Re: [Boost-users] [boost::spirit] Help! Unexpected Leading spaces got injected into a parse tree node

Subject: Re: [Boost-users] [boost::spirit] Help! Unexpected Leading spaces got injected into a parse tree node
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-10-18 14:53:11

AMDG

HT4N - wrote:
> I have a question regarding unexpected leading spaces got injected into a parse tree node.
>  
> Here is my grammar:
>  
> Text = leaf_node_d[+digit_p] >> root_node_d[ch_p('=')] >> leaf_node_d[+digit_p];
>  
> If I parse "5=5", as expected no extra leading spaces added to the resulting tree nodes.
>  
> If I parse "5=     5" (read:5 followed by = followed by 4 spaces and followed by 5), given my grammar definition of leaf_node_d[+digit_p], I am expecting the parse tree node value should not contain any leading spaces.
> Yet, I see that the extra 4 spaces is stored in the corresponding parse tree node as shown below. 
>  
> <snip>
> ==>       <value>     5</value>
>
> I am wondering if this is a by design or unexpected behavior. If it is a by design behavior, is there a way to trim leading/trailing spaces.
>   

Perhaps you should use lexeme_d[leaf_node_d[+digit_p]]?

In Christ,
Steven Watanabe