Variable resolution over experimental symbol API

src/main/java/org/nixos/idea/lang/builtins/NixBuiltin.java

@@ -200,7 +200,11 @@ private NixBuiltin(@NotNull String name,
         this.global = GLOBAL_SCOPE.contains(name);
     }
 
-    public HighlightingType highlightingType() {
+    public @NotNull String name() {
+        return name;
+    }
+
+    public @NotNull HighlightingType highlightingType() {
         return highlightingType;
     }
 

src/main/java/org/nixos/idea/lang/references/NixNavigationTarget.java

@@ -0,0 +1,59 @@
+package org.nixos.idea.lang.references;
+
+import com.intellij.model.Pointer;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.platform.backend.navigation.NavigationRequest;
+import com.intellij.platform.backend.navigation.NavigationTarget;
+import com.intellij.platform.backend.presentation.TargetPresentation;
+import com.intellij.psi.SmartPointerManager;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.TestOnly;
+import org.nixos.idea.psi.NixPsiElement;
+
+@SuppressWarnings("UnstableApiUsage")
+public final class NixNavigationTarget implements NavigationTarget {
+
+    private final @NotNull NixPsiElement myIdentifier;
+    private final @NotNull TargetPresentation myTargetPresentation;
+    private @Nullable Pointer<NavigationTarget> myPointer;
+
+    public NixNavigationTarget(@NotNull NixPsiElement identifier, @NotNull TargetPresentation targetPresentation) {
+        myIdentifier = identifier;
+        myTargetPresentation = targetPresentation;
+    }
+
+    private NixNavigationTarget(@NotNull Pointer<NavigationTarget> pointer,
+                                @NotNull NixPsiElement identifier,
+                                @NotNull TargetPresentation targetPresentation) {
+        myIdentifier = identifier;
+        myTargetPresentation = targetPresentation;
+        myPointer = pointer;
+    }
+
+    @TestOnly
+    TextRange getRangeInFile() {
+        return myIdentifier.getTextRange();
+    }
+
+    @Override
+    public @NotNull Pointer<NavigationTarget> createPointer() {
+        if (myPointer == null) {
+            TargetPresentation targetPresentation = myTargetPresentation;
+            myPointer = Pointer.uroborosPointer(
+                    SmartPointerManager.createPointer(myIdentifier),
+                    (identifier, pointer) -> new NixNavigationTarget(pointer, identifier, targetPresentation));
+        }
+        return myPointer;
+    }
+
+    @Override
+    public @NotNull TargetPresentation computePresentation() {
+        return myTargetPresentation;
+    }
+
+    @Override
+    public @Nullable NavigationRequest navigationRequest() {
+        return NavigationRequest.sourceNavigationRequest(myIdentifier.getContainingFile(), myIdentifier.getTextRange());
+    }
+}

src/main/java/org/nixos/idea/lang/references/NixScopeReference.java

@@ -0,0 +1,20 @@
+package org.nixos.idea.lang.references;
+
+import org.jetbrains.annotations.NotNull;
+import org.nixos.idea.lang.references.symbol.NixSymbol;
+import org.nixos.idea.psi.NixPsiElement;
+
+import java.util.Collection;
+
+@SuppressWarnings("UnstableApiUsage")
+public final class NixScopeReference extends NixSymbolReference {
+
+    public NixScopeReference(@NotNull NixPsiElement element, @NotNull NixPsiElement identifier, @NotNull String variableName) {
+        super(element, identifier, variableName);
+    }
+
+    @Override
+    public @NotNull Collection<NixSymbol> resolveReference() {
+        return myElement.getScope().resolveVariable(myName);
+    }
+}

