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In order for the Consulo to parse a Simple Language file, tokens and elements must be defined based on IElementType. The Simple Language grammar must also be defined to generate a parser.

Reference: Implementing a Parser and PSI

3.1. Define a Token Type ​

Create SimpleTokenType in the org.consulo.sdk.language.psi package (see the simple_language_plugin code sample) by subclassing IElementType.

java
package org.consulo.sdk.language.psi;

import consulo.language.ast.IElementType;
import org.consulo.sdk.language.SimpleLanguage;

import jakarta.annotation.Nonnull;

public class SimpleTokenType extends IElementType {

  public SimpleTokenType(@Nonnull String debugName) {
    super(debugName, SimpleLanguage.INSTANCE);
  }

  @Override
  public String toString() {
    return "SimpleTokenType." + super.toString();
  }

}

3.2. Define an Element Type ​

Create the SimpleElementType in the org.consulo.sdk.language.psi package by subclassing IElementType.

java
package org.consulo.sdk.language.psi;

import consulo.language.ast.IElementType;
import org.consulo.sdk.language.SimpleLanguage;

import jakarta.annotation.Nonnull;

public class SimpleElementType extends IElementType {

  public SimpleElementType(@Nonnull String debugName) {
    super(debugName, SimpleLanguage.INSTANCE);
  }

}

3.3. Define the Grammar ​

Define a grammar for the Simple Language in the org/consulo/sdk/language/Simple.bnf file.

properties
{
  parserClass="org.consulo.sdk.language.parser.SimpleParser"

  extends="consulo.language.impl.psi.ASTWrapperPsiElement"

  psiClassPrefix="Simple"
  psiImplClassSuffix="Impl"
  psiPackage="org.consulo.sdk.language.psi"
  psiImplPackage="org.consulo.sdk.language.psi.impl"

  elementTypeHolderClass="org.consulo.sdk.language.psi.SimpleTypes"
  elementTypeClass="org.consulo.sdk.language.psi.SimpleElementType"
  tokenTypeClass="org.consulo.sdk.language.psi.SimpleTokenType"
}

simpleFile ::= item_*

private item_ ::= (property|COMMENT|CRLF)

property ::= (KEY? SEPARATOR VALUE?) | KEY

As shown, a properties file can contain properties, comments, and line breaks.

Please see Grammar-Kit documentation for more details on BNF syntax.

The grammar defines the flexibility of the support for a language. The above grammar specifies that a property may have or may not have key and value. This flexibility allows the Consulo to recognize incorrectly defined properties and provide corresponding code analysis and quick-fixes.

Note that the SimpleTypes class in the elementTypeHolderClass field above specifies the name of a class that gets generated from the grammar; it doesn't exist at this point.

3.4. Generate a Parser ​

Now that the grammar is defined generate a parser with PSI classes via Generate Parser Code from the context menu on the Simple.bnf file. This step generates a parser and PSI elements in the /src/main/gen folder of the project. Mark this folder as Generated Sources Root and make sure everything compiles without errors.

TIP

The maven-consulo-plugin can be used to automate parser generation as part of the Maven build.

Parser