Add support for incremental text document (not XML document) to minimize

JSON didChange request size when document changed. This incremental
support is only available with experimental.incrementalSupport.enabled
(see #133)

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/XMLLanguageServer.java

@@ -32,9 +32,9 @@
 import org.eclipse.lsp4j.services.TextDocumentService;
 import org.eclipse.lsp4j.services.WorkspaceService;
 import org.eclipse.lsp4xml.commons.ParentProcessWatcher.ProcessLanguageServer;
+import org.eclipse.lsp4xml.commons.TextDocument;
 import org.eclipse.lsp4xml.dom.XMLDocument;
 import org.eclipse.lsp4xml.logs.LogHelper;
-import org.eclipse.lsp4xml.commons.TextDocument;
 import org.eclipse.lsp4xml.services.XMLLanguageService;
 import org.eclipse.lsp4xml.settings.InitializationOptionsSettings;
 import org.eclipse.lsp4xml.settings.LogsSettings;
@@ -70,7 +70,9 @@ public CompletableFuture<InitializeResult> initialize(InitializeParams params) {
 		xmlTextDocumentService.updateClientCapabilities(params.getCapabilities());
 		this.parentProcessId = params.getProcessId();
 		ServerCapabilities capabilities = new ServerCapabilities();
-		capabilities.setTextDocumentSync(TextDocumentSyncKind.Full);
+		capabilities
+				.setTextDocumentSync(xmlTextDocumentService.isIncrementalSupport() ? TextDocumentSyncKind.Incremental
+						: TextDocumentSyncKind.Full);
 		capabilities.setDocumentSymbolProvider(true);
 		capabilities.setDocumentHighlightProvider(true);
 		capabilities.setCompletionProvider(new CompletionOptions(false, Arrays.asList(".", ":", "<", "\"", "=", "/")));

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/XMLTextDocumentService.java

@@ -65,7 +65,9 @@
 import org.eclipse.lsp4xml.dom.XMLParser;
 import org.eclipse.lsp4xml.services.XMLLanguageService;
 import org.eclipse.lsp4xml.services.extensions.CompletionSettings;
+import org.eclipse.lsp4xml.settings.XMLExperimentalCapabilities;
 import org.eclipse.lsp4xml.settings.XMLFormattingOptions;
+import org.eclipse.lsp4xml.utils.JSONUtility;
 
 /**
  * XML text document service.
@@ -106,7 +108,7 @@ public XMLTextDocumentService(XMLLanguageServer xmlLanguageServer) {
 		this.xmlLanguageServer = xmlLanguageServer;
 		this.documents = new TextDocuments();
 		XMLParser parser = XMLParser.getInstance();
-		this.xmlDocuments = new LanguageModelCache<XMLDocument>(10, 60, document -> parser.parse(document));
+		this.xmlDocuments = new LanguageModelCache<XMLDocument>(10, 60, documents, document -> parser.parse(document));
 		this.sharedCompletionSettings = new CompletionSettings();
 		this.sharedFoldingsSettings = new FoldingRangeCapabilities();
 		this.sharedFormattingOptions = new XMLFormattingOptions(true); // to be sure that formattings options is not
@@ -122,6 +124,15 @@ public void updateClientCapabilities(ClientCapabilities capabilities) {
 					&& textDocumentClientCapabilities.getCodeAction().getCodeActionLiteralSupport() != null;
 		}
 
+		// Experimental capabilities
+		// get value of "experimental.incrementalSupport.enabled"
+		XMLExperimentalCapabilities experimental = JSONUtility.toModel(capabilities.getExperimental(),
+				XMLExperimentalCapabilities.class);
+		boolean incrementalSupport = experimental != null && experimental.getIncrementalSupport() != null
+				&& experimental.getIncrementalSupport().getEnabled() != null
+						? experimental.getIncrementalSupport().getEnabled()
+						: false;
+		documents.setIncremental(incrementalSupport);
 	}
 
 	public TextDocument getDocument(String uri) {
@@ -314,4 +325,8 @@ public void setSharedFormattingOptions(XMLFormattingOptions formattingOptions) {
 		this.sharedFormattingOptions = formattingOptions;
 	}
 
+	public boolean isIncrementalSupport() {
+		return documents.isIncremental();
+	}
+
 }

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/commons/ITextDocumentFactory.java

