Record and propagate namespaces from the <resources> element correctly.

* Reduces the size of merged values.xml
* Improves correctness of merged xml

Sadly, this is also backwards compatible by allowing multiple definitions of a prefix with different namespaces.
Will be cleaned up after transition.

--
MOS_MIGRATED_REVID=127481147

8 files changed, 190 insertions, 27 deletions

diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/ArrayXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/ArrayXmlResourceValue.java
index 5c9d64b637..71e24691ca 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/ArrayXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/ArrayXmlResourceValue.java
@@ -23,7 +23,6 @@ import com.google.devtools.build.android.FullyQualifiedName;
 import com.google.devtools.build.android.XmlResourceValue;
 import com.google.devtools.build.android.XmlResourceValues;
 import com.google.devtools.build.android.proto.SerializeFormat;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
@@ -31,7 +30,6 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
-
 import javax.annotation.concurrent.Immutable;
 import javax.xml.namespace.QName;
 import javax.xml.stream.XMLEventReader;
@@ -139,7 +137,8 @@ public class ArrayXmlResourceValue implements XmlResourceValue {
   }
 
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
     return XmlResourceValues.serializeProtoDataValue(
         output,
         XmlResourceValues.newSerializableDataValueBuilder(source)
@@ -147,6 +146,7 @@ public class ArrayXmlResourceValue implements XmlResourceValue {
                 SerializeFormat.DataValueXml.newBuilder()
                     .addAllListValue(values)
                     .setType(SerializeFormat.DataValueXml.XmlType.ARRAY)
+                    .putAllNamespace(namespaces.asMap())
                     .putAllAttribute(attributes)
                     .setValueType(arrayType.toString())));
   }
@@ -181,7 +181,8 @@ public class ArrayXmlResourceValue implements XmlResourceValue {
     throw new IllegalArgumentException(this + " is not a combinable resource.");
   }
 
-  public static XmlResourceValue parseArray(XMLEventReader eventReader, StartElement start)
+  public static XmlResourceValue parseArray(
+      XMLEventReader eventReader, StartElement start, Namespaces.Collector namespacesCollector)
       throws XMLStreamException {
     List<String> values = new ArrayList<>();
     for (XMLEvent element = XmlResourceValues.nextTag(eventReader);
@@ -193,7 +194,8 @@ public class ArrayXmlResourceValue implements XmlResourceValue {
               String.format("Expected start element %s", element), element.getLocation());
         }
         String contents =
-            XmlResourceValues.readContentsAsString(eventReader, element.asStartElement().getName());
+            XmlResourceValues.readContentsAsString(
+                eventReader, element.asStartElement().getName(), namespacesCollector);
         values.add(contents != null ? contents : "");
       }
     }
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/AttrXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/AttrXmlResourceValue.java
index 5686b04e72..ca7a984bd8 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/AttrXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/AttrXmlResourceValue.java
@@ -32,7 +32,6 @@ import com.google.devtools.build.android.XmlResourceValue;
 import com.google.devtools.build.android.XmlResourceValues;
 import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.protobuf.InvalidProtocolBufferException;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
@@ -43,7 +42,6 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Objects;
 import java.util.Set;
-
 import javax.annotation.CheckReturnValue;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
@@ -331,12 +329,15 @@ public class AttrXmlResourceValue implements XmlResourceValue {
 
   @SuppressWarnings("deprecation")
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
     SerializeFormat.DataValue.Builder builder =
         XmlResourceValues.newSerializableDataValueBuilder(source);
     SerializeFormat.DataValueXml.Builder xmlValueBuilder =
         SerializeFormat.DataValueXml.newBuilder();
-    xmlValueBuilder.setType(SerializeFormat.DataValueXml.XmlType.ATTR);
+    xmlValueBuilder
+        .setType(SerializeFormat.DataValueXml.XmlType.ATTR)
+        .putAllNamespace(namespaces.asMap());
     for (Entry<String, ResourceXmlAttrValue> entry : formats.entrySet()) {
       xmlValueBuilder
           .getMutableMappedXmlValue()
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/IdXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/IdXmlResourceValue.java
index b300e43851..1b56f8b0c7 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/IdXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/IdXmlResourceValue.java
@@ -23,12 +23,10 @@ import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.devtools.build.android.proto.SerializeFormat.DataValueXml.Builder;
 import com.google.devtools.build.android.proto.SerializeFormat.DataValueXml.XmlType;
 import com.google.protobuf.CodedOutputStream;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
 import java.util.Objects;
-
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
@@ -82,8 +80,12 @@ public class IdXmlResourceValue implements XmlResourceValue {
   }
 
