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Split a standalone function for accessing an attribute set field

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This commit is contained in:
regnat 2021-06-02 16:42:59 +02:00
parent 074e0678bd
commit b012852cb2
2 changed files with 47 additions and 50 deletions
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95
src/libexpr/eval.cc
View file

@ -1107,68 +1107,63 @@ void ExprVar::eval(EvalState & state, Env & env, Value & v)
v = *v2; v = *v2;
} }
static string showAttrPath(EvalState & state, Env & env, const AttrPath & attrPath)
{
std::ostringstream out;
bool first = true;
for (auto & i : attrPath) {
if (!first) out << '.'; else first = false;
try {
out << getName(i, state, env);
} catch (Error & e) {
assert(!i.symbol.set());
out << "\"${" << *i.expr << "}\"";
}
}
return out.str();
}
unsigned long nrLookups = 0; unsigned long nrLookups = 0;
MakeError(MissingField, Error);
void EvalState::getAttrField(Value & attrs, const std::vector<Symbol> & selector, const Pos & pos, Value & dest)
{
Pos * pos2 = 0;
Value * vAttrs = &attrs;
try {
for (auto & name : selector) {
nrLookups++;
Bindings::iterator j;
forceValue(*vAttrs, pos);
if (vAttrs->type() != nAttrs ||
(j = vAttrs->attrs->find(name)) == vAttrs->attrs->end()) {
throw MissingField("attribute '%s' missing", name);
}
vAttrs = j->value;
pos2 = j->pos;
if (countCalls && pos2) attrSelects[*pos2]++;
}
forceValue(*vAttrs, ( pos2 != NULL ? *pos2 : pos ) );
} catch (Error & e) {
if (pos2 && pos2->file != sDerivationNix) {
vector<string> strSelector;
addErrorTrace(e, *pos2, "while evaluating the attribute '%1%'", concatStringsSep(".", selector));
}
throw;
}
dest = *vAttrs;
}
void ExprSelect::eval(EvalState & state, Env & env, Value & v) void ExprSelect::eval(EvalState & state, Env & env, Value & v)
{ {
Value vTmp; Value vTmp;
Pos * pos2 = 0;
Value * vAttrs = &vTmp;
e->eval(state, env, vTmp); e->eval(state, env, vTmp);
std::vector<Symbol> selector;
for (auto & i : attrPath)
selector.push_back(getName(i, state, env));
try { try {
state.getAttrField(vTmp, selector, pos, v);
for (auto & i : attrPath) { } catch (MissingField & field) {
nrLookups++; if (def) {
Bindings::iterator j; def->eval(state, env, v);
Symbol name = getName(i, state, env); return;
if (def) { } else {
state.forceValue(*vAttrs, pos); throwEvalError(pos, field.what());
if (vAttrs->type() != nAttrs ||
(j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
{
def->eval(state, env, v);
return;
}
} else {
state.forceAttrs(*vAttrs, pos);
if ((j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
throwEvalError(pos, "attribute '%1%' missing", name);
}
vAttrs = j->value;
pos2 = j->pos;
if (state.countCalls && pos2) state.attrSelects[*pos2]++;
} }
state.forceValue(*vAttrs, ( pos2 != NULL ? *pos2 : this->pos ) );
} catch (Error & e) {
if (pos2 && pos2->file != state.sDerivationNix)
addErrorTrace(e, *pos2, "while evaluating the attribute '%1%'",
showAttrPath(state, env, attrPath));
throw;
} }
v = *vAttrs;
} }

2
src/libexpr/eval.hh
View file

@ -343,6 +343,8 @@ private:
friend struct ExprSelect; friend struct ExprSelect;
friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v); friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v);
friend void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v); friend void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v);
void getAttrField(Value & attrs, const std::vector<Symbol> & selector, const Pos & pos, Value & dest);
}; };