From 3612806d5ea470f5dd2fb5a6e7f5be9de716a67e Mon Sep 17 00:00:00 2001
From: Jonathan Bradley <jcb@pikum.xyz>
Date: Wed, 28 May 2025 12:46:51 -0400
Subject: pktmpln: first-pass, adds _1, _2, and _3

---
 Makefile  |  6 ++++++
 pk.h.in   | 21 +++++++++++++++++++++
 pktmpln.h | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+)
 create mode 100644 pktmpln.h

diff --git a/Makefile b/Makefile
index dc403d6..b0a59c2 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,7 @@ SRC =  \
 	pkstn.h \
 	pkuuid.h \
 	pkbktarr.h \
+	pktmpln.h \
 	test/pkmacros.c \
 	test/pkmacros.cpp \
 	test/pkmem-types.c \
@@ -52,6 +53,7 @@ all: options .WAIT clean .WAIT \
 	pktmr \
 	pkuuid \
 	pkbktarr \
+	pktmpln \
 	test/test-pkmem-types test/test-pkmem-types-cpp \
 	test/test-pkmem test/test-pkmem-cpp \
 	test/test-pkmacros test/test-pkmacros-cpp \
@@ -105,6 +107,8 @@ pkuuid: pkuuid.gch pkuuid.gchpp
 
 pkbktarr: pkbktarr.gch pkbktarr.gchpp
 
+pktmpln: pktmpln.gch pktmpln.gchpp
+
 build: pkmacros
 build: pkmem-types
 build: pkmem
@@ -127,6 +131,7 @@ build: pkbktarr
 	pktmr.h \
 	pkuuid.h \
 	pkbktarr.h \
+	pktmpln.h \
 	>> pk.h
 	echo "#endif /* PK_SINGLE_HEADER_FILE_H */" >> pk.h
 	sed -i -r \
@@ -207,6 +212,7 @@ test: pkstn test/test-pkstn test/test-pkstn-cpp
 test: pktmr test/test-pktmr test/test-pktmr-cpp
 test: pkuuid test/test-pkuuid test/test-pkuuid-cpp
 test: pkbktarr test/test-pkbktarr test/test-pkbktarr-cpp
+test: pktmpln
 test:
 	@echo ""
 	./test/test-pkmacros ; echo Result: $$? "\n"
diff --git a/pk.h.in b/pk.h.in
index 5142c76..d255320 100644
--- a/pk.h.in
+++ b/pk.h.in
@@ -251,6 +251,27 @@
 * arr.~pk_bkt_arr<int>(); // manually call dtor for globals
 * ```
 *
+********************************************************************************
+* pktmpl.h: only contains c++ templates, no IMPL.
+*
+* Provides template structs for trampolines, allowing c-style callbacks with
+*  capturing lambdas.
+*
+* Examples:
+* ```c++
+* int some_counter = 0;
+* using IterCbWrapper = pk_tmpln_1<void, int*, void*>;
+* IterCbWrapper cb_wrapper{};
+* cb_wrapper.func = [&some_counter](int *lhs)
+* {
+*   (void)lhs;
+*   some_counter += 1;
+*   return;
+* };
+* pk_bkt_arr_iterate(&bkt_arr, &IterCbWrapper::invoke, &cb_wrapper);
+* assert(some_count == 1);
+* ```
+*
 *******************************************************************************/
 
 #define PK_VERSION "@@PK_VERSION@@"
diff --git a/pktmpln.h b/pktmpln.h
new file mode 100644
index 0000000..64000ef
--- /dev/null
+++ b/pktmpln.h
@@ -0,0 +1,35 @@
+#ifndef PK_PKTMPLN_H
+#define PK_PKTMPLN_H
+
+#if defined (__cplusplus)
+#include <functional>
+template<typename Ret, typename A1, typename B1>
+struct pk_tmpln_1 {
+	using FuncType = std::function<Ret(A1)>;
+	FuncType func;
+	static Ret invoke(void *ptr, B1 b1) {
+		auto *self = static_cast<pk_tmpln_1*>(ptr);
+		return self->func(reinterpret_cast<A1>(b1));
+	}
+};
+template<typename Ret, typename A1, typename A2, typename B1, typename B2>
+struct pk_tmpln_2 {
+	using FuncType = std::function<Ret(A1, A2)>;
+	FuncType func;
+	static Ret invoke(void *ptr, B1 b1, B2 b2) {
+		auto *self = static_cast<pk_tmpln_2*>(ptr);
+		return self->func(reinterpret_cast<A1>(b1), reinterpret_cast<A2>(b2));
+	}
+};
+template<typename Ret, typename A1, typename A2, typename A3, typename B1, typename B2, typename B3>
+struct pk_tmpln_3 {
+	using FuncType = std::function<Ret(A1, A2, A3)>;
+	FuncType func;
+	static Ret invoke(void *ptr, B1 b1, B2 b2, B3 b3) {
+		auto *self = static_cast<pk_tmpln_3*>(ptr);
+		return self->func(reinterpret_cast<A1>(b1), reinterpret_cast<A2>(b2), reinterpret_cast<A3>(b3));
+	}
+};
+#endif
+
+#endif /* PK_PKTMPLN_H */
-- 
cgit v1.2.3