Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

235 lines (201 sloc) 9.927 kb
#lang typed/racket/base
(require racket/list
"lexical-structs.rkt"
"../sets.rkt")
(provide find-variable
extend-lexical-environment
extend-lexical-environment/names
extend-lexical-environment/parameter-names
extend-lexical-environment/boxed-names
extend-lexical-environment/placeholders
collect-lexical-references
lexical-references->compile-time-environment
place-prefix-mask
adjust-env-reference-depth
env-reference-depth)
;; Find where the variable is located in the lexical environment
(: find-variable (Symbol ParseTimeEnvironment -> LexicalAddress))
(define (find-variable name cenv)
(: find-pos (Symbol (Listof (U Symbol ModuleVariable False)) -> Natural))
(define (find-pos sym los)
(let ([elt (car los)])
(cond
[(and (symbol? elt) (eq? sym elt))
0]
[(and (ModuleVariable? elt) (eq? (ModuleVariable-name elt) sym))
0]
[else
(add1 (find-pos sym (cdr los)))])))
(let: loop : LexicalAddress
([cenv : ParseTimeEnvironment cenv]
[depth : Natural 0])
(cond [(empty? cenv)
(error 'find-variable "~s not in lexical environment" name)]
[else
(let: ([elt : ParseTimeEnvironmentEntry (first cenv)])
(cond
[(Prefix? elt)
(let: prefix-loop : LexicalAddress
([names : (Listof (U False Symbol GlobalBucket ModuleVariable)) (Prefix-names elt)]
[pos : Natural 0])
(cond [(empty? names)
(loop (rest cenv) (add1 depth))]
[else
(let: ([n : (U False Symbol GlobalBucket ModuleVariable) (first names)])
(cond
[(and (symbol? n) (eq? name n))
(make-EnvPrefixReference depth pos #f)]
[(and (ModuleVariable? n) (eq? name (ModuleVariable-name n)))
(make-EnvPrefixReference depth pos #t)]
[(and (GlobalBucket? n) (eq? name (GlobalBucket-name n)))
(make-EnvPrefixReference depth pos #f)]
[else
(prefix-loop (rest names) (add1 pos))]))]))]
[(NamedBinding? elt)
(cond
[(eq? (NamedBinding-name elt) name)
(make-EnvLexicalReference depth (NamedBinding-boxed? elt))]
[else
(loop (rest cenv) (add1 depth))])]
[(eq? elt #f)
(loop (rest cenv) (add1 depth))]))])))
(: list-index (All (A) A (Listof A) -> (U #f Natural)))
(define (list-index x l)
(let: loop : (U #f Natural) ([i : Natural 0]
[l : (Listof A) l])
(cond
[(empty? l)
#f]
[(eq? x (first l))
i]
[else
(loop (add1 i) (rest l))])))
(: extend-lexical-environment
(ParseTimeEnvironment ParseTimeEnvironmentEntry -> ParseTimeEnvironment))
;; Extends the lexical environment with procedure bindings.
(define (extend-lexical-environment cenv extension)
(cons extension cenv))
(: extend-lexical-environment/names (ParseTimeEnvironment (Listof Symbol) (Listof Boolean) ->
ParseTimeEnvironment))
(define (extend-lexical-environment/names cenv names boxed?)
(append (map (lambda: ([n : Symbol]
[b : Boolean]) (make-NamedBinding n #f b)) names boxed?)
cenv))
(: extend-lexical-environment/parameter-names (ParseTimeEnvironment (Listof Symbol) (Listof Boolean) -> ParseTimeEnvironment))
(define (extend-lexical-environment/parameter-names cenv names boxed?)
(append (map (lambda: ([n : Symbol]
[b : Boolean])
(make-NamedBinding n #t b)) names boxed?)
cenv))
(: extend-lexical-environment/boxed-names (ParseTimeEnvironment (Listof Symbol) -> ParseTimeEnvironment))
(define (extend-lexical-environment/boxed-names cenv names)
(append (map (lambda: ([n : Symbol]) (make-NamedBinding n #f #t)) names)
cenv))
(: extend-lexical-environment/placeholders
(ParseTimeEnvironment Natural -> ParseTimeEnvironment))
;; Add placeholders to the lexical environment (This represents what happens during procedure application.)