@@ -0,0 +1,30 @@
+/**
+ *  Copyright (c) 2018 Angelo ZERR.
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  which accompanies this distribution, and is available at
+ *  http://www.eclipse.org/legal/epl-v10.html
+ *
+ *  Contributors:
+ *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
+ */
+package org.eclipse.lsp4xml.commons;
+
+import org.eclipse.lsp4j.TextDocumentItem;
+
+/**
+ * {@link TextDocument} factory.
+ *
+ */
+public interface ITextDocumentFactory {
+
+	/**
+	 * Create a {@link TextDocument} instance from the given
+	 * {@link TextDocumentItem}.
+	 * 
+	 * @param document
+	 * @return a {@link TextDocument} instance from the given
+	 *         {@link TextDocumentItem}.
+	 */
+	TextDocument createDocument(TextDocumentItem document);
+}

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/commons/LanguageModelCache.java

@@ -28,6 +28,7 @@ public class LanguageModelCache<T> {
 
 	private final Map<String, LanguageModeInfo> languageModels;
 	private final Function<TextDocument, T> parse;
+	private final ITextDocumentFactory documentFactory;
 
 	class LanguageModeInfo {
 
@@ -44,9 +45,11 @@ public LanguageModeInfo(T languageModel, int version, String languageId, long cT
 		}
 	}
 
-	public LanguageModelCache(int maxEntries, int cleanupIntervalTimeInSec, Function<TextDocument, T> parse) {
+	public LanguageModelCache(int maxEntries, int cleanupIntervalTimeInSec, ITextDocumentFactory documentFactory,
+			Function<TextDocument, T> parse) {
 		this.languageModels = new HashMap<>();
 		this.parse = parse;
+		this.documentFactory = documentFactory;
 	}
 
 	public T get(TextDocumentItem document) {
@@ -76,10 +79,8 @@ private synchronized T parseAndGet(TextDocumentItem document, int version, Strin
 			return languageModel;
 		}
 		TextDocument textDocument = document instanceof TextDocument ? (TextDocument) document
-				: new TextDocument(document);
-		long start = System.currentTimeMillis();
+				: documentFactory.createDocument(document);
 		languageModel = parse.apply(textDocument);
-		//System.err.println("parsed in " + (System.currentTimeMillis() - start) + "ms");
 		languageModels.put(uri, new LanguageModeInfo(languageModel, version, languageId, System.currentTimeMillis()));
 		return languageModel;
 	}

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/commons/TextDocument.java

@@ -10,11 +10,13 @@
  */
 package org.eclipse.lsp4xml.commons;
 
+import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.eclipse.lsp4j.Position;
 import org.eclipse.lsp4j.Range;
+import org.eclipse.lsp4j.TextDocumentContentChangeEvent;
 import org.eclipse.lsp4j.TextDocumentItem;
 
 /**
@@ -28,15 +30,27 @@ public class TextDocument extends TextDocumentItem {
 
 	private ListLineTracker lineTracker;
 
-	public TextDocument(TextDocumentItem document) {
-		this(document.getText(), document.getUri());
+	// Buffer of the text document used only in incremental mode.
+	private final StringBuilder buffer;
+
+	// incremental support?
+	private final boolean incremental;
+
+	public TextDocument(TextDocumentItem document, boolean incremental) {
+		this(document.getText(), document.getUri(), incremental);
 		super.setVersion(document.getVersion());
 		super.setLanguageId(document.getLanguageId());
 	}
 
 	public TextDocument(String text, String uri) {
+		this(text, uri, false);
+	}
+
+	public TextDocument(String text, String uri, boolean incremental) {
 		super.setUri(uri);
 		super.setText(text);
+		buffer = incremental ? new StringBuilder(text) : null;
+		this.incremental = incremental;
 	}
 
 	@Override
@@ -110,4 +124,50 @@ private ListLineTracker getLineTracker() {
 		}
 		return lineTracker;
 	}
+
+	/**
+	 * Update text of the document by using the changes and according the
+	 * incremental support.
+	 * 
+	 * @param changes the text document changes.
+	 */
+	public void update(List<TextDocumentContentChangeEvent> changes) {
+		if (changes.size() < 1) {
+			// no changes, ignore it.
+			return;
+		}
+		if (incremental) {
+			try {
+				synchronized (buffer) {
+					for (TextDocumentContentChangeEvent changeEvent : changes) {
+
+						Range range = changeEvent.getRange();
+						int length = 0;
+
+						if (range != null) {
+							length = changeEvent.getRangeLength().intValue();
+						} else {
+							// range is optional and if not given, the whole file content is replaced
+							length = getText().length();
+							range = new Range(positionAt(0), positionAt(length));
+						}
+						String text = changeEvent.getText();
+						int startOffset = offsetAt(range.getStart());
+						buffer.replace(startOffset, startOffset + length, text);
+					}
+					setText(buffer.toString());
+				}
+			} catch (BadLocationException e) {
+				// Should never occurs.
+			}
+		} else {
+			// like vscode does, get the last changes
+			// see
+			// https://github.com/Microsoft/vscode-languageserver-node/blob/master/server/src/main.ts
+			TextDocumentContentChangeEvent last = changes.size() > 0 ? changes.get(changes.size() - 1) : null;
+			if (last != null) {
+				setText(last.getText());
+			}
+		}
+	}
 }

