Add view<Tag> for composite accessors, drop 3 named Vec/SortedIdVec getters

include/pup/graph/dag.hpp

@@ -156,21 +156,39 @@ template<typename T>
 [[nodiscard]]
 auto get(Graph const& graph, NodeId id) -> T;
 
-/// Get the parent directory node of a file node
-[[nodiscard]]
-auto get_parent_dir(Graph const& graph, NodeId id) -> NodeId;
-
-/// Get the input operand NodeIds of a command node
-[[nodiscard]]
-auto get_command_inputs(Graph const& graph, NodeId id) -> Vec<NodeId> const&;
+/// Role tags for composite-property access via view<Tag>.
+struct Inputs { };
+struct Outputs { };
+struct ExportedVars { };
+
+/// Storage type each role tag maps to.
+template<typename Tag>
+struct view_storage;
+
+template<>
+struct view_storage<Inputs> {
+    using type = Vec<NodeId>;
+};
+template<>
+struct view_storage<Outputs> {
+    using type = Vec<NodeId>;
+};
+template<>
+struct view_storage<ExportedVars> {
+    using type = SortedIdVec;
+};
 
-/// Get the output operand NodeIds of a command node
+/// Composite-property accessor returning a range-like const reference.
+/// Specialized per role tag out-of-line in dag.cpp. Use for collection
+/// properties (inputs, outputs, exported vars) where iteration is the
+/// natural access pattern.
+template<typename Tag>
 [[nodiscard]]
-auto get_command_outputs(Graph const& graph, NodeId id) -> Vec<NodeId> const&;
+auto view(Graph const& graph, NodeId id) -> typename view_storage<Tag>::type const&;
 
-/// Get the exported environment variables of a command node
+/// Get the parent directory node of a file node
 [[nodiscard]]
-auto get_exported_vars(Graph const& graph, NodeId id) -> SortedIdVec const&;
+auto get_parent_dir(Graph const& graph, NodeId id) -> NodeId;
 
 /// Get the parent command for InjectImplicitDeps commands
 [[nodiscard]]

src/cli/cmd_build.cpp

@@ -568,8 +568,8 @@ auto serialize_command_nodes(
             continue;
         }
 
-        auto inputs = pup::graph::get_command_inputs(g, id);
-        auto outputs = pup::graph::get_command_outputs(g, id);
+        auto inputs = pup::graph::view<pup::graph::Inputs>(g, id);
+        auto outputs = pup::graph::view<pup::graph::Outputs>(g, id);
         auto& pool = pup::global_pool();
 
         auto source_dir_sv = pup::graph::get_source_dir(g, id);

src/exec/scheduler.cpp

@@ -630,7 +630,7 @@ auto Scheduler::build_job_list(
         auto cmd_id = graph::expand_instruction(g, id, cache, source_root_sv, config_root_sv);
         auto display_id = graph::get_display_id(g, id);
 
-        auto const& exported_raw = graph::get_exported_vars(g, id);
+        auto const& exported_raw = graph::view<graph::ExportedVars>(g, id);
         auto exported_ids = Vec<StringId> {};
         exported_ids.reserve(exported_raw.size());
         for (auto raw_id : exported_raw) {

src/graph/dag.cpp

@@ -289,21 +289,24 @@ auto get_parent_dir(Graph const& graph, NodeId id) -> NodeId
     return node ? node->parent_dir : NodeId { 0 };
 }
 
-auto get_command_inputs(Graph const& graph, NodeId id) -> Vec<NodeId> const&
+template<>
+auto view<Inputs>(Graph const& graph, NodeId id) -> Vec<NodeId> const&
 {
     static auto const empty = Vec<NodeId> {};
     auto const* node = get_command_node(graph, id);
     return node ? node->inputs : empty;
 }
 
-auto get_command_outputs(Graph const& graph, NodeId id) -> Vec<NodeId> const&
+template<>
+auto view<Outputs>(Graph const& graph, NodeId id) -> Vec<NodeId> const&
 {
     static auto const empty = Vec<NodeId> {};
     auto const* node = get_command_node(graph, id);
     return node ? node->outputs : empty;
 }
 
-auto get_exported_vars(Graph const& graph, NodeId id) -> SortedIdVec const&
+template<>
+auto view<ExportedVars>(Graph const& graph, NodeId id) -> SortedIdVec const&
 {
     static auto const empty = SortedIdVec {};
     auto const* node = get_command_node(graph, id);

test/unit/test_graph.cpp

@@ -357,7 +357,7 @@ TEST_CASE("BuildGraph node types", "[graph]")
         CHECK(get_parent_dir(g, *cmd) == 0);
     }
 
-    SECTION("get_command_inputs and get_command_outputs accessors")
+    SECTION("view<Inputs> and view<Outputs>")
     {
         auto in1 = add_file_node(g, FileNode { .name = intern("a.c") });
         auto in2 = add_file_node(g, FileNode { .name = intern("b.c") });
@@ -373,17 +373,17 @@ TEST_CASE("BuildGraph node types", "[graph]")
         });
         REQUIRE(cmd.has_value());
 
-        auto const& inputs = get_command_inputs(g, *cmd);
+        auto const& inputs = view<Inputs>(g, *cmd);
         REQUIRE(inputs.size() == 2);
         CHECK(inputs[0] == *in1);
         CHECK(inputs[1] == *in2);
 
-        auto const& outputs = get_command_outputs(g, *cmd);
+        auto const& outputs = view<Outputs>(g, *cmd);
         REQUIRE(outputs.size() == 1);
         CHECK(outputs[0] == *out);
 
-        CHECK(get_command_inputs(g, *in1).empty());
-        CHECK(get_command_outputs(g, *in1).empty());
+        CHECK(view<Inputs>(g, *in1).empty());
+        CHECK(view<Outputs>(g, *in1).empty());
     }
 
     SECTION("all node types")