src/main/java/org/nixos/idea/lang/references/NixSymbolDeclaration.java

@@ -0,0 +1,57 @@
+package org.nixos.idea.lang.references;
+
+import com.intellij.model.psi.PsiSymbolDeclaration;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.platform.backend.navigation.NavigationTarget;
+import com.intellij.platform.backend.presentation.TargetPresentation;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.nixos.idea.lang.references.symbol.NixUserSymbol;
+import org.nixos.idea.psi.NixPsiElement;
+import org.nixos.idea.util.TextRangeFactory;
+
+@SuppressWarnings("UnstableApiUsage")
+public final class NixSymbolDeclaration implements PsiSymbolDeclaration {
+
+    private final @NotNull NixPsiElement myDeclarationElement;
+    private final @NotNull NixPsiElement myIdentifier;
+    private final @NotNull NixUserSymbol mySymbol;
+    private final @NotNull String myDeclarationElementName;
+    private final @Nullable String myDeclarationElementType;
+
+    public NixSymbolDeclaration(@NotNull NixPsiElement declarationElement, @NotNull NixPsiElement identifier,
+                                @NotNull NixUserSymbol symbol,
+                                @NotNull String declarationElementName, @Nullable String declarationElementType) {
+        myDeclarationElement = declarationElement;
+        myIdentifier = identifier;
+        mySymbol = symbol;
+        myDeclarationElementName = declarationElementName;
+        myDeclarationElementType = declarationElementType;
+    }
+
+    public @NotNull NixPsiElement getIdentifier() {
+        return myIdentifier;
+    }
+
+    public @NotNull NavigationTarget navigationTarget() {
+        return new NixNavigationTarget(myIdentifier, TargetPresentation.builder(mySymbol.presentation())
+                .presentableText(myDeclarationElementName)
+                .containerText(myDeclarationElementType)
+                .presentation());
+    }
+
+    @Override
+    public @NotNull NixPsiElement getDeclaringElement() {
+        return myDeclarationElement;
+    }
+
+    @Override
+    public @NotNull TextRange getRangeInDeclaringElement() {
+        return TextRangeFactory.relative(myIdentifier, myDeclarationElement);
+    }
+
+    @Override
+    public @NotNull NixUserSymbol getSymbol() {
+        return mySymbol;
+    }
+}

src/main/java/org/nixos/idea/lang/references/NixSymbolReference.java

@@ -0,0 +1,46 @@
+package org.nixos.idea.lang.references;
+
+import com.intellij.model.Symbol;
+import com.intellij.model.psi.PsiSymbolReference;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.psi.PsiElement;
+import org.jetbrains.annotations.NotNull;
+import org.nixos.idea.lang.references.symbol.NixSymbol;
+import org.nixos.idea.psi.NixPsiElement;
+import org.nixos.idea.util.TextRangeFactory;
+
+@SuppressWarnings("UnstableApiUsage")
+public abstract class NixSymbolReference implements PsiSymbolReference {
+
+    protected final @NotNull NixPsiElement myElement;
+    protected final @NotNull NixPsiElement myIdentifier;
+    protected final @NotNull String myName;
+
+    protected NixSymbolReference(@NotNull NixPsiElement element, @NotNull NixPsiElement identifier, @NotNull String name) {
+        myElement = element;
+        myIdentifier = identifier;
+        myName = name;
+    }
+
+    public @NotNull NixPsiElement getIdentifier() {
+        return myIdentifier;
+    }
+
+    @Override
+    public @NotNull PsiElement getElement() {
+        return myElement;
+    }
+
+    @Override
+    public @NotNull TextRange getRangeInElement() {
+        return TextRangeFactory.relative(myIdentifier, myElement);
+    }
+
+    @Override
+    public boolean resolvesTo(@NotNull Symbol target) {
+        // Check name as a shortcut to avoid resolving the reference when it cannot match anyway.
+        return target instanceof NixSymbol t &&
+                myName.equals(t.getName()) &&
+                PsiSymbolReference.super.resolvesTo(target);
+    }
+}

