\index produces invalid .idx entry (with manual style, \comma@parse, hyperref)

Question

(Note: This is somewhat related similar post, but the issue is quite different.)

I'm trying to make an index entry using \index that has a bolded page number, all while the hyperref package is loaded. Normally when hyperref sees a manually-inserted |textbf in an index entry it will do something clever like modify or remove the usual |hyperpage insertion. That's fine. No problem.

The trouble lies when I try to first parse argument of \index using the macro \comma@parse from the kvsetkeys package, as shown here:

%with hyperref is loaded, this produces a bad .idx entry
\comma@parse{But this fails on makeindex|textbf}{\index{\comma@entry}\@gobble}

The code above produces the following entry in the .idx file:

\indexentry{But this fails on makeindex|textbf|hyperpage}{1}

As you can see, there are two | symbols in the entry, causing the makeindex to reject it. hyperref should have caught this.

• If I disable hyperref, everything works fine.
• If I don't use the \comma@parse macro, everything works fine.
• The same thing happens if instead of |textbf I do |see etc.

It's as if using \comma@parse doesn't allow hyperref to do its job.

Is there a way I can get the .idx entry to be well-formed while keeping hyperref loaded?

Here's the MWE I'm using:

\documentclass[12pt]{book}

\usepackage{makeidx}\makeindex
\usepackage{lipsum}
\usepackage{kvsetkeys}
\usepackage{hyperref}

\begin{document}

\lipsum[1]

\index{1@This works fine|textbf}
\makeatletter
    \comma@parse{2@So does this}{\index{\comma@entry}\@gobble}
    \comma@parse{3@But this fails on makeindex|textbf}{\index{\comma@entry}\@gobble}
\makeatother

\printindex

\end{document}

And here's the .idx file that is created after typesetting:

\indexentry{This works fine|hyperindexformat{\textbf}}{1}
\indexentry{So does this|hyperpage}{1}
\indexentry{But this fails on makeindex|textbf|hyperpage}{1}

Answer 1

The | is hidden by macro \comma@entry. Therefore hyperref does not see it, when it appends |hyperpage for hyper-linked page numbers in the index. \expandafter helps:

\documentclass[12pt]{book}

\usepackage{makeidx}\makeindex
\usepackage{lipsum}
\usepackage{kvsetkeys}
\usepackage{hyperref}

\begin{document}

\lipsum[1]

\index{This works fine|textbf}%
\makeatletter
    \comma@parse{So does this}{\index{\comma@entry}\@gobble}%
    \comma@parse{This also works|textbf}{%
      \expandafter\index\expandafter{\comma@entry}\@gobble 
    }%
\makeatother

\printindex

\end{document}

Or much easier, \index is already used as command that takes an entry, thus it can be directly used as comma list processor:

\documentclass[12pt]{book}

\usepackage{makeidx}\makeindex
\usepackage{lipsum}
\usepackage{kvsetkeys}
\usepackage{hyperref}

\begin{document}

\lipsum[1]

\index{This works fine|textbf}%
\makeatletter
    \comma@parse{So does this}\index
    \comma@parse{This also works|textbf}\index
\makeatother

\printindex

\end{document}

Package splitidx

The trick of the previous example also works for commands with additional argument, if they precede the argument, which gets the list entry:

\comma@parse{my, comma, list}{\sindex[...]}

A macro \idxboldpage can be defined to get hyperlinked bold page numbers, as \sindex of package splitidx is not automatically supported by hyperref:

\newcommand*{\idxboldpage}[1]{%
  \textbf{\hyperpage{#1}}%
}

Then \index{...|idxboldpage} is used instead of \index{...|textbf}.

Full example:

\documentclass[12pt]{book}

\usepackage[makeindex]{splitidx}
\newindex[Author index]{authidx}
\newcommand*{\idxboldpage}[1]{%
  \textbf{\hyperpage{#1}}%
}

\usepackage{lipsum}
\usepackage{kvsetkeys}
\usepackage{hyperref}

\begin{document}

\lipsum[1]

\index{This works fine|textbf}%
\makeatletter
    \comma@parse{So does this}{\sindex[authidx]}
    \comma@parse{This also works|idxboldpage}{\sindex[authidx]}
\makeatother

\printindex[authidx]

\end{document}