- Foreword
- Proposals Process
- 200x Membership
- 1 Introduction
- 2 Terms, notation, and references
- 3 Usage requirements
- 4 Documentation requirements
- 5 Compliance and labeling
- 6 Glossary
- 7 The optional Block word set
- 8 The optional Double-Number word set
- 9 The optional Exception word set
- 10 The optional Facility word set
- 11 The optional File-Access word set
- 12 The optional Floating-Point word set
- 13 The optional Locals word set
- 14 The optional Memory-Allocation word set
- 15 The optional Programming-Tools word set
- 16 The optional Search-Order word set
- 17 The optional String word set
- 18 The optional Extended-Character word set
- Annex A: Rationale
- Annex B: Bibliography
- Annex C: Compatibility analysis
- Annex D: Portability guide
- Annex E: Reference Implementations
- Annex F: Test Suite
- Annex H: Alphabetic list of words
Annex E: Reference Implementations
E.1 Introduction
In the most recent review of this document, proposals were encouraged to include a reference implementation where possible. Where an implementation requires system specific knowledge it was documented.This appendix contains the reference implementations that have been accepted by the committee. This is not a complete reference implementation nor do the committee recommend these implementations. They are supplied solely for the purpose of providing a detailed understanding of a definitions requirement. System implementors are free to implement any operation in a manner that suits their system, but it must exhibit the same behavior as the reference implementation given here.
E.6 The Core word set
( empty the return stack and set the input source to the user input device )
POSTPONE [
REFILL
WHILE
['] INTERPRET CATCH
CASE
0 OF STATE @ 0= IF ." OK" THEN CR ENDOF
-1 OF ( Aborted ) ENDOF
-2 OF ( display message from ABORT" ) ENDOF
( default ) DUP ." Exception # " .
ENDCASE
REPEAT BYE
;
INTERPRET that embodies the text interpreter semantics
described in 3.4 The Forth text interpreter.
Further discussion of the interpret loop can be found in
A.6.2.0945 COMPILE,.
BL 1+ U< ;
: isnotspace? ( c -- f )
isspace? 0= ;
: xt-skip ( addr1 n1 xt -- addr2 n2 )
\ skip all characters satisfying xt ( c -- f )
>R
BEGIN
DUP
WHILE
OVER C@ R@ EXECUTE
WHILE
1 /STRING
REPEAT THEN
R> DROP ;
: parse-name ( "name" -- c-addr u )
SOURCE >IN @ /STRING
['] isspace? xt-skip OVER >R
['] isnotspace? xt-skip ( end-word restlen r: start-word )
2DUP 1 MIN + SOURCE DROP - >IN !
DROP R> TUCK - ;
E.8 The optional Double-Number word set
The corresponding implementation of TO disregards the issue that TO must also work for integer VALUEs and locals.
E.10 The optional Exception word set
SP@- ( -- addr )
returns the address corresponding to the top of data stack. SP!- ( addr -- )
sets the stack pointer to addr, thus restoring the stack depth to the same depth that existed just before addr was acquired by executingSP@. RP@- ( -- addr )
returns the address corresponding to the top of return stack. RP!- ( addr -- )
sets the return stack pointer to addr, thus restoring the return stack depth to the same depth that existed just before addr was acquired by executingRP@.
: CATCH ( xt -- exception# | 0 \ return addr on stack
SP@ >R ( xt ) \ save data stack pointer
HANDLER @ >R ( xt ) \ and previous handler
RP@ HANDLER ! ( xt ) \ set current handler
EXECUTE ( ) \ execute returns if no THROW
R> HANDLER ! ( ) \ restore previous handler
R> DROP ( ) \ discard saved stack ptr
0 ( 0 ) \ normal completion
;
HANDLER variable should be in
the per-task variable area (i.e., a user variable).
This sample implementation does not explicitly handle the case in which CATCH has never been called (i.e., the ABORT behavior). One solution would be to execute a CATCH within QUIT, so that there is always an "exception handler of last resort" present, as shown in E.6.1.2050 QUIT.
