Move /src to /subprojects

This will facilitate breaking up Nix into multiple packages for each
component with Meson.

subprojects/libexpr/get-drvs.hh

@@ -0,0 +1,101 @@
+#pragma once
+///@file
+
+#include "eval.hh"
+#include "path.hh"
+
+#include <string>
+#include <map>
+
+
+namespace nix {
+
+/**
+ * A "parsed" package attribute set.
+ */
+struct PackageInfo
+{
+public:
+    typedef std::map<std::string, std::optional<StorePath>> Outputs;
+
+private:
+    EvalState * state;
+
+    mutable std::string name;
+    mutable std::string system;
+    mutable std::optional<std::optional<StorePath>> drvPath;
+    mutable std::optional<StorePath> outPath;
+    mutable std::string outputName;
+    Outputs outputs;
+
+    /**
+     * Set if we get an AssertionError
+     */
+    bool failed = false;
+
+    const Bindings * attrs = nullptr, * meta = nullptr;
+
+    const Bindings * getMeta();
+
+    bool checkMeta(Value & v);
+
+public:
+    /**
+     * path towards the derivation
+     */
+    std::string attrPath;
+
+    PackageInfo(EvalState & state) : state(&state) { };
+    PackageInfo(EvalState & state, std::string attrPath, const Bindings * attrs);
+    PackageInfo(EvalState & state, ref<Store> store, const std::string & drvPathWithOutputs);
+
+    std::string queryName() const;
+    std::string querySystem() const;
+    std::optional<StorePath> queryDrvPath() const;
+    StorePath requireDrvPath() const;
+    StorePath queryOutPath() const;
+    std::string queryOutputName() const;
+    /**
+     * Return the unordered map of output names to (optional) output paths.
+     * The "outputs to install" are determined by `meta.outputsToInstall`.
+     */
+    Outputs queryOutputs(bool withPaths = true, bool onlyOutputsToInstall = false);
+
+    StringSet queryMetaNames();
+    Value * queryMeta(const std::string & name);
+    std::string queryMetaString(const std::string & name);
+    NixInt queryMetaInt(const std::string & name, NixInt def);
+    NixFloat queryMetaFloat(const std::string & name, NixFloat def);
+    bool queryMetaBool(const std::string & name, bool def);
+    void setMeta(const std::string & name, Value * v);
+
+    /*
+    MetaInfo queryMetaInfo(EvalState & state) const;
+    MetaValue queryMetaInfo(EvalState & state, const string & name) const;
+    */
+
+    void setName(const std::string & s) { name = s; }
+    void setDrvPath(StorePath path) { drvPath = {{std::move(path)}}; }
+    void setOutPath(StorePath path) { outPath = {{std::move(path)}}; }
+
+    void setFailed() { failed = true; };
+    bool hasFailed() { return failed; };
+};
+
+
+typedef std::list<PackageInfo, traceable_allocator<PackageInfo>> PackageInfos;
+
+
+/**
+ * If value `v` denotes a derivation, return a PackageInfo object
+ * describing it. Otherwise return nothing.
+ */
+std::optional<PackageInfo> getDerivation(EvalState & state,
+    Value & v, bool ignoreAssertionFailures);
+
+void getDerivations(EvalState & state, Value & v, const std::string & pathPrefix,
+    Bindings & autoArgs, PackageInfos & drvs,
+    bool ignoreAssertionFailures);
+
+
+}