[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PATCH] psyntax: custom ellipses using 'with-ellipsis' or R7RS syntax-ru
|
From: |
Mark H Weaver |
|
Subject: |
[PATCH] psyntax: custom ellipses using 'with-ellipsis' or R7RS syntax-rules |
|
Date: |
Wed, 18 Dec 2013 19:33:06 -0500 |
Hello all,
This patch implements a new primitive syntax form 'with-ellipsis' that
changes the ellipsis identifier within a lexical scope, and uses this to
implement the R7RS extension to 'syntax-rules'. I'd like to apply this
to the stable-2.0 branch.
It took me quite a while to figure out the right way to generalize this
R7RS feature for the syntax-case system. My first idea was to make
'syntax' a syntax parameter, but further thought made it clear that this
would be inadequate. Consider all of the other macros based on 'syntax'
and 'syntax-case': things such as 'with-syntax', 'quasisyntax', etc.
It was obvious that 'with-ellipsis' should modify the lexical
environment somehow, but how? First of all, consider that a single
'syntax' or 'syntax-case' form might, in general, be composed of
identifiers from many different lexical environments. The lexical
environment of the 'syntax' keyword is not the right environment to look
at for the entire template, because in a 'quasisyntax' or 'syntax-rules'
form, that's the lexical environment of the 'quasisyntax' or
'syntax-rules' macro.
It soon became clear that I must search the lexical environment of each
identifier within a pattern or template to determine if that identifier
is an ellipsis. But what identifier should it look up in that lexical
environment? Again, my first thought was to look up the identifier
itself, but that's not right either. A 'with-ellipsis' form must not
only add a new ellipsis identifier; it must also disable the special
meaning of the previous ellipsis identifier.
In the end, here's how this works: 'with-ellipsis' binds a special
identifier named #{ $sc-ellipsis }# using a new 'ellipsis' binding type.
The new ellipsis identifier is stored within the binding. In order to
determine whether an identifier X is an ellipsis, the binding for
#{ $sc-ellipsis }# is looked up in the lexical environment of X. If the
binding is found and has binding-type 'ellipsis', then X is compared to
the identifier stored in the binding using 'bound-id=?'. Otherwise, X
is compared to '...' using 'free-id=?' as was done before.
After much thought, I'm fairly confident that this is the only good
approach. I'd like to push this to stable-2.0.
Comments and suggestions welcome.
>From 619bb46010696f232f09f124049739becfe94611 Mon Sep 17 00:00:00 2001
From: Mark H Weaver <address@hidden>
Date: Wed, 18 Dec 2013 18:49:37 -0500
Subject: [PATCH] psyntax: custom ellipses using 'with-ellipsis' or R7RS
syntax-rules.
* module/ice-9/psyntax.scm (binding-type): Update the header comment
to mention the new 'ellipsis' binding type.
(ellipsis?): Add 'r' and 'mod' as arguments. Search the lexical
environment for an ellipsis binding, and use it.
(gen-syntax): Adapt to the additional arguments of 'ellipsis?'.
(with-ellipsis): New core syntax.
(convert-pattern): Add unary 'ellipsis?' procedure as an argument.
(gen-clause): Adapt to the additional arguments of 'ellipsis?'.
Pass unary 'ellipsis?' procedure to 'convert-pattern'.
(syntax-case): Adapt to the additional arguments of 'ellipsis?'.
(syntax-local-binding): Support new 'ellipsis' binding type.
(syntax-rules): Add support for a custom ellipsis identifier as
the first operand, as per R7RS. Collect common code within new
local procedure 'expand-syntax-rules'.
* module/ice-9/psyntax-pp.scm: Regenerate.
* module/ice-9/local-eval.scm (analyze-identifiers): Add support for
'ellipsis' binding type.
* doc/ref/api-macros.texi (Syntax Rules): Add docs for R7RS custom
ellipsis syntax. Use @dots{}.
(Syntax Case): Add docs for 'with-ellipsis'. Use @dots{}.
(Syntax Transformer Helpers): Update to include new 'ellipsis'
binding type.
* test-suite/tests/syntax.test: Add tests.
---
doc/ref/api-macros.texi | 73 +++++++++++++-
module/ice-9/local-eval.scm | 8 ++-
module/ice-9/psyntax-pp.scm | 225 ++++++++++++++++++++++++++++++------------
module/ice-9/psyntax.scm | 108 +++++++++++++++-----
test-suite/tests/syntax.test | 106 ++++++++++++++++++++-
5 files changed, 423 insertions(+), 97 deletions(-)
diff --git a/doc/ref/api-macros.texi b/doc/ref/api-macros.texi
index a3fa83f..61137f0 100644
--- a/doc/ref/api-macros.texi
+++ b/doc/ref/api-macros.texi
@@ -136,7 +136,7 @@ same @var{letrec-syntax}.
