com.felipebz.flr.examples.grammars.PegGrammar.kt Maven / Gradle / Ivy

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/**
 * FLR
 * Copyright (C) 2010-2023 SonarSource SA
 * Copyright (C) 2021-2023 Felipe Zorzo
 * mailto:felipe AT felipezorzo DOT com DOT br
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package com.felipebz.flr.examples.grammars

import com.felipebz.flr.api.Grammar
import com.felipebz.flr.grammar.GrammarRuleKey
import com.felipebz.flr.grammar.LexerlessGrammarBuilder

/**
 * PEG grammar.
 */
public enum class PegGrammar : GrammarRuleKey {
    GRAMMAR, RULE, RULE_KEY, STRING, ATOM, FIRST_OF_EXPRESSION, SEQUENCE_EXPRESSION, ZERO_OR_MORE_EXPRESSION, ONE_OR_MORE_EXPRESSION, OPTIONAL_EXPRESSION, NEXT_NOT_EXPRESSION, NEXT_EXPRESSION, ASSIGN, SEMICOLON, OR, NOT, AND, QUESTION, PLUS, STAR, OPEN, CLOSE, WHITESPACE;

    public companion object {
        @JvmStatic
        public fun create(): Grammar {
            val b = LexerlessGrammarBuilder.create()
            b.rule(GRAMMAR).`is`(WHITESPACE, b.zeroOrMore(RULE), b.endOfInput())
            b.rule(RULE).`is`(RULE_KEY, ASSIGN, FIRST_OF_EXPRESSION, SEMICOLON)
            b.rule(FIRST_OF_EXPRESSION).`is`(SEQUENCE_EXPRESSION, b.zeroOrMore(OR, SEQUENCE_EXPRESSION))
            b.rule(SEQUENCE_EXPRESSION).`is`(
                b.oneOrMore(
                    b.firstOf(
                        ZERO_OR_MORE_EXPRESSION,
                        ONE_OR_MORE_EXPRESSION,
                        OPTIONAL_EXPRESSION,
                        NEXT_NOT_EXPRESSION,
                        NEXT_EXPRESSION,
                        ATOM
                    )
                )
            )
            b.rule(ZERO_OR_MORE_EXPRESSION).`is`(ATOM, STAR)
            b.rule(ONE_OR_MORE_EXPRESSION).`is`(ATOM, PLUS)
            b.rule(OPTIONAL_EXPRESSION).`is`(ATOM, QUESTION)
            b.rule(NEXT_NOT_EXPRESSION).`is`(NOT, ATOM)
            b.rule(NEXT_EXPRESSION).`is`(AND, ATOM)
            b.rule(ATOM).`is`(
                b.firstOf(
                    RULE_KEY, STRING,
                    b.sequence(OPEN, FIRST_OF_EXPRESSION, CLOSE)
                )
            )
            b.rule(RULE_KEY).`is`(b.regexp("\\p{javaJavaIdentifierStart}\\p{javaJavaIdentifierPart}*+"), WHITESPACE)
            b.rule(STRING).`is`(b.regexp("\"[^\"]*+\""), WHITESPACE)
            b.rule(ASSIGN).`is`("=", WHITESPACE)
            b.rule(SEMICOLON).`is`(";", WHITESPACE)
            b.rule(OR).`is`("|", WHITESPACE)
            b.rule(NOT).`is`("!", WHITESPACE)
            b.rule(AND).`is`("&", WHITESPACE)
            b.rule(QUESTION).`is`("?", WHITESPACE)
            b.rule(PLUS).`is`("+", WHITESPACE)
            b.rule(STAR).`is`("*", WHITESPACE)
            b.rule(OPEN).`is`("(", WHITESPACE)
            b.rule(CLOSE).`is`(")", WHITESPACE)
            b.rule(WHITESPACE).`is`(b.regexp("\\s*+"))
            return b.build()
        }
    }
}