perf: cache CSSTokenProvider#getToken return values

org.eclipse.tm4e.ui/src/main/java/org/eclipse/tm4e/ui/text/TMPresentationReconciler.java

@@ -90,9 +90,6 @@
  */
 public class TMPresentationReconciler implements IPresentationReconciler {
 
-	/** The default text attribute if none is returned as data by the current token. */
-	private final Token defaultToken;
-
 	/** The target viewer. */
 	@Nullable
 	private ITextViewer viewer;
@@ -125,7 +122,6 @@ public class TMPresentationReconciler implements IPresentationReconciler {
 	private boolean throwError;
 
 	public TMPresentationReconciler() {
-		this.defaultToken = new Token(null);
 		this.internalListener = new InternalListener();
 		this.fDefaultTextAttribute = new TextAttribute(null);
 		if (PreferenceUtils.isDebugGenerateTest()) {
@@ -528,6 +524,9 @@ private void colorize(final IRegion damage, final TMDocumentModel model) throws
 			TMUIPlugin.logTrace("Render from: " + fromLineIndex + " to: " + toLineIndex);
 		final var presentation = new TextPresentation(damage, 1000);
 		Exception error = null;
+
+		final var tokenProvider = this.tokenProvider;
+
 		try {
 			int lastStart = presentation.getExtent().getOffset();
 			int length = 0;
@@ -561,7 +560,8 @@ private void colorize(final IRegion damage, final TMDocumentModel model) throws
 							tokenStartIndex = damage.getOffset() - startLineOffset;
 						} else {
 							tokenStartIndex = damage.getOffset() - startLineOffset;
-							final IToken token = toToken(currentToken);
+							final IToken token = tokenProvider == null ? ITokenProvider.DEFAULT_TOKEN
+									: tokenProvider.getToken(currentToken.type);
 							lastAttribute = getTokenTextAttribute(token);
 							length += getTokenLengh(tokenStartIndex, nextToken, lineIndex, doc);
 							firstToken = false;
@@ -573,7 +573,7 @@ private void colorize(final IRegion damage, final TMDocumentModel model) throws
 						break;
 					}
 
-					final IToken token = toToken(currentToken);
+					final IToken token = tokenProvider == null ? ITokenProvider.DEFAULT_TOKEN : tokenProvider.getToken(currentToken.type);
 					final TextAttribute attribute = getTokenTextAttribute(token);
 					if (lastAttribute.equals(attribute)) {
 						length += getTokenLengh(tokenStartIndex, nextToken, lineIndex, doc);
@@ -616,17 +616,6 @@ private boolean isAfterRegion(final TMToken token, final int startLineOffset, fi
 		return token.startIndex + startLineOffset >= damage.getOffset() + damage.getLength();
 	}
 
-	private IToken toToken(final TMToken token) {
-		final var tokenProvider = this.tokenProvider;
-		if (tokenProvider != null) {
-			final IToken result = tokenProvider.getToken(token.type);
-			if (result != null) {
-				return result;
-			}
-		}
-		return defaultToken;
-	}
-
 	private int getTokenLengh(final int tokenStartIndex, @Nullable final TMToken nextToken, final int line,
 			final IDocument document) throws BadLocationException {
 		if (nextToken != null) {

org.eclipse.tm4e.ui/src/main/java/org/eclipse/tm4e/ui/themes/ITokenProvider.java

@@ -13,6 +13,7 @@
 
 import org.eclipse.jdt.annotation.Nullable;
 import org.eclipse.jface.text.rules.IToken;
+import org.eclipse.jface.text.rules.Token;
 import org.eclipse.swt.graphics.Color;
 
 /**
@@ -21,14 +22,15 @@
  */
 public interface ITokenProvider {
 
+	IToken DEFAULT_TOKEN = new Token(null);
+
 	/**
-	 * Returns the Eclipse {@link IToken} from the given type and null otherwise.
+	 * Returns the Eclipse {@link IToken} from the given type and {@link #DEFAULT_TOKEN} otherwise.
 	 *
 	 * @param type
-	 * 
-	 * @return the Eclipse {@link IToken} from the given type and null otherwise.
+	 *
+	 * @return the Eclipse {@link IToken} from the given type and {@link #DEFAULT_TOKEN} otherwise.
 	 */
-	@Nullable
 	IToken getToken(String type);
 
 	@Nullable

org.eclipse.tm4e.ui/src/main/java/org/eclipse/tm4e/ui/themes/Theme.java

@@ -81,11 +81,10 @@ public String getName() {
 		return name;
 	}
 
-	@Nullable
 	@Override
 	public IToken getToken(final String type) {
 		final ITokenProvider provider = getTokenProvider();
-		return provider != null ? provider.getToken(type) : null;
+		return provider == null ? ITokenProvider.DEFAULT_TOKEN : provider.getToken(type);
 	}
 
 	@Nullable

org.eclipse.tm4e.ui/src/main/java/org/eclipse/tm4e/ui/themes/css/CSSTokenProvider.java

@@ -16,6 +16,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.eclipse.jdt.annotation.Nullable;
 import org.eclipse.jface.text.TextAttribute;
@@ -46,6 +47,7 @@ public List<IStyle> getStyles() {
 	}
 
 	private final Map<IStyle, @Nullable IToken> tokenMaps = new HashMap<>();
+	private final Map<String, IToken> getTokenReturnValueCache = new ConcurrentHashMap<>();
 
 	private final CSSParser parser;
 
@@ -80,17 +82,20 @@ public CSSTokenProvider(final InputStream in) {
 		this.parser = parser == null ? new NoopCSSParser() : parser;
 	}
 
-	@Nullable
 	@Override
 	public IToken getToken(@Nullable final String type) {
-		if (type == null)
-			return null;
+		if (type == null || type.isEmpty())
+			return DEFAULT_TOKEN;
+
+		return getTokenReturnValueCache.computeIfAbsent(type, this::getTokenInternal);
+	}
 
+	private IToken getTokenInternal(final String type) {
 		final IStyle style = parser.getBestStyle(StringUtils.splitToArray(type, '.'));
 		if (style == null)
-			return null;
-
-		return tokenMaps.get(style);
+			return DEFAULT_TOKEN;
+		final IToken token = tokenMaps.get(style);
+		return token == null ? DEFAULT_TOKEN : token;
 	}
 
 	@Nullable