To make use of dynamic attributes they have to be set up in corpus config file .

DYNAMIC feature requires to be set to a of some internal function or to a name of function from external shared library.

DYNLIB has to be set to "internal" or to the name of shared library accordingly.

Internal functions

- striplastn        (str,n) - returns str striped from last n characters
- lowercase   (str, locale) - returns str in lowercase
- getfirstn        (str, n) - returns first n characters of str
- getnchar         (str, n) - returns n-th character of str
- getnextchars (str,attr,n) - returns n characters after attr(character)
- getnextchar   (str, attr) - returns the character after attr(character)

ATTRIBUTE   lemma {
          DYNAMIC    striplastn
          DYNLIB     internal
          ARG1       "2"
          FUNTYPE    i
          FROMATTR   lempos
          TYPE       index
}
ATTRIBUTE   lc {
          DYNAMIC    lowercase
          DYNLIB     internal
          ARG1       "C"
          FUNTYPE    s
          FROMATTR   word
          TYPE       index
          TRANSQUERY yes
}
ATTRIBUTE   tag {
         DYNAMIC     getfirstn
         DYNLIB      internal
         ARG1        "3"
         FUNTYPE     i
         FROMATTR    ambtag
         TYPE        index
}
ATTRIBUTE   k {
         DYNAMIC     getnchar
         DYNLIB      internal
         ARG1        1
         FUNTYPE     i
         FROMATTR    tag
         TYPE        index
}
ATTRIBUTE   g {
         DYNAMIC     getnextchar
         DYNLIB      internal
         ARG1        "g"
         FUNTYPE     c
         FROMATTR    tag
         TYPE        index
}
ATTRIBUTE   g3 {
         DYNAMIC     getnextchar
         DYNLIB      internal
         ARG1        "g"
         ARG2        3
         FUNTYPE     ci
         FROMATTR    tag
         TYPE        index
}

Shared library

Following example function takes the year of publishing of the document and determins the epoch from which the document comes.

• the source code (epoch.c):

  #include <stdio.h>
  
  const char * epoch (char* year)
  {
         int y;
         sscanf(year, "%d",&y);
         if(y<1990) return ("before 1990");
         if(y<2001) return ("1990-2000");
         if(y<2005) return ("2001-2004");
         if(y<2009) return ("2005-2008");
         return ("2009 and later");
  }
  

• to compile the library use:

  gcc -shared -o epoch.so epoch.c
  

• the important part from the corpus configuration file:

  STRUCTURE doc {
      ATTRIBUTE year
      ATTRIBUTE time {
           DYNAMIC         epoch
           DYNLIB          "/corpora/vert/greek/epoch.so"
           FUNTYPE         0
           FROMATTR        year
           TYPE            index
           TRANSQUERY      yes
           }
  }
  

The dynamic attribute will not be created when compiling the corpus using encodevert, it is necessary to create it additionaly using mkdynattr:

mkdynattr <corpus> <dynattr>
mkdynattr gkwac0.5 doc.time