Skylark debug server: add serialization code

Small self-contained part of the debug server (see unknown commit for the
larger picture).

PiperOrigin-RevId: 197140094

2 files changed, 160 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD
new file mode 100644
index 0000000000..42768bb69d
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/BUILD
@@ -0,0 +1,20 @@
+package(default_visibility = ["//src:__subpackages__"])
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]),
+    visibility = ["//src/main/java/com/google/devtools/build/lib:__pkg__"],
+)
+
+java_library(
+    name = "server",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib:skylarkinterface",
+        "//src/main/java/com/google/devtools/build/lib:syntax",
+        "//src/main/java/com/google/devtools/build/lib/collect/nestedset",
+        "//src/main/java/com/google/devtools/build/lib/skylarkdebug/proto:skylark_debugging_java_proto",
+        "//third_party:guava",
+        "//third_party:jsr305",
+    ],
+)
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerialization.java b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerialization.java
new file mode 100644
index 0000000000..70d716332a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkdebug/server/DebuggerSerialization.java
@@ -0,0 +1,140 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.skylarkdebug.server;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Ordering;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetView;
+import com.google.devtools.build.lib.skylarkdebugging.SkylarkDebuggingProtos;
+import com.google.devtools.build.lib.skylarkdebugging.SkylarkDebuggingProtos.Value;
+import com.google.devtools.build.lib.syntax.ClassObject;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.EvalUtils;
+import com.google.devtools.build.lib.syntax.Printer;
+import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+import java.lang.reflect.Array;
+import java.util.Map;
+
+/** Helper class for creating {@link SkylarkDebuggingProtos.Value} from skylark objects. */
+final class DebuggerSerialization {
+
+  static Value getValueProto(String label, Object value) {
+    // TODO(bazel-team): prune cycles, and provide a way to limit breadth/depth of children reported
+    return Value.newBuilder()
+        .setLabel(label)
+        // TODO(bazel-team): omit type details for non-Skylark values
+        .setType(EvalUtils.getDataTypeName(value))
+        .setDescription(Printer.repr(value))
+        .addAllChild(getChildren(value))
+        .build();
+  }
+
+  private static Value errorValue(String errorMessage) {
+    return Value.newBuilder().setLabel("Error").setDescription(errorMessage).build();
+  }
+
+  private static ImmutableList<Value> getChildren(Object value) {
+    // TODO(bazel-team): move child-listing logic to SkylarkValue where practical
+    if (value instanceof ClassObject) {
+      return getChildren((ClassObject) value);
+    }
+    if (value instanceof SkylarkNestedSet) {
+      return getChildren((SkylarkNestedSet) value);
+    }
+    if (value instanceof NestedSetView) {
+      return getChildren((NestedSetView) value);
+    }
+    if (value instanceof Map) {
+      return getChildren(((Map) value).entrySet());
+    }
+    if (value instanceof Map.Entry) {
+      return getChildren((Map.Entry) value);
+    }
+    if (value instanceof Iterable) {
+      return getChildren((Iterable) value);
+    }
+    if (value.getClass().isArray()) {
+      return getArrayChildren(value);
+    }
+    // fallback to assuming there are no children
+    return ImmutableList.of();
+  }
+
+  private static ImmutableList<Value> getChildren(ClassObject classObject) {
+    ImmutableList.Builder<Value> builder = ImmutableList.builder();
+    ImmutableList<String> keys;
+    try {
+      keys = Ordering.natural().immutableSortedCopy(classObject.getFieldNames());
+    } catch (EvalException e) {
+      return ImmutableList.of(errorValue("Error retrieving field names: " + e.getMessage()));
+    }
+    for (String key : keys) {
+      Object value;
+      try {
+        value = classObject.getValue(key);
+      } catch (EvalException e) {
+        return ImmutableList.of(
+            errorValue(
+                String.format("Error retrieving value for field '%s': %s", key, e.getMessage())));
+      }
+      if (value != null) {
+        builder.add(getValueProto(key, value));
+      }
+    }
+    return builder.build();
+  }
+
+  private static ImmutableList<Value> getChildren(SkylarkNestedSet nestedSet) {
+    Class<?> type = nestedSet.getContentType().getType();
+    return ImmutableList.<Value>builder()
+        .add(
+            Value.newBuilder()
+                .setLabel("order")
+                .setType("Traversal order")
+                .setDescription(nestedSet.getOrder().getSkylarkName())
+                .build())
+        .addAll(getChildren(new NestedSetView<>(nestedSet.getSet(type))))
+        .build();
+  }
+
+  private static ImmutableList<Value> getChildren(NestedSetView<?> nestedSet) {
+    return ImmutableList.of(
+        getValueProto("directs", nestedSet.directs()),
+        getValueProto("transitives", nestedSet.transitives()));
+  }
+
+  private static ImmutableList<Value> getChildren(Map.Entry<?, ?> entry) {
+    return ImmutableList.of(
+        getValueProto("key", entry.getKey()), getValueProto("value", entry.getValue()));
+  }
+
+  private static ImmutableList<Value> getChildren(Iterable<?> iterable) {
+    ImmutableList.Builder<Value> builder = ImmutableList.builder();
+    int index = 0;
+    for (Object value : iterable) {
+      builder.add(getValueProto(String.format("[%d]", index++), value));
+    }
+    return builder.build();
+  }
+
+  private static ImmutableList<Value> getArrayChildren(Object array) {
+    ImmutableList.Builder<Value> builder = ImmutableList.builder();
+    int index = 0;
+    for (int i = 0; i < Array.getLength(array); i++) {
+      builder.add(getValueProto(String.format("[%d]", index++), Array.get(array, i)));
+    }
+    return builder.build();
+  }
+}