@code{syntax-rules} macros are simple, pattern-driven syntax transformers, with
a beauty worthy of Scheme.
address@hidden {Syntax} syntax-rules literals (pattern template)...
address@hidden {Syntax} syntax-rules literals (pattern template) @dots{}
Create a syntax transformer that will rewrite an expression using the rules
embodied in the @var{pattern} and @var{template} clauses.
@end deffn
@@ -363,6 +363,26 @@ Cast into this form, our @code{when} example is
significantly shorter:
(if c (begin e ...)))
@end example
address@hidden Specifying a custom ellipsis identifier
+
+When writing macros that generate macro definitions, it is convenient to
+use a different ellipsis identifier at each level. Guile allows the
+desired ellipsis identifier to be specified as the first operand to
address@hidden, as per R7RS. For example:
+
address@hidden
+(define-syntax define-quotation-macros
+ (syntax-rules ()
+ ((_ (macro-name head-symbol) ...)
+ (begin (define-syntax macro-name
+ (syntax-rules ::: ()
+ ((_ x :::)
+ (quote (head-symbol x :::)))))
+ ...))))
+(define-quotation-macros (quote-a a) (quote-b b) (quote-c c))
+(quote-a 1 2 3) @result{} (a 1 2 3)
address@hidden example
+
@subsubsection Further Information
For a formal definition of @code{syntax-rules} and its pattern language, see
@@ -389,7 +409,7 @@ Primer for the Merely Eccentric}.
@code{syntax-case} macros are procedural syntax transformers, with a power
worthy of Scheme.
address@hidden {Syntax} syntax-case syntax literals (pattern [guard] exp)...
address@hidden {Syntax} syntax-case syntax literals (pattern [guard] exp)
@dots{}
Match the syntax object @var{syntax} against the given patterns, in order. If a
@var{pattern} matches, return the result of evaluating the associated
@var{exp}.
@end deffn
@@ -631,9 +651,9 @@ variable environment, and we can do so using
@code{syntax-case} itself:
However there are easier ways to write this. @code{with-syntax} is often
convenient:
address@hidden {Syntax} with-syntax ((pat val)...) exp...
address@hidden {Syntax} with-syntax ((pat val) @dots{}) exp @dots{}
Bind patterns @var{pat} from their corresponding values @var{val}, within the
-lexical context of @var{exp...}.
+lexical context of @var{exp} @enddots{}.
@example
;; better
@@ -681,6 +701,44 @@ edition 3 or 4, in the chapter on syntax. Dybvig was the
primary author of the
@code{syntax-case} system. The book itself is available online at
@uref{http://scheme.com/tspl4/}.
address@hidden Custom ellipsis identifiers for syntax-case macros
+
+When writing procedural macros that generate macro definitions, it is
+convenient to use a different ellipsis identifier at each level. Guile
+supports this for procedural macros using the @code{with-ellipsis}
+special form:
+
address@hidden {Syntax} with-ellipsis ellipsis body @dots{}
address@hidden must be an identifier. Evaluate @var{body} in a special
+lexical environment such that all macro patterns and templates within
address@hidden will use @var{ellipsis} as the ellipsis identifier instead of
+the usual three dots (@code{...}).
address@hidden deffn
+
+For example:
+
address@hidden
+(define-syntax define-quotation-macros
+ (lambda (x)
+ (syntax-case x ()
+ ((_ (macro-name head-symbol) ...)
+ #'(begin (define-syntax macro-name
+ (lambda (x)
+ (with-ellipsis :::
+ (syntax-case x ()
+ ((_ x :::)
+ #'(quote (head-symbol x :::)))))))
+ ...)))))
+(define-quotation-macros (quote-a a) (quote-b b) (quote-c c))
+(quote-a 1 2 3) @result{} (a 1 2 3)
address@hidden example
+
+Note that the effect of @code{with-ellipsis} does not propagate within
+nested syntax binding forms such as @code{define-syntax},
address@hidden, or @code{letrec-syntax}. It also does not affect the
+ellipsis identifier of the generated code, unless @code{with-ellipsis}
+is included around the generated code.
+
@node Syntax Transformer Helpers
@subsection Syntax Transformer Helpers
@@ -740,8 +798,11 @@ of @code{eq?}) identifying this binding.
A syntax transformer, either local or global. The value is the
transformer procedure.
@item pattern-variable
-A pattern variable, bound via syntax-case. The value is an opaque
-object, internal to the expander.
