Lint

Require that methods such as Pair.forEach and
MatcherAssert.assertThat are used via static import, and
enforce in LintTest.

Require use of
org.checkerframework.checker.nullness.qual.Nullable rather
than javax.annotation.Nullable, and similarly NonNull.

src/main/java/net/hydromatic/morel/Shell.java

@@ -43,6 +43,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.Runnables;
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.jline.reader.EndOfFileException;
 import org.jline.reader.LineReader;
@@ -71,7 +72,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
-import javax.annotation.Nonnull;
 
 import static net.hydromatic.morel.util.Static.str;
 
@@ -277,7 +277,7 @@ public void run() {
   /** Instantiates a class.
    *
    * <p>Assumes that the class has a public no-arguments constructor. */
-  @Nonnull private static <T> T instantiate(String className,
+  @NonNull private static <T> T instantiate(String className,
       @SuppressWarnings("SameParameterValue") Class<T> clazz) {
     try {
       final Class<?> aClass = Class.forName(className);

src/main/java/net/hydromatic/morel/ast/Ast.java

@@ -430,7 +430,7 @@ public Pat accept(Shuttle shuttle) {
 
     @Override AstWriter unparse(AstWriter w, int left, int right) {
       w.append("{");
-      Ord.forEachIndexed(args, (i, k, v) ->
+      Ord.forEachIndexed(args, (i, k, v) -> // lint:skip
           w.append(i > 0 ? ", " : "").append(k).append(" = ").append(v, 0, 0));
       if (ellipsis) {
         w.append(args.isEmpty() ? "..." : ", ...");
@@ -642,7 +642,7 @@ public RecordType accept(Shuttle shuttle) {
 
     AstWriter unparse(AstWriter w, int left, int right) {
       w.append("{");
-      Ord.forEachIndexed(fieldTypes, (i, field, type) ->
+      Ord.forEachIndexed(fieldTypes, (i, field, type) -> // lint:skip
           w.append(i > 0 ? ", " : "")
               .id(field).append(": ").append(type, 0, 0));
       return w.append("}");
@@ -1210,7 +1210,7 @@ public Exp accept(Shuttle shuttle) {
 
     @Override AstWriter unparse(AstWriter w, int left, int right) {
       w.append("{");
-      Ord.forEachIndexed(args, (i, k, v) ->
+      Ord.forEachIndexed(args, (i, k, v) -> // lint:skip
           w.append(i > 0 ? ", " : "").append(k).append(" = ").append(v, 0, 0));
       return w.append("}");
     }

src/main/java/net/hydromatic/morel/ast/AstBuilder.java

@@ -26,13 +26,13 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSortedMap;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.math.BigDecimal;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.function.BiFunction;
-import javax.annotation.Nullable;
 
 /** Builds parse tree nodes. */
 public enum AstBuilder {
@@ -340,7 +340,7 @@ public Ast.From from(Pos pos, List<Ast.FromStep> steps) {
   }
 
   public Ast.From from(Pos pos, List<Ast.FromStep> steps,
-      @Nullable Ast.Exp implicitYieldExp) {
+      Ast.@Nullable Exp implicitYieldExp) {
     return new Ast.From(pos, ImmutableList.copyOf(steps), implicitYieldExp);
   }
 
@@ -369,7 +369,7 @@ public Ast.FunBind funBind(Pos pos,
   }
 
   public Ast.FunMatch funMatch(Pos pos, String name,
-      Iterable<? extends Ast.Pat> patList, @Nullable Ast.Type returnType,
+      Iterable<? extends Ast.Pat> patList, Ast.@Nullable Type returnType,
       Ast.Exp exp) {
     return new Ast.FunMatch(pos, name, ImmutableList.copyOf(patList),
         returnType, exp);
@@ -458,7 +458,7 @@ public Ast.Exp map(Pos pos, Ast.Exp e1, Ast.Exp e2) {
   }
 
   public Ast.Scan scan(Pos pos, Ast.Pat pat, Ast.Exp exp,
-      @Nullable Ast.Exp condition) {
+      Ast.@Nullable Exp condition) {
     return new Ast.Scan(pos, pat, exp, condition);
   }
 

src/main/java/net/hydromatic/morel/ast/AstNode.java

@@ -18,16 +18,16 @@
  */
 package net.hydromatic.morel.ast;
 
-import java.util.Objects;
+import static java.util.Objects.requireNonNull;
 
