Split `OutputsSpec` and `ExtendedOutputsSpec`, use the former more

`DerivedPath::Built` and `DerivationGoal` were previously using a
regular set with the convention that the empty set means all outputs.
But it is easy to forget about this rule when processing those sets.
Using `OutputSpec` forces us to get it right.

1 files changed, 41 insertions, 5 deletions

diff --git a/src/libstore/outputs-spec.hh b/src/libstore/outputs-spec.hh
index 5ed711a62..e81695da9 100644
--- a/src/libstore/outputs-spec.hh
+++ b/src/libstore/outputs-spec.hh
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <optional>
 #include <set>
 #include <variant>
 
@@ -13,31 +14,66 @@ struct AllOutputs {
     bool operator < (const AllOutputs & _) const { return false; }
 };
 
+typedef std::variant<AllOutputs, OutputNames> _OutputsSpecRaw;
+
+struct OutputsSpec : _OutputsSpecRaw {
+    using Raw = _OutputsSpecRaw;
+    using Raw::Raw;
+
+    using Names = OutputNames;
+    using All = AllOutputs;
+
+    inline const Raw & raw() const {
+        return static_cast<const Raw &>(*this);
+    }
+
+    inline Raw & raw() {
+        return static_cast<Raw &>(*this);
+    }
+
+    bool contains(const std::string & output) const;
+
+    /* Modify the receiver outputs spec so it is the union of it's old value
+       and the argument. Return whether the output spec needed to be modified
+       --- if it didn't it was already "large enough". */
+    bool merge(const OutputsSpec & outputs);
+
+    /* Parse a string of the form 'output1,...outputN' or
+       '*', returning the outputs spec. */
+    static OutputsSpec parse(std::string_view s);
+    static std::optional<OutputsSpec> parseOpt(std::string_view s);
+
+    std::string to_string() const;
+};
+
 struct DefaultOutputs {
     bool operator < (const DefaultOutputs & _) const { return false; }
 };
 
-typedef std::variant<DefaultOutputs, AllOutputs, OutputNames> _ExtendedOutputsSpecRaw;
+typedef std::variant<DefaultOutputs, OutputsSpec> _ExtendedOutputsSpecRaw;
 
 struct ExtendedOutputsSpec : _ExtendedOutputsSpecRaw {
     using Raw = _ExtendedOutputsSpecRaw;
     using Raw::Raw;
 
-    using Names = OutputNames;
-    using All = AllOutputs;
     using Default = DefaultOutputs;
+    using Explicit = OutputsSpec;
 
     inline const Raw & raw() const {
         return static_cast<const Raw &>(*this);
     }
 
     /* Parse a string of the form 'prefix^output1,...outputN' or
-       'prefix^*', returning the prefix and the outputs spec. */
-    static std::pair<std::string, ExtendedOutputsSpec> parse(std::string s);
+       'prefix^*', returning the prefix and the extended outputs spec. */
+    static std::pair<std::string_view, ExtendedOutputsSpec> parse(std::string_view s);
 
     std::string to_string() const;
 };
 
+
+void to_json(nlohmann::json &, const OutputsSpec &);
+void from_json(const nlohmann::json &, OutputsSpec &);
+
 void to_json(nlohmann::json &, const ExtendedOutputsSpec &);
 void from_json(const nlohmann::json &, ExtendedOutputsSpec &);