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#include "attr-path.hh"
#include "eval-inline.hh"
#include "util.hh"
namespace nix {
static Strings parseAttrPath(std::string_view s)
{
Strings res;
std::string cur;
auto i = s.begin();
while (i != s.end()) {
if (*i == '.') {
res.push_back(cur);
cur.clear();
} else if (*i == '"') {
++i;
while (1) {
if (i == s.end())
throw ParseError("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;
}
std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s)
{
std::vector<Symbol> res;
for (auto & a : parseAttrPath(s))
res.push_back(state.symbols.create(a));
return res;
}
std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const std::string & attrPath,
Bindings & autoArgs, Value & vIn)
{
Strings tokens = parseAttrPath(attrPath);
Value * v = &vIn;
Pos pos = noPos;
for (auto & attr : tokens) {
/* Is i an index (integer) or a normal attribute name? */
auto attrIndex = string2Int<unsigned int>(attr);
/* Evaluate the expression. */
Value * vNew = state.allocValue();
state.autoCallFunction(autoArgs, *v, *vNew);
v = vNew;
state.forceValue(*v, noPos);
/* It should evaluate to either a set or an expression,
according to what is specified in the attrPath. */
if (!attrIndex) {
if (v->type() != nAttrs)
throw TypeError(
"the expression selected by the selection path '%1%' should be a set but is %2%",
attrPath,
showType(*v));
if (attr.empty())
throw Error("empty attribute name in selection path '%1%'", attrPath);
Bindings::iterator a = v->attrs->find(state.symbols.create(attr));
if (a == v->attrs->end()) {
std::set<std::string> attrNames;
for (auto & attr : *v->attrs)
attrNames.insert(attr.name);
auto suggestions = Suggestions::bestMatches(attrNames, attr);
throw AttrPathNotFound(suggestions, "attribute '%1%' in selection path '%2%' not found", attr, attrPath);
}
v = &*a->value;
pos = *a->pos;
}
else {
if (!v->isList())
throw TypeError(
"the expression selected by the selection path '%1%' should be a list but is %2%",
attrPath,
showType(*v));
if (*attrIndex >= v->listSize())
throw AttrPathNotFound("list index %1% in selection path '%2%' is out of range", *attrIndex, attrPath);
v = v->listElems()[*attrIndex];
pos = noPos;
}
}
return {v, pos};
}
Pos findPackageFilename(EvalState & state, Value & v, std::string what)
{
Value * v2;
try {
auto dummyArgs = state.allocBindings(0);
v2 = findAlongAttrPath(state, "meta.position", *dummyArgs, v).first;
} catch (Error &) {
throw NoPositionInfo("package '%s' has no source location information", what);
}
// FIXME: is it possible to extract the Pos object instead of doing this
// toString + parsing?
auto pos = state.forceString(*v2, noPos, "while evaluating the 'meta.position' attribute of a derivation");
auto colon = pos.rfind(':');
if (colon == std::string::npos)
throw ParseError("cannot parse meta.position attribute '%s'", pos);
std::string filename(pos, 0, colon);
unsigned int lineno;
try {
lineno = std::stoi(std::string(pos, colon + 1, std::string::npos));
} catch (std::invalid_argument & e) {
throw ParseError("cannot parse line number '%s'", pos);
}
Symbol file = state.symbols.create(filename);
return { foFile, file, lineno, 0 };
}
}
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