Initial version

example/include/process/predicate.hpp

@@ -0,0 +1,76 @@
+#ifndef PROCESS_CONTROLLER_PREDICATE_HPP
+#define PROCESS_CONTROLLER_PREDICATE_HPP
+
+#include "process_definition.hpp" // TODO: generate to <build>/idl/process/process_definition.hpp
+
+#include <string>
+#include <functional>
+#include <type_traits>
+
+namespace process::controller {
+namespace predicate {
+    /**
+     * combines two predicates into one using a given binary operation
+     */
+    template <typename P1, typename P2, typename Op>
+    [[nodiscard]] inline auto combine(const P1& p1, const P2& p2, const Op op) noexcept -> std::function<bool(const ProcessDefinition&)>
+    {
+        static_assert(std::is_invocable_r_v<bool, decltype(op), bool, bool>);
+        static_assert(std::is_invocable_r_v<bool, decltype(p1), const ProcessDefinition&>);
+        static_assert(std::is_invocable_r_v<bool, decltype(p2), const ProcessDefinition&>);
+        return [p1, p2, op](const ProcessDefinition& arg) noexcept -> bool {
+            static_assert(std::is_invocable_r_v<bool, decltype(op), bool, bool>);
+            static_assert(std::is_invocable_r_v<bool, decltype(p1), const ProcessDefinition&>);
+            static_assert(std::is_invocable_r_v<bool, decltype(p2), const ProcessDefinition&>);
+            return op(p1(arg), p2(arg));
+        };
+    }
+
+    /**
+     * combines two predicates using logical or
+     *
+     * returns a function operating on the same argument as p1 and p2
+     */
+    template <typename P1, typename P2>
+    [[nodiscard]] inline auto Or(const P1& p1, const P2& p2) noexcept -> std::function<bool(const ProcessDefinition&)>
+    {
+        return combine(p1, p2, std::logical_or {});
+    }
+
+    /**
+     * equivalent to `const true`
+     */
+    [[nodiscard]] constexpr bool allow_all(const ProcessDefinition&) noexcept { return true; }
+
+    /**
+     * returns a function that checks whether the node of a ProcessDefinition equals a given string
+     */
+    [[nodiscard]] inline std::function<bool(const ProcessDefinition&)> node_equals(const std::string& node) noexcept
+    {
+        return [node](const ProcessDefinition& pd) noexcept -> bool {
+            return pd.node() == node;
+        };
+    }
+
+    /**
+     * returns true iff the node specifies "any node", i.e. '*'
+     */
+    [[nodiscard]] inline std::function<bool(const ProcessDefinition&)> is_any_node() noexcept
+    {
+        return node_equals("*");
+    }
+
+    /**
+     * returns a function that checks whether the node of a ProcessDefinition matches a given pattern
+     *
+     * TODO implement more sophisticated glob matching, we currently support '*' and exact match
+     */
+    [[nodiscard]] inline std::function<bool(const ProcessDefinition&)> node_matches(const std::string& pattern) noexcept
+    {
+        return Or(is_any_node(), node_equals(pattern));
+    }
+
+}
+}
+
+#endif /* PROCESS_CONTROLLER_PREDICATE_HPP */