Treat single-character upper case identifiers as UpperCamelCase

as a concession to Android `R` classes.

PiperOrigin-RevId: 424878859

Author: cushon

core/src/main/java/com/google/googlejavaformat/java/TypeNameClassifier.java

@@ -164,7 +164,7 @@ static JavaCaseFormat from(String name) {
         hasLowercase |= Character.isLowerCase(c);
       }
       if (firstUppercase) {
-        return hasLowercase ? UPPER_CAMEL : UPPERCASE;
+        return (hasLowercase || name.length() == 1) ? UPPER_CAMEL : UPPERCASE;
       } else {
         return hasUppercase ? LOWER_CAMEL : LOWERCASE;
       }

core/src/test/java/com/google/googlejavaformat/java/TypeNameClassifierTest.java

@@ -43,6 +43,7 @@ public void caseFormat() throws Exception {
     assertThat(JavaCaseFormat.from("a_$")).isEqualTo(JavaCaseFormat.LOWERCASE);
     assertThat(JavaCaseFormat.from("_")).isEqualTo(JavaCaseFormat.LOWERCASE);
     assertThat(JavaCaseFormat.from("_A")).isEqualTo(JavaCaseFormat.UPPERCASE);
+    assertThat(JavaCaseFormat.from("A")).isEqualTo(JavaCaseFormat.UPPER_CAMEL);
   }
 
   private static Optional<Integer> getPrefix(String qualifiedName) {
@@ -62,6 +63,7 @@ public void typePrefixLength() {
     assertThat(getPrefix("ClassName.CONST")).hasValue(1);
     assertThat(getPrefix("ClassName.varName")).hasValue(1);
     assertThat(getPrefix("ClassName.Inner.varName")).hasValue(2);
+    assertThat(getPrefix("com.R.foo")).hasValue(2);
   }
 
   @Test

core/src/test/resources/com/google/googlejavaformat/java/testdata/b26306390.input

@@ -0,0 +1,3 @@
+class B26306390 {
+  int resourceId = com.some.extremely.verbose.pkg.name.R.string.some_extremely_long_resource_identifier_that_exceeds_the_column_limit;
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/b26306390.output

@@ -0,0 +1,5 @@
+class B26306390 {
+  int resourceId =
+      com.some.extremely.verbose.pkg.name.R.string
+          .some_extremely_long_resource_identifier_that_exceeds_the_column_limit;
+}