Tutorial 004

README.md

@@ -7,6 +7,7 @@
 * 001 - Java calls C void method without parameters, C writes to console
 * 002 - C returns the sum of the two passed int parameters
 * 003 - C returns the center Point of two Point structs
+* 004 - Java calls C++ main (default entry point) and main2 without parameters, C++ writes to stdout
 
 #### Prerequisites
 

panama-tutorial-004/lib/build.bat

@@ -0,0 +1,21 @@
+SET PATH=c:\Program Files\Java\jdk-panama-nightly\bin\;%PATH%
+SET JAVA_HOME=c:\Program Files\Java\jdk-panama-nightly\
+
+rd /s /q target
+
+mkdir target\g++
+g++ -shared -static -o target\g++\helloworldcpp.dll -Wall helloworldcpp.cpp
+
+jextract --source -d target\jextract\classes --target-package com.github.tornaia.panama.tutorial004.cpp -I target\g++ -l helloworldcpp helloworldcpp.h
+jextract -d target\jextract\classes --target-package com.github.tornaia.panama.tutorial004.cpp -I target\g++ -l helloworldcpp helloworldcpp.h
+
+mkdir target\jar
+jar -cvf target\jar\helloworldcpp.h.jar -C target\jextract\classes .
+
+jdeps --generate-module-info target/jdeps --module-path panama.tutorial004c --add-modules jdk.incubator.foreign target\jar\helloworldcpp.h.jar
+del target\jar\helloworldcpp.h.jar
+
+copy target\jdeps\helloworldcpp.h\module-info.java target\jextract\classes\module-info.java
+javac -d target\jextract\classes target\jextract\classes\module-info.java
+
+jar -cvf target\jar\helloworldcpp.h.jar -C target\jextract\classes .

panama-tutorial-004/lib/helloworldcpp.cpp

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+#include "helloworldcpp.h"
+
+#include <iostream>
+#include <string>
+#include <stdio.h>
+
+extern int main() {
+    std::cout << "Hello World from c++/main!" << std::endl;
+    return 0;
+}
+
+extern int main2() {
+    std::cout << "Hello World from c++/main2!" << std::endl;
+    return 0;
+}

panama-tutorial-004/lib/helloworldcpp.h

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+#ifndef helloworldcpp_h
+#define helloworldcpp_h
+
+// https://stackoverflow.com/questions/53393585/why-name-mangling-has-no-effect-on-main-function-in-c
+extern int main();
+
+// https://en.wikipedia.org/wiki/Name_mangling#Real-world_effects_of_C++_name_mangling
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+    extern int main2();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* helloworldcpp_h */

panama-tutorial-004/pom.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>panama-tutorial-004</artifactId>
+    <version>0.1-SNAPSHOT</version>
+    <name>Panama Tutorial 004</name>
+
+    <parent>
+        <groupId>com.github.tornaia</groupId>
+        <artifactId>panama-tutorial-parent</artifactId>
+        <version>0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.github.tornaia</groupId>
+            <artifactId>panama-tutorial-004-cpp</artifactId>
+            <version>${project.version}</version>
+            <scope>system</scope>
+            <systemPath>${project.basedir}/lib/target/jar/helloworldcpp.h.jar</systemPath>
+        </dependency>
+    </dependencies>
+</project>

panama-tutorial-004/src/main/java/com/github/tornaia/panama/tutorial004/Tutorial004.java

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+package com.github.tornaia.panama.tutorial004;
+
+import com.github.tornaia.panama.tutorial004.cpp.helloworldcpp_h;
+
+public class Tutorial004 {
+
+    public static void main(String[] args) {
+        System.out.println("Start");
+        helloworldcpp_h.main();
+        helloworldcpp_h.main2();
+        System.out.println("End");
+    }
+}

panama-tutorial-004/src/main/java/module-info.java

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+module panama.tutorial004j {
+    requires jdk.incubator.foreign;
+    requires helloworldcpp.h;
+}

panama-tutorial-004/src/test/java/com/github/tornaia/panama/tutorial004/Tutorial004Test.java

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+package com.github.tornaia.panama.tutorial004;
+
+import org.junit.Test;
+
+public class Tutorial004Test {
+
+    @Test
+    public void test() {
+        Tutorial004.main(null);
+    }
+}

pom.xml

@@ -46,6 +46,7 @@
         <module>panama-tutorial-001</module>
         <module>panama-tutorial-002</module>
         <module>panama-tutorial-003</module>
+        <module>panama-tutorial-004</module>
     </modules>
 
     <build>