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// See "Fast Intersection Algorithms for Sorted Sequences" by Baeza-Yates et al.
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// https://cs.uwaterloo.ca/~ajsaling/papers/intersection_alg_app10.pdf
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// The only downsides I can think of are not having a linear access pattern
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// for similar sets, and having to maintain a more intricate algorithm.
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//
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// Adaptive
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// ===
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// Finally one could run try a simultaneous scan, count misses and fall back
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// to double binary search when the counter hit some threshold and/or ratio.
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if (left.size() < right.size()) {
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for (auto & l : left) {
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Bindings::iterator r = right.find(l.name);
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if (r != right.end())
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attrs.insert(*r);
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}
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}
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else {
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for (auto & r : right) {
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Bindings::iterator l = left.find(r.name);
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if (l != left.end())
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attrs.insert(r);
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}
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}
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v.mkAttrs(attrs.alreadySorted());
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}
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static RegisterPrimOp primop_intersectAttrs({
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.name = "__intersectAttrs",
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.args = {"e1", "e2"},
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.doc = R"(
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Return a set consisting of the attributes in the set *e2* which have the
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same name as some attribute in *e1*.
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Performs in O(*n* log *m*) where *n* is the size of the smaller set and *m* the larger set's size.
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)",
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.fun = prim_intersectAttrs,
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});
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static void prim_catAttrs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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auto attrName = state.symbols.create(state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.catAttrs"));
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state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.catAttrs");
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SmallValueVector<nonRecursiveStackReservation> res(args[1]->listSize());
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size_t found = 0;
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for (auto v2 : args[1]->listItems()) {
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state.forceAttrs(*v2, pos, "while evaluating an element in the list passed as second argument to builtins.catAttrs");
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Bindings::iterator i = v2->attrs->find(attrName);
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if (i != v2->attrs->end())
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res[found++] = i->value;
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}
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state.mkList(v, found);
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for (unsigned int n = 0; n < found; ++n)
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v.listElems()[n] = res[n];
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}
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static RegisterPrimOp primop_catAttrs({
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.name = "__catAttrs",
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.args = {"attr", "list"},
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.doc = R"(
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Collect each attribute named *attr* from a list of attribute
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sets. Attrsets that don't contain the named attribute are
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ignored. For example,
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```nix
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builtins.catAttrs "a" [{a = 1;} {b = 0;} {a = 2;}]
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```
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evaluates to `[1 2]`.
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)",
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.fun = prim_catAttrs,
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});
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static void prim_functionArgs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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static void prim_functionArgs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
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{
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{
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state.forceValue(*args[0], pos);
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state.forceValue(*args[0], pos);
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@ -2806,19 +2518,16 @@ static void prim_functionArgs(EvalState & state, const PosIdx pos, Value * * arg
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}
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}
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if (!args[0]->isLambda())
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if (!args[0]->isLambda())
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state.error<TypeError>("'functionArgs' requires a function").atPos(pos).debugThrow();
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state.error<TypeError>("'functionArgs' requires a function").atPos(pos).debugThrow();
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if (!args[0]->lambda.fun->hasFormals()) {
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if (!args[0]->lambda.fun->hasFormals()) {
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||||||
v.mkAttrs(&state.emptyBindings);
|
v.mkAttrs(&state.emptyBindings);
|
||||||
return;
|
return;
|
||||||
}
|
}
|
||||||
|
|
||||||
auto attrs = state.buildBindings(args[0]->lambda.fun->formals->formals.size());
|
auto attrs = state.buildBindings(args[0]->lambda.fun->formals->formals.size());
|
||||||
for (auto & i : args[0]->lambda.fun->formals->formals)
|
for (auto & i : args[0]->lambda.fun->formals->formals)
|
||||||
// !!! should optimise booleans (allocate only once)
|
// !!! should optimise booleans (allocate only once)
|
||||||
attrs.alloc(i.name, i.pos).mkBool(i.def);
|
attrs.alloc(i.name, i.pos).mkBool(i.def);
|
||||||
v.mkAttrs(attrs);
|
v.mkAttrs(attrs);
|
||||||
}
|
}
|
||||||
|
|
||||||
static RegisterPrimOp primop_functionArgs({
|
static RegisterPrimOp primop_functionArgs({
|
||||||
.name = "__functionArgs",
|
.name = "__functionArgs",
|
||||||
.args = {"f"},
|
.args = {"f"},
|
||||||
|
|
@ -2828,7 +2537,6 @@ static RegisterPrimOp primop_functionArgs({
|
||||||
denoting whether the corresponding argument has a default value. For
|
denoting whether the corresponding argument has a default value. For
|
||||||
instance, `functionArgs ({ x, y ? 123}: ...) = { x = false; y =
|
instance, `functionArgs ({ x, y ? 123}: ...) = { x = false; y =
|
||||||
true; }`.
