From f3ac693da347e5f00c7f168fcdd4a070303d9ce2 Mon Sep 17 00:00:00 2001
From: Sameer Rahmani <lxsameer@gnu.org>
Date: Tue, 24 Dec 2019 17:31:45 +0000
Subject: [PATCH] Very basic java interop has been added

---
 src/main/java/serene/simple/ListNode.java     | 63 ++++++++++++++++++-
 src/main/java/serene/simple/RootScope.java    |  2 +
 .../java/serene/simple/builtin/PlusFn.java    | 14 +++++
 .../java/serene/simple/builtin/QuitFn.java    |  2 +-
 4 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 src/main/java/serene/simple/builtin/PlusFn.java

diff --git a/src/main/java/serene/simple/ListNode.java b/src/main/java/serene/simple/ListNode.java
index 0ae6165..8f1da6c 100644
--- a/src/main/java/serene/simple/ListNode.java
+++ b/src/main/java/serene/simple/ListNode.java
@@ -9,6 +9,9 @@ import serene.simple.builtin.AFn;
 
 import static java.util.Arrays.asList;
 
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
 public class ListNode<T extends Node> extends Node implements Iterable<T> {
   public static final ListNode<?> EMPTY = new ListNode<>();
 
@@ -47,13 +50,18 @@ public class ListNode<T extends Node> extends Node implements Iterable<T> {
 
   @Override
   public Object eval(BaseScope scope) {
-    Object f = this.first().eval(scope);
+    SymbolNode firstElement = (SymbolNode) this.first();
     List<Object> args = new ArrayList<Object>();
 
     for (T node : this.rest()) {
       args.add(node.eval(scope));
     }
 
+    if (firstElement.name.startsWith(".")) {
+      return this.evalInterop(scope, firstElement, args.subList(1, args.size()));
+    }
+
+    Object f = firstElement.eval(scope);
     if (f instanceof AFn) {
       return evalBuiltin(scope, (AFn) f, args);
     }
@@ -71,6 +79,59 @@ public class ListNode<T extends Node> extends Node implements Iterable<T> {
     return fn.apply(args.toArray());
   }
 
+  public Object evalInterop(BaseScope scope, SymbolNode firstElement, List<Object> rest)
+    throws SereneException {
+
+    String mName = firstElement.name.substring(1, firstElement.name.length());
+    Object target = this.rest().first().eval(scope);
+
+    if (mName.startsWith("-")) {
+      return this.evalInteropProperty(
+        scope,
+        target,
+        mName.substring(1, firstElement.name.length()));
+    }
+
+    try {
+      System.out.println(target.getClass().getName());
+      Method f = target.getClass().getMethod(mName);
+      return f.invoke(target, rest.toArray());
+    }
+    catch(NoSuchMethodException e) {
+      throw new SereneException(
+        String.format(
+          "Can't find method '%s' on object '%s'.",
+          mName,
+          this.rest().first()));
+    }
+    catch (InvocationTargetException e) {
+      Throwable cause = e.getCause();
+      throw new SereneException(
+        String.format(
+          "Invocation of '%s' failed because of: %s%n",
+          mName, cause.getMessage()));
+    }
+    catch (IllegalAccessException e) {
+      throw new SereneException(
+        String.format("Illegal access from '%s'", mName));
+    }
+  }
+
+  public Object evalInteropProperty(BaseScope scope, Object target, String propertyName)
+    throws SereneException {
+    try {
+      Class<?> targetClass = target.getClass();
+      return targetClass.getField(propertyName);
+    }
+    catch(NoSuchFieldException e) {
+      throw new SereneException(
+        String.format(
+          "Can't find field '%s' on object '%s'.",
+          propertyName,
+          target.toString()));
+    }
+  }
+
   public T first() {
     if (this != EMPTY) {
       return this.first;
diff --git a/src/main/java/serene/simple/RootScope.java b/src/main/java/serene/simple/RootScope.java
index c26290d..65b0e6f 100644
--- a/src/main/java/serene/simple/RootScope.java
+++ b/src/main/java/serene/simple/RootScope.java
@@ -3,6 +3,7 @@ package serene.simple;
 import java.util.HashMap;
 import serene.simple.builtin.PrintlnFn;
 import serene.simple.builtin.QuitFn;
+import serene.simple.builtin.PlusFn;
 
 
 public class RootScope extends BaseScope {
@@ -10,6 +11,7 @@ public class RootScope extends BaseScope {
   private final HashMap<String, Object> symbolsMapping = new HashMap<String, Object>() {{
       put("println", new PrintlnFn());
       put("quit", new QuitFn());
+      put("+", new PlusFn());
     }};
     // "+", PlusFn,
     // "-", MinusFn,
diff --git a/src/main/java/serene/simple/builtin/PlusFn.java b/src/main/java/serene/simple/builtin/PlusFn.java
new file mode 100644
index 0000000..27821d6
--- /dev/null
+++ b/src/main/java/serene/simple/builtin/PlusFn.java
@@ -0,0 +1,14 @@
+package serene.simple.builtin;
+
+import serene.simple.BaseScope;
+
+
+public class PlusFn extends AFn {
+  public String fnName() {
+    return "+";
+  };
+
+  public Object eval(BaseScope scope) {
+    return 0;
+  }
+}
diff --git a/src/main/java/serene/simple/builtin/QuitFn.java b/src/main/java/serene/simple/builtin/QuitFn.java
index fd14154..ea227a7 100644
--- a/src/main/java/serene/simple/builtin/QuitFn.java
+++ b/src/main/java/serene/simple/builtin/QuitFn.java
@@ -5,7 +5,7 @@ import serene.simple.BaseScope;
 
 public class QuitFn extends AFn {
   public String fnName() {
-    return "println";
+    return "quit";
   };
 
   public Object eval(BaseScope scope) {