forked from lix-project/lix
4fc4eb6c93
The attrError variable is no longer used but still allocated on every call to the findAlongAttrPath function.
128 lines
3.6 KiB
C++
128 lines
3.6 KiB
C++
#include "attr-path.hh"
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#include "eval-inline.hh"
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#include "util.hh"
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namespace nix {
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static Strings parseAttrPath(const string & s)
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{
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Strings res;
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string cur;
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string::const_iterator i = s.begin();
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while (i != s.end()) {
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if (*i == '.') {
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res.push_back(cur);
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cur.clear();
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} else if (*i == '"') {
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++i;
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while (1) {
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if (i == s.end())
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throw Error(format("missing closing quote in selection path '%1%'") % s);
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if (*i == '"') break;
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cur.push_back(*i++);
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}
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} else
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cur.push_back(*i);
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++i;
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}
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if (!cur.empty()) res.push_back(cur);
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return res;
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}
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std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attrPath,
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Bindings & autoArgs, Value & vIn)
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{
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Strings tokens = parseAttrPath(attrPath);
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Value * v = &vIn;
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Pos pos = noPos;
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for (auto & attr : tokens) {
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/* Is i an index (integer) or a normal attribute name? */
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enum { apAttr, apIndex } apType = apAttr;
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unsigned int attrIndex;
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if (string2Int(attr, attrIndex)) apType = apIndex;
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/* Evaluate the expression. */
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Value * vNew = state.allocValue();
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state.autoCallFunction(autoArgs, *v, *vNew);
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v = vNew;
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state.forceValue(*v);
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/* It should evaluate to either a set or an expression,
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according to what is specified in the attrPath. */
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if (apType == apAttr) {
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if (v->type != tAttrs)
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throw TypeError(
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format("the expression selected by the selection path '%1%' should be a set but is %2%")
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% attrPath % showType(*v));
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if (attr.empty())
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throw Error(format("empty attribute name in selection path '%1%'") % attrPath);
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Bindings::iterator a = v->attrs->find(state.symbols.create(attr));
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if (a == v->attrs->end())
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throw AttrPathNotFound("attribute '%1%' in selection path '%2%' not found", attr, attrPath);
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v = &*a->value;
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pos = *a->pos;
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}
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else if (apType == apIndex) {
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if (!v->isList())
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throw TypeError(
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format("the expression selected by the selection path '%1%' should be a list but is %2%")
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% attrPath % showType(*v));
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if (attrIndex >= v->listSize())
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throw AttrPathNotFound("list index %1% in selection path '%2%' is out of range", attrIndex, attrPath);
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v = v->listElems()[attrIndex];
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pos = noPos;
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}
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}
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return {v, pos};
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}
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Pos findDerivationFilename(EvalState & state, Value & v, std::string what)
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{
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Value * v2;
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try {
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auto dummyArgs = state.allocBindings(0);
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v2 = findAlongAttrPath(state, "meta.position", *dummyArgs, v).first;
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} catch (Error &) {
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throw NoPositionInfo("package '%s' has no source location information", what);
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}
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// FIXME: is it possible to extract the Pos object instead of doing this
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// toString + parsing?
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auto pos = state.forceString(*v2);
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auto colon = pos.rfind(':');
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if (colon == std::string::npos)
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throw Error("cannot parse meta.position attribute '%s'", pos);
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std::string filename(pos, 0, colon);
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unsigned int lineno;
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try {
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lineno = std::stoi(std::string(pos, colon + 1));
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} catch (std::invalid_argument & e) {
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throw Error("cannot parse line number '%s'", pos);
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}
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Symbol file = state.symbols.create(filename);
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return { file, lineno, 0 };
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}
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}
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