在 yacc 中将多种数据类型分配给非终端

发布于 2024-10-15 21:37:17 字数 1110 浏览 6 评论 0原文

我正在开发一个班级项目，我们必须在其中构建一个解析器。我们目前正处于在 yacc 中构建解析器的阶段。目前让我困惑的是我读到您需要为每个非终结符分配一个类型。但在某些情况下，我会遇到这样的问题：

...
%union {
    Type dataType;
    int integerConstant;
    bool boolConstant;
    char *stringConstant;
    double doubleConstant;
    char identifier[MaxIdentLen+1]; // +1 for terminating null
    Decl *decl;
    List<Decl*> *declList;
}

%token   <identifier> T_Identifier
%token   <stringConstant> T_StringConstant 
%token   <integerConstant> T_IntConstant
%token   <doubleConstant> T_DoubleConstant
%token   <boolConstant> T_BoolConstant

...

%%
...
Expr                :    /* some rules */
                    |    Constant { /* Need to figure out what to do here */ }
                    |    /* some more rules */
                    ;

Constant            :    T_IntConstant { $$=$1 }
                    |    T_DoubleConstant { $$=$1 }
                    |    T_BoolConstant { $$=$1 }
                    |    T_StringConstant { $$=$1 }
                    |    T_Null { $$=$1 }
...

你如何为 expr 分配一个类型，因为它有时不能是整数、双精度数或布尔值等？

原文

I'm working on a project for class in which we have to build a parser. We're currently in the stage of building the parser in yacc. The thing currently confusing me is I've read that you need to assign a type to each nonterminal. In some cases though I'll have Something like:

...
%union {
    Type dataType;
    int integerConstant;
    bool boolConstant;
    char *stringConstant;
    double doubleConstant;
    char identifier[MaxIdentLen+1]; // +1 for terminating null
    Decl *decl;
    List<Decl*> *declList;
}

%token   <identifier> T_Identifier
%token   <stringConstant> T_StringConstant 
%token   <integerConstant> T_IntConstant
%token   <doubleConstant> T_DoubleConstant
%token   <boolConstant> T_BoolConstant

...

%%
...
Expr                :    /* some rules */
                    |    Constant { /* Need to figure out what to do here */ }
                    |    /* some more rules */
                    ;

Constant            :    T_IntConstant { $=$1 }
                    |    T_DoubleConstant { $=$1 }
                    |    T_BoolConstant { $=$1 }
                    |    T_StringConstant { $=$1 }
                    |    T_Null { $=$1 }
...

How can you assing a type to expr since can't it sometimes be an integer or double, or bool, etc?

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薄暮涼年 2024-10-22 21:37:17

在规则中添加类型

TypesConstant            :    T_IntConstant    { lt;integerConstant>$=$1 }
                         |    T_DoubleConstant { lt;doubleConstant>$=$1 }
                         |    ...

您可以通过查看 https://www.gnu.org/software/bison/manual/html_node/Action-Types.html#Action-Types 了解更多详细信息。

You can add the type in the rule by

TypesConstant            :    T_IntConstant    { lt;integerConstant>$=$1 }
                         |    T_DoubleConstant { lt;doubleConstant>$=$1 }
                         |    ...

See https://www.gnu.org/software/bison/manual/html_node/Action-Types.html#Action-Types for more details.

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