15.4.1367  src/lib/x-kit/widget/fancy/graphviz/text/load-file-g.pkg

# load-file-g.pkg

# Compiled by:
#     src/lib/x-kit/widget/xkit-widget.sublib

stipulate
    package vb =  view_buffer;                                  # view_buffer   is from   src/lib/x-kit/widget/fancy/graphviz/text/view-buffer.pkg
    package u  =  approximate_ml_lex::user_declarations;
herein

    generic package  load_file_g  (

        io: api {
                Input_Stream;
                open_for_read:   String -> Input_Stream;
                close_input:     Input_Stream -> Void;
                read_n:         (Input_Stream, Int) -> String;
            }

    ): Load_File {


        fun load_file (filename, range)
            =
            {   stream = io::open_for_read  filename;

                lexer = approximate_ml_lex::make_lexer
                            #
                            (fn n = io::read_n (stream, n));

                fun scan_file lines
                    =
                    scan_line ([], lines)
                    where

                        fun scan_line (toks, lines)
                            =
                             case (lexer())
                                 #
                                 u::EOF     =>            (reverse toks) ! lines;
                                 u::NL      => scan_file ((reverse toks) ! lines);
                                 u::TOK tok => scan_line (tok ! toks, lines);
                                 u::COM lst => scan_list (lst,  toks, lines);
                                 u::STR lst => scan_list (lst,  toks, lines);
                            esac

                        also
                        fun scan_list ([], toks, lines)
                                =>
                                scan_line (toks, lines);

                            scan_list (u::NL ! r, toks, lines)
                                =>
                                scan_list (r, [], (reverse toks) ! lines);

                            scan_list (u::TOK tok ! r, toks, lines)
                                =>
                                scan_list (r, tok ! toks, lines);

                            scan_list _
                                =>
                                raise exception FAIL "load_file";
                        end;
                    end;

                lines =  scan_file [];

                io::close_input  stream;

                case range
                    #
                    NULL =>
                        reverse lines;

                    THE { first, last }
                        =>
                        {   fun skip (0, lines)     =>  lines;
                                skip (i, [])        =>  [];
                                skip (i, _ ! lines) =>  skip (i - 1, lines);
                            end;

                            fun proj (0, _,     lines) =>  lines;
                                proj (_, [],    lines) =>  lines;
                                proj (i, l ! r, lines) =>  proj (i - 1, r, l ! lines);
                            end;

                            proj
                              ( (last-first)+1,
                                skip ((length lines)-last, lines),
                                []
                              );
                        };
                esac;
            }
            except _ = [];

    };                          # generic package load_file_g
end;