?DUP IF ( exc# ) \ 0 THROW is no-op
HANDLER @ RP! ( exc# ) \ restore prev return stack
R> HANDLER ! ( exc# ) \ restore prev handler
R> SWAP >R ( saved-sp ) \ exc# on return stack
SP! DROP R> ( exc# ) \ restore stack
\ Return to the caller of CATCH because return
\ stack is restored to the state that existed
\ when CATCH began execution
THEN
;
E.12 The optional Facility word set
E.14 The optional File-Access word set
included-names variable.
\ copy a memory block into a newly allocated region in the heap
SWAP >R
DUP ALLOCATE THROW
SWAP 2DUP R> ROT ROT MOVE ;
: name-add ( addr u listp -- )
>R save-mem ( addr1 u )
3 CELLS ALLOCATE THROW \ allocate list node
R@ @ OVER ! \ set next pointer
DUP R> ! \ store current node in list var
CELL+ 2! ;
: name-present? ( addr u list -- f )
ROT ROT 2>R BEGIN ( list R: addr u )
DUP
WHILE
DUP CELL+ 2@ 2R@ COMPARE 0= IF
DROP 2R> 2DROP TRUE EXIT
THEN
@
REPEAT
( DROP 0 ) 2R> 2DROP ;
: name-join ( addr u list -- )
>R 2DUP R@ @ name-present? IF
R> DROP 2DROP
ELSE
R> name-add
THEN ;
VARIABLE included-names 0 included-names !
: included ( i*x addr u -- j*x )
2DUP included-names name-join
INCLUDED ;
: REQUIRED ( i*x addr u -- i*x )
2DUP included-names @ name-present? 0= IF
included
ELSE
2DROP
THEN ;
E.16 The optional Floating-Point word set
E.18 The optional Locals word set
: match-or-end? ( c-addr1 u1 c-addr2 u2 -- f )
2 PICK 0= >R COMPARE 0= R> OR ;
: scan-args
\ 0 c-addr1 u1 -- c-addr1 u1 ... c-addrn un n c-addrn+1 un+1
BEGIN
2DUP S" |" match-or-end? 0= WHILE
2DUP S" --" match-or-end? 0= WHILE
2DUP S" :}" match-or-end? 0= WHILE
ROT 1+ PARSE-NAME
AGAIN THEN THEN THEN ;
: scan-locals
\ n c-addr1 u1 -- c-addr1 u1 ... c-addrn un n c-addrn+1 un+1
2DUP S" |" COMPARE 0= 0= IF
EXIT
THEN
2DROP PARSE-NAME
BEGIN
2DUP S" --" match-or-end? 0= WHILE
2DUP S" :}" match-or-end? 0= WHILE
ROT 1+ PARSE-NAME
POSTPONE undefined-value
AGAIN THEN THEN ;
: scan-end ( c-addr1 u1 -- c-addr2 u2 )
BEGIN
2DUP S" :}" match-or-end? 0= WHILE
2DROP PARSE-NAME
REPEAT ;
: define-locals ( c-addr1 u1 ... c-addrn un n -- )
0 ?DO
(LOCAL)
LOOP
0 0 (LOCAL) ;
: {: ( -- )
0 PARSE-NAME
scan-args scan-locals scan-end
2DROP define-locals
; IMMEDIATE
E.20 The optional Programming-Tools word set
HIDE, REVEAL and
IMMEDIATE? are non-standard words.
