Add ITable/NetworkTable GetKeys and GetSubTables accessors.

java/lib/NetworkTablesJNI.cpp

@@ -15,6 +15,7 @@ static jclass booleanCls = nullptr;
 static jclass doubleCls = nullptr;
 static jclass stringCls = nullptr;
 static jclass connectionInfoCls = nullptr;
+static jclass entryInfoCls = nullptr;
 static jclass keyNotDefinedEx = nullptr;
 static jclass persistentEx = nullptr;
 
@@ -52,6 +53,12 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {
   if (!connectionInfoCls) return JNI_ERR;
   env->DeleteLocalRef(local);
 
+  local = env->FindClass("edu/wpi/first/wpilibj/networktables/EntryInfo");
+  if (!local) return JNI_ERR;
+  entryInfoCls = static_cast<jclass>(env->NewGlobalRef(local));
+  if (!entryInfoCls) return JNI_ERR;
+  env->DeleteLocalRef(local);
+
   local =
       env->FindClass("edu/wpi/first/wpilibj/networktables/NetworkTableKeyNotDefined");
   keyNotDefinedEx = static_cast<jclass>(env->NewGlobalRef(local));
@@ -76,6 +83,7 @@ JNIEXPORT void JNICALL JNI_OnUnload(JavaVM *vm, void *reserved) {
   if (doubleCls) env->DeleteGlobalRef(doubleCls);
   if (stringCls) env->DeleteGlobalRef(stringCls);
   if (connectionInfoCls) env->DeleteGlobalRef(connectionInfoCls);
+  if (entryInfoCls) env->DeleteGlobalRef(entryInfoCls);
   if (keyNotDefinedEx) env->DeleteGlobalRef(keyNotDefinedEx);
   if (persistentEx) env->DeleteGlobalRef(persistentEx);
   jvm = nullptr;
@@ -347,6 +355,14 @@ static jobject ToJavaObject(JNIEnv *env, const nt::ConnectionInfo &info) {
                         (jlong)info.last_update, (jint)info.protocol_version);
 }
 
+static jobject ToJavaObject(JNIEnv *env, const nt::EntryInfo &info) {
+  static jmethodID constructor =
+      env->GetMethodID(entryInfoCls, "<init>", "(Ljava/lang/String;IIJ)V");
+  JavaLocal<jstring> name(env, ToJavaString(env, info.name));
+  return env->NewObject(entryInfoCls, constructor, name.obj(), (jint)info.type,
+                        (jint)info.flags, (jlong)info.last_change);
+}
+
 //
 // Exception throwers
 //
@@ -836,6 +852,24 @@ JNIEXPORT void JNICALL Java_edu_wpi_first_wpilibj_networktables_NetworkTablesJNI
   nt::DeleteAllEntries();
 }
 
+/*
+ * Class:     edu_wpi_first_wpilibj_networktables_NetworkTablesJNI
+ * Method:    getEntries
+ * Signature: (Ljava/lang/String;I)[Ledu/wpi/first/wpilibj/networktables/EntryInfo;
+ */
+JNIEXPORT jobjectArray JNICALL Java_edu_wpi_first_wpilibj_networktables_NetworkTablesJNI_getEntries
+  (JNIEnv *env, jclass, jstring prefix, jint types)
+{
+  auto arr = nt::GetEntryInfo(JavaStringRef(env, prefix), types);
+  jobjectArray jarr = env->NewObjectArray(arr.size(), entryInfoCls, nullptr);
+  if (!jarr) return nullptr;
+  for (size_t i = 0; i < arr.size(); ++i) {
+    JavaLocal<jobject> jelem(env, ToJavaObject(env, arr[i]));
+    env->SetObjectArrayElement(jarr, i, jelem);
+  }
+  return jarr;
+}
+
 /*
  * Class:     edu_wpi_first_wpilibj_networktables_NetworkTablesJNI
  * Method:    flush

java/src/edu/wpi/first/wpilibj/networktables/NetworkTable.java

@@ -367,13 +367,47 @@ public class NetworkTable implements ITable, IRemote {
   }
 
   public boolean containsSubTable(String key) {
-    String subtablePrefix = path + key + PATH_SEPARATOR;
-    //List keys = node.getEntryStore().keys();
-    //for (int i = 0; i < keys.size(); ++i) {
-    //  if (((String)keys.get(i)).startsWith(subtablePrefix))
-    //    return true;
-    //}
-    return false;
+    EntryInfo[] entries = NetworkTablesJNI.getEntries(path + PATH_SEPARATOR + key + PATH_SEPARATOR, 0);
+    return entries.length != 0;
+  }
+
+  /**
+   * @param types bitmask of types; 0 is treated as a "don't care".
+   * @return keys currently in the table
+   */
+  public Set<String> getKeys(int types) {
+    Set<String> keys = new HashSet<String>();
+    int prefixLen = path.length() + 1;
+    for (EntryInfo entry : NetworkTablesJNI.getEntries(path + PATH_SEPARATOR, types)) {
+      String relativeKey = entry.name.substring(prefixLen);
+      if (relativeKey.indexOf(PATH_SEPARATOR) != -1)
+        continue;
+      keys.add(relativeKey);
+    }
+    return keys;
+  }
+
+  /**
+   * @return keys currently in the table
+   */
+  public Set<String> getKeys() {
+    return getKeys(0);
+  }
+
+  /**
+   * @return subtables currently in the table
+   */
+  public Set<String> getSubTables() {
+    Set<String> keys = new HashSet<String>();
+    int prefixLen = path.length() + 1;
+    for (EntryInfo entry : NetworkTablesJNI.getEntries(path + PATH_SEPARATOR, 0)) {
+      String relativeKey = entry.name.substring(prefixLen);
+      int endSubTable = relativeKey.indexOf(PATH_SEPARATOR);
+      if (endSubTable == -1)
+        continue;
+      keys.add(relativeKey.substring(0, endSubTable));
+    }
+    return keys;
   }
 
   /**

java/src/edu/wpi/first/wpilibj/networktables/NetworkTablesJNI.java

@@ -98,7 +98,7 @@ public class NetworkTablesJNI {
   public static native void deleteEntry(String key);
   public static native void deleteAllEntries();
 
-  // public static native EntryInfo[] getEntryInfo(String prefix, int types);
+  public static native EntryInfo[] getEntries(String prefix, int types);
 
   public static native void flush();
 

java/src/edu/wpi/first/wpilibj/tables/ITable.java

@@ -1,6 +1,7 @@
 package edu.wpi.first.wpilibj.tables;
 
 import java.util.NoSuchElementException;
+import java.util.Set;
 
 
 /**
@@ -30,6 +31,22 @@ public interface ITable {
    */
   public ITable getSubTable(String key);
 
+  /**
+   * @param types bitmask of types; 0 is treated as a "don't care".
+   * @return keys currently in the table
+   */
+  public Set<String> getKeys(int types);
+
+  /**
+   * @return keys currently in the table
+   */
+  public Set<String> getKeys();
+
+  /**
+   * @return subtables currently in the table
+   */
+  public Set<String> getSubTables();
+
   /**
    * Makes a key's value persistent through program restarts.
    * The key cannot be null.