The first level of syntax highlighting is based on the lexer output, and is provided by SyntaxHighlighter. A plugin can also define color settings based on ColorSettingPage so the user can configure highlight colors. The SimpleSyntaxHighlighter, SimpleSyntaxHighlighterFactory, and SimpleColorSettingsPage discussed on this page are demonstrated in the simple_language_plugin code sample.

Reference: Syntax Highlighting and Error Highlighting

5.1. Define a Syntax Highlighter

The Simple Language syntax highlighter class extends SyntaxHighlighterBase. As recommended in Color Scheme Management, the Simple Language highlighting text attributes are specified as a dependency on one of standard Consulo keys. For the Simple Language, define only one scheme.

package org.consulo.sdk.language;

import consulo.colorScheme.DefaultLanguageHighlighterColors;
import consulo.colorScheme.HighlighterColors;
import consulo.colorScheme.TextAttributesKey;
import consulo.language.ast.IElementType;
import consulo.language.ast.TokenType;
import consulo.language.editor.highlight.SyntaxHighlighterBase;
import consulo.language.lexer.Lexer;
import org.consulo.sdk.language.psi.SimpleTypes;

import jakarta.annotation.Nonnull;

import static consulo.colorScheme.TextAttributesKey.createTextAttributesKey;

public class SimpleSyntaxHighlighter extends SyntaxHighlighterBase {

  public static final TextAttributesKey SEPARATOR =
      createTextAttributesKey("SIMPLE_SEPARATOR", DefaultLanguageHighlighterColors.OPERATION_SIGN);
  public static final TextAttributesKey KEY =
      createTextAttributesKey("SIMPLE_KEY", DefaultLanguageHighlighterColors.KEYWORD);
  public static final TextAttributesKey VALUE =
      createTextAttributesKey("SIMPLE_VALUE", DefaultLanguageHighlighterColors.STRING);
  public static final TextAttributesKey COMMENT =
      createTextAttributesKey("SIMPLE_COMMENT", DefaultLanguageHighlighterColors.LINE_COMMENT);
  public static final TextAttributesKey BAD_CHARACTER =
      createTextAttributesKey("SIMPLE_BAD_CHARACTER", HighlighterColors.BAD_CHARACTER);

  private static final TextAttributesKey[] BAD_CHAR_KEYS = new TextAttributesKey[]{BAD_CHARACTER};
  private static final TextAttributesKey[] SEPARATOR_KEYS = new TextAttributesKey[]{SEPARATOR};
  private static final TextAttributesKey[] KEY_KEYS = new TextAttributesKey[]{KEY};
  private static final TextAttributesKey[] VALUE_KEYS = new TextAttributesKey[]{VALUE};
  private static final TextAttributesKey[] COMMENT_KEYS = new TextAttributesKey[]{COMMENT};
  private static final TextAttributesKey[] EMPTY_KEYS = new TextAttributesKey[0];

  @Nonnull
  @Override
  public Lexer getHighlightingLexer() {
    return new SimpleLexerAdapter();
  }

  @Nonnull
  @Override
  public TextAttributesKey[] getTokenHighlights(IElementType tokenType) {
    if (tokenType.equals(SimpleTypes.SEPARATOR)) {
      return SEPARATOR_KEYS;
    }
    if (tokenType.equals(SimpleTypes.KEY)) {
      return KEY_KEYS;
    }
    if (tokenType.equals(SimpleTypes.VALUE)) {
      return VALUE_KEYS;
    }
    if (tokenType.equals(SimpleTypes.COMMENT)) {
      return COMMENT_KEYS;
    }
    if (tokenType.equals(TokenType.BAD_CHARACTER)) {
      return BAD_CHAR_KEYS;
    }
    return EMPTY_KEYS;
  }

}

5.2. Define a Syntax Highlighter Factory

The factory provides a standard way for the Consulo to instantiate the syntax highlighter for Simple Language files. Here, SimpleSyntaxHighlighterFactory subclasses SyntaxHighlighterFactory.

package org.consulo.sdk.language;

import consulo.annotation.component.ExtensionImpl;
import consulo.language.Language;
import consulo.language.editor.highlight.SyntaxHighlighter;
import consulo.language.editor.highlight.SyntaxHighlighterFactory;
import consulo.project.Project;
import consulo.virtualFileSystem.VirtualFile;

import jakarta.annotation.Nonnull;
import jakarta.annotation.Nullable;

