X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fscheme.4th;h=36a8106236fb9e4910a51d4cc0d11ea09de439d7;hb=effe46c25202697eecbecb427828f466a710c8bc;hp=e94796c550ef26630bb7ab426c42a4f58716b225;hpb=1611b5484902b38774e0e61b84a14868dcc30152;p=scheme.forth.jl.git diff --git a/src/scheme.4th b/src/scheme.4th index e94796c..36a8106 100644 --- a/src/scheme.4th +++ b/src/scheme.4th @@ -407,6 +407,9 @@ variable read-line-buffer-offset : make-frame ( vars vals -- frame ) cons ; +: add-frame-to-env ( frame env -- env ) + cons ; + : frame-vars ( frame -- vars ) car ; @@ -421,99 +424,90 @@ variable read-line-buffer-offset ; : extend-env ( vars vals env -- env ) - >R >R - make-frame - R> R> - cons + -2rot make-frame + 2swap add-frame-to-env ; -objvar vars -objvar vals - -: get-vars-vals-frame ( var frame -- bool ) - 2dup frame-vars vars obj! - frame-vals vals obj! +: get-vals-frame ( var frame -- vals | nil ) + 2dup frame-vars + 2swap frame-vals ( var vars vals ) begin - vars obj@ nil objeq? false = + nil? false = while - 2dup vars obj@ car objeq? if - 2drop true + + -2rot ( vals var vars ) + 2over 2over car objeq? if + 2drop 2drop exit then - vars obj@ cdr vars obj! - vals obj@ cdr vals obj! + cdr 2rot cdr repeat - 2drop false + 2drop 2drop 2drop + nil ; -: get-vars-vals ( var env -- vars? vals? bool ) +: get-vals ( var env -- vals | nil ) begin nil? false = while 2over 2over first-frame - get-vars-vals-frame if - 2drop 2drop - vars obj@ vals obj@ true + get-vals-frame nil? false = if + 2swap 2drop 2swap 2drop exit then + 2drop + enclosing-env repeat - 2drop 2drop - false + 2swap 2drop ; -hide vars -hide vals - -objvar var - +objvar var \ Used only for error messages : lookup-var ( var env -- val ) 2over var obj! - get-vars-vals if - 2swap 2drop car - else - except-message: ." tried to read unbound variable '" var obj@ print ." '." recoverable-exception throw + + get-vals nil? if + except-message: ." tried to read unbound variable '" var obj@ print ." '." + recoverable-exception throw then + + car ; : set-var ( var val env -- ) - >R >R 2swap R> R> ( val var env ) - 2over var obj! - get-vars-vals if - 2swap 2drop ( val vals ) - set-car! + 2rot 2dup var obj! ( val env var ) + 2swap ( val var env ) + get-vals nil? if + except-message: ." tried to set unbound variable '" var obj@ print ." '." + recoverable-exception throw else - except-message: ." tried to set unbound variable '" var obj@ print ." '." recoverable-exception throw + ( val vals ) + set-car! then ; - hide var -objvar env - : define-var ( var val env -- ) - env obj! + first-frame ( var val frame ) + 2rot 2swap 2over 2over ( val var frame var frame ) - 2over env obj@ ( var val var env ) - get-vars-vals if - 2swap 2drop ( var val vals ) - set-car! + get-vals-frame nil? if 2drop - else - env obj@ - first-frame ( var val frame ) + -2rot 2swap 2rot add-binding + else + ( val var frame vals ) + 2swap 2drop 2swap 2drop + set-car! then ; -hide env - : make-procedure ( params body env -- proc ) nil cons cons cons @@ -536,6 +530,8 @@ global-env obj! nil rsp@ 1- rsp0 do i 1+ @ fixnum-type 2swap cons loop + + rsp@ 1- rsp0 - fixnum-type 2swap cons ; : cons-param-stack ( -- listobj ) @@ -551,6 +547,8 @@ global-env obj! 2swap cons 2 +loop + + depth 2- 2/ fixnum-type 2swap cons ; : make-continuation @@ -566,18 +564,70 @@ global-env obj! : continuation->rstack-list drop pair-type cdr ; -: restore-param-stack ( continuation -- obj_stack continuation ) +: stack-list-len ( stack-list -- n ) + car drop +; - 2dup >R >R +: restore-param-stack ( continuation -- obj_stack ) continuation->pstack-list + 2dup >R >R - ( Idea: allocate stack space first using psp!, + ( Allocate stack space first using psp!, then copy objects from list. ) + + car drop 2* + object-stack-base @ psp0 + + psp! + + R> R> 2dup cdr + 2swap + stack-list-len 1- 0 swap do + + 2dup car + PSP0 object-stack-base @ + i 2* + 2 + ! + PSP0 object-stack-base @ + i 2* + 1 + ! + cdr + + -1 +loop + + 2drop +; + +: restore-return-stack ( continuation -- ) + + continuation->rstack-list + + 2dup cdr 2swap stack-list-len ( list n ) + + dup RSP0 + RSP! \ expand return stack to accommodate entries + + ( list n ) + + 1- \ initial offset n-1 + 0 \ final offset 0 + swap + do + 2dup cdr 2swap car drop + RSP0 i 1+ + ! + -1 +loop + + 2drop ; -: restore-continuation - \ TODO: replace current parameter and return stacks with - \ contents of continuation object. +: restore-continuation-with-arg ( continuation obj -- ) + + >R >R \ Store obj on return stack + + 2dup >R >R \ Store copy of continuation on return stack + + restore-param-stack + + R> R> \ Pop continuation from return stack + + R> R> \ Pop obj from return stack + + 2swap + + restore-return-stack ; \ }}} @@ -1723,7 +1773,22 @@ parse-idx-stack parse-idx-sp ! endof continuation-type of - \ TODO: Apply continuation + 2swap + nil? if + except-message: ." Continuations expect exactly 1 argument." + recoverable-exception throw + then + + 2dup cdr + + nil? not if + except-message: ." Continuations expect exactly 1 argument." + recoverable-exception throw + then + + 2drop car + + restore-continuation-with-arg endof except-message: ." object '" drop print ." ' not applicable." recoverable-exception throw @@ -2006,6 +2071,21 @@ parse-idx-stack parse-idx-sp ! \ ---- Garbage Collection ---- {{{ +( Notes on garbage collection: + This is a mark-sweep garbage collector, invoked by cons. + The roots of the object tree used by the marking routine + include all objects in the parameter stack, and several + other fixed roots such as global-env, symbol-table, macro-table, + and the console-i/o-port. + + NO OTHER OBJECTS WILL BE MARKED! + + This places implicit restrictions on when cons can be invoked. + Invoking cons when live objects are stored on the return stack + or in other variables than the above will result in possible + memory corruption if the cons triggers the GC. ) + + : pairlike? ( obj -- obj bool ) pair-type istype? if true exit then string-type istype? if true exit then