Re: [Boost-users] calc2_ast.cpp

Subject: Re: [Boost-users] calc2_ast.cpp
From: Olivier Austina (olivier.austina_at_[hidden])
Date: 2013-10-03 08:28:11

Thank you Larry.

Regards
Olivier

2013/10/2 Larry Evans <cppljevans_at_[hidden]>

> On 10/02/13 12:13, Olivier Austina wrote:
>
>> Hi,
>> this is a basic question (I am sorry).
>> I am try to undestand the  calc2_ast.cpp example at
>> http://www.boost.org/doc/libs/**1_41_0/libs/spirit/example/qi/**
>> calc2_ast.cpp<http://www.boost.org/doc/libs/1_41_0/libs/spirit/example/qi/calc2_ast.cpp>
>> I think the instruction expression_ast() : expr(nil()){} is an
>> inheritance.
>>
> expr is a member variable of expression_ast.
>
>> Where can I find the definition of expr()?
>>
> See below.
>
>> This is the code
>> struct expression_ast
>>      {
>>          typedef
>>              boost::variant<
>>                  nil // can't happen!
>>                , unsigned int
>>                , boost::recursive_wrapper<**expression_ast>
>>                , boost::recursive_wrapper<**binary_op>
>>                , boost::recursive_wrapper<**unary_op>
>>              >
>>          type;
>>
>> *expression_ast() : expr(nil()){};*
>>
>>          template <typename Expr>
>>          expression_ast(Expr const& expr)
>>            : expr(expr) {}
>>
>>          expression_ast& operator+=(expression_ast const& rhs);
>>          expression_ast& operator-=(expression_ast const& rhs);
>>          expression_ast& operator*=(expression_ast const& rhs);
>>          expression_ast& operator/=(expression_ast const& rhs);
>>
>>          type expr;
>>
> Here's the definition of expr.
>
>>      };
>>
>>      //expression_ast bbb;
>>      struct binary_op
>>      {
>>          binary_op(
>>              char op
>>            , expression_ast const& left
>>            , expression_ast const& right)
>>          : op(op), left(left), right(right) {}
>>
>>          char op;
>>          expression_ast left;
>>          expression_ast right;
>>      };
>>
>>
>> Thank you.
>>
>>
>>
>> Regards
>> Olivier
>>
>>
>>
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>

>>
>>
>
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