Filter implementation

src/main/native/jni_utils.cc

@@ -38,6 +38,8 @@ const char CLS_JBOOL[] = "org/bblfsh/client/v2/JBool";
 const char CLS_JUINT[] = "org/bblfsh/client/v2/JUint";
 const char CLS_JARR[] = "org/bblfsh/client/v2/JArray";
 const char CLS_JOBJ[] = "org/bblfsh/client/v2/JObject";
+const char CLS_ITER[] = "org/bblfsh/client/v2/libuast/Libuast$UastIterExt";
+const char CLS_JITER[] = "org/bblfsh/client/v2/libuast/Libuast$UastIter";
 
 // Method signatures
 const char METHOD_JNODE_KEY_AT[] = "(I)Ljava/lang/String;";
@@ -54,6 +56,9 @@ const char METHOD_RE_INIT[] = "(Ljava/lang/String;)V";
 const char METHOD_RE_INIT_CAUSE[] =
     "(Ljava/lang/String;Ljava/lang/Throwable;)V";
 
+const char METHOD_ITER_INIT[] = "(Lorg/bblfsh/client/v2/NodeExt;IJJ)V";
+const char METHOD_JITER_INIT[] = "(Lorg/bblfsh/client/v2/JNode;IJJ)V";
+
 // Field signatures
 const char FIELD_ITER_NODE[] = "Ljava/lang/Object;";
 

src/main/native/jni_utils.h

@@ -20,6 +20,8 @@ extern const char CLS_JBOOL[];
 extern const char CLS_JUINT[];
 extern const char CLS_JARR[];
 extern const char CLS_JOBJ[];
+extern const char CLS_ITER[];
+extern const char CLS_JITER[];
 
 // Method signatures
 extern const char METHOD_JNODE_KEY_AT[];
@@ -29,6 +31,8 @@ extern const char METHOD_JARR_ADD[];
 extern const char METHOD_OBJ_TO_STR[];
 extern const char METHOD_RE_INIT[];
 extern const char METHOD_RE_INIT_CAUSE[];
+extern const char METHOD_ITER_INIT[];
+extern const char METHOD_JITER_INIT[];
 
 // Field signatures
 extern const char FIELD_ITER_NODE[];

src/main/native/org_bblfsh_client_v2_libuast_Libuast.cc

@@ -105,7 +105,7 @@ class ContextExt {
   NodeHandle toHandle(jobject obj) {
     if (!obj) return 0;
 
-    JNIEnv *env = getJNIEnv();
+    JNIEnv *env = getJNIEnv();  // TODO: refactor to JNI util LongField()
     jclass cls = env->FindClass(CLS_NODE);
     checkJvmException("failed to find class " + std::string(CLS_NODE));
 
@@ -153,6 +153,18 @@ class ContextExt {
     return iter;
   }
 
+  // Filter queries an external UAST.
+  // Borrows the reference.
+  uast::Iterator<NodeHandle> *Filter(jobject node, std::string query) {
+    if (!assertNotContext(node)) return nullptr;
+
+    NodeHandle unode = toHandle(node);
+    if (unode == 0) unode = ctx->RootNode();
+
+    auto it = ctx->Filter(unode, query);
+    return it;
+  }
+
   // Encode serializes the external UAST.
   // Borrows the reference.
   jobject Encode(jobject node, UastFormat format) {
@@ -163,6 +175,30 @@ class ContextExt {
   }
 };
 
+// creates new UastIterExt from the given context
+jobject filterUastIterExt(ContextExt *ctx, jstring jquery, JNIEnv *env) {
+  const char *q = env->GetStringUTFChars(jquery, 0);
+  std::string query = std::string(q);
+  env->ReleaseStringUTFChars(jquery, q);
+
+  auto node = ctx->RootNode();
+  uast::Iterator<NodeHandle> *it = nullptr;
+  try {
+    it = ctx->Filter(node, query);
+  } catch (const std::exception &e) {
+    ThrowByName(env, CLS_RE, e.what());
+    return nullptr;
+  }
+
+  // new UastIterExt()
+  jobject iter = NewJavaObject(env, CLS_ITER, METHOD_ITER_INIT, 0, 0, it, ctx);
+  if (env->ExceptionCheck() || !iter) {
+    delete (it);
+    checkJvmException("failed create new UastIterExt class");
+  }
+  return iter;
+}
+
 // ================================================
 // UAST Node interface (called from libuast)
 // ================================================
@@ -174,7 +210,6 @@ class Node : public uast::Node<Node *> {
   jobject obj;  // Node owns a (global) reference
   NodeKind kind;
 
