boolstr.sa


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-- Copyright (C) 2000 by K Hopper, University of Waikato, New Zealand        --
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partial class BOOL_STR < $TEXT, $ANCHORED_FMT

partial class BOOL_STR < $TEXT, $ANCHORED_FMT is -- This partial class provides for the conversion of logical quantities -- to/from text strings. -- Version 1.0 Sep 98. Copyright K Hopper, U of Waikato -- Development History -- ------------------- -- Date Who By Detail -- ---- ------ ------ -- 28 Sep 98 kh Original from BOOL class private shared Names : ARRAY{STR} ; -- for external representation! private const Msg_Cnt : CARD := 2 ; private shared lib : LIBCHARS ; -- The index value corresponding to self.card when self is true shall be -- the element of this array which contains a text representation of true, -- the other element shall contain a text representation of false. private check_names( loc_lib : LIBCHARS) pre ~void(loc_lib) post (lib = loc_lib) and (Names.asize = Msg_Cnt) is -- This auxiliary routine attempts to set the value of the Names array -- if void or of a different culture to the required one. If this action -- is not successful then an exception is raised. if void(Names) or (lib /= loc_lib) then lib := loc_lib ; Names := lib.culture.resources.read(SYS::rune_name(self),Msg_Cnt) end end ; private equals( first, second : STR ) : BOOL pre ~void(first) and ~void(second) post true is -- This predicate tests for string equality up to the length of -- first! The test is case independent. one : STR := first.lower ; two : STR := second.lower ; loop if ~(one.elt! = two.elt!) then return false; end; end ; return true end ; private lookup( str : STR ) : SAME pre ~void(str) post true is -- This function returns the truth value specified in text -- string form in str. Matching the string in the table is done -- independently of case until the str is found to be unambiguous. if equals(str,Names[0]) then return false elsif equals(str,Names[1]) then return true else -- Not a boolean string! SYS_ERROR::create.error(self,SYS_EXCEPT::Bad_Value,str) ; return void -- to keep compiler happy! end end ; is_bool( str : STR ) : CONVERSION_RESULTS pre true post (result = CONVERSION_RESULTS::All_Right) or (result = CONVERSION_RESULTS::Out_of_Range) or (result = CONVERSION_RESULTS::Empty) is -- This routine checks that the format of of the leading characters of -- the given string in the given repertoire and encoding corresponds to that -- required for a real number, returning the relevant result state. if str.size = 0 then return CONVERSION_RESULTS::Empty end ; check_names(str.index_lib) ; protect dummy : BOOL := lookup(str) ; return CONVERSION_RESULTS::All_Right when STR then return CONVERSION_RESULTS::Out_of_Range when SAME then return CONVERSION_RESULTS::Out_of_Range end end ; build( loc_cursor : STR_CURSOR ) : SAME pre ~void(loc_cursor) and ~loc_cursor.is_done post (void(result) and (initial(loc_cursor.index) = loc_cursor.index)) or (initial(loc_cursor.index) < loc_cursor.index) is -- This routine creates the truth value corresponding to the textual -- representation contained in the string indicated or the cursor has not -- been moved! start_index : CARD := loc_cursor.index ; loc_lib : LIBCHARS := loc_cursor.buffer.index_lib ; loc_cursor.skip_space ; -- skip padding me : SAME ; loc_str : STR := STR::create(loc_lib) + loc_cursor.get_item ; -- in non-alphabetic scripts at least one character must be tested! loc_str := loc_str + loc_cursor.get_pred(bind(_.is_alpha(loc_str.index_lib))) ; -- more up to a non-letter item! if is_bool(loc_str) = CONVERSION_RESULTS::All_Right then return lookup(loc_str) else -- back to original position! loc_cursor.set_index(start_index) ; return void end end ; create( str : STR ) : SAME is -- This is the creation routine from a string which is any of the -- abbreviations listed in the Name table. If the name table has not been -- read in this is done first. return build(str.cursor) end ; str( lib : LIBCHARS ) : STR pre ~void(lib) post (result = Names[card]) is -- This routine provides a string representation of self in the default -- character repertoire and encoding. check_names(lib) ; return Names[card] end ; str : STR pre true -- post (result = Names[card]) is -- This routine provides a string representation of self in the default -- character repertoire and encoding. if self then return "true"; else return "false"; end; --return str(LIBCHARS::default) end ; fmt( format : ANCHORED_DESCR, lib : LIBCHARS ) : STR 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 is -- This routine returns the formatted string representation of self in -- accordance with the string format. return fmt(format,LIBCHARS::default) end ; end ; -- BOOL_STR