jvm-has-method

src/main/java/com/vectron/fcl/Fcl.java

@@ -350,6 +350,7 @@ public class Fcl {
         addPrimitive(".", () -> show(stack.pop()));
         addPrimitive("jvm-call-static", interOp::jvmCallStatic);
         addPrimitive("jvm-call-method", interOp::jvmCallMethod);
+        addPrimitive("jvm-has-method", interOp::jvmHasMethod);
         addPrimitive("jvm-static-var", interOp::jvmStaticVar);
         addPrimitive("jvm-null", () -> stack.push(null));
         addPrimitive("asc*", this::sortAsc);

src/main/java/com/vectron/fcl/interop/JvmInterOp.java

@@ -2,6 +2,7 @@ package com.vectron.fcl.interop;
 
 import com.vectron.fcl.FclStack;
 import com.vectron.fcl.exceptions.InterOpFailed;
+import com.vectron.fcl.types.Bool;
 import com.vectron.fcl.types.JvmObj;
 import com.vectron.fcl.types.Obj;
 
@@ -31,6 +32,15 @@ public class JvmInterOp {
         spec.invoke(stack);
     }
 
+    public void jvmHasMethod() {
+        String methodName = stack.pop().asStr().value();
+        Obj receiver = stack.pop();
+        MethodSpec spec = MethodSpec.parseDynamic(
+                methodName,
+                receiver instanceof JvmObj ? ((JvmObj) receiver).value() : receiver);
+        stack.push(spec.exists() ? Bool.TRUE : Bool.FALSE);
+    }
+
     public void jvmStaticVar() {
         String spec = stack.pop().asStr().value();
         String[] parts = spec.split("/");

src/main/java/com/vectron/fcl/interop/MethodSpec.java

@@ -71,6 +71,20 @@ class MethodSpec {
         }
     }
 
+    public boolean exists() {
+        List<Class<?>> types = new ArrayList<>();
+        for (int i = 0; i < arity; i++) {
+            Class<?> clazz = typeOf(typeSpec.charAt(i));
+            types.add(clazz);
+        }
+        try {
+            clazz.getMethod(methodName, types.toArray(new Class[0]));
+            return true;
+        } catch (ReflectiveOperationException e) {
+            return false;
+        }
+    }
+
     public static void processResult(Object result, FclStack stack) {
         if (result != null) {
             if (result instanceof Number)

src/main/res/raw/misc.forth

@@ -1,4 +1,7 @@
 : hist ( c -- m )
+    dup 'iterator' jvm-has-method not if
+        drop #[ ]# exit
+    then
     <map> -> tbl {
        -> elem
        tbl elem at -> count

src/test/java/com/vectron/fcl/FclTest.java

@@ -26,6 +26,7 @@ import static com.vectron.fcl.types.Bool.TRUE;
 import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -391,6 +392,12 @@ public class FclTest {
         assertEquals(1.5430, evalPop("1 cosh").doubleValue(), 0.001);
         assertEquals(0.7616, evalPop("1 tanh").doubleValue(), 0.001);
         assertEquals(1, evalPop("1.3 'intValue' jvm-call-method").doubleValue(), 0.01);
+        assertFalse(evalPop("1.3 'nosuch' jvm-has-method").boolValue());
+        assertTrue(evalPop("1.3 'round' jvm-has-method").boolValue());
+        assertTrue(evalPop("[ 1 2 ] 'iterator' jvm-has-method").boolValue());
+        assertTrue(evalPop("[ 1 2 ] 'append/O' jvm-has-method").boolValue());
+        assertFalse(evalPop("[ 1 2 ] 'append/i' jvm-has-method").boolValue());
+        assertFalse(evalPop("[ 1 2 ] 'append/OO' jvm-has-method").boolValue());
     }
 
     @Test
@@ -1122,6 +1129,7 @@ public class FclTest {
     public void testHist() {
         assertEquals("#[ 'a' 2 'b' 3 'c' 1 ]#", evalPop("'ababbc' hist").toString());
         assertEquals("#[  ]#", evalPop("'' hist").toString());
+        assertEquals("#[  ]#", evalPop("12 hist").toString());
     }
 
     private String transcript() {