 /** Abstract syntax tree node. */
 public abstract class AstNode {
   public final Pos pos;
   public final Op op;
 
   public AstNode(Pos pos, Op op) {
-    this.pos = Objects.requireNonNull(pos);
-    this.op = Objects.requireNonNull(op);
+    this.pos = requireNonNull(pos);
+    this.op = requireNonNull(op);
   }
 
   /** Converts this node into an ML string.

src/main/java/net/hydromatic/morel/ast/Core.java

@@ -43,6 +43,7 @@
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Ordering;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -51,7 +52,6 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.function.ObjIntConsumer;
-import javax.annotation.Nullable;
 
 import static net.hydromatic.morel.ast.CoreBuilder.core;
 import static net.hydromatic.morel.util.Ord.forEachIndexed;
@@ -478,9 +478,10 @@ public static class RecordPat extends Pat {
 
     @Override AstWriter unparse(AstWriter w, int left, int right) {
       w.append("{");
-      forEachIndexed(type().argNameTypes.keySet(), args, (i, name, arg) ->
-          w.append(i > 0 ? ", " : "").append(name)
-              .append(" = ").append(arg, 0, 0));
+      forEachIndexed(type().argNameTypes.keySet(), args,
+          (i, name, arg) ->
+              w.append(i > 0 ? ", " : "").append(name)
+                  .append(" = ").append(arg, 0, 0));
       return w.append("}");
     }
 
@@ -1428,10 +1429,10 @@ public static class Group extends FromStep {
     @Override protected AstWriter unparse(AstWriter w, From from, int ordinal,
         int left, int right) {
       w.append(" group");
-      Pair.forEachIndexed(groupExps, (i, id, exp) ->
+      Pair.forEachIndexed(groupExps, (i, id, exp) -> // lint:skip
           w.append(i == 0 ? " " : ", ")
               .append(id, 0, 0).append(" = ").append(exp, 0, 0));
-      Pair.forEachIndexed(aggregates, (i, name, aggregate) ->
+      Pair.forEachIndexed(aggregates, (i, name, aggregate) -> // lint:skip
           w.append(i == 0 ? " compute " : ", ")
               .append(name, 0, 0).append(" = ").append(aggregate, 0, 0));
       return w;

src/main/java/net/hydromatic/morel/ast/FromBuilder.java

@@ -23,7 +23,6 @@
 import net.hydromatic.morel.compile.RefChecker;
 import net.hydromatic.morel.type.Binding;
 import net.hydromatic.morel.type.TypeSystem;
-import net.hydromatic.morel.util.Pair;
 import net.hydromatic.morel.util.PairList;
 
 import com.google.common.collect.ImmutableList;
@@ -174,7 +173,7 @@ && getLast(((Core.From) exp).steps).bindings.size() == 1
         bindings = null;
       } else if (pat instanceof Core.TuplePat) {
         final Core.TuplePat tuplePat = (Core.TuplePat) pat;
-        Pair.forEach(tuplePat.args, lastStep.bindings,
+        forEach(tuplePat.args, lastStep.bindings,
             (arg, binding) ->
                 nameExps.add(((Core.IdPat) arg).name, core.id(binding.id)));
         bindings = null;

src/main/java/net/hydromatic/morel/ast/Pos.java

@@ -29,7 +29,6 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.function.Function;
-import javax.annotation.Nonnull;
 
 /** Position of a parse-tree node. */
 public class Pos {
@@ -221,7 +220,7 @@ public Pos plusAll(Iterable<Pos> poses) {
     return sum(poses, startLine, startColumn, endLine, endColumn);
   }
 
-  public Pos plusAll(@Nonnull List<? extends AstNode> nodes) {
+  public Pos plusAll(@NonNull List<? extends AstNode> nodes) {
     //noinspection StaticPseudoFunctionalStyleMethod,ConstantConditions
     return plusAll(Lists.transform(nodes, (AstNode node) -> node.pos));
   }

src/main/java/net/hydromatic/morel/compile/BuiltIn.java

@@ -32,6 +32,7 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSortedMap;
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.ArrayList;
@@ -42,7 +43,6 @@
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.UnaryOperator;
-import javax.annotation.Nonnull;
 
 import static net.hydromatic.morel.type.PrimitiveType.BOOL;
 import static net.hydromatic.morel.type.PrimitiveType.CHAR;
@@ -1645,7 +1645,7 @@ public enum BuiltIn {
   }
 
