我不明白为什么这个乳胶代码不能按预期工作：
\documentclass{article}
\usepackage{xstring}
\newcommand{\doparamG}[2]{%
\StrCut{#2}{"}\LeftString\RightString%
\doparam{#1}{\LeftString}%
\StrCut{\RightString}{"}\RLeftString\RRightString%
\StrLen{\RLeftString}[\rlstrLen]%
\StrLen{\RRightString}[\rrstrLen]%
\ifnum\rlstrLen > 0 M:#1{\RLeftString}\fi%
\ifnum\rrstrLen > 0 \doparamG{#1}{\RRightString}\fi%
}
\newcommand{\doparam}[2]{%
\StrCut{#2}{ }\LeftString\RightString%
\StrLen{\LeftString}[\lstrLen]%
\StrLen{\RightString}[\rstrLen]%
\ifnum\lstrLen > 0 #1{\LeftString}\fi%
\ifnum\rstrLen > 0 \doparam{#1}{\RightString}\fi%
}
\newcommand{\doparamGDEBUG}[2]{%
\StrCut{#2}{"}\LeftString\RightString%
Left:\LeftString\\%
\StrCut{\RightString}{"}\RLeftString\RRightString%
\StrLen{\RLeftString}[\rlstrLen]%
\StrLen{\RRightString}[\rrstrLen]%
Middle:\RLeftString ,len: \rlstrLen\\%\ifnum\rlstrLen > 0 #1{\RLeftString}\fi%
Right:\RRightString ,len: \rrstrLen\\%\ifnum\rrstrLen > 0 \doparamGDBG{#1}{\RRightString}\fi%
\ifnum\rrstrLen > 0 \doparamGDEBUG{#1}{\RRightString}\fi%
}
\newcommand{\justnewline}[1]{#1\\}
\begin{document}
Simple test:\\
\doparam{\justnewline}{ line1 line2 line3 }
\doparamG{\justnewline}{ "line 4" line5 "line 6" }
But we have:\\
\doparamGDEBUG{\justnewline}{ "line 4" line5 "line 6" }
\end{document}
答案1
替代方案expl3和一些黑客技术。
\documentclass{scrartcl}
\usepackage{etoolbox}
\usepackage{xparse}
\newcommand\justpar[1]{#1\par}
\ExplSyntaxOn
\NewDocumentCommand \doparam { O{\justpar} m }
{
\abdollah_doparam:Nn #1 { #2 }
}
\cs_new_protected:Npn \abdollah_doparam:Nn #1 #2
{
\tl_set:Nn \l_tmpa_tl { #2 }
\tl_replace_all:Nnn \l_tmpa_tl { " } { \abdollah_doparam_quote:w }
\tl_set:Nx \l_tmpa_tl { \l_tmpa_tl }
\seq_set_split:NnV \l_tmpa_seq { ~ } \l_tmpa_tl
\seq_map_inline:Nn \l_tmpa_seq { \tl_if_empty:nF {##1} { #1 {##1} } }
}
\cs_new:Npn \abdollah_doparam_quote:w #1 \abdollah_doparam_quote:w { { #1 } }
\ExplSyntaxOff
\begin{document}
\doparam{ line1 line2 line3 "line 4" line5 "line 6" }
\end{document}