separate guest import and export code

crates/cpp/tests/native_strings/Makefile

@@ -1,30 +1,32 @@
-CXXFLAGS=-g -O0 -I../../helper-types
+CXXFLAGS=-g -O0 -I../../helper-types -I../../cpp_host -I../../guest --std=c++17
 WIT_BINDGEN=../../../../target/debug/wit-bindgen
 
 all: libstrings.so app-strings
 
-libstrings.so: the_world.pie.o guest.pie.o
-	$(CXX) $(CXXFLAGS) -shared -o $@ $^ -Wl,--version-script=guest.lds
+libstrings.so:
+	cd guest && make $@
 
-%.pie.o: %.cpp
-	$(CXX) $(CXXFLAGS) -fPIE -o $@ -c $^
+app-strings: ./cpp_host/the_world_native.o main.o ./cpp_host/guest_imported_fns.o
+	$(CXX) $(CXXFLAGS) -o $@ $^ -g -L./guest -lstrings
 
-app-strings: the_world_native.o main.o
-	$(CXX) $(CXXFLAGS) -o $@ $^ -L. -lstrings
+the_world_native.o:
+	cd cpp_host && make $@
 
 bindgen: wit/strings.wit
 	$(WIT_BINDGEN) cpp wit --wasm64 --format
 	$(WIT_BINDGEN) cpp wit --wasm64 --format --direct
 	cd rust/src ; ../../$(WIT_BINDGEN) rust ../../wit --wasm64
 
-guest.wasm: the_world.cpp guest.cpp
+guest.wasm: the_world.cpp guest_1.cpp
 	/opt/wasi-sdk/bin/clang++ -o $@ $^ $(CXXFLAGS) 
 
-guest_release.wasm: the_world.cpp guest.cpp
+guest_release.wasm: the_world.cpp guest_1.cpp
 	/opt/wasi-sdk/bin/clang++ -o $@ $^ $(CXXFLAGS) -g0 -O3
 
 clean:
-	-rm *.o libstrings.so app-strings
+	-rm *.o app-strings
+	cd guest && make clean
+	cd cpp_host && make clean
 
 run:
 	LD_LIBRARY_PATH=. ./app-strings

crates/cpp/tests/native_strings/README.md

@@ -0,0 +1,25 @@
+# Native string example
+
+In this example, there is a guest, a native host (cpp_host) and an application.
+The `guest + native host` together form the actual `guest` code, which exports some APIs.
+Now the application which is `host`, will use the guest exported calls.
+The application/host also imports some calls, those are part of the `guest_imported_functions.cpp`
+
+The directory strucutre is as below:
+```
+├── cpp_host (Native host code)
+├── guest    (Guest code)
+├── guest_imported_fns.cpp ( host application imported calls)
+├── main.cpp (Application)
+└── wit (Wit file that is used for generating the code)
+
+```
+
+# Call-graph for a function
+
+This is how the example works, call graph for the function `A` (communication between the guest_1 and guest_2 using the mesh/native host code)
+
+guest_1->exports::foo::foo::strings::A(a){native host export call}->fooX3AfooX2FstringsX23a(){native host export binding(lifting)}
+-> exports::foo::foo::strings::A(wit::string &&x){guest_1 export implementation}
+-> foo::foo::strings::A(std::string_view x){guest import call}->fooX3AfooX2FstringsX00a() {native host import binding(lowering)}
+-> foo::foo::strings::A(std::string_view x) { guest_2 import implementation}

crates/cpp/tests/native_strings/cpp_host/Makefile

@@ -0,0 +1,14 @@
+CXXFLAGS=-g -O0 -I../../../helper-types --std=c++17
+WIT_BINDGEN=../../../../target/debug/wit-bindgen
+
+all: the_world_native.o guest_imported_fns.o
+
+the_world_native.o:
+	$(CXX) $(CXXFLAGS) -fPIE -o $@ -c the_world_native.cpp
+
+guest_imported_fns.o:
+	$(CXX) $(CXXFLAGS) -fPIE -o $@ -c guest_imported_fns.cpp
+
+
+clean:
+	-rm *.o

