Cup 和 Jflex 中的 JSON 验证语法答案

【问题标题】：JSON Validation Grammar in Cup and JflexCup 和 Jflex 中的 JSON 验证语法
【发布时间】：2017-11-08 00:05:11
【问题描述】：

我为数组编写了以下cup文件：

    terminal COMMA, LSQBRACKET, RSQBRACKET;
    terminal Integer NUMBER;
    non terminal array, value_list, value;
    non terminal Integer expr;
    array ::= LSQBRACKET value_list RSQBRACKET;
    value_list ::= value_list COMMA value | value;
    value::= expr:e {: System.out.println(" value: "+e+""); :} ;
    expr ::= NUMBER:n
    {: RESULT=n; :}

Jflex和Cup的Json验证的整个语法如何写？

【问题讨论】：

标签： json grammar jflex cup

【解决方案1】：

来自simple-json library

package org.json.simple.parser;

%%

%{
private StringBuffer sb=new StringBuffer();

int getPosition(){
    return yychar;
}

%}

%table
%unicode
%state STRING_BEGIN

%yylexthrow ParseException
%char

HEX_D = [a-fA-F0-9]
INT = [-]?[0-9]+
DOUBLE = {INT}((\.[0-9]+)?([eE][-+]?[0-9]+)?)
WS = [ \t\r\n]
UNESCAPED_CH = [^\"\\]
FALLBACK_CH = .
%%

<STRING_BEGIN> \"               { yybegin(YYINITIAL);return new Yytoken(Yytoken.TYPE_VALUE, sb.toString());}
<STRING_BEGIN> {UNESCAPED_CH}+  { sb.append(yytext());}
<STRING_BEGIN> \\\"             {sb.append('"');}
<STRING_BEGIN> \\\\             {sb.append('\\');}
<STRING_BEGIN> \\\/             {sb.append('/');}
<STRING_BEGIN> \\b              {sb.append('\b');}
<STRING_BEGIN> \\f              {sb.append('\f');}
<STRING_BEGIN> \\n              {sb.append('\n');}
<STRING_BEGIN> \\r              {sb.append('\r');}
<STRING_BEGIN> \\t              {sb.append('\t');}
<STRING_BEGIN> \\u{HEX_D}{HEX_D}{HEX_D}{HEX_D}  {   try{
                                                        int ch=Integer.parseInt(yytext().substring(2),16);
                                                        sb.append((char)ch);
                                                    }
                                                    catch(Exception e){
                                                        throw new ParseException(yychar, ParseException.ERROR_UNEXPECTED_EXCEPTION, e);
                                                    }
                                                }
<STRING_BEGIN> \\               {sb.append('\\');}

<YYINITIAL> \"                  { sb = null; sb = new StringBuffer(); yybegin(STRING_BEGIN);}
<YYINITIAL> {INT}               { Long val=Long.valueOf(yytext()); return new Yytoken(Yytoken.TYPE_VALUE, val);}
<YYINITIAL> {DOUBLE}            { Double val=Double.valueOf(yytext()); return new Yytoken(Yytoken.TYPE_VALUE, val);}
<YYINITIAL> "true"|"false"      { Boolean val=Boolean.valueOf(yytext()); return new Yytoken(Yytoken.TYPE_VALUE, val);}
<YYINITIAL> "null"              { return new Yytoken(Yytoken.TYPE_VALUE, null);}
<YYINITIAL> "{"                 { return new Yytoken(Yytoken.TYPE_LEFT_BRACE,null);}
<YYINITIAL> "}"                 { return new Yytoken(Yytoken.TYPE_RIGHT_BRACE,null);}
<YYINITIAL> "["                 { return new Yytoken(Yytoken.TYPE_LEFT_SQUARE,null);}
<YYINITIAL> "]"                 { return new Yytoken(Yytoken.TYPE_RIGHT_SQUARE,null);}
<YYINITIAL> ","                 { return new Yytoken(Yytoken.TYPE_COMMA,null);}
<YYINITIAL> ":"                 { return new Yytoken(Yytoken.TYPE_COLON,null);}
<YYINITIAL> {WS}+               {}
<YYINITIAL> {FALLBACK_CH}       { throw new ParseException(yychar, ParseException.ERROR_UNEXPECTED_CHAR, new Character(yycharat(0)));}

【讨论】：