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#include "libexpr/attr-path.hh"
#include <absl/strings/numbers.h>
#include "libexpr/eval-inline.hh"
#include "libutil/util.hh"
namespace nix {
static Strings parseAttrPath(const std::string& s) {
Strings res;
std::string cur;
std::string::const_iterator i = s.begin();
while (i != s.end()) {
if (*i == '.') {
res.push_back(cur);
cur.clear();
} else if (*i == '"') {
++i;
while (true) {
if (i == s.end()) {
throw Error(format("missing closing quote in selection path '%1%'") %
s);
}
if (*i == '"') {
break;
}
cur.push_back(*i++);
}
} else {
cur.push_back(*i);
}
++i;
}
if (!cur.empty()) {
res.push_back(cur);
}
return res;
}
Value* findAlongAttrPath(EvalState& state, const std::string& attrPath,
Bindings& autoArgs, Value& vIn) {
Strings tokens = parseAttrPath(attrPath);
Error attrError =
Error(format("attribute selection path '%1%' does not match expression") %
attrPath);
Value* v = &vIn;
for (auto& attr : tokens) {
/* Is i an index (integer) or a normal attribute name? */
enum { apAttr, apIndex } apType = apAttr;
unsigned int attrIndex;
if (absl::SimpleAtoi(attr, &attrIndex)) {
apType = apIndex;
}
/* Evaluate the expression. */
Value* vNew = state.allocValue();
state.autoCallFunction(autoArgs, *v, *vNew);
v = vNew;
state.forceValue(*v);
/* It should evaluate to either a set or an expression,
according to what is specified in the attrPath. */
if (apType == apAttr) {
if (v->type != tAttrs) {
throw TypeError(format("the expression selected by the selection path "
"'%1%' should be a set but is %2%") %
attrPath % showType(*v));
}
if (attr.empty()) {
throw Error(format("empty attribute name in selection path '%1%'") %
attrPath);
}
Bindings::iterator a = v->attrs->find(state.symbols.Create(attr));
if (a == v->attrs->end()) {
throw Error(
format("attribute '%1%' in selection path '%2%' not found") % attr %
attrPath);
}
v = &*(a->second).value;
}
else if (apType == apIndex) {
if (!v->isList()) {
throw TypeError(format("the expression selected by the selection path "
"'%1%' should be a list but is %2%") %
attrPath % showType(*v));
}
if (attrIndex >= v->listSize()) {
throw Error(
format("list index %1% in selection path '%2%' is out of range") %
attrIndex % attrPath);
}
v = v->listElems()[attrIndex];
}
}
return v;
}
} // namespace nix
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