|
true; }`.
|
||||||
|
|
||||||
"Formal argument" here refers to the attributes pattern-matched by
|
"Formal argument" here refers to the attributes pattern-matched by
|
||||||
the function. Plain lambdas are not included, e.g. `functionArgs (x:
|
the function. Plain lambdas are not included, e.g. `functionArgs (x:
|
||||||
...) = { }`.
|
...) = { }`.
|
||||||
|
|
@ -2837,117 +2545,7 @@ static RegisterPrimOp primop_functionArgs({
|
||||||
});
|
});
|
||||||
|
|
||||||
/* */
|
/* */
|
||||||
static void prim_mapAttrs(EvalState & state, const PosIdx pos, Value * * args, Value & v)
|
|
||||||
{
|
|
||||||
state.forceAttrs(*args[1], pos, "while evaluating the second argument passed to builtins.mapAttrs");
|
|
||||||
|
|
||||||
auto attrs = state.buildBindings(args[1]->attrs->size());
|
|
||||||
|
|
||||||
for (auto & i : *args[1]->attrs) {
|
|
||||||
Value * vName = state.allocValue();
|
|
||||||
Value * vFun2 = state.allocValue();
|
|
||||||
vName->mkString(state.symbols[i.name]);
|
|
||||||
vFun2->mkApp(args[0], vName);
|
|
||||||
attrs.alloc(i.name).mkApp(vFun2, i.value);
|
|
||||||
}
|
|
||||||
|
|
||||||
v.mkAttrs(attrs.alreadySorted());
|
|
||||||
}
|
|
||||||
|
|
||||||
static RegisterPrimOp primop_mapAttrs({
|
|
||||||
.name = "__mapAttrs",
|
|
||||||
.args = {"f", "attrset"},
|
|
||||||
.doc = R"(
|
|
||||||
Apply function *f* to every element of *attrset*. For example,
|
|
||||||
|
|
||||||
```nix
|
|
||||||
builtins.mapAttrs (name: value: value * 10) { a = 1; b = 2; }
|
|
||||||
```
|
|
||||||
|
|
||||||
evaluates to `{ a = 10; b = 20; }`.
|
|
||||||
)",
|
|
||||||
.fun = prim_mapAttrs,
|
|
||||||
});
|
|
||||||
|
|
||||||
static void prim_zipAttrsWith(EvalState & state, const PosIdx pos, Value * * args, Value & v)
|
|
||||||
{
|
|
||||||
// we will first count how many values are present for each given key.
|
|
||||||
// we then allocate a single attrset and pre-populate it with lists of
|
|
||||||
// appropriate sizes, stash the pointers to the list elements of each,
|
|
||||||
// and populate the lists. after that we replace the list in the every
|
|
||||||
// attribute with the merge function application. this way we need not
|
|
||||||
// use (slightly slower) temporary storage the GC does not know about.
|
|
||||||
|
|
||||||
std::map<Symbol, std::pair<size_t, Value * *>> attrsSeen;
|
|
||||||
|
|
||||||
state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.zipAttrsWith");
|
|
||||||
state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.zipAttrsWith");
|
|
||||||
const auto listSize = args[1]->listSize();
|
|
||||||
const auto listElems = args[1]->listElems();
|
|
||||||
|
|
||||||
for (unsigned int n = 0; n < listSize; ++n) {
|
|
||||||
Value * vElem = listElems[n];
|
|
||||||
state.forceAttrs(*vElem, noPos, "while evaluating a value of the list passed as second argument to builtins.zipAttrsWith");
|
|
||||||
for (auto & attr : *vElem->attrs)
|
|
||||||
attrsSeen[attr.name].first++;
|
|
||||||
}
|
|
||||||
|
|
||||||
auto attrs = state.buildBindings(attrsSeen.size());
|
|
||||||
for (auto & [sym, elem] : attrsSeen) {
|
|
||||||
auto & list = attrs.alloc(sym);
|
|
||||||
state.mkList(list, elem.first);
|
|
||||||
elem.second = list.listElems();
|
|
||||||
}
|
|
||||||
v.mkAttrs(attrs.alreadySorted());
|
|
||||||
|
|
||||||
for (unsigned int n = 0; n < listSize; ++n) {
|
|
||||||
Value * vElem = listElems[n];
|
|
||||||
for (auto & attr : *vElem->attrs)
|
|
||||||
*attrsSeen[attr.name].second++ = attr.value;
|
|
||||||
}
|
|
||||||
|
|
||||||
for (auto & attr : *v.attrs) {
|
|
||||||
auto name = state.allocValue();
|
|
||||||
name->mkString(state.symbols[attr.name]);
|
|
||||||
auto call1 = state.allocValue();
|
|
||||||
call1->mkApp(args[0], name);
|
|
||||||
auto call2 = state.allocValue();
|
|
||||||
call2->mkApp(call1, attr.value);
|
|
||||||
attr.value = call2;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
static RegisterPrimOp primop_zipAttrsWith({
|
|
||||||
.name = "__zipAttrsWith",
|
|
||||||
.args = {"f", "list"},
|
|
||||||
.doc = R"(
|
|
||||||
Transpose a list of attribute sets into an attribute set of lists,
|
|
||||||
then apply `mapAttrs`.