-  jobject keys;
   std::string *str;
 
   // kindOf returns a kind of a JVM object.
@@ -208,26 +243,22 @@ class Node : public uast::Node<Node *> {
 
   // Node creates a new node associated with a given JVM object and sets the
   // kind. Creates a new global reference.
-  Node(Interface *i, NodeKind k, jobject v) : keys(nullptr), str(nullptr) {
+  Node(Interface *i, NodeKind k, jobject v) : str(nullptr) {
     iface = i;
     obj = getJNIEnv()->NewGlobalRef(v);
     kind = k;
   }
 
   // Node creates a new node associated with a given JVM object and
   // automatically determines the kind. Creates a new global reference.
-  Node(Interface *i, jobject v) : keys(nullptr), str(nullptr) {
+  Node(Interface *i, jobject v) : str(nullptr) {
     iface = i;
     obj = getJNIEnv()->NewGlobalRef(v);
     kind = kindOf(v);
   }
 
   ~Node() {
     JNIEnv *env = getJNIEnv();
-    if (keys) {
-      env->DeleteGlobalRef(keys);
-      keys = nullptr;
-    }
     if (obj) {
       env->DeleteGlobalRef(obj);
     }
@@ -503,7 +534,7 @@ class Context {
   }
 
   // Iterate returns iterator over an external UAST tree.
-  // Borrows the reference.
+  // Creates a new reference.
   uast::Iterator<Node *> *Iterate(jobject jnode, TreeOrder order) {
     if (!assertNotContext(jnode)) return nullptr;
 
@@ -512,6 +543,18 @@ class Context {
     return iter;
   }
 
+  // Filter queries UAST.
+  // Creates a new reference.
+  uast::Iterator<Node *> *Filter(jobject node, std::string query) {
+    if (!assertNotContext(node)) return nullptr;
+
+    Node *unode = toNode(node);
+    if (unode == nullptr) unode = ctx->RootNode();
+
+    auto it = ctx->Filter(unode, query);
+    return it;
+  }
+
   // Encode serializes UAST.
   // Creates a new reference.
   jobject Encode(jobject jnode, UastFormat format) {
@@ -602,10 +645,10 @@ Java_org_bblfsh_client_v2_libuast_Libuast_00024UastIter_nativeInit(
 JNIEXPORT void JNICALL
 Java_org_bblfsh_client_v2_libuast_Libuast_00024UastIter_nativeDispose(
     JNIEnv *env, jobject self) {
-  // this.ctx - delete Context as iterator owns it
+  // this.ctx - delete as iterator owns it for both .iterate()/.filter() cases
   auto ctx = getHandle<Context>(env, self, "ctx");
-  setHandle<Context>(env, self, 0, "ctx");
   delete (ctx);
+  setHandle<Context>(env, self, 0, "ctx");
 
   // this.iter
   auto iter = getHandle<uast::Iterator<Node *>>(env, self, "iter");
@@ -697,16 +740,37 @@ Java_org_bblfsh_client_v2_libuast_Libuast_00024UastIterExt_nativeNext(
   return ctx->lookup(node);
 }
 
-// TODO(#83): implement
-JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_libuast_Libuast_filter(
-    JNIEnv *, jobject, jobject, jstring) {
-  return nullptr;
-}
-
 // ==========================================
 //              v2.Context()
 // ==========================================
 
+JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_Context_filter(
+    JNIEnv *env, jobject self, jstring jquery, jobject jnode) {
+  Context *ctx = getHandle<Context>(env, self, nativeContext);
+
+  const char *q = env->GetStringUTFChars(jquery, 0);
+  std::string query = std::string(q);
+  env->ReleaseStringUTFChars(jquery, q);
+
+  uast::Iterator<Node *> *it = nullptr;
+  try {
+    // global ref will be deleted by Interface destructor on ctx deletion
+    it = ctx->Filter(env->NewGlobalRef(jnode), query);
+  } catch (const std::exception &e) {
+    ThrowByName(env, CLS_RE, e.what());
+    return nullptr;
+  }
+
+  // new UastIter()
+  jobject iter =
+      NewJavaObject(env, CLS_JITER, METHOD_JITER_INIT, 0, 0, it, ctx);
+  if (env->ExceptionCheck() || !iter) {
+    delete (it);
+    checkJvmException("failed create new UastIter class");
+  }
+  return iter;
+}
+
 JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_Context_encode(
     JNIEnv *env, jobject self, jobject jnode) {
   UastFormat fmt = UAST_BINARY;  // TODO(#107): make it argument
@@ -738,6 +802,12 @@ Java_org_bblfsh_client_v2_ContextExt_root(JNIEnv *env, jobject self) {
   return p->RootNode();
 }
 
+JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_ContextExt_filter(
+    JNIEnv *env, jobject self, jstring jquery) {
+  ContextExt *ctx = getHandle<ContextExt>(env, self, nativeContext);
+  return filterUastIterExt(ctx, jquery, env);
+}
+
 JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_ContextExt_encode(
     JNIEnv *env, jobject self, jobject node) {
   UastFormat fmt = UAST_BINARY;  // TODO(#107): make it argument
@@ -765,6 +835,12 @@ JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_NodeExt_load(JNIEnv *env,
   return node;
 }
 
+JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_NodeExt_filter(
+    JNIEnv *env, jobject self, jstring jquery) {
+  auto *ctx = getHandle<ContextExt>(env, self, "ctx");
+  return filterUastIterExt(ctx, jquery, env);
+}
+
 JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
   JNIEnv *env;
   if (vm->GetEnv(reinterpret_cast<void **>(&env), JNI_VERSION_1_8) != JNI_OK) {

src/main/scala/org/bblfsh/client/v2/BblfshClient.scala

@@ -114,10 +114,6 @@ object BblfshClient {
     maxMsgSize: Int = DEFAULT_MAX_MSG_SIZE
   ): BblfshClient = new BblfshClient(host, port, maxMsgSize)
 
-  def filter(node: NodeExt, query: String): List[NodeExt] = Libuast.synchronized {
-    libuast.filter(node, query)
-  }
-
   /**
     * Decodes bytes from wired format of bblfsh protocol.v2.
     * Requires a buffer in Direct mode.
@@ -166,13 +162,17 @@ object BblfshClient {
     Libuast.UastIter(node, treeOrder)
   }
 
-  // Enables API: resp.uast.decode().load().filter("//query")
-  // TODO(83): implement XPath query
-  // implicit class NodeExtMethods(val node: NodeExt) {
-  //   def filter(query: String): List[NodeExt] = {
-  //     BblfshClient.filter(node, query)
-  //   }
-  // }
+  /** Factory method for iterator over an native node, filtered by XPath query */
+  def filter(node: NodeExt, query: String):  Libuast.UastIterExt = Libuast.synchronized {
+    node.filter(query)
+  }
+
+  /** Factory method for iterator over an managed node, filtered by XPath query */
+  def filter(node: JNode, query: String):  Libuast.UastIter = Libuast.synchronized {
+    val ctx = Context()
+    ctx.filter(query, node)
+    // do not dispose the context, iterator steals it
+  }
 
 }
 

src/main/scala/org/bblfsh/client/v2/ContextExt.scala

@@ -2,6 +2,8 @@ package org.bblfsh.client.v2
 
 import java.nio.ByteBuffer
 
+import org.bblfsh.client.v2.libuast.Libuast.{UastIter, UastIterExt}
+
 /**
   * Represents Go-side constructed tree, result of Libuast.decode()
   *
@@ -10,7 +12,7 @@ import java.nio.ByteBuffer
 case class ContextExt(nativeContext: Long) {
     // @native def load(): JNode // TODO(bzz): clarify when it's needed VS just .root().load()
     @native def root(): NodeExt
-    @native def filter()
+    @native def filter(query: String): UastIterExt
     @native def encode(n: NodeExt): ByteBuffer
 
     @native def dispose()
@@ -27,7 +29,7 @@ case class ContextExt(nativeContext: Long) {
   */
 case class Context(nativeContext: Long) {
     @native def root(): JNode
-    @native def filter()
+    @native def filter(query: String, node: JNode): UastIter
     @native def encode(n: JNode): ByteBuffer
 
     @native def dispose()

src/main/scala/org/bblfsh/client/v2/NodeExt.scala

@@ -3,8 +3,11 @@ package org.bblfsh.client.v2
 import java.io.Serializable
 import java.nio.ByteBuffer
 
+import org.bblfsh.client.v2.libuast.Libuast.UastIterExt
+
 import scala.collection.mutable
 
+
 /**
   * UAST representation for the nodes originated from the Go side.
   * This is equivalent of pyuast.NodeExt API.
@@ -14,6 +17,7 @@ import scala.collection.mutable
   */
 case class NodeExt(ctx: Long, handle: Long) {
   @native def load(): JNode
+  @native def filter(query: String): UastIterExt
 }