KeyFors.java

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.*;

public class KeyFors {

    public void withoutKeyFor() {
        Map<String, String> map = new HashMap<String, String>();
        String key = "key";

        //:: error: (assignment.type.incompatible)
        @NonNull String value = map.get(key);
    }

    public void withKeyFor() {
        Map<String, String> map = new HashMap<String, String>();
        @SuppressWarnings("assignment.type.incompatible")
        @KeyFor("map") String key = "key";

        @NonNull String value = map.get(key);
    }

    public void withCollection() {
        Map<String, String> map = new HashMap<String, String>();
        List<@KeyFor("map") String> keys = new ArrayList<@KeyFor("map") String>();

        @KeyFor("map") String key = keys.get(0);
        @NonNull String value = map.get(key);
        value = map.get(keys.get(0));
    }

    public void withIndirectReference() {
        class Container {
            Map<String, String> map = new HashMap<String, String>();
        }

        Container container = new Container();
        @SuppressWarnings("assignment.type.incompatible")
        @KeyFor("container.map") String key = "m";

        @NonNull String value = container.map.get(key);
    }

    /** Returns a sorted version of m.keySet(). */
    public static <K extends Comparable<? super K>, V> Collection<@KeyFor("#1") K> sortedKeySet(
            Map<K, V> m) {
        throw new RuntimeException();
    }

    static HashMap<Integer, Object> call_hashmap = new HashMap<Integer, Object>();

    public void testForLoop(HashMap<String, String> lastMap) {
        Collection<@KeyFor("lastMap") String> sorted = sortedKeySet(lastMap);
        for (@KeyFor("lastMap") String key : sorted) {
            @NonNull String al = lastMap.get(key);
        }
        for (@KeyFor("call_hashmap") Integer i : sortedKeySet(call_hashmap)) {}
    }

    static class Otherclass {
        static Map<String, String> map = new HashMap<String, String>();
    }

    public void testStaticKeyFor(@KeyFor("Otherclass.map") String s1, String s2) {
        Otherclass.map.get(s1).toString();
        //:: error: (dereference.of.nullable)
        Otherclass.map.get(s2).toString();

        Otherclass o = new Otherclass();
        o.map.get(s1).toString();
        //TODO:: error: (dereference.of.nullable)
        o.map.get(s2).toString();
    }

    public class Graph<T> {

        HashMap<T, List<@KeyFor("childMap") T>> childMap;

        public Graph(HashMap<T, List<@KeyFor("childMap") T>> childMap) {
            this.childMap = childMap;
        }

        public void addNode(T n) {
            // body omitted, not relevant to test case
        }

        public void addEdge2(T parent, T child) {
            addNode(parent);
            @SuppressWarnings("cast.unsafe")
            @KeyFor("childMap") T parent2 = (@KeyFor("childMap") T) parent;
            @NonNull List<@KeyFor("childMap") T> l = childMap.get(parent2);
        }

        // TODO: This is a feature request to have KeyFor inferred
        //    public void addEdge3( T parent, T child ) {
        //      addNode(parent);
        //      parent = (@KeyFor("childMap") T) parent;
        //      @NonNull List<T> l = childMap.get(parent);
        //    }

    }

    /* TODO: add logic that after a call to "put" the first argument is
    annotated with @KeyFor. A "@KeyForAfter" annotation to
    support this in a general way might be overkill.
    Similarly, for calls to "remove" we need to invalidate all (?)
    KeyFor annotations.*/

    void keyForFlow() {
        Map<String, String> leaders = new LinkedHashMap<String, String>();
        Set<@KeyFor("leaders") String> varsUsedPreviously =
                new LinkedHashSet<@KeyFor("leaders") String>();
        String varName = "hello";
        leaders.put(varName, "goodbye");
        @KeyFor("leaders") String kf = varName;
    }

    public static void mapPut(String start) {
        Map<String, Integer> n2e = new HashMap<>();
        n2e.put(start, new Integer(0));
        @KeyFor("n2e") String start2 = start;
    }
}