|
|
||||||
|
|
||||||
`f` receives two arguments: the attribute name and a non-empty
|
|
||||||
list of all values encountered for that attribute name.
|
|
||||||
|
|
||||||
The result is an attribute set where the attribute names are the
|
|
||||||
union of the attribute names in each element of `list`. The attribute
|
|
||||||
values are the return values of `f`.
|
|
||||||
|
|
||||||
```nix
|
|
||||||
builtins.zipAttrsWith
|
|
||||||
(name: values: { inherit name values; })
|
|
||||||
[ { a = "x"; } { a = "y"; b = "z"; } ]
|
|
||||||
```
|
|
||||||
|
|
||||||
evaluates to
|
|
||||||
|
|
||||||
```
|
|
||||||
{
|
|
||||||
a = { name = "a"; values = [ "x" "y" ]; };
|
|
||||||
b = { name = "b"; values = [ "z" ]; };
|
|
||||||
}
|
|
||||||
```
|
|
||||||
)",
|
|
||||||
.fun = prim_zipAttrsWith,
|
|
||||||
});
|
|
||||||
|
|
||||||
|
|
||||||
/*************************************************************
|
/*************************************************************
|
||||||
|
|
@ -3428,58 +3026,6 @@ static RegisterPrimOp primop_partition({
|
||||||
.fun = prim_partition,
|
.fun = prim_partition,
|
||||||
});
|
});
|
||||||
|
|
||||||
static void prim_groupBy(EvalState & state, const PosIdx pos, Value * * args, Value & v)
|
|
||||||
{
|
|
||||||
state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.groupBy");
|
|
||||||
state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.groupBy");
|
|
||||||
|
|
||||||
ValueVectorMap attrs;
|
|
||||||
|
|
||||||
for (auto vElem : args[1]->listItems()) {
|
|
||||||
Value res;
|
|
||||||
state.callFunction(*args[0], *vElem, res, pos);
|
|
||||||
auto name = state.forceStringNoCtx(res, pos, "while evaluating the return value of the grouping function passed to builtins.groupBy");
|
|
||||||
auto sym = state.symbols.create(name);
|
|
||||||
auto vector = attrs.try_emplace(sym, ValueVector()).first;
|
|
||||||
vector->second.push_back(vElem);
|
|
||||||
}
|
|
||||||
|
|
||||||
auto attrs2 = state.buildBindings(attrs.size());
|
|
||||||
|
|
||||||
for (auto & i : attrs) {
|
|
||||||
auto & list = attrs2.alloc(i.first);
|
|
||||||
auto size = i.second.size();
|
|
||||||
state.mkList(list, size);
|
|
||||||
memcpy(list.listElems(), i.second.data(), sizeof(Value *) * size);
|
|
||||||
}
|
|
||||||
|
|
||||||
v.mkAttrs(attrs2.alreadySorted());
|
|
||||||
}
|
|
||||||
|
|
||||||
static RegisterPrimOp primop_groupBy({
|
|
||||||
.name = "__groupBy",
|
|
||||||
.args = {"f", "list"},
|
|
||||||
.doc = R"(
|
|
||||||
Groups elements of *list* together by the string returned from the
|
|
||||||
function *f* called on each element. It returns an attribute set
|
|
||||||
where each attribute value contains the elements of *list* that are
|
|
||||||
mapped to the same corresponding attribute name returned by *f*.
