Sweep preconditions to prepare for C# running (#319)

* Sweep preconditions to prepare for C# running

Author: jkschneider

src/main/java/org/openrewrite/staticanalysis/ControlFlowIndentation.java

@@ -66,7 +66,7 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
             public J visit(@Nullable Tree tree, ExecutionContext ctx) {
                 if (tree instanceof JavaSourceFile) {
                     JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                    TabsAndIndentsStyle style = ((SourceFile) cu).getStyle(TabsAndIndentsStyle.class);
+                    TabsAndIndentsStyle style = cu.getStyle(TabsAndIndentsStyle.class);
                     if (style == null) {
                         style = IntelliJ.tabsAndIndents();
                     }

src/main/java/org/openrewrite/staticanalysis/CovariantEquals.java

@@ -15,14 +15,20 @@
  */
 package org.openrewrite.staticanalysis;
 
-import org.openrewrite.ExecutionContext;
-import org.openrewrite.Incubating;
-import org.openrewrite.Recipe;
-import org.openrewrite.TreeVisitor;
+import org.openrewrite.*;
+import org.openrewrite.java.AnnotationMatcher;
+import org.openrewrite.java.JavaIsoVisitor;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.MethodMatcher;
+import org.openrewrite.java.service.AnnotationService;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.JavaType;
 
 import java.time.Duration;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Set;
+import java.util.stream.Stream;
 
 @Incubating(since = "7.0.0")
 public class CovariantEquals extends Recipe {
@@ -35,7 +41,7 @@ public String getDisplayName() {
     @Override
     public String getDescription() {
         return "Checks that classes and records which define a covariant `equals()` method also override method `equals(Object)`. " +
-                "Covariant `equals()` means a method that is similar to `equals(Object)`, but with a covariant parameter type (any subtype of `Object`).";
+               "Covariant `equals()` means a method that is similar to `equals(Object)`, but with a covariant parameter type (any subtype of `Object`).";
     }
 
