1:- module(lsp_changes, [handle_doc_changes/2,
    2                        doc_text_fallback/2,
    3                        doc_text/2]).

   12:- use_module(library(readutil), [read_file_to_codes/3]).   13
   14:- dynamic doc_text/2.

 handle_doc_changes(+File:atom, +Changes:list) is det

Track Changes to the file File.

   19handle_doc_changes(_, []) :- !.
   20handle_doc_changes(Path, [Change|Changes]) :-
   21    handle_doc_change(Path, Change),
   22    handle_doc_changes(Path, Changes).
   23
   24handle_doc_change(Path, Change) :-
   25    _{range: _{start: _{line: StartLine, character: StartChar},
   26               end:   _{line: _EndLine0,   character: _EndChar}},
   27      rangeLength: ReplaceLen, text: Text} :< Change,
   28    !,
   29    atom_codes(Text, ChangeCodes),
   30    doc_text_fallback(Path, OrigCodes),
   31    replace_codes(OrigCodes, StartLine, StartChar, ReplaceLen, ChangeCodes,
   32                  NewText),
   33    retractall(doc_text(Path, _)),
   34    assertz(doc_text(Path, NewText)).
   35handle_doc_change(Path, Change) :-
   36    _{range: _{start: _{line: StartLine, character: StartChar},
   37               end:   _{line: EndLine,   character: EndChar}},
   38      text: Text} :< Change,
   39    !,
   40    atom_codes(Text, ChangeCodes),
   41    doc_text_fallback(Path, OrigCodes),
   42    replace_codes_range(OrigCodes, StartLine, StartChar, EndLine, EndChar, ChangeCodes,
   43                        NewText),
   44    retractall(doc_text(Path, _)),
   45    assertz(doc_text(Path, NewText)).
   46handle_doc_change(Path, Change) :-
   47    retractall(doc_text(Path, _)),
   48    atom_codes(Change.text, TextCodes),
   49    assertz(doc_text(Path, TextCodes)).

 doc_text_fallback(+Path:atom, -Text:text) is det

Get the contents of the file at Path, either with the edits we've been tracking in memory, or from the file on disc if no edits have occured.

   56doc_text_fallback(Path, Text) :-
   57    doc_text(Path, Text), !.
   58doc_text_fallback(Path, Text) :-
   59    read_file_to_codes(Path, Text, []),
   60    assertz(doc_text(Path, Text)).

 replace_codes_range(Text, StartLine, StartChar, EndLine, EndChar, ReplaceText, -NewText) is det

   63replace_codes_range(Text, StartLine, StartChar, EndLine, EndChar, ReplaceText, NewText) :-
   64    phrase(replace_range(start, 0, 0, StartLine, StartChar, EndLine, EndChar, ReplaceText),
   65           Text,
   66           NewText).
   67
   68replace_range(start, StartLine, StartChar, StartLine, StartChar, EndLine, EndChar, NewText), NewText -->
   69    !,
   70    replace_range(finish, StartLine, StartChar, StartLine, StartChar, EndLine, EndChar, NewText).
   71replace_range(finish, EndLine, EndChar, _, _, EndLine, EndChar, _) --> !, [].
   72replace_range(start, StartLine, 0, StartLine, StartChar, EndLine, EndChar, NewText), Take -->
   73    { length(Take, StartChar) },
   74    Take, !,
   75    replace_range(start, StartLine, StartChar, StartLine, StartChar, EndLine, EndChar, NewText).
   76replace_range(finish, EndLine, Char, StartLine, StartChar, EndLine, EndChar, NewText) -->
   77    !, { ToSkip is EndChar - Char },
   78    skip(ToSkip),
   79    replace_range(finish, EndLine, EndChar, StartLine, StartChar, EndLine, EndChar, NewText).
   80replace_range(start, Line0, _, StartLine, StartChar, EndLine, EndChar, NewText), Line -->
   81    line(Line),
   82    { succ(Line0, Line1) },
   83    replace_range(start, Line1, 0, StartLine, StartChar, EndLine, EndChar, NewText).
   84replace_range(finish, Line0, _, StartLine, StartChar, EndLine, EndChar, NewText) -->
   85    line(_),
   86    { succ(Line0, Line1) },
   87    replace_range(finish, Line1, 0, StartLine, StartChar, EndLine, EndChar, NewText).

 replace_codes(Text, StartLine, StartChar, ReplaceLen, ReplaceText, -NewText) is det

   90replace_codes(Text, StartLine, StartChar, ReplaceLen, ReplaceText, NewText) :-
   91    phrase(replace(StartLine, StartChar, ReplaceLen, ReplaceText),
   92           Text,
   93           NewText).
   94
   95replace(0, 0, 0, NewText), NewText --> !, [].
   96replace(0, 0, Skip, NewText) -->
   97    !, skip(Skip),
   98    replace(0, 0, 0, NewText).
   99replace(0, Chars, Skip, NewText), Take -->
  100    { length(Take, Chars) },
  101    Take, !,
  102    replace(0, 0, Skip, NewText).
  103replace(Lines1, Chars, Skip, NewText), Line -->
  104    line(Line), !,
  105    { succ(Lines0, Lines1) },
  106    replace(Lines0, Chars, Skip, NewText).
  107
  108skip(0) --> !, [].
  109skip(N) --> [_], { succ(N0, N) }, skip(N0).
  110
  111line([0'\n]) --> [0'\n], !.
  112line([C|Cs]) --> [C], line(Cs)