问题：

ANTLR4:匹配所有输入备选方案精确一次

翟弘

2023-03-14

rule: ('example\r\n' | 'example2\r\n') nextRule

example
example2

example2
example

example
example
example2

卜鹏

2023-03-14

在ANTLR中，我如何制定一个规则，以任何顺序只匹配它的所有替代项一次？

“它的所有备选方案只有一次”就是规则：altA altB altC...。这是容易的部分。要求rule接受任何排列中的所有选项alta、altb、altc等，意味着适应每一种排列。对于较小的数字，这很容易手动处理(规则：（altA altB altB altA）；)。但是没有自动的快捷方式，我知道为你自动处理所有的排列。

这里有一些方法，以防没有内置的方法，并且假设您不能放松您的需求。警告：我不知道你问题的全部范围；我不知道你的语法；我不知道你为什么想要你所要求的；我不知道您更喜欢哪一类解决方案，除了您可能喜欢它比这些选项更容易之外。

field : modifiers ID EOF;

modifiers
    : PUBLIC STATIC FINAL //ABC
    | PUBLIC FINAL STATIC //ACB
    | STATIC PUBLIC FINAL //BAC
    | STATIC FINAL PUBLIC //BCA
    | FINAL PUBLIC STATIC //CAB
    | FINAL STATIC PUBLIC //CBA
    ;

field 
    locals [java.util.HashSet<String> names = new java.util.HashSet<String>();]
    : modifiers ID EOF;

modifiers
    //Ensure that the full number of modifiers have been provided
    : {$field::names.size() < 3}? modifier modifiers
    | {$field::names.size() == 3}? //match nothing once we have (any) three modifiers
    ;

modifier
    //Ensure that no duplicates have been provided
    : {!$field::names.contains("public")}? PUBLIC {$field::names.add("public");}
    | {!$field::names.contains("static")}? STATIC {$field::names.add("static");}
    | {!$field::names.contains("final")}? FINAL {$field::names.add("final");}
    ;

//partial grammar

field : modifier* ID EOF; //accept any modifiers in any order

modifier  
    : PUBLIC
    | STATIC
    | FINAL
    ;

//snippet of calling code
//initialize lexer and parser

parser.addParseListener(new MyGrammarBaseListener() {
    @Override
    public void exitField(FieldContext ctx) {
        // The field rule has finished. Let's verify that no modifiers
        // were duplicated.

        //TODO check for duplicates, ensure all modifiers are specified.
        //TODO log errors accordingly.

    }
});

//Call the parser.
parser.field();

语法保持干净。修饰符可以任意出现在输入中id之前，以任何数量和顺序出现。调用代码通过它选择的任何方法执行测试，记录它想要的任何错误。

下面是一个uberexample，它将我提到的三个选项结合在一起，以便更清楚地理解我所说的内容。

grammar Modifiers;

//Hard-coded version : all the permutations are specified //
permutationField : permutationModifiers ID EOF;

permutationModifiers
    : PUBLIC STATIC FINAL //ABC
    | PUBLIC FINAL STATIC //ACB
    | STATIC PUBLIC FINAL //BAC
    | STATIC FINAL PUBLIC //BCA
    | FINAL PUBLIC STATIC //CAB
    | FINAL STATIC PUBLIC //CBA
    ;

// Predicate version : use semantic predicates to prevent duplicates and ensure all the modifiers are provided //

predicateField 
    locals [java.util.HashSet<String> names = new java.util.HashSet<String>();]
    : predicateModifiers ID EOF;

predicateModifiers
    //Ensure that the full number of modifiers have been provided
    : {$predicateField::names.size() < 3}? predicateModifier predicateModifiers
    | {$predicateField::names.size() == 3}? //match nothing once we have (any) three modifiers
    ;

predicateModifier
    //Ensure that no duplicates have been provided
    : {!$predicateField::names.contains("public")}? PUBLIC {$predicateField::names.add("public");}
    | {!$predicateField::names.contains("static")}? STATIC {$predicateField::names.add("static");}
    | {!$predicateField::names.contains("final")}? FINAL {$predicateField::names.add("final");}
    ;

//Listener version : test everything when the parser calls the listener //

listenerField : listenerModifier* ID EOF;

listenerModifier  
    : PUBLIC
    | STATIC
    | FINAL
    ;


PUBLIC : 'public';
STATIC : 'static';
FINAL  : 'final';
FOO    : 'foo';
ID     : [a-zA-Z]+;
WS     : [ \r\n\t]+ -> skip;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.BaseErrorListener;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Recognizer;
import org.antlr.v4.runtime.misc.Nullable;

public class ModifiersTest {

    public static void main(String[] args) {

        run("public static final x", "ok");
        run("final static public x", "ok");
        run("static public static final x", "too many modifiers");
        run("static x", "missing modifiers");
        run("final final x", "missing & duplicated modifiers");
    }

    private static void run(String code, String title) {
        System.out.printf("%n---%n**Input : %s**%n%n\t%s%n%n", title, code);