     @Override
@@ -50,6 +56,98 @@ public Duration getEstimatedEffortPerOccurrence() {
 
     @Override
     public TreeVisitor<?, ExecutionContext> getVisitor() {
-        return new CovariantEqualsVisitor<>();
+        MethodMatcher objectEquals = new MethodMatcher("* equals(java.lang.Object)");
+        return new JavaIsoVisitor<ExecutionContext>() {
+
+            @Override
+            public J.ClassDeclaration visitClassDeclaration(J.ClassDeclaration classDecl, ExecutionContext ctx) {
+                J.ClassDeclaration cd = super.visitClassDeclaration(classDecl, ctx);
+                Stream<J.MethodDeclaration> mds = cd.getBody().getStatements().stream()
+                        .filter(J.MethodDeclaration.class::isInstance)
+                        .map(J.MethodDeclaration.class::cast);
+                if (cd.getKind() != J.ClassDeclaration.Kind.Type.Interface && mds.noneMatch(m -> objectEquals.matches(m, classDecl))) {
+                    cd = (J.ClassDeclaration) new ChangeCovariantEqualsMethodVisitor(cd).visit(cd, ctx, getCursor().getParentOrThrow());
+                    assert cd != null;
+                }
+                return cd;
+            }
+
+            class ChangeCovariantEqualsMethodVisitor extends JavaIsoVisitor<ExecutionContext> {
+                private final AnnotationMatcher OVERRIDE_ANNOTATION = new AnnotationMatcher("@java.lang.Override");
+
+                private final J.ClassDeclaration enclosingClass;
+
+                public ChangeCovariantEqualsMethodVisitor(J.ClassDeclaration enclosingClass) {
+                    this.enclosingClass = enclosingClass;
+                }
+
+                @Override
+                public J.MethodDeclaration visitMethodDeclaration(J.MethodDeclaration method, ExecutionContext ctx) {
+                    J.MethodDeclaration m = super.visitMethodDeclaration(method, ctx);
+                    updateCursor(m);
+
+                    /*
+                     * Looking for "public boolean equals(EnclosingClassType)" as the method signature match.
+                     * We'll replace it with "public boolean equals(Object)"
+                     */
+                    JavaType.FullyQualified type = enclosingClass.getType();
+                    if (type == null || type instanceof JavaType.Unknown) {
+                        return m;
+                    }
+
+                    String ecfqn = type.getFullyQualifiedName();
+                    if (m.hasModifier(J.Modifier.Type.Public) &&
+                        m.getReturnTypeExpression() != null &&
+                        JavaType.Primitive.Boolean.equals(m.getReturnTypeExpression().getType()) &&
+                        new MethodMatcher(ecfqn + " equals(" + ecfqn + ")").matches(m, enclosingClass)) {
+
+                        if (!service(AnnotationService.class).matches(getCursor(), OVERRIDE_ANNOTATION)) {
+                            m = JavaTemplate.builder("@Override").build()
+                                    .apply(updateCursor(m),
+                                            m.getCoordinates().addAnnotation(Comparator.comparing(J.Annotation::getSimpleName)));
+                        }
+
+                        /*
+                         * Change parameter type to Object, and maybe change input parameter name representing the other object.
+                         * This is because we prepend these type-checking replacement statements to the existing "equals(..)" body.
+                         * Therefore we don't want to collide with any existing variable names.
+                         */
+                        J.VariableDeclarations.NamedVariable oldParamName = ((J.VariableDeclarations) m.getParameters().get(0)).getVariables().get(0);
+                        String paramName = "obj".equals(oldParamName.getSimpleName()) ? "other" : "obj";
+                        m = JavaTemplate.builder("Object #{}").build()
+                                .apply(updateCursor(m),
+                                        m.getCoordinates().replaceParameters(),
+                                        paramName);
+
+                        /*
+                         * We'll prepend this type-check and type-cast to the beginning of the existing
+                         * equals(..) method body statements, and let the existing equals(..) method definition continue
+                         * with the logic doing what it was doing.
+                         */
+                        String equalsBodyPrefixTemplate = "if (#{} == this) return true;\n" +
+                                                          "if (#{} == null || getClass() != #{}.getClass()) return false;\n" +
+                                                          "#{} #{} = (#{}) #{};\n";
+                        JavaTemplate equalsBodySnippet = JavaTemplate.builder(equalsBodyPrefixTemplate).contextSensitive().build();
+
+                        assert m.getBody() != null;
+                        Object[] params = new Object[]{
+                                paramName,
+                                paramName,
+                                paramName,
+                                enclosingClass.getSimpleName(),
+                                oldParamName.getSimpleName(),
+                                enclosingClass.getSimpleName(),
+                                paramName
+                        };
+
+                        m = equalsBodySnippet.apply(new Cursor(getCursor().getParent(), m),
+                                m.getBody().getStatements().get(0).getCoordinates().before(),
+                                params);
+                    }
+
+                    return m;
+                }
+            }
+        };
     }
 }

src/main/java/org/openrewrite/staticanalysis/CovariantEqualsVisitor.java

@@ -61,7 +61,7 @@ private static class DefaultComesLastFromCompilationUnitStyle extends JavaIsoVis
         public J visit(@Nullable Tree tree, ExecutionContext ctx) {
             if (tree instanceof JavaSourceFile) {
                 JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                DefaultComesLastStyle style = ((SourceFile) cu).getStyle(DefaultComesLastStyle.class);
+                DefaultComesLastStyle style = cu.getStyle(DefaultComesLastStyle.class);
                 if (style == null) {
                     style = Checkstyle.defaultComesLast();
                 }
@@ -70,5 +70,4 @@ public J visit(@Nullable Tree tree, ExecutionContext ctx) {
             return (J) tree;
         }
     }
-
 }