|
|
||||||
|
|
||||||
For example,
|
|
||||||
|
|
||||||
```nix
|
|
||||||
builtins.groupBy (builtins.substring 0 1) ["foo" "bar" "baz"]
|
|
||||||
```
|
|
||||||
|
|
||||||
evaluates to
|
|
||||||
|
|
||||||
```nix
|
|
||||||
{ b = [ "bar" "baz" ]; f = [ "foo" ]; }
|
|
||||||
```
|
|
||||||
)",
|
|
||||||
.fun = prim_groupBy,
|
|
||||||
});
|
|
||||||
|
|
||||||
static void prim_concatMap(EvalState & state, const PosIdx pos, Value * * args, Value & v)
|
static void prim_concatMap(EvalState & state, const PosIdx pos, Value * * args, Value & v)
|
||||||
{
|
{
|
||||||
state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.concatMap");
|
state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.concatMap");
|
||||||
|
|
|
||||||
|
|
@ -44,13 +44,25 @@ struct RegisterPrimOp
|
||||||
/**
|
/**
|
||||||
* Load a ValueInitializer from a DSO and return whatever it initializes
|
* Load a ValueInitializer from a DSO and return whatever it initializes
|
||||||
*/
|
*/
|
||||||
void prim_importNative(EvalState & state, const PosIdx pos, Value * * args, Value & v);
|
void prim_importNative(EvalState & state, const PosIdx pos, Value ** args, Value & v);
|
||||||
|
|
||||||
/**
|
/**
|
||||||
* Execute a program and parse its output
|
* Execute a program and parse its output
|
||||||
*/
|
*/
|
||||||
void prim_exec(EvalState & state, const PosIdx pos, Value * * args, Value & v);
|
void prim_exec(EvalState & state, const PosIdx pos, Value ** args, Value & v);
|
||||||
|
|
||||||
void makePositionThunks(EvalState & state, const PosIdx pos, Value & line, Value & column);
|
void makePositionThunks(EvalState & state, const PosIdx pos, Value & line, Value & column);
|
||||||
|
|
||||||
|
#if HAVE_BOEHMGC
|
||||||
|
typedef std::list<Value *, gc_allocator<Value *>> ValueList;
|
||||||
|
#else
|
||||||
|
typedef std::list<Value *> ValueList;
|
||||||
|
#endif
|
||||||
|
|
||||||
|
/**
|
||||||
|
* getAttr wrapper
|
||||||
|
*/
|
||||||
|
|
||||||
|
Bindings::iterator getAttr(EvalState & state, Symbol attrSym, Bindings * attrSet, std::string_view errorCtx);
|
||||||
|
|
||||||
}
|
}
|
||||||
|
|
|
||||||
543
src/libexpr/primops/attrset.cc
Normal file
543
src/libexpr/primops/attrset.cc
Normal file
|
|
@ -0,0 +1,543 @@
|
||||||
|
#include "gc-small-vector.hh"
|
||||||
|
#include "primops.hh"
|
||||||
|
|
||||||
|
namespace nix {
|
||||||
|
|
||||||
|
Bindings::iterator
|
||||||
|
getAttr(EvalState & state, Symbol attrSym, Bindings * attrSet, std::string_view errorCtx)
|
||||||
|
{
|
||||||
|
Bindings::iterator value = attrSet->find(attrSym);
|
||||||
|
if (value == attrSet->end()) {
|
||||||
|
state.error<TypeError>("attribute '%s' missing", state.symbols[attrSym])
|
||||||
|
.withTrace(noPos, errorCtx)
|
||||||
|
.debugThrow();
|
||||||
|
}
|
||||||
|
return value;
|
||||||
|
}
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.attrNames
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_attrNames(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
state.forceAttrs(*args[0], pos, "while evaluating the argument passed to builtins.attrNames");
|
||||||
|
|
||||||
|
state.mkList(v, args[0]->attrs->size());
|
||||||
|
|
||||||
|
size_t n = 0;
|
||||||
|
for (auto & i : *args[0]->attrs) {
|
||||||
|
(v.listElems()[n++] = state.allocValue())->mkString(state.symbols[i.name]);
|
||||||
|
}
|
||||||
|
|
||||||
|
std::sort(v.listElems(), v.listElems() + n, [](Value * v1, Value * v2) {
|
||||||
|
return strcmp(v1->string.s, v2->string.s) < 0;
|
||||||
|
});
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_attrNames({
|
||||||
|
.name = "__attrNames",
|
||||||
|
.args = {"set"},
|
||||||
|
.doc = R"(
|
||||||
|
Return the names of the attributes in the set *set* in an
|
||||||
|
alphabetically sorted list. For instance, `builtins.attrNames { y
|
||||||
|
= 1; x = "foo"; }` evaluates to `[ "x" "y" ]`.
|
||||||
|
)",
|
||||||
|
.fun = prim_attrNames,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.attrNames
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_attrValues(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
state.forceAttrs(*args[0], pos, "while evaluating the argument passed to builtins.attrValues");
|
||||||
|
|
||||||
|
state.mkList(v, args[0]->attrs->size());
|
||||||
|
|
||||||
|
unsigned int n = 0;
|
||||||
|
for (auto & i : *args[0]->attrs) {
|
||||||
|
v.listElems()[n++] = (Value *) &i;
|
||||||
|
}
|
||||||
|
|
||||||
|
std::sort(v.listElems(), v.listElems() + n, [&](Value * v1, Value * v2) {
|
||||||
|
std::string_view s1 = state.symbols[((Attr *) v1)->name],
|
||||||
|
s2 = state.symbols[((Attr *) v2)->name];
|
||||||
|
return s1 < s2;
|
||||||
|
});
|
||||||
|
|
||||||
|
for (unsigned int i = 0; i < n; ++i) {
|
||||||
|
v.listElems()[i] = ((Attr *) v.listElems()[i])->value;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_attrValues({
|
||||||
|
.name = "__attrValues",
|
||||||
|
.args = {"set"},
|
||||||
|
.doc = R"(
|
||||||
|
Return the values of the attributes in the set *set* in the order
|
||||||
|
corresponding to the sorted attribute names.
