Can one set a specific character variant in xelatex for the word first letter only?

Question

I'd like to have some code to set, document wide, a specific character variant for the letter "v" only if it is the first in the word. The solution in the MWE is not a solution because I have a document of several hundreds of pages. Any suggestion? Thanks.

\documentclass[a4paper,14pt,openright,twoside]{memoir}
\usepackage[T1]{fontenc}
\usepackage[scale=1,osf,nf,lf]{ebgaramond}
\usepackage{fontspec}
\usepackage{microtype}
\usepackage{csquotes}
\usepackage{realscripts}

\begin{document}

Normal set:
{\fontshape{it}
    \addfontfeature{RawFeature=+hlig}
        \addfontfeature{CharacterVariant=5:2}
            \addfontfeature{RawFeature=+liga}
                \addfontfeature{RawFeature=+dlig}
                    \addfontfeature{RawFeature=+swsh}
                        \addfontfeature{Numbers=OldStyle}
                            \selectfont 

Ha visto un valvassore vivere come un valvassino invidioso che gridava evviva!}         

Nice to have:
{\fontshape{it}
    \addfontfeature{RawFeature=+hlig}
        \addfontfeature{CharacterVariant=5:1}
            \addfontfeature{RawFeature=+liga}
                \addfontfeature{RawFeature=+dlig}
                    \addfontfeature{RawFeature=+swsh}
                        \addfontfeature{Numbers=OldStyle}
                            \selectfont                 

Ha {\addfontfeature{CharacterVariant=5:2}v}isto un {\addfontfeature{CharacterVariant=5:2}v}alvassore {\addfontfeature{CharacterVariant=5:2}v}ivere come un {\addfontfeature{CharacterVariant=5:2}v}alvassino invidioso che gridava evviva!} 
\end{document}

Answer 1

You may use a character class:

\documentclass[a4paper,14pt,openright,twoside]{memoir}
\usepackage{fontspec}

\setmainfont{EB Garamond}[
  Numbers=Lining,
  ItalicFeatures={
    RawFeature=+hlig,
    RawFeature=+liga,
    RawFeature=+dlig,
    RawFeature=+swsh,
    Numbers=OldStyle,
  },
]
\newfontfamily\varv{EB Garamond}[
  Numbers=Lining,
  ItalicFeatures={
    RawFeature=+hlig,
    RawFeature=+liga,
    RawFeature=+dlig,
    RawFeature=+swsh,
    Numbers=OldStyle,
    CharacterVariant=5:2,
  },
]

\XeTeXinterchartokenstate=1
\newXeTeXintercharclass\vclass
\XeTeXcharclass`v=\vclass
\XeTeXinterchartoks 255 \vclass = {\openswashv}

\makeatletter
\newcommand\openswashv{%
  % by preceding the v with U+200C it's not at the boundary any more
  \ifnum\strcmp{\f@shape}{it}=\z@
    \begingroup\varv^^^^200cv\endgroup
    \nobreak\hspace{0pt}% allow hyphenation in the rest of the word
    \expandafter\@gobble
  \fi
}
\makeatother


\begin{document}

Normal font:
  Ha visto un valvassore vivere come un valvassino invidioso che gridava evviva!

Italic font: {\itshape
  Ha visto un valvassore vivere come un valvassino invidioso che gridava evviva!
}

\end{document}

This allows hyphenation on the rest of the word (but could give some wrong hyphenation point with languages different from Italian). I checked and EB Garamond doesn't define any kerning pair between v and another letter.

You should ask the font developer for a stylistic set.