The IntelliJ Platform includes a powerful framework for implementing formatting for custom languages. A formatter enables reformatting code automatically based on code style settings. The formatter controls spaces, indents, wrap, and alignment.
The formatting model represents the formatting structure of a file as a tree of Block objects, with associated indent, wrap, alignment and spacing settings. The goal is to cover each PSI element with such a block. Since each block builds its children's blocks, it can generate extra blocks or skip any PSI elements. Define SimpleBlock based on AbstractBlock.
// Copyright 2000-2020 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package org.intellij.sdk.language;
import com.intellij.formatting.*;
import com.intellij.lang.ASTNode;
import com.intellij.psi.TokenType;
import com.intellij.psi.formatter.common.AbstractBlock;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import java.util.ArrayList;
import java.util.List;
public class SimpleBlock extends AbstractBlock {
private final SpacingBuilder spacingBuilder;
protected SimpleBlock(@NotNull ASTNode node, @Nullable Wrap wrap, @Nullable Alignment alignment,
SpacingBuilder spacingBuilder) {
super(node, wrap, alignment);
this.spacingBuilder = spacingBuilder;
}
@Override
protected List<Block> buildChildren() {
List<Block> blocks = new ArrayList<>();
ASTNode child = myNode.getFirstChildNode();
while (child != null) {
if (child.getElementType() != TokenType.WHITE_SPACE) {
Block block = new SimpleBlock(child, Wrap.createWrap(WrapType.NONE, false), Alignment.createAlignment(),
spacingBuilder);
blocks.add(block);
}
child = child.getTreeNext();
}
return blocks;
}
@Override
public Indent getIndent() {
return Indent.getNoneIndent();
}
@Nullable
@Override
public Spacing getSpacing(@Nullable Block child1, @NotNull Block child2) {
return spacingBuilder.getSpacing(this, child1, child2);
}
@Override
public boolean isLeaf() {
return myNode.getFirstChildNode() == null;
}
}
Define a Formatting Model Builder
Define a formatter that removes extra spaces except for the single spaces around the property separator. For example, reformat "foo = bar" to "foo = bar".
// Copyright 2000-2021 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package org.intellij.sdk.language;
import com.intellij.formatting.*;
import com.intellij.psi.codeStyle.CodeStyleSettings;
import org.intellij.sdk.language.psi.SimpleTypes;
import org.jetbrains.annotations.NotNull;
public class SimpleFormattingModelBuilder implements FormattingModelBuilder {
private static SpacingBuilder createSpaceBuilder(CodeStyleSettings settings) {
return new SpacingBuilder(settings, SimpleLanguage.INSTANCE)
.around(SimpleTypes.SEPARATOR)
.spaceIf(settings.getCommonSettings(SimpleLanguage.INSTANCE.getID()).SPACE_AROUND_ASSIGNMENT_OPERATORS)
.before(SimpleTypes.PROPERTY)
.none();
}
@Override
public @NotNull FormattingModel createModel(@NotNull FormattingContext formattingContext) {
final CodeStyleSettings codeStyleSettings = formattingContext.getCodeStyleSettings();
return FormattingModelProvider
.createFormattingModelForPsiFile(formattingContext.getContainingFile(),
new SimpleBlock(formattingContext.getNode(),
Wrap.createWrap(WrapType.NONE, false),
Alignment.createAlignment(),
createSpaceBuilder(codeStyleSettings)),
codeStyleSettings);
}
}
Register the Formatter
The SimpleFormattingModelBuilder implementation is registered with the IntelliJ Platform in the plugin configuration file using the com.intellij.lang.formatter extension point.
Open the example Simple Language properties file in the IDE Development Instance. Add some extra spaces around the = separator between language and English. Reformat the code by selecting Code | Show Reformat File Dialog and choose Run.
