Implemenet document highlight request for labels

src/main/kotlin/texlab/LanguageServerImpl.kt

@@ -50,6 +50,7 @@ class LanguageServerImpl : LanguageServer {
             hoverProvider = true
             documentFormattingProvider = true
             referencesProvider = true
+            documentHighlightProvider = true
         }
 
         return CompletableFuture.completedFuture(InitializeResult(capabilities))

src/main/kotlin/texlab/TextDocumentServiceImpl.kt

@@ -17,6 +17,10 @@ import texlab.diagnostics.*
 import texlab.folding.*
 import texlab.formatting.BibtexFormatter
 import texlab.formatting.BibtexFormatterConfig
+import texlab.highlight.AggregateHighlightProvider
+import texlab.highlight.HighlightProvider
+import texlab.highlight.HighlightRequest
+import texlab.highlight.LatexLabelHighlightProvider
 import texlab.link.AggregateLinkProvider
 import texlab.link.LatexIncludeLinkProvider
 import texlab.link.LinkProvider
@@ -104,6 +108,9 @@ class TextDocumentServiceImpl(private val workspace: Workspace) : TextDocumentSe
                     LatexLabelDefinitionProvider,
                     BibtexEntryDefinitionProvider)
 
+    private val highlightProvider: HighlightProvider =
+            AggregateHighlightProvider(LatexLabelHighlightProvider)
+
     private val metadataProvider: PackageMetadataProvider = CtanPackageMetadataProvider()
 
     private val referenceProvider: ReferenceProvider =
@@ -296,6 +303,19 @@ class TextDocumentServiceImpl(private val workspace: Workspace) : TextDocumentSe
         }
     }
 
+    override fun documentHighlight(params: TextDocumentPositionParams):
+            CompletableFuture<MutableList<out DocumentHighlight>> {
+        synchronized(workspace) {
+            val uri = URI.create(params.textDocument.uri)
+            val document = workspace.documents.firstOrNull { it.uri == uri }
+                    ?: return CompletableFuture.completedFuture(null)
+
+            val request = HighlightRequest(document, params.position)
+            val highlights = highlightProvider.getHighlights(request)
+            return CompletableFuture.completedFuture(highlights?.toMutableList())
+        }
+    }
+
     fun build(params: BuildParams): CompletableFuture<BuildStatus> {
         return CompletableFuture.supplyAsync {
             val childUri = URI.create(params.textDocument.uri)

src/main/kotlin/texlab/highlight/AggregateHighlightProvider.kt

@@ -0,0 +1,15 @@
+package texlab.highlight
+
+import org.eclipse.lsp4j.DocumentHighlight
+
+class AggregateHighlightProvider(private vararg val providers: HighlightProvider) : HighlightProvider {
+    override fun getHighlights(request: HighlightRequest): List<DocumentHighlight>? {
+        for (provider in providers) {
+            val highlights = provider.getHighlights(request)
+            if (highlights != null) {
+                return highlights
+            }
+        }
+        return null
+    }
+}

src/main/kotlin/texlab/highlight/HighlightProvider.kt

@@ -0,0 +1,7 @@
+package texlab.highlight
+
+import org.eclipse.lsp4j.DocumentHighlight
+
+interface HighlightProvider {
+    fun getHighlights(request: HighlightRequest): List<DocumentHighlight>?
+}

src/main/kotlin/texlab/highlight/HighlightRequest.kt

@@ -0,0 +1,6 @@
+package texlab.highlight
+
+import org.eclipse.lsp4j.Position
+import texlab.Document
+
+data class HighlightRequest(val document: Document, val position: Position)

src/main/kotlin/texlab/highlight/LatexLabelHighlightProvider.kt

@@ -0,0 +1,33 @@
+package texlab.highlight
+
+import org.eclipse.lsp4j.DocumentHighlight
+import org.eclipse.lsp4j.DocumentHighlightKind
+import texlab.LatexDocument
+import texlab.contains
+import texlab.syntax.latex.LatexLabel
+
+object LatexLabelHighlightProvider : HighlightProvider {
+    override fun getHighlights(request: HighlightRequest): List<DocumentHighlight>? {
+        if (request.document !is LatexDocument) {
+            return null
+        }
+
+        val label = request.document.tree.labelDefinitions
+                .plus(request.document.tree.labelReferences)
+                .firstOrNull { it.name.range.contains(request.position) }
+                ?: return null
+
+        return request.document.tree.labelDefinitions
+                .plus(request.document.tree.labelReferences)
+                .filter { it.name.text == label.name.text }
+                .map { DocumentHighlight(it.name.range, getHighlightKind(it)) }
+    }
+
+    private fun getHighlightKind(label: LatexLabel): DocumentHighlightKind {
+        return if (label.command.name.text == "\\label") {
+            DocumentHighlightKind.Write
+        } else {
+            DocumentHighlightKind.Read
+        }
+    }
+}