(define (extend-lexical-environment/placeholders cenv n)
(append (build-list n (lambda: ([i : Natural]) #f))
cenv))
(: collect-lexical-references ((Listof LexicalAddress)
->
(Listof (U EnvLexicalReference EnvWholePrefixReference))))
;; Given a list of lexical addresses, computes a set of unique references.
;; Multiple lexical addresses to a single prefix should be treated identically.
(define (collect-lexical-references addresses)
(let: ([prefix-references : (Setof EnvWholePrefixReference) (new-set)]
[lexical-references : (Setof EnvLexicalReference) (new-set)])
(let: loop : (Listof (U EnvLexicalReference EnvWholePrefixReference))
([addresses : (Listof LexicalAddress) addresses])
(cond
[(empty? addresses)
(append (set->list prefix-references)
((inst sort
EnvLexicalReference
EnvLexicalReference)
(set->list lexical-references)
lex-reference<?))]
[else
(let ([addr (first addresses)])
(cond
[(EnvLexicalReference? addr)
(set-insert! lexical-references
addr)
(loop (rest addresses))]
[(EnvPrefixReference? addr)
(set-insert! prefix-references
(make-EnvWholePrefixReference (EnvPrefixReference-depth addr)))
(loop (rest addresses))]))]))))
(: lex-reference<? (EnvLexicalReference EnvLexicalReference -> Boolean))
(define (lex-reference<? x y)
(< (EnvLexicalReference-depth x)
(EnvLexicalReference-depth y)))
(: lexical-references->compile-time-environment ((Listof EnvReference) ParseTimeEnvironment ParseTimeEnvironment
(Listof Symbol)
-> ParseTimeEnvironment))
;; Creates a lexical environment containing the closure's bindings.
(define (lexical-references->compile-time-environment refs cenv new-cenv symbols-to-keep)
(let: loop : ParseTimeEnvironment ([refs : (Listof EnvReference) (reverse refs)]
[new-cenv : ParseTimeEnvironment new-cenv])
(cond
[(empty? refs)
new-cenv]
[else
(let: ([a-ref : EnvReference (first refs)])
(cond
[(EnvLexicalReference? a-ref)
(loop (rest refs)
(cons (list-ref cenv (EnvLexicalReference-depth a-ref))
new-cenv))]
[(EnvWholePrefixReference? a-ref)
(loop (rest refs)
(cons (place-prefix-mask
(ensure-Prefix (list-ref cenv (EnvWholePrefixReference-depth a-ref)))
symbols-to-keep)
new-cenv))]))])))
(: ensure-Prefix (Any -> Prefix))
(define (ensure-Prefix x)
(if (Prefix? x)
x
(error 'ensure-Prefix "~s" x)))
(: place-prefix-mask (Prefix (Listof Symbol) -> Prefix))
;; Masks elements of the prefix off.
(define (place-prefix-mask a-prefix symbols-to-keep)
(make-Prefix
(map (lambda: ([n : (U False Symbol GlobalBucket ModuleVariable)])
(cond [(eq? n #f)
n]
[(symbol? n)
(if (member n symbols-to-keep)
n
#f)]
[(GlobalBucket? n)
(if (member (GlobalBucket-name n) symbols-to-keep)
n
#f)]
[(ModuleVariable? n)
(if (member (ModuleVariable-name n) symbols-to-keep)
n
#f)]))
(Prefix-names a-prefix))))
(: adjust-env-reference-depth (EnvReference Natural -> EnvReference))
(define (adjust-env-reference-depth target n)
(cond
[(EnvLexicalReference? target)
(make-EnvLexicalReference (+ n (EnvLexicalReference-depth target))
(EnvLexicalReference-unbox? target))]
[(EnvPrefixReference? target)
(make-EnvPrefixReference (+ n (EnvPrefixReference-depth target))
(EnvPrefixReference-pos target)
(EnvPrefixReference-modvar? target))]
[(EnvWholePrefixReference? target)
(make-EnvWholePrefixReference (+ n (EnvWholePrefixReference-depth target)))]))
(: env-reference-depth ((U EnvLexicalReference EnvPrefixReference EnvWholePrefixReference) -> Natural))
(define (env-reference-depth a-ref)
(cond
[(EnvLexicalReference? a-ref)
(EnvLexicalReference-depth a-ref)]
[(EnvPrefixReference? a-ref)
(EnvPrefixReference-depth a-ref)]
[(EnvWholePrefixReference? a-ref)
(EnvWholePrefixReference-depth a-ref)]))
Jump to Line
Something went wrong with that request. Please try again.