1:- module(onepointfour_basics_stringy_length,
    2          [
    3           stringy_length/2
    4          ,stringy_length/3
    5          ,stringy_length_type/3
    6          ,stringy_length_type/4
    7          ]).    8
    9:- use_module(library('onepointfour_basics/checks.pl')).   10
   11/*  MIT License Follows (https://opensource.org/licenses/MIT)
   12
   13    Copyright 2021 David Tonhofer <ronerycoder@gluino.name>
   14
   15    Permission is hereby granted, free of charge, to any person obtaining
   16    a copy of this software and associated documentation files
   17    (the "Software"), to deal in the Software without restriction,
   18    including without limitation the rights to use, copy, modify, merge,
   19    publish, distribute, sublicense, and/or sell copies of the Software,
   20    and to permit persons to whom the Software is furnished to do so,
   21    subject to the following conditions:
   22
   23    The above copyright notice and this permission notice shall be
   24    included in all copies or substantial portions of the Software.
   25
   26    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   27    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   28    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   29    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
   30    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
   31    TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   32    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   33*/

 stringy_length(+Stringy, ?Length)

Determine the length of Stringy, which may be an atom or a string.

This is not really needed a atom_length/2 and string_length/2 work for both strings and atoms, but it removes the specificity of calling atom_length/2 or string_length/2.

Length may be instantiated to a integer. In that case, the predicate verifies the length of Stringy against Length.

This predicates behaves softly, i.e. preferentially fails on bad input.

   48stringy_length(Stringy,Length) :-
   49   stringy_length_type(Stringy,Length,_,soft).

 stringy_length(+Stringy, ?Length, @Tuned)

As stringy_length/2, but setting Tuned to hard will make the predicate throw if Length is bound but negative.

   56stringy_length(Stringy,Length,Tuned) :-
   57   stringy_length_type(Stringy,Length,_,Tuned).

 stringy_length_type(+Stringy, ?Length, ?Type)

As stringy_length/2, but additionally takes the Type of the stringy, which is unified with one of atom or string.

   64stringy_length_type(Stringy,Length,Type) :-
   65   stringy_length_type(Stringy,Length,Type,soft).

 stringy_length_type(+Stringy, ?Length, ?Type, @Tuned)

As stringy_length_type/3, but setting Tuned to hard will make the predicate throw if Type is bound but not one of string, atom (and also if Length is bound but negative).

   73stringy_length_type(Stringy,Length,Type,Tuned) :-
   74   check_that(Stringy,[hard(nonvar),hard(stringy)]),
   75   check_that(Length,[break(var),hard(integer),tuned(pos0int)],Tuned),
   76   check_that(Type,[break(var),tuned(stringy_typeid)],Tuned),
   77   stringy_length_decide(Stringy,Length,Type).
   78
   79stringy_length_decide(Stringy,Length,atom)   :- atom(Stringy),!,atom_length(Stringy,Length).
   80stringy_length_decide(Stringy,Length,string) :- string(Stringy),!,string_length(Stringy,Length)