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/commons/TextDocuments.java

@@ -23,14 +23,37 @@
 /**
  * A manager for simple text documents
  */
-public class TextDocuments {
+public class TextDocuments implements ITextDocumentFactory {
+
+	private boolean incremental;
 
 	private final Map<String, TextDocument> documents;
 
 	public TextDocuments() {
 		documents = new HashMap<>();
 	}
 
+	/**
+	 * Set the incremental support.
+	 * 
+	 * @param incremental
+	 */
+	public void setIncremental(boolean incremental) {
+		this.incremental = incremental;
+		documents.clear();
+	}
+
+	/**
+	 * Returns true if text document is managed in incremental mode and false
+	 * otherwise.
+	 * 
+	 * @return true if text document is managed in incremental mode and false
+	 *         otherwise.
+	 */
+	public boolean isIncremental() {
+		return incremental;
+	}
+
 	/**
 	 * Returns the document for the given URI. Returns undefined if the document is
 	 * not mananged by this instance.
@@ -44,21 +67,20 @@ public TextDocument get(String uri) {
 
 	public void onDidOpenTextDocument(DidOpenTextDocumentParams params) {
 		TextDocumentItem document = params.getTextDocument();
-		documents.put(document.getUri(), new TextDocument(document));
+		documents.put(document.getUri(), createDocument(document));
+	}
+
+	@Override
+	public TextDocument createDocument(TextDocumentItem document) {
+		return new TextDocument(document, incremental);
 	}
 
 	public void onDidChangeTextDocument(DidChangeTextDocumentParams params) {
 		List<TextDocumentContentChangeEvent> changes = params.getContentChanges();
-		// like vscode does, get the last changes
-		// see
-		// https://github.com/Microsoft/vscode-languageserver-node/blob/master/server/src/main.ts
-		TextDocumentContentChangeEvent last = changes.size() > 0 ? changes.get(changes.size() - 1) : null;
-		if (last != null) {
-			TextDocument document = get(params.getTextDocument().getUri());
-			if (document != null) {
-				document.setVersion(params.getTextDocument().getVersion());
-				document.setText(last.getText());
-			}
+		TextDocument document = get(params.getTextDocument().getUri());
+		if (document != null) {
+			document.setVersion(params.getTextDocument().getVersion());
+			document.update(changes);
 		}
 	}
 

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/settings/XMLExperimentalCapabilities.java

@@ -0,0 +1,28 @@
+/**
+ *  Copyright (c) 2018 Angelo ZERR
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  which accompanies this distribution, and is available at
+ *  http://www.eclipse.org/legal/epl-v10.html
+ *
+ *  Contributors:
+ *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
+ */
+package org.eclipse.lsp4xml.settings;
+
+/**
+ * XML experimental capabilities.
+ *
+ */
+public class XMLExperimentalCapabilities {
+
+	private XMLIncrementalSupportCapabilities incrementalSupport;
+
+	public void setIncrementalSupport(XMLIncrementalSupportCapabilities incrementalSupport) {
+		this.incrementalSupport = incrementalSupport;
+	}
+
+	public XMLIncrementalSupportCapabilities getIncrementalSupport() {
+		return incrementalSupport;
+	}
+}

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/settings/XMLFormattingOptions.java

@@ -1,3 +1,13 @@
+/**
+ *  Copyright (c) 2018 Angelo ZERR
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  which accompanies this distribution, and is available at
+ *  http://www.eclipse.org/legal/epl-v10.html
+ *
+ *  Contributors:
+ *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
+ */
 package org.eclipse.lsp4xml.settings;
 
 import org.eclipse.lsp4j.FormattingOptions;

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/settings/XMLIncrementalSupportCapabilities.java

@@ -0,0 +1,29 @@
+/**
+ *  Copyright (c) 2018 Angelo ZERR
+ *  All rights reserved. This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License v1.0
+ *  which accompanies this distribution, and is available at
+ *  http://www.eclipse.org/legal/epl-v10.html
+ *
+ *  Contributors:
+ *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
+ */
+package org.eclipse.lsp4xml.settings;
+
+/**
+ * XML experimental incremental support capabilities.
+ *
+ */
+public class XMLIncrementalSupportCapabilities {
+
+	private Boolean enabled;
+
+	public Boolean getEnabled() {
+		return enabled;
+	}
+
+	public void setEnabled(Boolean enabled) {
+		this.enabled = enabled;
+	}
+
+}