1 BEGIN \ level
BEGIN BL WORD COUNT DUP WHILE \ level adr len
2DUP S" [IF]" COMPARE 0= IF \ level adr len
2DROP 1+ \ level'
ELSE \ level adr len
2DUP S" [ELSE]" COMPARE 0= IF \ level adr len
2DROP 1- DUP IF 1+ THEN \ level'
ELSE \ level adr len
S" [THEN]" COMPARE 0= IF \ level
1- \ level'
THEN
THEN
THEN ?DUP 0= IF EXIT THEN \ level'
REPEAT 2DROP \ level
REFILL 0= UNTIL \ level
DROP
; IMMEDIATE
E.22 The optional Search-Order word set
0 ( c-addr 0 )
#order @ 0 ?DO
OVER COUNT ( c-addr 0 c-addr' u )
I CELLS context + @ ( c-addr 0 c-addr' u wid )
SEARCH-WORDLIST ( c-addr 0; 0 | w 1 | q -1 )
?DUP IF ( c-addr 0; w 1 | w -1 )
2SWAP 2DROP LEAVE ( w 1 | w -1 )
THEN ( c-addr 0 )
LOOP ( c-addr 0 | w 1 | w -1 )
;
E.24 The optional String word set
[UNDEFINED] place [IF]
: place \ c-addr1 u c-addr2 --
\ Copy the string described by c-addr1 u as a counted
\ string at the memory address described by c-addr2.
2DUP 2>R
1 CHARS + SWAP MOVE
2R> C!
;
[THEN]
: "/COUNTED-STRING" S" /COUNTED-STRING" ;
"/COUNTED-STRING" ENVIRONMENT? 0= [IF] 256 [THEN]
CHARS CONSTANT string-max
WORDLIST CONSTANT wid-subst
\ Wordlist ID of the wordlist used to hold substitution names and replacement text.
[DEFINED] VFXforth [IF] \ VFX Forth
: makeSubst \ c-addr len -- c-addr
\ Given a name string create a substution and storage space.
\ Return the address of the buffer for the substitution text.
\ This word requires system specific knowledge of the host Forth.
\ Some systems may need to perform case conversion here.
GET-CURRENT >R wid-subst SET-CURRENT
($create) \ like CREATE but takes c-addr/len
R> SET-CURRENT
HERE string-max ALLOT 0 OVER C! \ create buffer space
;
[THEN]
[DEFINED] (WID-CREATE) [IF] \ SwiftForth
: makeSubst \ c-addr len -- c-addr
wid-subst (WID-CREATE) \ like CREATE but takes c-addr/len/wid
LAST @ >CREATE !
HERE string-max ALLOT 0 OVER C! \ create buffer space
;
[THEN]
: findSubst \ c-addr len -- xt flag | 0
\ Given a name string, find the substitution.
\ Return xt and flag if found, or just zero if not found.
\ Some systems may need to perform case conversion here.
wid-subst SEARCH-WORDLIST
;
: REPLACES \ text tlen name nlen --
\ Define the string text/tlen as the text to substitute for the substitution named name/nlen.
\ If the substitution does not exist it is created.
2DUP findSubst IF
NIP NIP EXECUTE \ get buffer address
ELSE
makeSubst
THEN
place \ copy as counted string
;
[UNDEFINED] bounds [IF]
: bounds \ addr len -- addr+len addr
OVER + SWAP
;
[THEN]
[UNDEFINED] -rot [IF]
: -rot \ a b c -- c a b
ROT ROT
;
[THEN]
CHAR % CONSTANT delim
\ Character used as the substitution name delimiter.
string-max BUFFER: Name
\ Holds substitution name as a counted string.
VARIABLE DestLen
\ Maximum length of the destination buffer.
2VARIABLE Dest
\ Holds destination string current length and address.
VARIABLE SubstErr
\ Holds zero or an error code.
: addDest \ char --
\ Add the character to the destination string.
Dest @ DestLen @ < IF
Dest 2@ + C! 1 CHARS Dest +!
ELSE
DROP -1 SubstErr !
THEN
;
: formName \ c-addr len -- c-addr' len'
\ Given a source string pointing at a leading delimiter, place the name string in the name buffer.