+A pattern variable, bound via @code{syntax-case}. The value is an
+opaque object, internal to the expander.
address@hidden ellipsis
+An internal binding, bound via @code{with-ellipsis}. The value is the
+(anti-marked) local ellipsis identifier.
@item displaced-lexical
A lexical variable that has gone out of scope. This can happen if a
badly-written procedural macro saves a syntax object, then attempts to
diff --git a/module/ice-9/local-eval.scm b/module/ice-9/local-eval.scm
index 28f30b9..bd3588b 100644
--- a/module/ice-9/local-eval.scm
+++ b/module/ice-9/local-eval.scm
@@ -1,6 +1,6 @@
;;; -*- mode: scheme; coding: utf-8; -*-
;;;
-;;; Copyright (C) 2012 Free Software Foundation, Inc.
+;;; Copyright (C) 2012, 2013 Free Software Foundation, Inc.
;;;
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
@@ -179,6 +179,12 @@
(cdr val)
t)
patterns))))
+ ((ellipsis)
+ (lp ids capture formals
+ (cons (lambda (x)
+ #`(with-ellipsis #,val #,x))
+ wrappers)
+ patterns))
(else
(error "what" type val))))))))))
diff --git a/module/ice-9/psyntax-pp.scm b/module/ice-9/psyntax-pp.scm
index f5f764b..a9015b2 100644
--- a/module/ice-9/psyntax-pp.scm
+++ b/module/ice-9/psyntax-pp.scm
@@ -1096,9 +1096,17 @@
(syntax-violation #f "nonprocedure transformer" p)))))
(expand-void (lambda () (build-void #f)))
(ellipsis?
- (lambda (x)
- (and (nonsymbol-id? x)
- (free-id=? x '#(syntax-object ... ((top)) (hygiene guile))))))
+ (lambda (e r mod)
+ (and (nonsymbol-id? e)
+ (let* ((id (make-syntax-object
+ '#{ $sc-ellipsis }#
+ (syntax-object-wrap e)
+ (syntax-object-module e)))
+ (n (id-var-name id '(())))
+ (b (lookup n r mod)))
+ (if (eq? (car b) 'ellipsis)
+ (bound-id=? e (cdr b))
+ (free-id=? e '#(syntax-object ... ((top)) (hygiene
guile))))))))
(lambda-formals
(lambda (orig-args)
(letrec*
@@ -1567,14 +1575,15 @@
(let ((var.lev (cdr b)))
(gen-ref src (car var.lev) (cdr var.lev) maps)))
(lambda (var maps) (values (list 'ref var) maps))))
- ((ellipsis? e) (syntax-violation 'syntax "misplaced
ellipsis" src))
+ ((ellipsis? e r mod)
+ (syntax-violation 'syntax "misplaced ellipsis" src))
(else (values (list 'quote e) maps))))
(let* ((tmp e) (tmp-1 ($sc-dispatch tmp '(any any))))
- (if (and tmp-1 (apply (lambda (dots e) (ellipsis? dots)) tmp-1))
- (apply (lambda (dots e) (gen-syntax src e r maps (lambda (x)
#f) mod))
+ (if (and tmp-1 (apply (lambda (dots e) (ellipsis? dots r mod))
tmp-1))
+ (apply (lambda (dots e) (gen-syntax src e r maps (lambda (e r
mod) #f) mod))
tmp-1)
(let ((tmp-1 ($sc-dispatch tmp '(any any . any))))
- (if (and tmp-1 (apply (lambda (x dots y) (ellipsis? dots))
tmp-1))
+ (if (and tmp-1 (apply (lambda (x dots y) (ellipsis? dots r
mod)) tmp-1))
(apply (lambda (x dots y)
(let f ((y y)
(k (lambda (maps)
@@ -1585,7 +1594,7 @@
(syntax-violation 'syntax
"extra ellipsis" src)
(values (gen-map x (car
maps)) (cdr maps))))))))
(let* ((tmp y) (tmp ($sc-dispatch tmp '(any .