|
||||||
|
)",
|
||||||
|
.fun = prim_attrValues,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.catAttrs
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_catAttrs(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
auto attrName = state.symbols.create(state.forceStringNoCtx(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.catAttrs"
|
||||||
|
));
|
||||||
|
state.forceList(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.catAttrs"
|
||||||
|
);
|
||||||
|
|
||||||
|
SmallValueVector<nonRecursiveStackReservation> res(args[1]->listSize());
|
||||||
|
size_t found = 0;
|
||||||
|
|
||||||
|
for (auto v2 : args[1]->listItems()) {
|
||||||
|
state.forceAttrs(
|
||||||
|
*v2,
|
||||||
|
pos,
|
||||||
|
"while evaluating an element in the list passed as second argument to builtins.catAttrs"
|
||||||
|
);
|
||||||
|
Bindings::iterator i = v2->attrs->find(attrName);
|
||||||
|
if (i != v2->attrs->end()) {
|
||||||
|
res[found++] = i->value;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
state.mkList(v, found);
|
||||||
|
for (unsigned int n = 0; n < found; ++n) {
|
||||||
|
v.listElems()[n] = res[n];
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_catAttrs({
|
||||||
|
.name = "__catAttrs",
|
||||||
|
.args = {"attr", "list"},
|
||||||
|
.doc = R"(
|
||||||
|
Collect each attribute named *attr* from a list of attribute
|
||||||
|
sets. Attrsets that don't contain the named attribute are
|
||||||
|
ignored. For example,
|
||||||
|
|
||||||
|
```nix
|
||||||
|
builtins.catAttrs "a" [{a = 1;} {b = 0;} {a = 2;}]
|
||||||
|
```
|
||||||
|
|
||||||
|
evaluates to `[1 2]`.
|
||||||
|
)",
|
||||||
|
.fun = prim_catAttrs,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.getAttr
|
||||||
|
*/
|
||||||
|
|
||||||
|
void prim_getAttr(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
auto attr = state.forceStringNoCtx(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.getAttr"
|
||||||
|
);
|
||||||
|
state.forceAttrs(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.getAttr"
|
||||||
|
);
|
||||||
|
Bindings::iterator i = getAttr(
|
||||||
|
state,
|
||||||
|
state.symbols.create(attr),
|
||||||
|
args[1]->attrs,
|
||||||
|
"in the attribute set under consideration"
|
||||||
|
);
|
||||||
|
// !!! add to stack trace?
|
||||||
|
if (state.countCalls && i->pos) {
|
||||||
|
state.attrSelects[i->pos]++;
|
||||||
|
}
|
||||||
|
state.forceValue(*i->value, pos);
|
||||||
|
v = *i->value;
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_getAttr({
|
||||||
|
.name = "__getAttr",
|
||||||
|
.args = {"s", "set"},
|
||||||
|
.doc = R"(
|
||||||
|
`getAttr` returns the attribute named *s* from *set*. Evaluation
|
||||||
|
aborts if the attribute doesn’t exist. This is a dynamic version of
|
||||||
|
the `.` operator, since *s* is an expression rather than an
|
||||||
|
identifier.
|
||||||
|
)",
|
||||||
|
.fun = prim_getAttr,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.groupBy
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_groupBy(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
state.forceFunction(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.groupBy"
|
||||||
|
);
|
||||||
|
state.forceList(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.groupBy"
|
||||||
|
);
|
||||||
|
|
||||||
|
ValueVectorMap attrs;
|
||||||
|
|
||||||
|
for (auto vElem : args[1]->listItems()) {
|
||||||
|
Value res;
|
||||||
|
state.callFunction(*args[0], *vElem, res, pos);
|
||||||
|
auto name = state.forceStringNoCtx(
|
||||||
|
res,
|
||||||
|
pos,
|
||||||
|
"while evaluating the return value of the grouping function passed to builtins.groupBy"
|
||||||
|
);
|
||||||
|
auto sym = state.symbols.create(name);
|
||||||
|
auto vector = attrs.try_emplace(sym, ValueVector()).first;
|
||||||
|
vector->second.push_back(vElem);
|
||||||
|
}
|
||||||
|
|
||||||
|
auto attrs2 = state.buildBindings(attrs.size());
|
||||||
|
|
||||||
|
for (auto & i : attrs) {
|
||||||
|
auto & list = attrs2.alloc(i.first);
|
||||||
|
auto size = i.second.size();
|
||||||
|
state.mkList(list, size);
|
||||||
|
memcpy(list.listElems(), i.second.data(), sizeof(Value *) * size);
|
||||||
|
}
|
||||||
|
|
||||||
|
v.mkAttrs(attrs2.alreadySorted());
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_groupBy({
|
||||||
|
.name = "__groupBy",
|
||||||
|
.args = {"f", "list"},
|
||||||
|
.doc = R"(
|
||||||
|
Groups elements of *list* together by the string returned from the
|
||||||
|
function *f* called on each element. It returns an attribute set
|
||||||
|
where each attribute value contains the elements of *list* that are
|
||||||
|
mapped to the same corresponding attribute name returned by *f*.
