1 files changed, 75 insertions, 0 deletions
diff --git a/nullaway/src/main/java/com/uber/nullaway/generics/GenericTypePrettyPrintingVisitor.java b/nullaway/src/main/java/com/uber/nullaway/generics/GenericTypePrettyPrintingVisitor.java
new file mode 100644
index 0000000..b6c2f9c
--- /dev/null
+++ b/nullaway/src/main/java/com/uber/nullaway/generics/GenericTypePrettyPrintingVisitor.java
@@ -0,0 +1,75 @@
+package com.uber.nullaway.generics;
+
+import static java.util.stream.Collectors.joining;
+
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.tools.javac.code.Attribute;
+import com.sun.tools.javac.code.BoundKind;
+import com.sun.tools.javac.code.Type;
+import com.sun.tools.javac.code.Types;
+
+/**
+ * A visitor that pretty prints a generic type including its type-use nullability annotations, for
+ * use in error messages.
+ *
+ * <p>This code is a modified and extended version of code in {@link
+ * com.google.errorprone.util.Signatures}
+ */
+final class GenericTypePrettyPrintingVisitor extends Types.DefaultTypeVisitor<String, Void> {
+
+  private final VisitorState state;
+
+  GenericTypePrettyPrintingVisitor(VisitorState state) {
+    this.state = state;
+  }
+
+  @Override
+  public String visitWildcardType(Type.WildcardType t, Void unused) {
+    // NOTE: we have not tested this code yet as we do not yet support wildcard types
+    StringBuilder sb = new StringBuilder();
+    sb.append(t.kind);
+    if (t.kind != BoundKind.UNBOUND) {
+      sb.append(t.type.accept(this, null));
+    }
+    return sb.toString();
+  }
+
+  @Override
+  public String visitClassType(Type.ClassType t, Void s) {
+    StringBuilder sb = new StringBuilder();
+    Type enclosingType = t.getEnclosingType();
+    if (!ASTHelpers.isSameType(enclosingType, Type.noType, state)) {
+      sb.append(enclosingType.accept(this, null)).append('.');
+    }
+    for (Attribute.TypeCompound compound : t.getAnnotationMirrors()) {
+      sb.append('@');
+      sb.append(compound.type.accept(this, null));
+      sb.append(' ');
+    }
+    sb.append(t.tsym.getSimpleName());
+    if (t.getTypeArguments().nonEmpty()) {
+      sb.append('<');
+      sb.append(
+          t.getTypeArguments().stream().map(a -> a.accept(this, null)).collect(joining(", ")));
+      sb.append(">");
+    }
+    return sb.toString();
+  }
+
+  @Override
+  public String visitCapturedType(Type.CapturedType t, Void s) {
+    return t.wildcard.accept(this, null);
+  }
+
+  @Override
+  public String visitArrayType(Type.ArrayType t, Void unused) {
+    // TODO properly print cases like int @Nullable[]
+    return t.elemtype.accept(this, null) + "[]";
+  }
+
+  @Override
+  public String visitType(Type t, Void s) {
+    return t.toString();
+  }
+}