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
-    Builder xmlValue = SerializeFormat.DataValueXml.newBuilder().setType(XmlType.ID);
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
+    Builder xmlValue =
+        SerializeFormat.DataValueXml.newBuilder()
+            .setType(XmlType.ID)
+            .putAllNamespace(namespaces.asMap());
     if (value != null) {
       xmlValue.setValue(value);
     }
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/Namespaces.java b/src/tools/android/java/com/google/devtools/build/android/xml/Namespaces.java
new file mode 100644
index 0000000000..cbaabea740
--- /dev/null
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/Namespaces.java
@@ -0,0 +1,159 @@
+// Copyright 2016 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.android.xml;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.android.DataResourceXml;
+import com.google.devtools.build.android.XmlResourceValue;
+import com.google.devtools.build.android.XmlResourceValues;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.Set;
+import java.util.logging.Logger;
+import javax.xml.namespace.QName;
+import javax.xml.stream.events.Attribute;
+import javax.xml.stream.events.Namespace;
+import javax.xml.stream.events.StartElement;
+
+/**
+ * Represents a collection of xml namespaces.
+ *
+ * <p>Each &lt;resources&gt; can have xmlns declarations. Since the merging process generates the
+ * resources tag to combining multiple {@link DataResourceXml}s, the Namespaces must be tracked and
+ * kept with each value.
+ */
+public class Namespaces implements Iterable<Entry<String, String>> {
+  private static final Logger logger = Logger.getLogger(Namespaces.class.getCanonicalName());
+  private static final Namespaces EMPTY_INSTANCE =
+      new Namespaces(ImmutableMap.<String, String>of());
+
+  /**
+   * Collects prefix and uri pairs from elements.
+   */
+  public static class Collector {
+    private Map<String, String> prefixToUri = new HashMap<>();
+
+    public Namespaces toNamespaces() {
+      return Namespaces.from(prefixToUri);
+    }
+
+    /**
+     * Collects all the prefix and uri pairs from a start element.
+     *
+     * <p>Since {@link Namespaces} represents top level declarations, collectFrom ignores any prefix
+     * that is declared on the element. Those will be handled by the {@link XmlResourceValue}
+     * individually.
+     *
+     * @param start The element to collect prefix and uris from.
+     * @return The current namespace builder.
+     */
+    public Collector collectFrom(StartElement start) {
+      Iterator<Attribute> attributes = XmlResourceValues.iterateAttributesFrom(start);
+      Iterator<Namespace> localNamespaces = XmlResourceValues.iterateNamespacesFrom(start);
+      // Collect the local prefixes to make sure a prefix isn't declared locally.
+      Set<String> prefixes = new HashSet<>();
+      while (localNamespaces.hasNext()) {
+        prefixes.add(localNamespaces.next().getPrefix());
+      }
+      collectFrom(start.getName(), prefixes);
+      while (attributes.hasNext()) {
+        collectFrom(attributes.next().getName(), prefixes);
+      }
+      return this;
+    }
+
+    void collectFrom(QName name, Set<String> localPrefixes) {
+      String prefix = name.getPrefix();
+      if (!prefix.isEmpty() && !localPrefixes.contains(prefix)) {
+        // If the prefix exists and is not a locally declared prefix, add the prefix and uri.
+        prefixToUri.put(prefix, name.getNamespaceURI());
+      }
+    }
+  }
+
+  public static Collector collector() {
+    return new Collector();
+  }
+
+  public static Namespaces from(Map<String, String> prefixToUri) {
+    if (prefixToUri.isEmpty()) {
+      return empty();
+    }
+    return new Namespaces(ImmutableMap.copyOf(prefixToUri));
+  }
+
+  public static Namespaces empty() {
+    return EMPTY_INSTANCE;
+  }
+
+  private ImmutableMap<String, String> prefixToUri;
+
+  private Namespaces(ImmutableMap<String, String> prefixToUri) {
+    this.prefixToUri = prefixToUri;
+  }
+
+  /** Combines two {@link Namespaces} into a new instance and returns it. */
+  public Namespaces union(Namespaces other) {
+    // No prefixes to add, return the other.
+    if (prefixToUri.isEmpty()) {
+      return other;
+    }
+    // TODO(corysmith): Issue error when prefixes are mapped to different uris.
+    // Keeping behavior for backwards compatibility.
+    Map<String, String> combinedNamespaces = new LinkedHashMap<>();
+    combinedNamespaces.putAll(other.prefixToUri);
+    for (Entry<String, String> namespace : prefixToUri.entrySet()) {
+      String prefix = namespace.getKey();
+      String namespaceUri = namespace.getValue();
+      if (combinedNamespaces.containsKey(prefix)
+          && !combinedNamespaces.get(prefix).equals(namespaceUri)) {
+        logger.warning(
+            String.format(
+                "%s has multiple namespaces: %s and %s. Using %s."
+                    + " This will be an error in the future.",
+                prefix, namespaceUri, combinedNamespaces.get(prefix), namespaceUri));
+      }
+      combinedNamespaces.put(prefix, namespaceUri);
+    }
+    return Namespaces.from(combinedNamespaces);
+  }
+
+  @Override
+  public Iterator<Entry<String, String>> iterator() {
+    return prefixToUri.entrySet().iterator();
+  }
+
+  public Map<String, String> asMap() {
+    return prefixToUri;
+  }
+
+  @Override
+  public int hashCode() {
+    return prefixToUri.hashCode();
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (obj instanceof Namespaces) {
+      Namespaces other = (Namespaces) obj;
+      return Objects.equals(prefixToUri, other.prefixToUri);
+    }
+    return false;
+  }
+}
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/PluralXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/PluralXmlResourceValue.java
index 29b2a2608f..1e708afb1c 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/PluralXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/PluralXmlResourceValue.java
@@ -23,13 +23,11 @@ import com.google.devtools.build.android.XmlResourceValues;
 import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.devtools.build.android.proto.SerializeFormat.DataValueXml.XmlType;
 import com.google.protobuf.CodedOutputStream;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
 import java.util.Map.Entry;
 import java.util.Objects;
-
 import javax.annotation.concurrent.Immutable;
 import javax.xml.namespace.QName;
 