|
||||||
|
|
||||||
|
For example,
|
||||||
|
|
||||||
|
```nix
|
||||||
|
builtins.groupBy (builtins.substring 0 1) ["foo" "bar" "baz"]
|
||||||
|
```
|
||||||
|
|
||||||
|
evaluates to
|
||||||
|
|
||||||
|
```nix
|
||||||
|
{ b = [ "bar" "baz" ]; f = [ "foo" ]; }
|
||||||
|
```
|
||||||
|
)",
|
||||||
|
.fun = prim_groupBy,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.hasAttr
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_hasAttr(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
auto attr = state.forceStringNoCtx(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.hasAttr"
|
||||||
|
);
|
||||||
|
state.forceAttrs(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.hasAttr"
|
||||||
|
);
|
||||||
|
v.mkBool(args[1]->attrs->find(state.symbols.create(attr)) != args[1]->attrs->end());
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_hasAttr({
|
||||||
|
.name = "__hasAttr",
|
||||||
|
.args = {"s", "set"},
|
||||||
|
.doc = R"(
|
||||||
|
`hasAttr` returns `true` if *set* has an attribute named *s*, and
|
||||||
|
`false` otherwise. This is a dynamic version of the `?` operator,
|
||||||
|
since *s* is an expression rather than an identifier.
|
||||||
|
)",
|
||||||
|
.fun = prim_hasAttr,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.intersectAttrs
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_intersectAttrs(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
state.forceAttrs(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.intersectAttrs"
|
||||||
|
);
|
||||||
|
state.forceAttrs(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.intersectAttrs"
|
||||||
|
);
|
||||||
|
|
||||||
|
Bindings & left = *args[0]->attrs;
|
||||||
|
Bindings & right = *args[1]->attrs;
|
||||||
|
|
||||||
|
auto attrs = state.buildBindings(std::min(left.size(), right.size()));
|
||||||
|
|
||||||
|
// The current implementation has good asymptotic complexity and is reasonably
|
||||||
|
// simple. Further optimization may be possible, but does not seem productive,
|
||||||
|
// considering the state of eval performance in 2022.
|
||||||
|
//
|
||||||
|
// I have looked for reusable and/or standard solutions and these are my
|
||||||
|
// findings:
|
||||||
|
//
|
||||||
|
// STL
|
||||||
|
// ===
|
||||||
|
// std::set_intersection is not suitable, as it only performs a simultaneous
|
||||||
|
// linear scan; not taking advantage of random access. This is O(n + m), so
|
||||||
|
// linear in the largest set, which is not acceptable for callPackage in Nixpkgs.
|
||||||
|
//
|
||||||
|
// Simultaneous scan, with alternating simple binary search
|
||||||
|
// ===
|
||||||
|
// One alternative algorithm scans the attrsets simultaneously, jumping
|
||||||
|
// forward using `lower_bound` in case of inequality. This should perform
|
||||||
|
// well on very similar sets, having a local and predictable access pattern.
|
||||||
|
// On dissimilar sets, it seems to need more comparisons than the current
|
||||||
|
// algorithm, as few consecutive attrs match. `lower_bound` could take
|
||||||
|
// advantage of the decreasing remaining search space, but this causes
|
||||||
|
// the medians to move, which can mean that they don't stay in the cache
|
||||||
|
// like they would with the current naive `find`.
|
||||||
|
//
|
||||||
|
// Double binary search
|
||||||
|
// ===
|
||||||
|
// The optimal algorithm may be "Double binary search", which doesn't
|
||||||
|
// scan at all, but rather divides both sets simultaneously.
|
||||||
|
// See "Fast Intersection Algorithms for Sorted Sequences" by Baeza-Yates et al.
|
||||||
|
// https://cs.uwaterloo.ca/~ajsaling/papers/intersection_alg_app10.pdf
|
||||||
|
// The only downsides I can think of are not having a linear access pattern
|
||||||
|
// for similar sets, and having to maintain a more intricate algorithm.
