如何通过 biber sourcemapping 包装“sortname”字段？

Question

此问题与另一个问题。

在我的自定义条目类型中，我使用了两个备用字段：（author人名）和usera（机构名称）。

在任何预先存在的排序模板（例如 nty、anyvt 等）中，都usera必须将该字段视为author/editor字段进行处理。

因此，在没有/不想创建自定义排序模板的情况下，我想到sortname通过源映射使用该字段。

% !TEX encoding = UTF-8 Unicode
% !TEX program = lualatex
% !BIB program = biber

\begin{filecontents}{\jobname.bib}
@customa{a,
  author = {Smith, John},
  title  = {Title},
  date   = {2000},
}
@customa{b,
  usera = {M M},
  title  = {Title},
  date   = {3000},
}
@customa{c,
  usera = {A Z},
  title  = {Title},
  date   = {1000},
}
@customa{d,
  author = {Doe, Jane},
  title  = {Title},
  date   = {4000},
}
\end{filecontents}

\documentclass{article}
\usepackage[style=authortitle]{biblatex}
  \addbibresource{\jobname.bib}

\DeclareSourcemap{
  \maps{
    \map{
      \pertype{customa}
      \step[fieldsource=usera, match=\regexp{\A(.*)\Z}, final]
      \step[fieldset=sortname, fieldvalue={\{$1\}}]
    }
  }
}

\DeclareBibliographyDriver{customa}{%
  \usebibmacro{bibindex}%
  \usebibmacro{begentry}%
  \printfield{usera}%
  \printnames{author}%
  \newunit\newblock
  \usebibmacro{title}%
  \newunit\newblock
  \printdate%
  \usebibmacro{finentry}}

\begin{document}
\nocite{*}
\printbibliography
\end{document}

源映射代码应等同于以下.bib 文件：

@customa{a,
  author = {Smith, John},
  title  = {Title},
  date   = {2000},
}
@customa{b,
  usera = {M M},
  title  = {Title},
  date   = {3000},
  sortname = {{M M}},
}
@customa{c,
  usera = {A Z},
  title  = {Title},
  date   = {1000},
  sortname = {{A Z}},
}
@customa{d,
  author = {Doe, Jane},
  title  = {Title},
  date   = {4000},
}

但排序并不像预期的那样。

Answer 1

以保留花括号的方式将其转义以进行源映射操作可能会有点麻烦。我发现下面的操作按预期工作。

\documentclass{article}
\usepackage[style=authortitle]{biblatex}

\DeclareSourcemap{
  \maps{
    \map{
      \pertype{customa}
      \step[fieldsource=usera, match=\regexp{\A(.*)\Z}, final]
      \step[fieldset=sortname, fieldvalue=\regexp{{$1}}]
    }
  }
}

\DeclareBibliographyDriver{customa}{%
  \usebibmacro{bibindex}%
  \usebibmacro{begentry}%
  \printfield{usera}%
  \printnames{author}%
  \newunit\newblock
  \usebibmacro{title}%
  \newunit\newblock
  \printdate%
  \usebibmacro{finentry}}

\begin{filecontents}{\jobname.bib}
@customa{a,
  author = {Smith, John},
  title  = {Title},
  date   = {2000},
}
@customa{b,
  usera = {M M},
  title  = {Title},
  date   = {3000},
}
@customa{c,
  usera = {A Z},
  title  = {Title},
  date   = {1000},
}
@customa{d,
  author = {Doe, Jane},
  title  = {Title},
  date   = {4000},
}
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
\nocite{*}
\printbibliography
\end{document}