@ExtensionImpl
final class SimpleSyntaxHighlighterFactory extends SyntaxHighlighterFactory {

  @Nonnull
  @Override
  public Language getLanguage() {
    return SimpleLanguage.INSTANCE;
  }

  @Nonnull
  @Override
  public SyntaxHighlighter getSyntaxHighlighter(@Nullable Project project, @Nullable VirtualFile virtualFile) {
    return new SimpleSyntaxHighlighter();
  }

}

5.3. Register the Syntax Highlighter Factory

The SyntaxHighlighterFactory base class is annotated with @ExtensionAPI(ComponentScope.APPLICATION). To register the factory with the Consulo, annotate the SimpleSyntaxHighlighterFactory implementation class with @ExtensionImpl.

5.4. Run the Project

Open the example Simple Language properties file (test.simple) in the IDE Development Instance. The colors for Simple Language Key, Separator, and Value highlighting default to the IDE Language Defaults for Keyword, Braces, Operators, and Strings, respectively.

5.5. Define a Color Settings Page

The color settings page adds the ability for users to customize color settings for the highlighting in Simple Language files. The SimpleColorSettingsPage implements ColorSettingsPage.

package org.consulo.sdk.language;

import consulo.annotation.component.ExtensionImpl;
import consulo.colorScheme.TextAttributesKey;
import consulo.colorScheme.setting.AttributesDescriptor;
import consulo.colorScheme.setting.ColorDescriptor;
import consulo.language.editor.colorScheme.setting.ColorSettingsPage;
import consulo.language.editor.highlight.SyntaxHighlighter;
import consulo.ui.image.Image;

import jakarta.annotation.Nonnull;
import jakarta.annotation.Nullable;

import java.util.Map;

@ExtensionImpl
final class SimpleColorSettingsPage implements ColorSettingsPage {

  private static final AttributesDescriptor[] DESCRIPTORS = new AttributesDescriptor[]{
      new AttributesDescriptor("Key", SimpleSyntaxHighlighter.KEY),
      new AttributesDescriptor("Separator", SimpleSyntaxHighlighter.SEPARATOR),
      new AttributesDescriptor("Value", SimpleSyntaxHighlighter.VALUE),
      new AttributesDescriptor("Bad value", SimpleSyntaxHighlighter.BAD_CHARACTER)
  };

  @Override
  public Image getIcon() {
    return SimpleIcons.FILE;
  }

  @Nonnull
  @Override
  public SyntaxHighlighter getHighlighter() {
    return new SimpleSyntaxHighlighter();
  }

  @Nonnull
  @Override
  public String getDemoText() {
    return "# You are reading the \".properties\" entry.\n" +
        "! The exclamation mark can also mark text as comments.\n" +
        "website = https://en.wikipedia.org/\n" +
        "language = English\n" +
        "# The backslash below tells the application to continue reading\n" +
        "# the value onto the next line.\n" +
        "message = Welcome to \\\n" +
        "          Wikipedia!\n" +
        "# Add spaces to the key\n" +
        "key\\ with\\ spaces = This is the value that could be looked up with the key \"key with spaces\".\n" +
        "# Unicode\n" +
        "tab : \\u0009";
  }

  @Nullable
  @Override
  public Map<String, TextAttributesKey> getAdditionalHighlightingTagToDescriptorMap() {
    return null;
  }

  @Nonnull
  @Override
  public AttributesDescriptor[] getAttributeDescriptors() {
    return DESCRIPTORS;
  }

  @Nonnull
  @Override
  public ColorDescriptor[] getColorDescriptors() {
    return ColorDescriptor.EMPTY_ARRAY;
  }

  @Nonnull
  @Override
  public String getDisplayName() {
    return "Simple";
  }

}

5.6. Register the Color Settings Page

The ColorSettingsPage interface is annotated with @ExtensionAPI. To register the Simple Language color settings page with the Consulo, annotate the SimpleColorSettingsPage implementation class with @ExtensionImpl.

5.7. Run the Project

In the IDE Development Instance, open the Simple Language highlight settings page: Preferences/Settings | Editor | Color Scheme | Simple. Each color initially inherits from a Language Defaults value.