|
||||||
|
//
|
||||||
|
// Adaptive
|
||||||
|
// ===
|
||||||
|
// Finally one could run try a simultaneous scan, count misses and fall back
|
||||||
|
// to double binary search when the counter hit some threshold and/or ratio.
|
||||||
|
|
||||||
|
if (left.size() < right.size()) {
|
||||||
|
for (auto & l : left) {
|
||||||
|
Bindings::iterator r = right.find(l.name);
|
||||||
|
if (r != right.end()) {
|
||||||
|
attrs.insert(*r);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
} else {
|
||||||
|
for (auto & r : right) {
|
||||||
|
Bindings::iterator l = left.find(r.name);
|
||||||
|
if (l != left.end()) {
|
||||||
|
attrs.insert(r);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
v.mkAttrs(attrs.alreadySorted());
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_intersectAttrs({
|
||||||
|
.name = "__intersectAttrs",
|
||||||
|
.args = {"e1", "e2"},
|
||||||
|
.doc = R"(
|
||||||
|
Return a set consisting of the attributes in the set *e2* which have the
|
||||||
|
same name as some attribute in *e1*.
|
||||||
|
|
||||||
|
Performs in O(*n* log *m*) where *n* is the size of the smaller set and *m* the larger set's size.
|
||||||
|
)",
|
||||||
|
.fun = prim_intersectAttrs,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.mapAttrs
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_mapAttrs(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
state.forceAttrs(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.mapAttrs"
|
||||||
|
);
|
||||||
|
|
||||||
|
auto attrs = state.buildBindings(args[1]->attrs->size());
|
||||||
|
|
||||||
|
for (auto & i : *args[1]->attrs) {
|
||||||
|
Value * vName = state.allocValue();
|
||||||
|
Value * vFun2 = state.allocValue();
|
||||||
|
vName->mkString(state.symbols[i.name]);
|
||||||
|
vFun2->mkApp(args[0], vName);
|
||||||
|
attrs.alloc(i.name).mkApp(vFun2, i.value);
|
||||||
|
}
|
||||||
|
|
||||||
|
v.mkAttrs(attrs.alreadySorted());
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_mapAttrs({
|
||||||
|
.name = "__mapAttrs",
|
||||||
|
.args = {"f", "attrset"},
|
||||||
|
.doc = R"(
|
||||||
|
Apply function *f* to every element of *attrset*. For example,
|
||||||
|
|
||||||
|
```nix
|
||||||
|
builtins.mapAttrs (name: value: value * 10) { a = 1; b = 2; }
|
||||||
|
```
|
||||||
|
|
||||||
|
evaluates to `{ a = 10; b = 20; }`.
|
||||||
|
)",
|
||||||
|
.fun = prim_mapAttrs,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.mapAttrs
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_removeAttrs(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
state.forceAttrs(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.removeAttrs"
|
||||||
|
);
|
||||||
|
state.forceList(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.removeAttrs"
|
||||||
|
);
|
||||||
|
|
||||||
|
/* Get the attribute names to be removed.
|
||||||
|
We keep them as Attrs instead of Symbols so std::set_difference
|
||||||
|
can be used to remove them from attrs[0]. */
|
||||||
|
// 64: large enough to fit the attributes of a derivation
|
||||||
|
boost::container::small_vector<Attr, 64> names;
|
||||||
|
names.reserve(args[1]->listSize());
|
||||||
|
for (auto elem : args[1]->listItems()) {
|
||||||
|
state.forceStringNoCtx(
|
||||||
|
*elem,
|
||||||
|
pos,
|
||||||
|
"while evaluating the values of the second argument passed to builtins.removeAttrs"
|
||||||
|
);
|
||||||
|
names.emplace_back(state.symbols.create(elem->string.s), nullptr);
|
||||||
|
}
|
||||||
|
std::sort(names.begin(), names.end());
|
||||||
|
|
||||||
|
/* Copy all attributes not in that set. Note that we don't need
|
||||||
|
to sort v.attrs because it's a subset of an already sorted
|
||||||
|
vector. */
|
||||||
|
auto attrs = state.buildBindings(args[0]->attrs->size());
|
||||||
|
std::set_difference(
|
||||||
|
args[0]->attrs->begin(),
|
||||||
|
args[0]->attrs->end(),
|
||||||
|
names.begin(),
|
||||||
|
names.end(),
|
||||||
|
std::back_inserter(attrs)
|
||||||
|
);
|
||||||
|
v.mkAttrs(attrs.alreadySorted());
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_removeAttrs({
|
||||||
|
.name = "removeAttrs",
|
||||||
|
.args = {"set", "list"},
|
||||||
|
.doc = R"(
|
||||||
|
Remove the attributes listed in *list* from *set*. The attributes
|
||||||
|
don’t have to exist in *set*. For instance,
|
||||||
|
|
||||||
|
```nix
|
||||||
|
removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]
|
||||||
|
```
|
||||||
|
|
||||||
|
evaluates to `{ y = 2; }`.