src/main/java/org/nixos/idea/lang/references/NixUsage.java

@@ -0,0 +1,67 @@
+package org.nixos.idea.lang.references;
+
+import com.intellij.find.usages.api.PsiUsage;
+import com.intellij.find.usages.api.ReadWriteUsage;
+import com.intellij.find.usages.api.UsageAccess;
+import com.intellij.model.Pointer;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.SmartPointerManager;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.nixos.idea.psi.NixPsiElement;
+
+@SuppressWarnings("UnstableApiUsage")
+final class NixUsage implements PsiUsage, ReadWriteUsage {
+
+    private final @NotNull NixPsiElement myIdentifier;
+    private final boolean myIsDeclaration;
+    private @Nullable Pointer<NixUsage> myPointer;
+
+    NixUsage(@NotNull NixSymbolDeclaration declaration) {
+        myIdentifier = declaration.getIdentifier();
+        myIsDeclaration = true;
+    }
+
+    NixUsage(@NotNull NixSymbolReference reference) {
+        myIdentifier = reference.getIdentifier();
+        myIsDeclaration = false;
+    }
+
+    private NixUsage(@NotNull Pointer<NixUsage> pointer, @NotNull NixPsiElement identifier, boolean isDeclaration) {
+        myIdentifier = identifier;
+        myIsDeclaration = isDeclaration;
+        myPointer = pointer;
+    }
+
+    @Override
+    public @NotNull Pointer<NixUsage> createPointer() {
+        if (myPointer == null) {
+            boolean isDeclaration = myIsDeclaration;
+            myPointer = Pointer.uroborosPointer(
+                    SmartPointerManager.createPointer(myIdentifier),
+                    (identifier, pointer) -> new NixUsage(pointer, identifier, isDeclaration));
+        }
+        return myPointer;
+    }
+
+    @Override
+    public @NotNull PsiFile getFile() {
+        return myIdentifier.getContainingFile();
+    }
+
+    @Override
+    public @NotNull TextRange getRange() {
+        return myIdentifier.getTextRange();
+    }
+
+    @Override
+    public boolean getDeclaration() {
+        return myIsDeclaration;
+    }
+
+    @Override
+    public @Nullable UsageAccess computeAccess() {
+        return myIsDeclaration ? UsageAccess.Write : UsageAccess.Read;
+    }
+}

src/main/java/org/nixos/idea/lang/references/NixUsageSearcher.java

@@ -0,0 +1,66 @@
+package org.nixos.idea.lang.references;
+
+import com.intellij.find.usages.api.SearchTarget;
+import com.intellij.find.usages.api.Usage;
+import com.intellij.find.usages.api.UsageSearchParameters;
+import com.intellij.find.usages.api.UsageSearcher;
+import com.intellij.model.search.LeafOccurrence;
+import com.intellij.model.search.LeafOccurrenceMapper;
+import com.intellij.model.search.SearchContext;
+import com.intellij.model.search.SearchService;
+import com.intellij.psi.PsiElement;
+import com.intellij.util.Query;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.nixos.idea.lang.NixLanguage;
+import org.nixos.idea.lang.references.symbol.NixSymbol;
+import org.nixos.idea.lang.references.symbol.NixUserSymbol;
+import org.nixos.idea.psi.NixPsiElement;
+
+import java.util.Collection;
+import java.util.List;
+
+@SuppressWarnings("UnstableApiUsage")
+public final class NixUsageSearcher implements UsageSearcher, LeafOccurrenceMapper.Parameterized<NixSymbol, Usage> {
+
+    @Override
+    public @NotNull Collection<? extends Usage> collectImmediateResults(@NotNull UsageSearchParameters parameters) {
+        if (parameters.getTarget() instanceof NixUserSymbol symbol) {
+            return symbol.getDeclarations().stream().map(NixUsage::new).toList();
+        } else {
+            return List.of();
+        }
+    }
+
+    @Override
+    public @Nullable Query<? extends Usage> collectSearchRequest(@NotNull UsageSearchParameters parameters) {
+        SearchTarget target = parameters.getTarget();
+        if (target instanceof NixSymbol symbol) {
+            String name = symbol.getName();
+            return SearchService.getInstance()
+                    .searchWord(parameters.getProject(), name)
+                    .inContexts(SearchContext.IN_CODE_HOSTS, SearchContext.IN_CODE)
+                    .inScope(parameters.getSearchScope())
+                    .inFilesWithLanguage(NixLanguage.INSTANCE)
+                    .buildQuery(LeafOccurrenceMapper.withPointer(symbol.createPointer(), this));
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public @NotNull Collection<? extends Usage> mapOccurrence(@NotNull NixSymbol symbol, @NotNull LeafOccurrence occurrence) {
+        for (PsiElement element = occurrence.getStart(); element != null && element != occurrence.getScope(); element = element.getParent()) {
+            if (element instanceof NixPsiElement nixElement) {
+                List<NixUsage> usages = nixElement.getOwnReferences().stream()
+                        .filter(reference -> reference.resolvesTo(symbol))
+                        .map(NixUsage::new)
+                        .toList();
+                if (!usages.isEmpty()) {
+                    return usages;
+                }
+            }
+        }
+        return List.of();
+    }
+}