any))))
- (if (and tmp (apply (lambda (dots y)
(ellipsis? dots)) tmp))
+ (if (and tmp (apply (lambda (dots y)
(ellipsis? dots r mod)) tmp))
(apply (lambda (dots y)
(f y
(lambda (maps)
@@ -1810,6 +1819,30 @@
(syntax-violation 'case-lambda "bad case-lambda*" e))))))))
(global-extend
'core
+ 'with-ellipsis
+ (lambda (e r w s mod)
+ (let* ((tmp e) (tmp ($sc-dispatch tmp '(_ any any . each-any))))
+ (if (and tmp (apply (lambda (dots e1 e2) (id? dots)) tmp))
+ (apply (lambda (dots e1 e2)
+ (let ((id (if (symbol? dots)
+ '#{ $sc-ellipsis }#
+ (make-syntax-object
+ '#{ $sc-ellipsis }#
+ (syntax-object-wrap dots)
+ (syntax-object-module dots)))))
+ (let ((ids (list id))
+ (labels (list (gen-label)))
+ (bindings (list (cons 'ellipsis (source-wrap dots w
s mod)))))
+ (let ((nw (make-binding-wrap ids labels w))
+ (nr (extend-env labels bindings r)))
+ (expand-body (cons e1 e2) (source-wrap e nw s mod) nr
nw mod)))))
+ tmp)
+ (syntax-violation
+ 'with-ellipsis
+ "bad syntax"
+ (source-wrap e w s mod))))))
+ (global-extend
+ 'core
'let
(letrec*
((expand-let
@@ -2069,7 +2102,7 @@
'syntax-case
(letrec*
((convert-pattern
- (lambda (pattern keys)
+ (lambda (pattern keys ellipsis?)
(letrec*
((cvt* (lambda (p* n ids)
(let* ((tmp p*) (tmp ($sc-dispatch tmp '(any . any))))
@@ -2163,9 +2196,10 @@
(gen-clause
(lambda (x keys clauses r pat fender exp mod)
(call-with-values
- (lambda () (convert-pattern pat keys))
+ (lambda ()
+ (convert-pattern pat keys (lambda (e) (ellipsis? e r mod))))
(lambda (p pvars)
- (cond ((not (and-map (lambda (x) (not (ellipsis? (car x))))
pvars))
+ (cond ((not (and-map (lambda (x) (not (ellipsis? (car x) r
mod))) pvars))
(syntax-violation 'syntax-case "misplaced ellipsis" pat))
((not (distinct-bound-ids? (map car pvars)))
(syntax-violation 'syntax-case "duplicate pattern
variable" pat))
@@ -2245,7 +2279,7 @@
(tmp ($sc-dispatch tmp-1 '(_ any each-any . each-any))))
(if tmp
(apply (lambda (val key m)
- (if (and-map (lambda (x) (and (id? x) (not (ellipsis?
x)))) key)
+ (if (and-map (lambda (x) (and (id? x) (not (ellipsis? x r
mod)))) key)
(let ((x (gen-var 'tmp)))
(build-application
s
@@ -2361,6 +2395,13 @@
((memv key '(syntax)) (values 'pattern-variable
value))
((memv key '(displaced-lexical)) (values
'displaced-lexical #f))
((memv key '(global)) (values 'global (cons value
(cdr mod))))
+ ((memv key '(ellipsis))
+ (values
+ 'ellipsis
+ (make-syntax-object
+ (syntax-object-expression value)
+ (anti-mark (syntax-object-wrap value))
+ (syntax-object-module value))))
(else (values 'other #f)))))))))))
(syntax-locally-bound-identifiers
(lambda (id)
@@ -2547,56 +2588,116 @@
'syntax-rules
'macro
(lambda (xx)
- (let ((tmp-1 xx))
- (let ((tmp ($sc-dispatch tmp-1 '(_ each-any . #(each ((any . any)
any))))))
- (if tmp
- (apply (lambda (k keyword pattern template)
- (list '#(syntax-object lambda ((top)) (hygiene guile))
- '(#(syntax-object x ((top)) (hygiene guile)))
- (vector
- '(#(syntax-object macro-type ((top)) (hygiene
guile))
- .
- #(syntax-object syntax-rules ((top)) (hygiene
guile)))
- (cons '#(syntax-object patterns ((top)) (hygiene
guile)) pattern))
- (cons '#(syntax-object syntax-case ((top)) (hygiene
guile))
- (cons '#(syntax-object x ((top)) (hygiene
guile))
- (cons k
- (map (lambda (tmp-1 tmp)
- (list (cons
'#(syntax-object dummy ((top)) (hygiene guile)) tmp)
- (list
'#(syntax-object syntax ((top)) (hygiene guile))
- tmp-1)))
- template
- pattern))))))
- tmp)
- (let ((tmp ($sc-dispatch tmp-1 '(_ each-any any . #(each ((any .
any) any))))))
- (if (if tmp
- (apply (lambda (k docstring keyword pattern template)
- (string? (syntax->datum docstring)))
- tmp)
- #f)
- (apply (lambda (k docstring keyword pattern template)
- (list '#(syntax-object lambda ((top)) (hygiene guile))
- '(#(syntax-object x ((top)) (hygiene guile)))
- docstring
- (vector
- '(#(syntax-object macro-type ((top)) (hygiene
guile))
- .
