[platform] add SymbolReference and SymbolResolveResult (IDEA-190162)

platform/core-api/src/com/intellij/model/SymbolReference.java

@@ -0,0 +1,27 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.model;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+
+import static org.jetbrains.annotations.ApiStatus.Experimental;
+
+/**
+ * A reference to a {@link Symbol} or possibly several Symbols.
+ * <p/>
+ * SymbolReference may be backed by a {@link com.intellij.psi.PsiElement PsiElement} but is not required to.
+ * <p/>
+ * Examples:
+ * <ul>
+ * <li>the variable name used in an expression is a SymbolReference backed by a PsiElement which represent the expression</li>
+ * <li>fully qualified name of a class in Application or Test Run Configuration is a SymbolReference which is not backed by a PsiElement,
+ * but may be searched for and/or renamed</li>
+ * </ul>
+ */
+@Experimental
+public interface SymbolReference {
+
+  @NotNull
+  Collection<? extends SymbolResolveResult> resolveReference();
+}

platform/core-api/src/com/intellij/model/SymbolResolveResult.java

@@ -0,0 +1,18 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.model;
+
+import org.jetbrains.annotations.ApiStatus.Experimental;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A result of resolving a {@link SymbolReference}.
+ */
+@Experimental
+public interface SymbolResolveResult {
+
+  /**
+   * @return referenced Symbol
+   */
+  @NotNull
+  Symbol getTarget();
+}