-- The Optional Locals Word Set
Copyright (C) Tektronix, Inc. 1998 - 2001. All rights reserved.
description: The Portable Forth Environment does implement locals in such an extended form as that additional variable names can be declared anywhere in the compiled word.
Locals are names for values that live in a locals-frame on the return-stack - on entry to the procedure that locals-frame is carved from the return-stack and a frame-pointer is setup. Locals are in two forms, one is inialized by a chunk from the parameter-stack as it is with LOCALS| while the others are local variables declared later. The latter are left unitialized on setup of the locals-frame.
For unnamed returnstack locals, see words like R@ R! R'@ R'! R"@ R"! 2R@ 2R! but here the setup and cleanup of the return-stack frame is left to the user, possibly using some words like >R R> 2>R 2R> R>DROP while the locals-ext will take care to provide a frame-creation token and some cleanup-code for each EXIT or ;
FORTH
(LOCAL)
( .. )();
as:"paren-local";
compiling primitive (LOCAL)
an executable word (no special usage info)
or wrapper call around p4_paren_local
dpANS 13.6.1.0086 - standard forth word
FORTH
LOCALS|
( xN ... x2 x1 [name1 .. nameN <|>] -- )( | ); |
| ; |
create local identifiers to be used in the current definition. At runtime, each identifier will be assigned a value from the parameter stack. <br> The identifiers may be treated as if being a VALUE , it does also implement the ansi TO extensions for locals. Note that the identifiers are only valid inside the currently compiled word, the SEE decompiled word will show them as <A> <B> ... <N> a.s.o. <br> see also LVALUE
dpANS 13.6.2.1795 - standard forth word
EXTENSIONS
LVALUE
( value [name] -- )( | ); |
| ; |
declares a single local VALUE using (LOCAL) - a sequence of LVALUE declarations can replace a LOCALS| argument, ie. LOCALS| a b c | is the same as LVALUE a LVALUE b LVALUE c . This should also clarify the runtime stack behaviour of LOCALS| where the stack parameters seem to be assigned in reverse order as opposed to their textual identifier declarations. <br> compare with VALUE and the pfe's convenience word VAR.
: LVALUE
STATE @ IF
VALUE
ELSE
BL WORD COUNT DUP (LOCAL) (TO)
THEN
; IMMEDIATE
EXTENSIONS
LBUFFER:
( size [name] -- )( | ); |
| ; |
declares a single local VALUE using (LOCAL) - which will hold the address of an area like BUFFER: but carved from the return-stack (as in C with alloca). This local buffer will be automatically given up at the end of the word. The return-stack-pointer will be increased only at the time of this function (and the address assigned to the LVALUE) so that the provided size gets determined at runtime. Note that in some configurations the forth-return-stack area is quite small - for large string operations you should consider to use a POCKET-PAD in pfe.
: LBUFFER:
STATE @ IF
BUFFER:
ELSE
:NONAME ( size -- rp* ) R> RP@ - DUP RP! SWAP >R ;NONAME
COMPILE, POSTPONE LVALUE
THEN
; IMMEDIATE
ENVIRONMENT
LOCALS-EXT
( .. )();
as:"locals-minus-ext";
( 1994 ) constant LOCALS-EXT
an ordinary constant (no special usage info)
ENVIRONMENT
#LOCALS
( .. )();
as:"sharp-locals";
( MAX_LOCALS ) constant #LOCALS
an ordinary constant (no special usage info)
ENVIRONMENT
LOCALS-LOADED
( .. )( | ); |
| ; |
constructor primitive LOCALS-LOADED
an executable word (no special usage info)
or wrapper call around locals_init