   BuiltIn(@Nullable String structure, String mlName,
-      @Nonnull PrimitiveType preferredType,
+      @NonNull PrimitiveType preferredType,
       Function<TypeSystem, Type> typeFunction) {
     this(structure, mlName, null, typeFunction, preferredType, null);
   }

src/main/java/net/hydromatic/morel/compile/CalciteCompiler.java

@@ -65,6 +65,7 @@
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
 import org.apache.calcite.tools.RelBuilder;
 import org.apache.calcite.util.JsonBuilder;
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.ArrayList;
@@ -77,7 +78,6 @@
 import java.util.SortedMap;
 import java.util.TreeMap;
 import java.util.function.Predicate;
-import javax.annotation.Nonnull;
 
 import static net.hydromatic.morel.ast.CoreBuilder.core;
 import static net.hydromatic.morel.util.Ord.forEachIndexed;
@@ -784,7 +784,7 @@ private static RelContext getRelContext(RelContext cx, Environment env,
    * <p>Future work: rather than resolving by name, look up aggregate function
    * in environment, and compare with standard implementation of "sum" etc.;
    * support aggregate functions defined by expressions (e.g. lambdas). */
-  @Nonnull private SqlAggFunction aggOp(Core.Exp aggregate) {
+  @NonNull private SqlAggFunction aggOp(Core.Exp aggregate) {
     if (aggregate instanceof Core.Literal) {
       switch (((Core.Literal) aggregate).unwrap(BuiltIn.class)) {
       case RELATIONAL_SUM:

src/main/java/net/hydromatic/morel/compile/Inliner.java

@@ -28,7 +28,6 @@
 import net.hydromatic.morel.type.FnType;
 import net.hydromatic.morel.type.PrimitiveType;
 import net.hydromatic.morel.type.TypeSystem;
-import net.hydromatic.morel.util.Pair;
 
 import com.google.common.collect.ImmutableMap;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -38,6 +37,7 @@
 import java.util.Map;
 
 import static net.hydromatic.morel.ast.CoreBuilder.core;
+import static net.hydromatic.morel.util.Pair.forEach;
 
 import static java.util.Objects.requireNonNull;
 
@@ -176,7 +176,7 @@ public static Inliner of(TypeSystem typeSystem, Environment env,
           && tuplePat.args.stream().allMatch(arg -> arg.op == Op.ID_PAT)) {
         final ImmutableMap.Builder<Core.Id, Core.Id> builder =
             ImmutableMap.builder();
-        Pair.forEach(tuple.args, tuplePat.args, (arg, pat) ->
+        forEach(tuple.args, tuplePat.args, (arg, pat) ->
             builder.put(core.id((Core.IdPat) pat), (Core.Id) arg));
         return builder.build();
       }

src/main/java/net/hydromatic/morel/compile/Pretty.java

@@ -34,9 +34,9 @@
 import net.hydromatic.morel.util.Ord;
 
 import com.google.common.collect.Iterables;
+import org.checkerframework.checker.nullness.qual.NonNull;
 
 import java.util.List;
-import javax.annotation.Nonnull;
 
 import static net.hydromatic.morel.parse.Parsers.appendId;
 import static net.hydromatic.morel.util.Pair.forEachIndexed;
@@ -62,17 +62,17 @@ class Pretty {
   }
 
   /** Prints a value to a buffer. */
-  StringBuilder pretty(@Nonnull StringBuilder buf,
-      @Nonnull Type type, @Nonnull Object value) {
+  StringBuilder pretty(@NonNull StringBuilder buf,
+      @NonNull Type type, @NonNull Object value) {
     int lineEnd = lineWidth < 0 ? -1 : (buf.length() + lineWidth);
     return pretty1(buf, 0, new int[] {lineEnd}, 0, type, value, 0, 0);
   }
 
   /** Prints a value to a buffer. If the first attempt goes beyond
    * {@code lineEnd}, back-tracks, adds a newline and indent, and
    * tries again one time. */
-  private StringBuilder pretty1(@Nonnull StringBuilder buf, int indent,
-      int[] lineEnd, int depth, @Nonnull Type type, @Nonnull Object value,
+  private StringBuilder pretty1(@NonNull StringBuilder buf, int indent,
+      int[] lineEnd, int depth, @NonNull Type type, @NonNull Object value,
       int leftPrec, int rightPrec) {
     final int start = buf.length();
     final int end = lineEnd[0];
@@ -96,15 +96,15 @@ private StringBuilder pretty1(@Nonnull StringBuilder buf, int indent,
     return buf;
   }
 