- #(syntax-object syntax-rules ((top))
(hygiene guile)))
- (cons '#(syntax-object patterns ((top))
(hygiene guile)) pattern))
- (cons '#(syntax-object syntax-case ((top))
(hygiene guile))
- (cons '#(syntax-object x ((top)) (hygiene
guile))
- (cons k
- (map (lambda (tmp-1 tmp)
- (list (cons
'#(syntax-object dummy ((top)) (hygiene guile)) tmp)
- (list
'#(syntax-object syntax ((top)) (hygiene guile))
- tmp-1)))
- template
- pattern))))))
- tmp)
- (syntax-violation
- #f
- "source expression failed to match any pattern"
- tmp-1)))))))))
+ (letrec*
+ ((expand-syntax-rules
+ (lambda (dots keys docstrings clauses)
+ (let ((tmp-1 (list keys docstrings clauses)))
+ (let ((tmp ($sc-dispatch tmp-1 '(each-any each-any #(each ((any
. any) any))))))
+ (if tmp
+ (apply (lambda (k docstring keyword pattern template)
+ (let ((tmp (cons '#(syntax-object lambda ((top))
(hygiene guile))
+ (cons '(#(syntax-object x ((top))
(hygiene guile)))
+ (append
+ docstring
+ (list (vector
+ '(#(syntax-object
macro-type ((top)) (hygiene guile))
+ .
+ #(syntax-object
syntax-rules ((top)) (hygiene guile)))
+ (cons
'#(syntax-object patterns ((top)) (hygiene guile))
+ pattern))
+ (cons
'#(syntax-object syntax-case ((top)) (hygiene guile))
+ (cons
'#(syntax-object x ((top)) (hygiene guile))
+ (cons k
+
(map (lambda (tmp-1 tmp)
+
(list (cons '#(syntax-object
+
dummy
+
((top))
+
(hygiene guile))
+
tmp)
+
(list '#(syntax-object
+
syntax
+
((top))
+
(hygiene guile))
+
tmp-1)))
+
template
+
pattern))))))))))
+ (let ((form tmp))
+ (if dots
+ (let ((tmp dots))
+ (let ((dots tmp))
+ (list '#(syntax-object with-ellipsis
((top)) (hygiene guile))
+ dots
+ form)))
+ form))))
+ tmp)
+ (syntax-violation
+ #f
+ "source expression failed to match any pattern"
+ tmp-1)))))))
+ (let ((tmp xx))
+ (let ((tmp-1 ($sc-dispatch tmp '(_ each-any . #(each ((any . any)
any))))))
+ (if tmp-1
+ (apply (lambda (k keyword pattern template)
+ (expand-syntax-rules
+ #f
+ k
+ '()
+ (map (lambda (tmp-2 tmp-1 tmp) (list (cons tmp tmp-1)
tmp-2))
+ template
+ pattern
+ keyword)))
+ tmp-1)
+ (let ((tmp-1 ($sc-dispatch tmp '(_ each-any any . #(each ((any .
any) any))))))
+ (if (if tmp-1
+ (apply (lambda (k docstring keyword pattern template)
+ (string? (syntax->datum docstring)))
+ tmp-1)
+ #f)
+ (apply (lambda (k docstring keyword pattern template)
+ (expand-syntax-rules
+ #f
+ k
+ (list docstring)
+ (map (lambda (tmp-2 tmp-1 tmp) (list (cons tmp
tmp-1) tmp-2))
+ template
+ pattern
+ keyword)))
+ tmp-1)
+ (let ((tmp-1 ($sc-dispatch tmp '(_ any each-any . #(each
((any . any) any))))))
+ (if (if tmp-1
+ (apply (lambda (dots k keyword pattern template)
(identifier? dots))
+ tmp-1)
+ #f)
+ (apply (lambda (dots k keyword pattern template)
+ (expand-syntax-rules
+ dots
+ k
+ '()
+ (map (lambda (tmp-2 tmp-1 tmp) (list (cons
tmp tmp-1) tmp-2))
+ template
+ pattern
+ keyword)))
+ tmp-1)
+ (let ((tmp-1 ($sc-dispatch tmp '(_ any each-any any .
#(each ((any . any) any))))))
+ (if (if tmp-1
+ (apply (lambda (dots k docstring keyword pattern
template)
+ (if (identifier? dots) (string?