src/main/java/org/openrewrite/staticanalysis/DefaultComesLast.java

@@ -61,7 +61,7 @@ private static class EmptyBlockFromCompilationUnitStyle extends JavaIsoVisitor<E
         public J visit(@Nullable Tree tree, ExecutionContext ctx) {
             if (tree instanceof JavaSourceFile) {
                 JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                EmptyBlockStyle style = ((SourceFile) cu).getStyle(EmptyBlockStyle.class);
+                EmptyBlockStyle style = cu.getStyle(EmptyBlockStyle.class);
                 if (style == null) {
                     style = Checkstyle.emptyBlock();
                 }

src/main/java/org/openrewrite/staticanalysis/EmptyBlock.java

@@ -61,7 +61,7 @@ private static class EqualsAvoidsNullFromCompilationUnitStyle extends JavaIsoVis
         public J visit(@Nullable Tree tree, ExecutionContext ctx) {
             if (tree instanceof JavaSourceFile) {
                 JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                EqualsAvoidsNullStyle style = ((SourceFile) cu).getStyle(EqualsAvoidsNullStyle.class);
+                EqualsAvoidsNullStyle style = cu.getStyle(EqualsAvoidsNullStyle.class);
                 if (style == null) {
                     style = Checkstyle.equalsAvoidsNull();
                 }

src/main/java/org/openrewrite/staticanalysis/EqualsAvoidsNull.java

@@ -63,7 +63,7 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
             public J visit(@Nullable Tree tree, ExecutionContext ctx) {
                 if (tree instanceof JavaSourceFile) {
                     JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                    ExplicitInitializationStyle style = ((SourceFile) cu).getStyle(ExplicitInitializationStyle.class);
+                    ExplicitInitializationStyle style = cu.getStyle(ExplicitInitializationStyle.class);
                     if (style == null) {
                         style = Checkstyle.explicitInitialization();
                     }

src/main/java/org/openrewrite/staticanalysis/ExplicitInitialization.java

@@ -60,7 +60,7 @@ private static class FallThroughFromCompilationUnitStyle extends JavaIsoVisitor<
         public J visit(@Nullable Tree tree, ExecutionContext ctx) {
             if (tree instanceof JavaSourceFile) {
                 JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                FallThroughStyle style = ((SourceFile) cu).getStyle(FallThroughStyle.class);
+                FallThroughStyle style = cu.getStyle(FallThroughStyle.class);
                 if (style == null) {
                     style = Checkstyle.fallThrough();
                 }

src/main/java/org/openrewrite/staticanalysis/FallThrough.java

@@ -54,7 +54,7 @@ public J.Case visitCase(J.Case case_, P p) {
             J.Switch switch_ = getCursor().dropParentUntil(J.Switch.class::isInstance).getValue();
             if (Boolean.TRUE.equals(style.getCheckLastCaseGroup()) || !isLastCase(case_, switch_)) {
                 if (FindLastLineBreaksOrFallsThroughComments.find(switch_, c).isEmpty()) {
-                    c = (J.Case) new AddBreak<>(c).visit(c, p, getCursor().getParent());
+                    c = (J.Case) new AddBreak<>(c).visitNonNull(c, p, getCursor().getParentOrThrow());
                 }
             }
         }

src/main/java/org/openrewrite/staticanalysis/FallThroughVisitor.java

@@ -61,7 +61,7 @@ private static class HiddenFieldFromCompilationUnitStyle extends JavaIsoVisitor<
         public J visit(@Nullable Tree tree, ExecutionContext ctx) {
             if (tree instanceof JavaSourceFile) {
                 JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
-                HiddenFieldStyle style = ((SourceFile) cu).getStyle(HiddenFieldStyle.class);
+                HiddenFieldStyle style = cu.getStyle(HiddenFieldStyle.class);
                 if (style == null) {
                     style = Checkstyle.hiddenFieldStyle();
                 }