crates/cpp/tests/native_strings/cpp_host/guest_imported_fns.cpp

@@ -0,0 +1,20 @@
+#include "./the_world_cpp_native.h"
+#include <iostream>
+
+using namespace std;
+
+void foo::foo::strings::A(std::string_view x)
+{
+    std::cout << x << std::endl;
+}
+wit::string foo::foo::strings::B()
+{
+    wit::string b = wit::string::from_view(std::string_view("hello B"));
+    return b;
+}
+wit::string foo::foo::strings::C(std::string_view a, std::string_view b)
+{
+    std::cout << a << '|' << b << std::endl;
+    wit::string c = wit::string::from_view(std::string_view("hello C"));
+    return c;
+}

crates/cpp/tests/native_strings/the_world_native.cpp → crates/cpp/tests/native_strings/cpp_host/the_world_native.cpp

@@ -15,7 +15,7 @@ fooX3AfooX2FstringsX23c(uint8_t *, size_t, uint8_t *, size_t);
 extern "C" __attribute__((import_module("cabi_post_foo:foo/strings")))
 __attribute__((import_name("c"))) void
 cabi_post_fooX3AfooX2FstringsX23c(uint8_t *);
-extern "C" void fooX3AfooX2FstringsX00a(uint8_t *arg0, size_t arg1) {
+extern "C" void fooX3AfooX2FstringsX00a(uint8_t *arg0, size_t arg1) { 
   auto len0 = arg1;
 
   foo::foo::strings::A(std::string_view((char const *)(arg0), len0));
@@ -44,10 +44,10 @@ extern "C" void fooX3AfooX2FstringsX00c(uint8_t *arg0, size_t arg1,
   *((size_t *)(arg4 + 8)) = len3;
   *((uint8_t **)(arg4 + 0)) = ptr3;
 }
-void exports::foo::foo::strings::A(wit::string x) {
+void exports::foo::foo::strings::A(wit::string x) { 
   auto const &vec0 = x;
   auto ptr0 = vec0.data();
-  auto len0 = vec0.size();
+  auto len0 = vec0.size();  
   fooX3AfooX2FstringsX23a(ptr0, len0);
 }
 wit::guest_owned<std::string_view> exports::foo::foo::strings::B() {

crates/cpp/tests/native_strings/guest/Makefile

@@ -0,0 +1,35 @@
+CXXFLAGS=-g -O0 -I../../../helper-types --std=c++17
+WIT_BINDGEN=../../../../target/debug/wit-bindgen
+
+all: libstrings.so
+
+libstrings.so: the_world.pie.o guest.pie.o
+	$(CXX) $(CXXFLAGS) -shared -o $@ $^ -Wl,--version-script=guest.lds
+
+%.pie.o: %.cpp
+	$(CXX) $(CXXFLAGS) -fPIE -o $@ -c $^
+
+bindgen: wit/strings.wit
+	$(WIT_BINDGEN) cpp wit --wasm64 --format
+	cd cpp_host
+	$(WIT_BINDGEN) cpp wit --wasm64 --format --direct
+	cd -
+	cd rust/src ; ../../$(WIT_BINDGEN) rust ../../wit --wasm64
+
+guest.wasm: the_world.cpp guest.cpp
+	/opt/wasi-sdk/bin/clang++ -o $@ $^ $(CXXFLAGS)
+
+guest_release.wasm: the_world.cpp guest.cpp
+	/opt/wasi-sdk/bin/clang++ -o $@ $^ $(CXXFLAGS) -g0 -O3
+
+clean:
+	-rm *.o libstrings.so app-strings
+
+run:
+	LD_LIBRARY_PATH=. ./app-strings
+
+valgrind:
+	LD_LIBRARY_PATH=. valgrind ./app-strings
+
+w2c2_guest.c: guest_release.wasm
+	w2c2 $^ $@

crates/cpp/tests/native_strings/guest.cpp → crates/cpp/tests/native_strings/guest/guest.cpp

