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#include "lix/libexpr/attr-path.hh"
#include "lix/libutil/strings.hh"
#include "print-options.hh"
#include <algorithm>
#include <sstream>
namespace nix {
std::vector<std::string> parseAttrPath(std::string_view const s, bool allowRhsTrailingDot)
{
std::vector<std::string> res;
std::string cur;
bool haveData = false;
auto i = s.begin();
while (i != s.end()) {
if (*i == '.') {
if (!haveData) {
if (res.empty()) {
throw ParseError(
"Leading dot in attribute selection path '%1%' is not allowed! If the attribute name "
"is an empty string, use '\"\".foo.bar'",
s
);
} else {
throw ParseError(
"consecutive dots not allowed in selection path '%1%', use 'foo.\"\".bar' to denote "
"an "
"empty attribute name",
s
);
}
}
res.push_back(cur);
haveData = false;
cur.clear();
} else if (*i == '"') {
// If there is a quote there *will* be a named term even if it is empty.
++i;
haveData = true;
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);
haveData = true;
}
++i;
}
if (haveData) {
res.push_back(cur);
} else if (!allowRhsTrailingDot) {
throw ParseError("Trailing dot on the right-hand side of path expr '%1%' is not allowed!", s);
};
return res;
}
std::string unparseAttrPath(std::vector<std::string> const & attrPath)
{
// FIXME(jade): can probably be rewritten with ranges once libc++ has a
// fully featured implementation
// https://github.com/llvm/llvm-project/pull/65536
auto ret = std::ostringstream{};
bool first = true;
for (auto const & part : attrPath) {
if (!first) {
ret << ".";
}
first = false;
bool mustQuote = std::ranges::any_of(part, [](char c) -> bool {
return c == '"' || c == '.' || c == ' ';
});
if (mustQuote || part.empty()) {
ret << '"' << part << '"';
} else {
ret << part;
}
}
return ret.str();
}
std::pair<Value, PosIdx>
findAlongAttrPath(EvalState & state, const std::string & attrPath, Bindings & autoArgs, Value & vIn)
{
auto tokens = parseAttrPath(attrPath);
Value v = vIn;
PosIdx pos = noPos;
for (auto [attrPathIdx, attr] : enumerate(tokens)) {
/* Is i an index (integer) or a normal attribute name? */
auto attrIndex = string2Int<unsigned int>(attr);
/* Evaluate the expression. */
v = state.autoCallFunction(autoArgs, v, pos);
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) {
auto pathPart =
std::vector<std::string>(tokens.begin(), tokens.begin() + attrPathIdx);
state.ctx.errors
.make<TypeError>(
"the value being indexed in the selection path '%1%' at '%2%' should be a "
"set but is %3%: %4%",
attrPath,
unparseAttrPath(pathPart),
showType(v),
ValuePrinter(state, v, errorPrintOptions)
)
.debugThrow();
}
auto a = v.attrs()->get(state.ctx.symbols.create(attr));
if (!a) {
std::set<std::string> attrNames;
for (auto & attr : *v.attrs()) {
attrNames.emplace(state.ctx.symbols[attr.name]);
}
auto suggestions = Suggestions::bestMatches(attrNames, attr);
auto pathPart =
std::vector<std::string>(tokens.begin(), tokens.begin() + attrPathIdx);
throw AttrPathNotFound(
suggestions,
"attribute '%1%' in selection path '%2%' not found inside path '%3%', whose "
"contents are: %4%",
attr,
attrPath,
unparseAttrPath(pathPart),
ValuePrinter(state, v, errorPrintOptions)
);
}
v = a->value;
pos = a->pos;
} else {
if (!v.isList()) {
state.ctx.errors
.make<TypeError>(
"the expression selected by the selection path '%1%' should be a list but "
"is %2%: %3%",
attrPath,
showType(v),
ValuePrinter(state, v, errorPrintOptions)
)
.debugThrow();
}
if (*attrIndex >= v.listSize()) {
throw AttrPathNotFound(
"list index %1% in selection path '%2%' is out of range for list %3%",
*attrIndex,
attrPath,
ValuePrinter(state, v, errorPrintOptions)
);
}
v = v.listElems()[*attrIndex];
pos = noPos;
}
}
return {v, pos};
}
std::pair<SourcePath, uint32_t> findPackageFilename(EvalState & state, Value & v, std::string what)
{
Value v2 = [&]() {
try {
auto dummyArgs = state.ctx.mem.allocBindings(0);
return 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?
NixStringContext context;
auto path = state.coerceToPath(
noPos, v2, context, "while evaluating the 'meta.position' attribute of a derivation"
);
auto fn = path.canonical().abs();
auto fail = [fn]() {
throw ParseError("cannot parse 'meta.position' attribute '%s'", fn);
};
auto colon = fn.rfind(':');
if (colon == std::string::npos) fail();
// parsing as int32 instead of the uint32 we return for historical reasons.
// previously this was a stoi(), and we don't know what editors would do if
// we gave them line numbers that wouldn't fit into the int32 number space.
auto lineno = string2Int<int32_t>(std::string(fn, colon + 1, std::string::npos));
if (!lineno) fail();
return {CanonPath(fn.substr(0, colon)), *lineno};
}
}
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