b752dcddef
Fix totally broken handling of structs with immutable fields, as reported in bug 7398. svn: r354
190 lines
7.4 KiB
Scheme
190 lines
7.4 KiB
Scheme
;; (documentation (name match))
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;; <pre>Pattern Matching Syntactic Extensions for Scheme
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;;
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;; Special thanks go out to:
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;; Robert Bruce Findler for support and bug detection.
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;; Doug Orleans for pointing out that pairs should be reused while
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;; matching lists.
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;;
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;; Originally written by Andrew K. Wright, 1993 (wright@research.nj.nec.com)
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;; which in turn was adapted from code written by Bruce F. Duba, 1991.
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;;
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;; This macro package extends Scheme with several new expression forms.
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;; Following is a brief summary of the new forms. See the associated
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;; LaTeX documentation for a full description of their functionality.
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;;
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;;
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;; match expressions:
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;;
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;; exp ::= ...
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;; | (match exp clause ...)
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;; | (match-lambda clause ...)
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;; | (match-lambda* clause ...)
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;; | (match-let ((pat exp) ...) body ...)
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;; | (match-let var ((pat exp) ...) body ...)
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;; | (match-let* ((pat exp) ...) body ...)
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;; | (match-letrec ((pat exp) ...) body ...)
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;; | (match-define pat exp)
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;;
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;; clause ::= (pat body) | (pat (=> identifier) exp)
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;;
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;; patterns: matches:
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;;
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;; pat ::=
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;; identifier this binds an identifier if it
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;; doesn't conflict with
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;; ..k, var, $, =, and,
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;; or, not, ?, set!, or get!
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;; | _ anything
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;; | () the empty list
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;; | #t #t
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;; | #f #f
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;; | string a string
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;; | number a number
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;; | character a character
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;; | 'sexp an s-expression
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;; | 'symbol a symbol (special case of s-expr)
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;; | (lvp_1 ... lvp_n) list of n elements
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;; | (pat ... pat_n . pat_{n+1}) list of n or more
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;; | #(lvp_1 ... lvp_n) vector of n elements
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;; | #&pat box
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;; | ($ struct-name pat_1 ... pat_n) a structure
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;; | (= field pat) a field of a structure (field is
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;; an accessor)
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;; Actually field can be any function
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;; which can be
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;; applied to the data being matched.
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;; Ex: (match 5 ((= add1 b) b)) => 6
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;;
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;; | (and pat_1 ... pat_n) if all of pat_1 thru pat_n match
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;; | (or pat_1 ... pat_n) if any of pat_1 thru pat_n match
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;; | (not pat_1 ... pat_n) if all pat_1 thru pat_n don't match
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;; | (? predicate pat_1 ... pat_n) if predicate true and all of
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;; pat_1 thru pat_n match
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;; | (set! identifier) anything, and binds setter
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;; | (get! identifier) anything, and binds getter
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;; | `qp a quasi-pattern
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;;
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;; lvp ::= pat ooo greedily matches n or more of pat,
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;; each element must match pat
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;; | pat matches pat
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;;
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;; ooo ::= ... zero or more
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;; | ___ zero or more
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;; | ..k k or more
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;; | __k k or more
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;;
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;; quasi-patterns: matches:
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;;
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;; qp ::= () the empty list
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;; | #t #t
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;; | #f #f
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;; | string a string
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;; | number a number
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;; | character a character
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;; | identifier a symbol
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;; | (qp_1 ... qp_n) list of n elements
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;; | (qp_1 ... qp_n . qp_{n+1}) list of n or more
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;; | (qp_1 ... qp_n qp_n+1 ooo) list of n or more, each element
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;; of remainder must match qp_n+1
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;; | #(qp_1 ... qp_n) vector of n elements
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;; | #(qp_1 ... qp_n qp_n+1 ooo) vector of n or more, each element
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;; of remainder must match qp_n+1
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;; | #&qp box
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;; | ,pat a pattern
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;; | ,@(lvp . . . lvp-n)
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;; | ,@(pat . . . pat_n . pat_{n+1})
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;; | ,@`qp qp must evaluate to a list as
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;; so that this rule resembles the
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;; above two rules
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;;
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;; The names (quote, quasiquote, unquote, unquote-splicing, ?, _, $,
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;; and, or, not, set!, get!, list-no-order, hash-table, ..., ___)
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;; cannot be used as pattern variables.</pre>
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(module match mzscheme
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(provide
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match
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match-lambda
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match-lambda*
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match-let
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match-let*
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match-letrec
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match-define
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match-equality-test
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exn:misc:match?
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exn:misc:match-value
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define-match-expander
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match:test-no-order)
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;; FIXME: match-helper and match-error should each be split
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;; into a compile-time part and a run-time part.
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(require-for-syntax "private/convert-pat.ss"
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"private/match-helper.ss")
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(require (prefix plt: "private/match-internal-func.ss")
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"private/match-expander.ss"
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"private/match-helper.ss"
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"private/match-error.ss"
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"private/test-no-order.ss")
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(define-syntax (match-lambda stx)
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(syntax-case stx ()
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[(k clause ...)
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(with-syntax ([(new-clauses ...) (handle-clauses #'(clause ...))])
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#'(plt:match-lambda new-clauses ...))]))
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(define-syntax (match-lambda* stx)
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(syntax-case stx ()
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[(k clause ...)
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(with-syntax ([(new-clauses ...) (handle-clauses #'(clause ...))])
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#'(plt:match-lambda* new-clauses ...))]))
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(define-syntax (match-let stx)
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(syntax-case stx ()
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[(k name (clauses ...) body ...)
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(identifier? (syntax name))
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(with-syntax ([(new-clauses ...) (handle-clauses #'(clauses ...))])
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#'(plt:match-let name (new-clauses ...) body ...))]
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[(k (clauses ...) body ...)
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(with-syntax ([(new-clauses ...) (handle-clauses #'(clauses ...))])
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#'(plt:match-let (new-clauses ...) body ...))]))
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(define-syntax (match-let* stx)
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(syntax-case stx ()
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[(k (clauses ...) body ...)
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(with-syntax
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([(new-clauses ...) (handle-clauses #'(clauses ...))])
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#'(plt:match-let* (new-clauses ...) body ...))]))
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(define-syntax (match stx)
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(syntax-case stx ()
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[(_ exp clause ...)
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(with-syntax
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([(new-clauses ...) (handle-clauses #'(clause ...))])
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#'(plt:match exp new-clauses ...))]))
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(define-syntax (match-letrec stx)
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(syntax-case stx ()
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[(k (clauses ...) body ...)
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(with-syntax
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([(new-clauses ...) (handle-clauses #'(clauses ...))])
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#'(plt:match-letrec (new-clauses ...) body ...))]))
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(define-syntax (match-define stx)
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(syntax-case stx ()
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[(k pat exp)
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(with-syntax ([new-pat (convert-pat #'pat)])
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#'(plt:match-define new-pat exp))]))
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)
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