(syntax->datum docstring)) #f))
+ tmp-1)
+ #f)
+ (apply (lambda (dots k docstring keyword pattern
template)
+ (expand-syntax-rules
+ dots
+ k
+ (list docstring)
+ (map (lambda (tmp-2 tmp-1 tmp) (list
(cons tmp tmp-1) tmp-2))
+ template
+ pattern
+ keyword)))
+ tmp-1)
+ (syntax-violation
+ #f
+ "source expression failed to match any pattern"
+ tmp))))))))))))))
(define define-syntax-rule
(make-syntax-transformer
diff --git a/module/ice-9/psyntax.scm b/module/ice-9/psyntax.scm
index fa009d2..143d4c7 100644
--- a/module/ice-9/psyntax.scm
+++ b/module/ice-9/psyntax.scm
@@ -42,6 +42,9 @@
;;; Modified by Andy Wingo <address@hidden> according to the Git
;;; revision control logs corresponding to this file: 2009, 2010.
+;;; Modified by Mark H Weaver <address@hidden> according to the Git
+;;; revision control logs corresponding to this file: 2012, 2013.
+
;;; This code is based on "Syntax Abstraction in Scheme"
;;; by R. Kent Dybvig, Robert Hieb, and Carl Bruggeman.
@@ -509,6 +512,7 @@
;; (syntax . (<var> . <level>)) pattern variables
;; (global) assumed global variable
;; (lexical . <var>) lexical variables
+ ;; (ellipsis . <identifier>) custom ellipsis
;; (displaced-lexical) displaced lexicals
;; <level> ::= <nonnegative integer>
;; <var> ::= variable returned by build-lexical-var
@@ -528,6 +532,9 @@
;; a lexical variable is a lambda- or letrec-bound variable.
+ ;; an ellipsis binding is introduced by the 'with-ellipsis' special
+ ;; form.
+
;; a displaced-lexical identifier is a lexical identifier removed from
;; it's scope by the return of a syntax object containing the identifier.
;; a displaced lexical can also appear when a letrec-syntax-bound
@@ -1574,9 +1581,22 @@
(build-void no-source)))
(define ellipsis?
- (lambda (x)
- (and (nonsymbol-id? x)
- (free-id=? x #'(... ...)))))
+ (lambda (e r mod)
+ (and (nonsymbol-id? e)
+ ;; If there is a binding for the special identifier
+ ;; #{ $sc-ellipsis }# in the lexical environment of E,
+ ;; and if the associated binding type is 'ellipsis',
+ ;; then the binding's value specifies the custom ellipsis
+ ;; identifier within that lexical environment, and the
+ ;; comparison is done using 'bound-id=?'.
+ (let* ((id (make-syntax-object '#{ $sc-ellipsis }#
+ (syntax-object-wrap e)
+ (syntax-object-module e)))
+ (n (id-var-name id empty-wrap))
+ (b (lookup n r mod)))
+ (if (eq? (binding-type b) 'ellipsis)
+ (bound-id=? e (binding-value b))
+ (free-id=? e #'(... ...)))))))
(define lambda-formals
(lambda (orig-args)
@@ -1901,17 +1921,17 @@
(let ((var.lev (binding-value b)))
(gen-ref src (car var.lev) (cdr
var.lev) maps)))
(lambda (var maps) (values `(ref ,var)
maps)))
- (if (ellipsis? e)
+ (if (ellipsis? e r mod)
(syntax-violation 'syntax "misplaced
ellipsis" src)
(values `(quote ,e) maps)))))
(syntax-case e ()
((dots e)
- (ellipsis? #'dots)
- (gen-syntax src #'e r maps (lambda (x) #f)
mod))
+ (ellipsis? #'dots r mod)
+ (gen-syntax src #'e r maps (lambda (e r mod)
#f) mod))
((x dots . y)
;; this could be about a dozen lines of code,
except that we
;; choose to handle #'(x ... ...) forms
- (ellipsis? #'dots)
+ (ellipsis? #'dots r mod)
(let f ((y #'y)
(k (lambda (maps)
(call-with-values
@@ -1926,7 +1946,7 @@
(cdr maps))))))))
(syntax-case y ()
((dots . y)
- (ellipsis? #'dots)
+ (ellipsis? #'dots r mod)
(f #'y
(lambda (maps)
(call-with-values
@@ -2119,6 +2139,25 @@
#'((args e1 e2 ...) ...)))
(_ (syntax-violation 'case-lambda "bad case-lambda*"
e)))))
+ (global-extend 'core 'with-ellipsis
+ (lambda (e r w s mod)
+ (syntax-case e ()
+ ((_ dots e1 e2 ...)
