Antlr4 (CSharp Target)，语法= Java.g4:生成的javalext .cs无法编译

Question

我正在使用Antlr4cs-4.3.0与Visual Studio 2012， . net 4.5。我已经成功地生成并运行了一个由简单语法(calculator.g4)生成的解析器，因此我觉得我在Visual Studio中设置得很好。我现在正在尝试为Java生成一个解析器。g4语法，我从github.com/antlr/grammars-v4/java获得。生成的javalext .cs文件不会编译(见下面的代码和错误)——可能是因为它包含了只存在于java环境中的东西的引用。

如有任何建议，不胜感激。

罗伯特

private bool JavaLetterOrDigit_sempred(RuleContext _localctx, int predIndex) {
    switch (predIndex) {
        case 2: return Character.isJavaIdentifierPart(_input.LA(-1));
        case 3: return Character.isJavaIdentifierPart(Character.toCodePoint((char)_input.LA(-2),
                                                      (char)_input.LA(-1)));
    }
    return true;
}

错误:名称'Character'在当前上下文中不存在

错误:"Antlr4.Runtime。ICharStream'不包含'LA'的定义，也没有扩展方法'LA'接受类型为'Antlr4.Runtime '的第一个参数。

Answer 1

该语法包含Java代码。它只在以下规则中使用:

fragment
JavaLetter
    :   [a-zA-Z$_] // these are the "java letters" below 0xFF
    |   // covers all characters above 0xFF which are not a surrogate
        ~[u0000-u00FFuD800-uDBFF]
        {Character.isJavaIdentifierStart(_input.LA(-1))}?
    |   // covers UTF-16 surrogate pairs encodings for U+10000 to U+10FFFF
        [uD800-uDBFF] [uDC00-uDFFF]
        {Character.isJavaIdentifierStart(Character.toCodePoint((char)_input.LA(-2), (char)_input.LA(-1)))}?
    ;
fragment
JavaLetterOrDigit
    :   [a-zA-Z0-9$_] // these are the "java letters or digits" below 0xFF
    |   // covers all characters above 0xFF which are not a surrogate
        ~[u0000-u00FFuD800-uDBFF]
        {Character.isJavaIdentifierPart(_input.LA(-1))}?
    |   // covers UTF-16 surrogate pairs encodings for U+10000 to U+10FFFF
        [uD800-uDBFF] [uDC00-uDFFF]
        {Character.isJavaIdentifierPart(Character.toCodePoint((char)_input.LA(-2), (char)_input.LA(-1)))}?
    ;

移除{...}部分:

fragment
JavaLetter
    :   [a-zA-Z$_] // these are the "java letters" below 0xFF
    |   // covers all characters above 0xFF which are not a surrogate
        ~[u0000-u00FFuD800-uDBFF]
    |   // covers UTF-16 surrogate pairs encodings for U+10000 to U+10FFFF
        [uD800-uDBFF] [uDC00-uDFFF]
    ;
fragment
JavaLetterOrDigit
    :   [a-zA-Z0-9$_] // these are the "java letters or digits" below 0xFF
    |   // covers all characters above 0xFF which are not a surrogate
        ~[u0000-u00FFuD800-uDBFF]
    |   // covers UTF-16 surrogate pairs encodings for U+10000 to U+10FFFF
        [uD800-uDBFF] [uDC00-uDFFF]
    ;

和(可选地)在后面的阶段执行这些检查，或者用c#代码替换Java代码。

Answer 2

这是一个添加的静态类Character将使使用的Java代码也有效的C#代码。

public static class Character
{
    public static bool isJavaIdentifierPart(int c)
    {
        // some code here
    }
    public static int LA(this Antlr4.Runtime.ICharStream cs, int la)
    {
        return cs.La(la);
    }
    public static int toCodePoint(char c)
    {
         // some code here
    }
}