|
||||||
|
)",
|
||||||
|
.fun = prim_removeAttrs,
|
||||||
|
});
|
||||||
|
|
||||||
|
/**
|
||||||
|
* builtins.zipAttrsWith
|
||||||
|
*/
|
||||||
|
|
||||||
|
static void prim_zipAttrsWith(EvalState & state, const PosIdx pos, Value ** args, Value & v)
|
||||||
|
{
|
||||||
|
// we will first count how many values are present for each given key.
|
||||||
|
// we then allocate a single attrset and pre-populate it with lists of
|
||||||
|
// appropriate sizes, stash the pointers to the list elements of each,
|
||||||
|
// and populate the lists. after that we replace the list in the every
|
||||||
|
// attribute with the merge function application. this way we need not
|
||||||
|
// use (slightly slower) temporary storage the GC does not know about.
|
||||||
|
|
||||||
|
std::map<Symbol, std::pair<size_t, Value **>> attrsSeen;
|
||||||
|
|
||||||
|
state.forceFunction(
|
||||||
|
*args[0], pos, "while evaluating the first argument passed to builtins.zipAttrsWith"
|
||||||
|
);
|
||||||
|
state.forceList(
|
||||||
|
*args[1], pos, "while evaluating the second argument passed to builtins.zipAttrsWith"
|
||||||
|
);
|
||||||
|
const auto listSize = args[1]->listSize();
|
||||||
|
const auto listElems = args[1]->listElems();
|
||||||
|
|
||||||
|
for (unsigned int n = 0; n < listSize; ++n) {
|
||||||
|
Value * vElem = listElems[n];
|
||||||
|
state.forceAttrs(
|
||||||
|
*vElem,
|
||||||
|
noPos,
|
||||||
|
"while evaluating a value of the list passed as second argument to "
|
||||||
|
"builtins.zipAttrsWith"
|
||||||
|
);
|
||||||
|
for (auto & attr : *vElem->attrs) {
|
||||||
|
attrsSeen[attr.name].first++;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
auto attrs = state.buildBindings(attrsSeen.size());
|
||||||
|
for (auto & [sym, elem] : attrsSeen) {
|
||||||
|
auto & list = attrs.alloc(sym);
|
||||||
|
state.mkList(list, elem.first);
|
||||||
|
elem.second = list.listElems();
|
||||||
|
}
|
||||||
|
v.mkAttrs(attrs.alreadySorted());
|
||||||
|
|
||||||
|
for (unsigned int n = 0; n < listSize; ++n) {
|
||||||
|
Value * vElem = listElems[n];
|
||||||
|
for (auto & attr : *vElem->attrs) {
|
||||||
|
*attrsSeen[attr.name].second++ = attr.value;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
for (auto & attr : *v.attrs) {
|
||||||
|
auto name = state.allocValue();
|
||||||
|
name->mkString(state.symbols[attr.name]);
|
||||||
|
auto call1 = state.allocValue();
|
||||||
|
call1->mkApp(args[0], name);
|
||||||
|
auto call2 = state.allocValue();
|
||||||
|
call2->mkApp(call1, attr.value);
|
||||||
|
attr.value = call2;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
static RegisterPrimOp primop_zipAttrsWith({
|
||||||
|
.name = "__zipAttrsWith",
|
||||||
|
.args = {"f", "list"},
|
||||||
|
.doc = R"(
|
||||||
|
Transpose a list of attribute sets into an attribute set of lists,
|
||||||
|
then apply `mapAttrs`.
|
||||||
|
|
||||||
|
`f` receives two arguments: the attribute name and a non-empty
|
||||||
|
list of all values encountered for that attribute name.
|
||||||
|
|
||||||
|
The result is an attribute set where the attribute names are the
|
||||||
|
union of the attribute names in each element of `list`. The attribute
|
||||||
|
values are the return values of `f`.
|
||||||
|
|
||||||
|
```nix
|
||||||
|
builtins.zipAttrsWith
|
||||||
|
(name: values: { inherit name values; })
|
||||||
|
[ { a = "x"; } { a = "y"; b = "z"; } ]
|
||||||
|
```
|
||||||
|
|
||||||
|
evaluates to
|
||||||
|
|
||||||
|
```
|
||||||
|
{
|
||||||
|
a = { name = "a"; values = [ "x" "y" ]; };
|
||||||
|
b = { name = "b"; values = [ "z" ]; };
|
||||||
|
}
|
||||||
|
```
|
||||||
|
)",
|
||||||
|
.fun = prim_zipAttrsWith,
|
||||||
|
});
|
||||||
|
|
||||||
|
}
|
||||||
Loading…
Reference in a new issue