@@ -1,13 +1,16 @@
 #include "the_world_cpp.h"
 
-void exports::foo::foo::strings::A(wit::string &&x) {
+void exports::foo::foo::strings::A(wit::string &&x)
+{
     ::foo::foo::strings::A(x.get_view());
 }
 
-wit::string exports::foo::foo::strings::B() {
+wit::string exports::foo::foo::strings::B()
+{
     return ::foo::foo::strings::B();
 }
 
-wit::string exports::foo::foo::strings::C(wit::string &&x, wit::string &&b) {
+wit::string exports::foo::foo::strings::C(wit::string &&x, wit::string &&b)
+{
     return ::foo::foo::strings::C(x.get_view(), b.get_view());
 }

crates/cpp/tests/native_strings/the_world.cpp → crates/cpp/tests/native_strings/guest/the_world.cpp

@@ -34,7 +34,7 @@ fooX3AfooX2FstringsX00b(uint8_t *);
 extern "C" __attribute__((import_module("foo:foo/strings")))
 __attribute__((import_name("c"))) void
 fooX3AfooX2FstringsX00c(uint8_t *, size_t, uint8_t *, size_t, uint8_t *);
-void foo::foo::strings::A(std::string_view x) {
+void foo::foo::strings::A(std::string_view x) {  
   auto const &vec0 = x;
   auto ptr0 = (uint8_t *)(vec0.data());
   auto len0 = (size_t)(vec0.size());
@@ -63,9 +63,8 @@ wit::string foo::foo::strings::C(std::string_view a, std::string_view b) {
   return wit::string((char const *)(*((uint8_t **)(ptr2 + 0))), len3);
 }
 extern "C" __attribute__((__export_name__("foo:foo/strings#a"))) void
-fooX3AfooX2FstringsX23a(uint8_t *arg0, size_t arg1) {
-  auto len0 = arg1;
-
+fooX3AfooX2FstringsX23a(uint8_t *arg0, size_t arg1) { 
+  auto len0 = arg1; 
   exports::foo::foo::strings::A(wit::string((char const *)(arg0), len0));
 }
 extern "C" __attribute__((__export_name__("foo:foo/strings#b"))) uint8_t *

crates/cpp/tests/native_strings/main.cpp

@@ -1,20 +1,7 @@
 
-#include "the_world_cpp_native.h"
+#include "./cpp_host/the_world_cpp_native.h"
 #include <iostream>
 
-void foo::foo::strings::A(std::string_view x) {
-    std::cout << x << std::endl;
-}
-wit::string foo::foo::strings::B() {
-    wit::string b = wit::string::from_view(std::string_view("hello B"));
-    return b;
-}
-wit::string foo::foo::strings::C(std::string_view a, std::string_view b) {
-    std::cout << a << '|' << b << std::endl;
-    wit::string c = wit::string::from_view(std::string_view("hello C"));
-    return c;
-}
-
 int main() {
     wit::string a = wit::string::from_view(std::string_view("hello A"));
     exports::foo::foo::strings::A(a);

crates/cpp/tests/native_strings/rust/src/lib.rs

@@ -2,7 +2,10 @@ use std::alloc::Layout;
 
 use the_world::exports::foo::foo::strings::Guest;
 
+use the_world::exports::foo::foo::strings;
+#[macro_use]
 mod the_world;
+mod the_world_native;
 
 struct MyWorld;
 
@@ -22,6 +25,9 @@ impl Guest for MyWorld {
 
 the_world::export!(MyWorld with_types_in the_world);
 
+__export_foo_foo_strings_cabi!(MyWorld with_types_in strings);
+
+
 // the crate wit-bindgen-rt doesn't work on native
 #[no_mangle]
 pub unsafe extern "C" fn cabi_realloc(