Translate content in fields in bibliography entries (biblatex)

Question

I have in the @thesis entries in my .bib file the names of institutions and types written in the local language of the thesis. I need to translate these to English. As an example, I need to translate institution names like

Universitetet i Oslo

Universitetet i Bergen

Høgskolen i Agder

to

University of Oslo

University of Bergen

Agder University College

and translate type names like

Hovedoppgave

Hovedfagsavhandling

Masteroppgave

to

Main subject thesis

Main subject thesis

MA thesis

Based on similar conversions I've done (Change US postal codes (CA) to AP stylebook abbreviations (Calif.) in bibliography (biblatex)), I have a vague idea what to do, but I don't know how to accurately implement it:

\DeclareSourcemap{
  \maps[datatype = bibtex]{
    \map{
      \step[fieldsource = institution,
          match = , % <- strings like "Universitetet i Oslo", "Universitetet i Bergen"
          replace = ] % <- strings like "University of Oslo", "University of Bergen"
    }
    \map{
      \step[fieldsource = type,
          match = , % <- strings like "Hovedoppgave", "Masteroppgave"
          replace = ] % <- strings like "Main subject thesis", "MA thesis"
    }
  }
}

---

EDIT

There seems to be a problem doing this when the string I need to replace contains non-ascii characters like æøå:

\documentclass{article}
\usepackage[style = authoryear-comp]{biblatex}
\usepackage{fontspec,filecontents}
\begin{filecontents}{\jobname.bib}
@THESIS{aasen2004,
    AUTHOR = "Anita Aasen",
    INSTITUTION = "Universitetet i Oslo",
    TITLE = "Språklig nivellering i Oslo-regionen",
    TYPE = "Hovedfagsoppgave i nordisk språk og litteratur",
    YEAR = "2004",
    SUBTITLE = "Ungdommers valg av språklige varianter i Follo"}
\end{filecontents}
\DeclareSourcemap{
  \maps[datatype = bibtex]{
    \map{
       \step[fieldsource = type,
          match = {Hovedfagsoppgave i nordisk språk og litteratur}, 
          replace = {Main subject thesis}]
    }
  }
}
\addbibresource{\jobname.bib}
\begin{document}
\nocite{*}
\printbibliography
\end{document}

Answer 1

Here is a solution using \regexps

\DeclareSourcemap{
  \maps[datatype = bibtex]{
    \map{
      \step[fieldsource = institution,
          match = \regexp{Universitetet(\s)i},           
          replace = \regexp{University$1of}]
      \step[fieldsource = institution,
        match = \regexp{Høgskolen(\s)i(\s)(.*)},
        replace = \regexp{$3$1University$2College}
      ]
      }
    \map{
      \step[fieldsource = type,
          match = {Hovedoppgave}, 
          replace = {Main subject thesis} ]
      \step[fieldsource = type,
          match = {Hovedfagsavhandling}
          replace = {Main subject thesis}]
      \step[fieldsource = type,
          match = {Masteroppgave},
          replace = {MA Thesis}]
    }
  }
}

Answer 2

I would not use regex for this. Isn't it easier to define commands for the local strings and put them in different tex-files?For example:

swedish.tex:

\newcommand*{\strhogskolen}{Høgskolen i Agder}

english.tex:

\newcommand*{\strhogskolen}{Agder University College}

In your main-texfile then you just have to include the local file via \input{swedish} and use it in the biblatex-file like:

@book{somebook,
author={an author},
title={title},
location={\strhogskolen}
}