1 /STRING 2DUP delim scan >R DROP \ find length of residue
2DUP R> - DUP >R Name place \ save name in buffer
R> 1 CHARS + /STRING \ step over name and trailing %
;
: >dest \ c-addr len --
\ Add a string to the output string.
bounds ?DO
I C@ addDest
1 CHARS +LOOP
;
: processName \ -- flag
\ Process the last substitution name. Return true if found, 0 if not found.
Name COUNT findSubst DUP >R IF
EXECUTE COUNT >dest
ELSE
delim addDest Name COUNT >dest delim addDest
THEN
R>
;
: SUBSTITUTE \ src slen dest dlen -- dest dlen' n
\ Expand the source string using substitutions.
\ Note that this version is simplistic, performs no error checking,
\ and requires a global buffer and global variables.
Destlen ! 0 Dest 2! 0 -rot \ -- 0 src slen
0 SubstErr !
BEGIN
DUP 0 >
WHILE
OVER C@ delim <> IF \ character not %
OVER C@ addDest 1 /STRING
ELSE
OVER 1 CHARS + C@ delim = IF \ %% for one output %
delim addDest 2 /STRING \ add one % to output
ELSE
formName processName IF
ROT 1+ -rot \ count substitutions
THEN
THEN
THEN
REPEAT
2DROP Dest 2@ ROT SubstErr @ IF
DROP SubstErr @
THEN
;
\ Replace each '
%' character in the input string c-addr1 len1 with two '%' characters. \ The output is represented by c-addr2 len2.
\ If you pass a string through UNESCAPE and then SUBSTITUTE, you get the original string.
DUP 2SWAP OVER + SWAP ?DO
I C@ [CHAR] % = IF
[CHAR] % OVER C! 1+
THEN
I C@ OVER C! 1+
LOOP
OVER -
;
E.25 The optional Extended-Character word set
This reference implementation assumes the UTF-8 character encoding is being used.
0= IF DROP 0 EXIT THEN
\ length of UTF-8 char starting at u8-addr (accesses only u8-addr)
C@
DUP $80 U< IF DROP 1 EXIT THEN
DUP $c0 U< IF -77 THROW THEN
DUP $e0 U< IF DROP 2 EXIT THEN
DUP $f0 U< IF DROP 3 EXIT THEN
DUP $f8 U< IF DROP 4 EXIT THEN
DUP $fc U< IF DROP 5 EXIT THEN
DUP $fe U< IF DROP 6 EXIT THEN
-77 THROW ;
CREATE wc-table \ derived from wcwidth source code, for UCS32
0 0300 0357 wc,
0 035D 036F wc,
0 0483 0486 wc,
0 0488 0489 wc,
0 0591 05A1 wc,
0 05A3 05B9 wc,
0 05BB 05BD wc,
0 05BF 05BF wc,
0 05C1 05C2 wc,
0 05C4 05C4 wc,
0 0600 0603 wc,
0 0610 0615 wc,
0 064B 0658 wc,
0 0670 0670 wc,
0 06D6 06E4 wc,
0 06E7 06E8 wc,
0 06EA 06ED wc,
0 070F 070F wc,
0 0711 0711 wc,
0 0730 074A wc,
0 07A6 07B0 wc,
0 0901 0902 wc,
0 093C 093C wc,
0 0941 0948 wc,
0 094D 094D wc,
0 0951 0954 wc,
0 0962 0963 wc,
0 0981 0981 wc,
0 09BC 09BC wc,
0 09C1 09C4 wc,
0 09CD 09CD wc,
0 09E2 09E3 wc,
0 0A01 0A02 wc,
0 0A3C 0A3C wc,
0 0A41 0A42 wc,