+ (id? #'dots)
+ (let ((id (if (symbol? #'dots)
+ '#{ $sc-ellipsis }#
+ (make-syntax-object '#{ $sc-ellipsis }#
+ (syntax-object-wrap
#'dots)
+
(syntax-object-module #'dots)))))
+ (let ((ids (list id))
+ (labels (list (gen-label)))
+ (bindings (list (make-binding 'ellipsis
(source-wrap #'dots w s mod)))))
+ (let ((nw (make-binding-wrap ids labels w))
+ (nr (extend-env labels bindings r)))
+ (expand-body #'(e1 e2 ...) (source-wrap e nw s
mod) nr nw mod)))))
+ (_ (syntax-violation 'with-ellipsis "bad syntax"
+ (source-wrap e w s mod))))))
+
(global-extend 'core 'let
(let ()
(define (expand-let e r w s mod constructor ids vals exps)
@@ -2338,7 +2377,7 @@
(define convert-pattern
;; accepts pattern & keys
;; returns $sc-dispatch pattern & ids
- (lambda (pattern keys)
+ (lambda (pattern keys ellipsis?)
(define cvt*
(lambda (p* n ids)
(syntax-case p* ()
@@ -2427,10 +2466,10 @@
(define gen-clause
(lambda (x keys clauses r pat fender exp mod)
(call-with-values
- (lambda () (convert-pattern pat keys))
+ (lambda () (convert-pattern pat keys (lambda (e)
(ellipsis? e r mod))))
(lambda (p pvars)
(cond
- ((not (and-map (lambda (x) (not (ellipsis? (car
x)))) pvars))
+ ((not (and-map (lambda (x) (not (ellipsis? (car
x) r mod))) pvars))
(syntax-violation 'syntax-case "misplaced
ellipsis" pat))
((not (distinct-bound-ids? (map car pvars)))
(syntax-violation 'syntax-case "duplicate
pattern variable" pat))
@@ -2500,7 +2539,7 @@
(let ((e (source-wrap e w s mod)))
(syntax-case e ()
((_ val (key ...) m ...)
- (if (and-map (lambda (x) (and (id? x) (not
(ellipsis? x))))
+ (if (and-map (lambda (x) (and (id? x) (not
(ellipsis? x r mod))))
#'(key ...))
(let ((x (gen-var 'tmp)))
;; fat finger binding and references to temp
variable x
@@ -2604,6 +2643,11 @@
((syntax) (values 'pattern-variable value))
((displaced-lexical) (values 'displaced-lexical #f))
((global) (values 'global (cons value (cdr mod))))
+ ((ellipsis)
+ (values 'ellipsis
+ (make-syntax-object (syntax-object-expression value)
+ (anti-mark (syntax-object-wrap
value))
+ (syntax-object-module value))))
(else (values 'other #f))))))))
(define (syntax-locally-bound-identifiers id)
@@ -2797,25 +2841,35 @@
(define-syntax syntax-rules
(lambda (xx)
+ (define (expand-syntax-rules dots keys docstrings clauses)
+ (with-syntax
+ (((k ...) keys)
+ ((docstring ...) docstrings)
+ ((((keyword . pattern) template) ...) clauses))
+ (with-syntax
+ ((form #'(lambda (x)
+ docstring ... ; optional docstring
+ #((macro-type . syntax-rules)
+ (patterns pattern ...)) ; embed patterns as procedure
metadata
+ (syntax-case x (k ...)
+ ((dummy . pattern) #'template)
+ ...))))
+ (if dots
+ (with-syntax ((dots dots))
+ #'(with-ellipsis dots form))
+ #'form))))
(syntax-case xx ()
((_ (k ...) ((keyword . pattern) template) ...)
- #'(lambda (x)
- ;; embed patterns as procedure metadata
- #((macro-type . syntax-rules)
- (patterns pattern ...))
- (syntax-case x (k ...)
- ((dummy . pattern) #'template)
- ...)))
+ (expand-syntax-rules #f #'(k ...) #'() #'(((keyword . pattern)
template) ...)))
((_ (k ...) docstring ((keyword . pattern) template) ...)
(string? (syntax->datum #'docstring))
- #'(lambda (x)
- ;; the same, but allow a docstring
- docstring
- #((macro-type . syntax-rules)
- (patterns pattern ...))
- (syntax-case x (k ...)
- ((dummy . pattern) #'template)
- ...))))))
+ (expand-syntax-rules #f #'(k ...) #'(docstring) #'(((keyword . pattern)
template) ...)))
+ ((_ dots (k ...) ((keyword . pattern) template) ...)
+ (identifier? #'dots)
+ (expand-syntax-rules #'dots #'(k ...) #'() #'(((keyword . pattern)
template) ...)))
+ ((_ dots (k ...) docstring ((keyword . pattern) template) ...)
+ (and (identifier? #'dots) (string? (syntax->datum #'docstring)))
+ (expand-syntax-rules #'dots #'(k ...) #'(docstring) #'(((keyword .
pattern) template) ...))))))