        System.out.println("**Permutation Output**\n");
        runPermutationTest(code);
        System.out.println();

        System.out.println("**Predicate Output**\n");
        runPredicateTest(code);
        System.out.println();

        System.out.println("**Listener Output**\n");
        runListenerTest(code);
        System.out.println();

    }
    private static void runPermutationTest(String code) {
        ModifiersParser parser = createParser(code);

        parser.permutationField();
        System.out.println("\t(done)");
    }

    private static void runPredicateTest(String code) {
        ModifiersParser parser = createParser(code);

        parser.predicateField();
        System.out.println("\t(done)");
    }

    private static void runListenerTest(String code) {
        ModifiersParser parser = createParser(code);

        parser.addParseListener(new ModifiersBaseListener() {
            @Override
            public void exitListenerField(ModifiersParser.ListenerFieldContext ctx) {
                // The field rule has finished. Let's verify that no modifiers
                // were duplicated.

                HashSet<String> uniqueNames = new HashSet<String>();
                ArrayList<String> allNames = new ArrayList<String>();
                HashSet<String> expectedNames = new HashSet<String>();
                expectedNames.add("public");
                expectedNames.add("static");
                expectedNames.add("final");

                if (ctx.listenerModifier() != null && !ctx.listenerModifier().isEmpty()) {
                    List<ModifiersParser.ListenerModifierContext> modifiers = ctx.listenerModifier();

                    // Collect all the modifier names in a set.
                    for (ModifiersParser.ListenerModifierContext modifier : modifiers) {
                        uniqueNames.add(modifier.getText());
                        allNames.add(modifier.getText());
                    }
                }

                // Is the number of unique modifiers less than the number of
                // all given modifiers? If so, then there must be duplicates.
                if (uniqueNames.size() < allNames.size()) {
                    ArrayList<String> names = new ArrayList<String>(allNames);
                    for (String name : uniqueNames){
                        names.remove(name);
                    }
                    System.out.println("\tDetected duplicate modifiers : " + names);
                } else {
                    System.out.println("\t(No duplicate modifiers detected)");
                }

                //Are we missing any expected modifiers?
                if (!uniqueNames.containsAll(expectedNames)) {
                    ArrayList<String> names = new ArrayList<String>(expectedNames);
                    names.removeAll(uniqueNames);
                    System.out.println("\tDetected missing modifiers : " + names);
                } else {
                    System.out.println("\t(No missing modifiers detected)");
                }
            }
        });

        parser.listenerField();

        System.out.println("\t(done)");

    }

    private static ModifiersParser createParser(String code) {
        ANTLRInputStream input = new ANTLRInputStream(code);

        ModifiersLexer lexer = new ModifiersLexer(input);

        ModifiersParser parser = new ModifiersParser(new CommonTokenStream(lexer));

        BaseErrorListener errorListener = createErrorListener();

        lexer.addErrorListener(errorListener);
        parser.addErrorListener(errorListener);
        return parser;
    }

    private static BaseErrorListener createErrorListener() {
        BaseErrorListener errorListener = new BaseErrorListener() {

            @Override
            public void syntaxError(Recognizer<?, ?> recognizer, @Nullable Object offendingSymbol, int line,
                    int charPositionInLine, String msg, @Nullable RecognitionException e) {
                //Print the syntax error 
                System.out.printf("\t%s at (%d, %d)%n", msg, line, charPositionInLine);
            }
        };
        return errorListener;
    }
}

public static final x

(done)

(done)

(No duplicate modifiers detected)
(No missing modifiers detected)
(done)

final static public x

置换输出

(done)

谓词输出

(done)

侦听器输出

(No duplicate modifiers detected)
(No missing modifiers detected)
(done)

static public static final x

extraneous input 'static' expecting 'final' at (1, 14)
(done)

no viable alternative at input 'static' at (1, 14)
(done)

Detected duplicate modifiers : [static]
(No missing modifiers detected)
(done)

static x

no viable alternative at input 'staticx' at (1, 7)
(done)

no viable alternative at input 'x' at (1, 7)
(done)

(No duplicate modifiers detected)
Detected missing modifiers : [final, public]
(done)

输入：缺少和重复的修饰符

final final x

置换输出

no viable alternative at input 'finalfinal' at (1, 6)
(done)

谓词输出

no viable alternative at input 'final' at (1, 6)
(done)

Detected duplicate modifiers : [final]
Detected missing modifiers : [static, public]
(done)

ANTLR4:匹配所有输入备选方案精确一次

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