Optimize attribute qualification process and empty message creation

PiperOrigin-RevId: 892624189

Author: l46kok

common/src/main/java/dev/cel/common/internal/DefaultMessageFactory.java

@@ -52,7 +52,7 @@ public Optional<Message.Builder> newBuilder(String messageName) {
         DefaultInstanceMessageFactory.getInstance().getPrototype(descriptor.get());
 
     if (message.isPresent()) {
-      return message.map(Message::toBuilder);
+      return message.map(Message::newBuilderForType);
     }
 
     return Optional.of(DynamicMessage.newBuilder(descriptor.get()));

runtime/src/main/java/dev/cel/runtime/CelAttribute.java

@@ -17,7 +17,6 @@
 import com.google.auto.value.AutoOneOf;
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.common.primitives.UnsignedLong;
 import com.google.errorprone.annotations.Immutable;
@@ -184,9 +183,13 @@ public static CelAttribute create(String rootIdentifier) {
    */
   public static CelAttribute fromQualifiedIdentifier(String qualifiedIdentifier) {
     ImmutableList.Builder<Qualifier> qualifiers = ImmutableList.builder();
-    Splitter.on(".")
-        .split(qualifiedIdentifier)
-        .forEach((element) -> qualifiers.add(Qualifier.ofString(element)));
+    int start = 0;
+    int next;
+    while ((next = qualifiedIdentifier.indexOf('.', start)) != -1) {
+      qualifiers.add(Qualifier.ofString(qualifiedIdentifier.substring(start, next)));
+      start = next + 1;
+    }
+    qualifiers.add(Qualifier.ofString(qualifiedIdentifier.substring(start)));
     return new AutoValue_CelAttribute(qualifiers.build());
   }
 
@@ -206,7 +209,7 @@ public CelAttribute qualify(Qualifier qualifier) {
       return EMPTY;
     }
     return new AutoValue_CelAttribute(
-        ImmutableList.<Qualifier>builder().addAll(qualifiers()).add(qualifier).build());
+        ImmutableList.<Qualifier>builderWithExpectedSize(qualifiers().size() + 1).addAll(qualifiers()).add(qualifier).build());
   }
 
   @Override

runtime/src/main/java/dev/cel/runtime/CelAttributePattern.java

@@ -18,7 +18,6 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.Immutable;
 
@@ -62,9 +61,13 @@ public static CelAttributePattern create(String rootIdentifier) {
    */
   public static CelAttributePattern fromQualifiedIdentifier(String qualifiedIdentifier) {
     ImmutableList.Builder<CelAttribute.Qualifier> qualifiers = ImmutableList.builder();
-    Splitter.on(".")
-        .split(qualifiedIdentifier)
-        .forEach((String element) -> qualifiers.add(CelAttribute.Qualifier.ofString(element)));
+    int start = 0;
+    int next;
+    while ((next = qualifiedIdentifier.indexOf('.', start)) != -1) {
+      qualifiers.add(CelAttribute.Qualifier.ofString(qualifiedIdentifier.substring(start, next)));
+      start = next + 1;
+    }
+    qualifiers.add(CelAttribute.Qualifier.ofString(qualifiedIdentifier.substring(start)));
     return new AutoValue_CelAttributePattern(qualifiers.build());
   }
 
@@ -74,7 +77,7 @@ public static CelAttributePattern fromQualifiedIdentifier(String qualifiedIdenti
   /** Create a new attribute pattern that specifies a subfield of this pattern. */
   public CelAttributePattern qualify(CelAttribute.Qualifier qualifier) {
     return new AutoValue_CelAttributePattern(
-        ImmutableList.<CelAttribute.Qualifier>builder()
+        ImmutableList.<CelAttribute.Qualifier>builderWithExpectedSize(qualifiers().size() + 1)
             .addAll(qualifiers())
             .add(qualifier)
             .build());