-  private static void indent(@Nonnull StringBuilder buf, int indent) {
+  private static void indent(@NonNull StringBuilder buf, int indent) {
     for (int i = 0; i < indent; i++) {
       buf.append(' ');
     }
   }
 
-  private StringBuilder pretty2(@Nonnull StringBuilder buf,
-      int indent, int[] lineEnd, int depth, @Nonnull Type type,
-      @Nonnull Object value, int leftPrec, int rightPrec) {
+  private StringBuilder pretty2(@NonNull StringBuilder buf,
+      int indent, int[] lineEnd, int depth, @NonNull Type type,
+      @NonNull Object value, int leftPrec, int rightPrec) {
     if (value instanceof TypedVal) {
       final TypedVal typedVal = (TypedVal) value;
       final StringBuilder buf2 = new StringBuilder("val ");
@@ -378,9 +378,9 @@ private static Type unqualified(Type type) {
         : type;
   }
 
-  private StringBuilder printList(@Nonnull StringBuilder buf,
-      int indent, int[] lineEnd, int depth, @Nonnull Type elementType,
-      @Nonnull List<Object> list) {
+  private StringBuilder printList(@NonNull StringBuilder buf,
+      int indent, int[] lineEnd, int depth, @NonNull Type elementType,
+      @NonNull List<Object> list) {
     buf.append("[");
     int start = buf.length();
     for (Ord<Object> o : Ord.zip(list)) {

src/main/java/net/hydromatic/morel/compile/TypeResolver.java

@@ -44,7 +44,6 @@
 import net.hydromatic.morel.util.Tracers;
 import net.hydromatic.morel.util.Unifier;
 
-import com.google.common.base.Preconditions;
 import com.google.common.base.Suppliers;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
@@ -81,6 +80,8 @@
 import static net.hydromatic.morel.util.Static.transform;
 import static net.hydromatic.morel.util.Static.transformEager;
 
+import static com.google.common.base.Preconditions.checkArgument;
+
 import static java.lang.String.join;
 import static java.util.Objects.requireNonNull;
 
@@ -1542,7 +1543,7 @@ private Resolved(Environment env,
       this.originalNode = requireNonNull(originalNode);
       this.node = requireNonNull(node);
       this.typeMap = requireNonNull(typeMap);
-      Preconditions.checkArgument(originalNode instanceof Ast.FunDecl
+      checkArgument(originalNode instanceof Ast.FunDecl
           ? node instanceof Ast.ValDecl
           : originalNode.getClass() == node.getClass());
     }

src/main/java/net/hydromatic/morel/eval/EvalEnvs.java

@@ -23,18 +23,19 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.math.BigDecimal;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.function.BiConsumer;
-import javax.annotation.Nullable;
 
 import static net.hydromatic.morel.util.Pair.allMatch;
 import static net.hydromatic.morel.util.Pair.zip;
 import static net.hydromatic.morel.util.Static.skip;
 
+import static java.util.Objects.requireNonNull;
+
 /** Helpers for {@link EvalEnv}. */
 public class EvalEnvs {
   /** Creates an evaluation environment with the given (name, value) map. */
@@ -99,8 +100,8 @@ static class ArraySubEvalEnv implements EvalEnv {
 
     ArraySubEvalEnv(EvalEnv parentEnv, ImmutableList<String> names,
         @Nullable Object[] values) {
-      this.parentEnv = Objects.requireNonNull(parentEnv);
-      this.names = Objects.requireNonNull(names);
+      this.parentEnv = requireNonNull(parentEnv);
+      this.names = requireNonNull(names);
       this.values = values; // may be null
     }
 
@@ -145,7 +146,7 @@ static class PatSubEvalEnv extends ArraySubEvalEnv {
     PatSubEvalEnv(EvalEnv parentEnv, Core.Pat pat, ImmutableList<String> names,
         Object[] values) {
       super(parentEnv, ImmutableList.copyOf(names), values);
-      this.pat = Objects.requireNonNull(pat);
+      this.pat = requireNonNull(pat);
       assert !(pat instanceof Core.IdPat);
     }
   }