(define-syntax define-syntax-rule
(lambda (x)
diff --git a/test-suite/tests/syntax.test b/test-suite/tests/syntax.test
index 6fac0ba..142e2e5 100644
--- a/test-suite/tests/syntax.test
+++ b/test-suite/tests/syntax.test
@@ -1,7 +1,7 @@
;;;; syntax.test --- test suite for Guile's syntactic forms -*- scheme -*-
;;;;
;;;; Copyright (C) 2001, 2003, 2004, 2005, 2006, 2009, 2010,
-;;;; 2011, 2012 Free Software Foundation, Inc.
+;;;; 2011, 2012, 2013 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
@@ -19,6 +19,7 @@
(define-module (test-suite test-syntax)
#:use-module (ice-9 regex)
+ #:use-module (ice-9 local-eval)
#:use-module (test-suite lib))
@@ -1172,6 +1173,44 @@
(r 'outer))
#t)))
+(with-test-prefix "syntax-rules"
+
+ (pass-if-equal "custom ellipsis within normal ellipsis"
+ '((((a x) (a y) (a …))
+ ((b x) (b y) (b …))
+ ((c x) (c y) (c …)))
+ (((a x) (b x) (c x))
+ ((a y) (b y) (c y))
+ ((a …) (b …) (c …))))
+ (let ()
+ (define-syntax foo
+ (syntax-rules ()
+ ((_ y ...)
+ (syntax-rules … ()
+ ((_ x …)
+ '((((x y) ...) …)
+ (((x y) …) ...)))))))
+ (define-syntax bar (foo x y …))
+ (bar a b c)))
+
+ (pass-if-equal "normal ellipsis within custom ellipsis"
+ '((((a x) (a y) (a z))
+ ((b x) (b y) (b z))
+ ((c x) (c y) (c z)))
+ (((a x) (b x) (c x))
+ ((a y) (b y) (c y))
+ ((a z) (b z) (c z))))
+ (let ()
+ (define-syntax foo
+ (syntax-rules … ()
+ ((_ y …)
+ (syntax-rules ()
+ ((_ x ...)
+ '((((x y) …) ...)
+ (((x y) ...) …)))))))
+ (define-syntax bar (foo x y z))
+ (bar a b c))))
+
(with-test-prefix "syntax-case"
(pass-if-syntax-error "duplicate pattern variable"
@@ -1225,6 +1264,71 @@
((x ... y ... z ...) #f)))
(interaction-environment)))))
+(with-test-prefix "with-ellipsis"
+
+ (pass-if-equal "simple"
+ '(a 1 2 3)
+ (let ()
+ (define-syntax define-quotation-macros
+ (lambda (x)
+ (syntax-case x ()
+ ((_ (macro-name head-symbol) ...)
+ #'(begin (define-syntax macro-name
+ (lambda (x)
+ (with-ellipsis …
+ (syntax-case x ()
+ ((_ x …)
+ #'(quote (head-symbol x …)))))))
+ ...)))))
+ (define-quotation-macros (quote-a a) (quote-b b))
+ (quote-a 1 2 3)))
+
+ (pass-if-equal "disables normal ellipsis"
+ '(a ...)
+ (let ()
+ (define-syntax foo
+ (lambda (x)
+ (with-ellipsis …
+ (syntax-case x ()
+ ((_)
+ #'(quote (a ...)))))))
+ (foo)))
+
+ (pass-if-equal "doesn't affect ellipsis for generated code"
+ '(a b c)
+ (let ()
+ (define-syntax quotation-macro
+ (lambda (x)
+ (with-ellipsis …
+ (syntax-case x ()
+ ((_)
+ #'(lambda (x)
+ (syntax-case x ()
+ ((_ x ...)
+ #'(quote (x ...))))))))))
+ (define-syntax kwote (quotation-macro))
+ (kwote a b c)))
+
+ (pass-if-equal "doesn't propagate into syntax binders"
+ '(a b c)
+ (let ()
+ (with-ellipsis …
+ (define-syntax kwote
+ (lambda (x)
+ (syntax-case x ()
+ ((_ x ...)
+ #'(quote (x ...))))))
+ (kwote a b c))))
+
+ (pass-if-equal "works with local-eval"
+ 5
+ (let ((env (with-ellipsis … (the-environment))))
+ (local-eval '(syntax-case #'(a b c d e) ()
+ ((x …)
+ (length #'(x …))))
+ env))))
+
;;; Local Variables:
;;; eval: (put 'pass-if-syntax-error 'scheme-indent-function 1)
+;;; eval: (put 'with-ellipsis 'scheme-indent-function 1)
;;; End:
--
1.7.5.4
| [Prev in Thread] |
Current Thread |
[Next in Thread] |
- [PATCH] psyntax: custom ellipses using 'with-ellipsis' or R7RS syntax-rules,
Mark H Weaver <=