rangestr.sa


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------------------------->  GNU Sather - sourcefile  <-------------------------
-- Copyright (C) 2000 by K Hopper, University of Waikato, New Zealand        --
-- This file is part of the GNU Sather library. It is free software; you may --
-- redistribute  and/or modify it under the terms of the GNU Library General --
-- Public  License (LGPL)  as published  by the  Free  Software  Foundation; --
-- either version 2 of the license, or (at your option) any later version.   --
-- This  library  is distributed  in the  hope that it will  be  useful, but --
-- WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See Doc/LGPL for more details.       --
-- The license text is also available from:  Free Software Foundation, Inc., --
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partial class RANGE_STR{T} < $TEXT, $ANCHORED_FMT

partial class RANGE_STR{T} < $TEXT, $ANCHORED_FMT is -- This partial class implements formatting services for range classes. -- Version 1.0 Oct 98. Copyright K Hopper, U of Waikato -- Development History -- ------------------- -- Date Who By Detail -- ---- ------ ------ -- 2 Oct 98 kh Original from RAT_STR class private ellipsis( ch : CHAR, lib : LIBCHARS ) : BOOL pre ~void(lib) post result = (ch = lib.Fullstop.char) is -- This private routine returns true if ch is a full-stop (for an -- ellipsis), otherwise false. return ch = lib.Fullstop.char end ; private scan( cursor : STR_CURSOR ) : SAME pre ~void(cursor) post (result.is_empty and (initial(cursor.index) = cursor.index)) or (initial(cursor.index) < cursor.index) is -- This routine is the real number 'scanner' to obtain the real number -- value expected to be next in the indicated string - or returning with -- the string unchanged, returning void if there is a format error. start_index : CARD := cursor.index ; loc_lib : LIBCHARS := cursor.buffer.index_lib ; loc_low : T := T::build(cursor) ; if cursor.index = start_index then return empty else loc_start : CARD := cursor.index ; cursor.skip_space ; if ~ellipsis(cursor.item,loc_lib) then -- not a range! cursor.set_index(start_index) ; return empty else dummy : STR := cursor.get_upto(bind(ellipsis(_,loc_lib))) end end ; cursor.skip_space ; loc_start := cursor.index ; loc_high : T := T::build(cursor) + T::one ; if cursor.index = loc_start then cursor.set_index(start_index) ; return empty else return low(loc_low).high(loc_high) end end ; is_range( str : STR_CURSOR ) : CONVERSION_RESULTS pre true post (result = CONVERSION_RESULTS::All_Right) or (result = CONVERSION_RESULTS::Out_of_Range) or (result = CONVERSION_RESULTS::Bad_Format) or (result = CONVERSION_RESULTS::Empty) is -- This routine checks that the format of of the leading characters of -- the given string using the given repertoire and encoding corresponds to -- that required for a rational number, returning the relevant result state. if str.remaining = 0 then return CONVERSION_RESULTS::Empty end ; start_index : CARD := 0 ; loc_cursor : STR_CURSOR := str ; loc_res : SAME := scan(loc_cursor) ; if loc_cursor.index = start_index then return CONVERSION_RESULTS::Bad_Format else loc_cursor.set_index(start_index) ; return CONVERSION_RESULTS::All_Right end end ; build( loc_cursor : STR_CURSOR ) : SAME pre ~void(loc_cursor) post (result.is_empty and (initial(loc_cursor.index) = loc_cursor.index)) or (initial(loc_cursor.index) < loc_cursor.index) is -- This routine creates the real number corresponding to the textual -- representation contained in str which must have a digit both before and -- after a mandatory decimal mark! If the string indicated does not -- contain a real number as the next non-blank item in the string then zero is -- returned or if out of range then quiet_NaN is returned -- and the cursor -- has not been moved! return scan(loc_cursor) end ; create( str : STR ) : SAME pre (is_range(str.cursor) = CONVERSION_RESULTS::All_Right) post true is -- This routine creates the real number corresponding to the textual -- representation contained in str. return build(str.cursor) end ; str( lib : LIBCHARS ) : STR pre ~void(lib) post ~void(result) is -- This routine returns a string representation of self as a vulgar -- fraction (unless the value is integral) using the given repertoire and -- encoding. if is_empty then return STR::create + lib.Left_Bracket.char + lib.Right_Bracket.char else return STR::create + lib.Left_Bracket.char + low.str(lib) + lib.Fullstop.char + lib.Fullstop.char + lib.Fullstop.char + (high - T::one).str(lib) + lib.Right_Bracket.char end end ; str : STR is -- This routine returns a string representation of self as a vulgar -- fraction using the default repertoire and encoding. return str(LIBCHARS::default) end ; fmt( format : ANCHORED_DESCR, lib : LIBCHARS ) : STR pre ~void(format) and ~void(lib) post ~void(result) is -- This routine returns the formatted string representation of self in -- accordance with the string format. This provides special case treatment -- where the leading component is exactly one - it reduces the value string -- to the single leading character - which is therefore expected to differ -- for the two values!. res : STR := str(lib) ; loc_fill : STR := STR::create(lib) + format.filler.char ; if format.leading = 1 then res := res.head(1) elsif res.size < format.leading then -- needs a filler res := loc_fill.repeat(format.leading - res.size) + res end ; return res + loc_fill.repeat(format.trailing) end ; fmt( format : ANCHORED_DESCR ) : STR pre ~void(format) post ~void(result) is -- This routine returns the formatted string representation of self in -- accordance with the string format. return fmt(format,LIBCHARS::default) end ; end ; -- RANGE_STR{T}