5. Syntax Highlighter and Color Settings Page
tip
This page is part of multi-step Custom Language Support Tutorial. All previous steps must be executed in sequence for the code to work.
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 class extends SyntaxHighlighterBase. As recommended in Color Scheme Management, the Simple Language highlighting text attributes are specified as a dependency on one of standard IntelliJ Platform keys. For the Simple Language, define only one scheme.
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];
@NotNull
@Override
public Lexer getHighlightingLexer() {
return new SimpleLexerAdapter();
}
@Override
public TextAttributesKey @NotNull [] 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;
}
}The factory provides a standard way for the IntelliJ Platform to instantiate the syntax highlighter for Simple Language files. Here, SimpleSyntaxHighlighterFactory subclasses SyntaxHighlighterFactory.
final class SimpleSyntaxHighlighterFactory extends SyntaxHighlighterFactory {
@NotNull
@Override
public SyntaxHighlighter getSyntaxHighlighter(Project project, VirtualFile virtualFile) {
return new SimpleSyntaxHighlighter();
}
}Register the factory with the IntelliJ Platform in the plugin configuration file using the com.intellij.lang.syntaxHighlighterFactory extension point.
<extensions defaultExtensionNs="com.intellij">
<lang.syntaxHighlighterFactory
language="Simple"
implementationClass="org.intellij.sdk.language.SimpleSyntaxHighlighterFactory"/>
</extensions>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.
The color settings page adds the ability for users to customize color settings for the highlighting in Simple Language files. The SimpleColorSettingsPage implements ColorSettingsPage.
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 Icon getIcon() {
return SimpleIcons.FILE;
}
@NotNull
@Override
public SyntaxHighlighter getHighlighter() {
return new SimpleSyntaxHighlighter();
}
@NotNull
@Override
public String getDemoText() {
return """
# You are reading the ".properties" entry.
! The exclamation mark can also mark text as comments.
website = https://en.wikipedia.org/
language = English
# The backslash below tells the application to continue reading
# the value onto the next line.
message = Welcome to \\
Wikipedia!
# Add spaces to the key
key\\ with\\ spaces = This is the value that could be looked up with the key "key with spaces".
# Unicode
tab : \\u0009""";
}
@Nullable
@Override
public Map<String, TextAttributesKey> getAdditionalHighlightingTagToDescriptorMap() {
return null;
}
@Override
public AttributesDescriptor @NotNull [] getAttributeDescriptors() {
return DESCRIPTORS;
}
@Override
public ColorDescriptor @NotNull [] getColorDescriptors() {
return ColorDescriptor.EMPTY_ARRAY;
}
@NotNull
@Override
public String getDisplayName() {
return "Simple";
}
}It is supported to group related attributes like operators or braces by separating the nodes with //, e.g.:
AttributesDescriptor[] DESCRIPTORS = new AttributesDescriptor[] {
new AttributesDescriptor("Operators//Plus", MySyntaxHighlighter.PLUS),
new AttributesDescriptor("Operators//Minus", MySyntaxHighlighter.MINUS),
new AttributesDescriptor("Operators//Advanced//Sigma", MySyntaxHighlighter.SIGMA),
new AttributesDescriptor("Operators//Advanced//Pi", MySyntaxHighlighter.PI),
//...
};Register the Simple Language color settings page with the IntelliJ Platform in the plugin configuration file using the com.intellij.colorSettingsPage extension point.
<extensions defaultExtensionNs="com.intellij">
<colorSettingsPage
implementation="org.intellij.sdk.language.SimpleColorSettingsPage"/>
</extensions>Run the project by using the Gradle runIde task.
In the IDE Development Instance, open the Simple Language highlight settings page: Settings | Editor | Color Scheme | Simple. Each color initially inherits from a Language Defaults value.