0 0A47 0A48 wc,
0 0A4B 0A4D wc,
0 0A70 0A71 wc,
0 0A81 0A82 wc,
0 0ABC 0ABC wc,
0 0AC1 0AC5 wc,
0 0AC7 0AC8 wc,
0 0ACD 0ACD wc,
0 0AE2 0AE3 wc,
0 0B01 0B01 wc,
0 0B3C 0B3C wc,
0 0B3F 0B3F wc,
0 0B41 0B43 wc,
0 0B4D 0B4D wc,
0 0B56 0B56 wc,
0 0B82 0B82 wc,
0 0BC0 0BC0 wc,
0 0BCD 0BCD wc,
0 0C3E 0C40 wc,
0 0C46 0C48 wc,
0 0C4A 0C4D wc,
0 0C55 0C56 wc,
0 0CBC 0CBC wc,
0 0CBF 0CBF wc,
0 0CC6 0CC6 wc,
0 0CCC 0CCD wc,
0 0D41 0D43 wc,
0 0D4D 0D4D wc,
0 0DCA 0DCA wc,
0 0DD2 0DD4 wc,
0 0DD6 0DD6 wc,
0 0E31 0E31 wc,
0 0E34 0E3A wc,
0 0E47 0E4E wc,
0 0EB1 0EB1 wc,
0 0EB4 0EB9 wc,
0 0EBB 0EBC wc,
0 0EC8 0ECD wc,
0 0F18 0F19 wc,
0 0F35 0F35 wc,
0 0F37 0F37 wc,
0 0F39 0F39 wc,
0 0F71 0F7E wc,
0 0F80 0F84 wc,
0 0F86 0F87 wc,
0 0F90 0F97 wc,
0 0F99 0FBC wc,
0 0FC6 0FC6 wc,
0 102D 1030 wc,
0 1032 1032 wc,
0 1036 1037 wc,
0 1039 1039 wc,
0 1058 1059 wc,
1 0000 1100 wc,
2 1100 115f wc,
0 1160 11FF wc,
0 1712 1714 wc,
0 1732 1734 wc,
0 1752 1753 wc,
0 1772 1773 wc,
0 17B4 17B5 wc,
0 17B7 17BD wc,
0 17C6 17C6 wc,
0 17C9 17D3 wc,
0 17DD 17DD wc,
0 180B 180D wc,
0 18A9 18A9 wc,
0 1920 1922 wc,
0 1927 1928 wc,
0 1932 1932 wc,
0 1939 193B wc,
0 200B 200F wc,
0 202A 202E wc,
0 2060 2063 wc,
0 206A 206F wc,
0 20D0 20EA wc,
2 2329 232A wc,
0 302A 302F wc,
2 2E80 303E wc,
0 3099 309A wc,
2 3040 A4CF wc,
2 AC00 D7A3 wc,
2 F900 FAFF wc,
0 FB1E FB1E wc,
0 FE00 FE0F wc,
0 FE20 FE23 wc,
2 FE30 FE6F wc,
0 FEFF FEFF wc,
2 FF00 FF60 wc,
2 FFE0 FFE6 wc,
0 FFF9 FFFB wc,
0 1D167 1D169 wc,
0 1D173 1D182 wc,
0 1D185 1D18B wc,
0 1D1AA 1D1AD wc,
2 20000 2FFFD wc,
2 30000 3FFFD wc,
0 E0001 E0001 wc,
0 E0020 E007F wc,
0 E0100 E01EF wc,
HERE wc-table - CONSTANT #wc-table
\ inefficient table walk:
: XC-WIDTH ( xchar -- n )
wc-table #wc-table OVER + SWAP ?DO
DUP I 2@ WITHIN IF
DROP I 2 CELLS + @ UNLOOP EXIT THEN
3 CELLS +LOOP DROP 1 ;
ContributeContributions
JohanKotlinski
[123] licenseRequest for clarification2019-10-23 11:57:39
What is the license information for the reference implementations? May they be freely reused?
ruv
As I can see, a license is not mentioned anywhere in the standard.
Usually, reference implementations are licensed under some permissive license or even dedicated to the public domain. Particularly, the reference implementations that are the result of standardization processes are often dedicated to the public domain (see Wikipedia).
In any case, we may assume there is no any licensing fees.
PeterKnaggs
I have raised a new proposal to include licensing text.