@@ -128,7 +126,8 @@ public class PluralXmlResourceValue implements XmlResourceValue {
   }
 
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
     SerializeFormat.DataValue.Builder builder =
         XmlResourceValues.newSerializableDataValueBuilder(source);
     SerializeFormat.DataValue value =
@@ -137,6 +136,7 @@ public class PluralXmlResourceValue implements XmlResourceValue {
                 builder
                     .getXmlValueBuilder()
                     .setType(XmlType.PLURAL)
+                    .putAllNamespace(namespaces.asMap())
                     .putAllAttribute(attributes)
                     .putAllMappedStringValue(values))
             .build();
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/SimpleXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/SimpleXmlResourceValue.java
index 3e308a1fab..ef4e822b4f 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/SimpleXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/SimpleXmlResourceValue.java
@@ -13,6 +13,7 @@
 // limitations under the License.
 package com.google.devtools.build.android.xml;
 
+import com.android.resources.ResourceType;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.android.AndroidDataWritingVisitor;
@@ -22,15 +23,11 @@ import com.google.devtools.build.android.XmlResourceValue;
 import com.google.devtools.build.android.XmlResourceValues;
 import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.devtools.build.android.proto.SerializeFormat.DataValueXml.Builder;
-
-import com.android.resources.ResourceType;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.Objects;
-
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.xml.namespace.QName;
@@ -214,12 +211,14 @@ public class SimpleXmlResourceValue implements XmlResourceValue {
   }
 
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
     SerializeFormat.DataValue.Builder builder =
         XmlResourceValues.newSerializableDataValueBuilder(source);
     Builder xmlValueBuilder =
         builder
             .getXmlValueBuilder()
+            .putAllNamespace(namespaces.asMap())
             .setType(SerializeFormat.DataValueXml.XmlType.SIMPLE)
             // TODO(corysmith): Find a way to avoid writing strings to the serialized format
             // it's inefficient use of space and costs more when deserializing.
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/StyleXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/StyleXmlResourceValue.java
index c3edb182e4..60abda34fe 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/StyleXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/StyleXmlResourceValue.java
@@ -23,14 +23,12 @@ import com.google.devtools.build.android.XmlResourceValue;
 import com.google.devtools.build.android.XmlResourceValues;
 import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.devtools.build.android.proto.SerializeFormat.DataValueXml.XmlType;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Objects;
-
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
@@ -107,10 +105,12 @@ public class StyleXmlResourceValue implements XmlResourceValue {
   }
 
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
     SerializeFormat.DataValueXml.Builder xmlValueBuilder =
         SerializeFormat.DataValueXml.newBuilder()
             .setType(XmlType.STYLE)
+            .putAllNamespace(namespaces.asMap())
             .putAllMappedStringValue(values);
     if (parent != null) {
       xmlValueBuilder.setValue(parent);
diff --git a/src/tools/android/java/com/google/devtools/build/android/xml/StyleableXmlResourceValue.java b/src/tools/android/java/com/google/devtools/build/android/xml/StyleableXmlResourceValue.java
index 095ff7a1cb..82bf56584a 100644
--- a/src/tools/android/java/com/google/devtools/build/android/xml/StyleableXmlResourceValue.java
+++ b/src/tools/android/java/com/google/devtools/build/android/xml/StyleableXmlResourceValue.java
@@ -26,7 +26,6 @@ import com.google.devtools.build.android.XmlResourceValue;
 import com.google.devtools.build.android.XmlResourceValues;
 import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.devtools.build.android.proto.SerializeFormat.DataValueXml.XmlType;
-
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Path;
@@ -35,7 +34,6 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Objects;
-
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -138,13 +136,15 @@ public class StyleableXmlResourceValue implements XmlResourceValue {
   }
 
   @Override
-  public int serializeTo(Path source, OutputStream output) throws IOException {
+  public int serializeTo(Path source, Namespaces namespaces, OutputStream output)
+      throws IOException {
     return XmlResourceValues.serializeProtoDataValue(
         output,
         XmlResourceValues.newSerializableDataValueBuilder(source)
             .setXmlValue(
                 SerializeFormat.DataValueXml.newBuilder()
                     .setType(XmlType.STYLEABLE)
+                    .putAllNamespace(namespaces.asMap())
                     .addAllReferences(
                         Iterables.transform(attrs.entrySet(), FULLY_QUALIFIED_NAME_TO_DATA_KEY))));
   }