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preserves
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Special cases for label[...] and label{...}

This commit is contained in:
Tony Garnock-Jones 2018-10-08 20:53:53 +01:00
parent c02e790f71
commit 8dc6346c58
2 changed files with 16 additions and 8 deletions
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18
implementations/racket/preserves/main.rkt
View File

@ -283,8 +283,8 @@
(define (read-sequence terminator) (define (read-sequence terminator)
(sequence-fold '() (lambda (acc) (cons (read-value) acc)) reverse terminator)) (sequence-fold '() (lambda (acc) (cons (read-value) acc)) reverse terminator))
(define (read-dictionary-or-set) (define (read-dictionary-or-set seed)
(sequence-fold #f (sequence-fold seed
(lambda (acc) (lambda (acc)
(define k (read-value)) (define k (read-value))
(skip-whitespace) (skip-whitespace)
@ -447,18 +447,20 @@
(define (collect-fields head) (define (collect-fields head)
(match (peek-char i) (match (peek-char i)
[#\( [#\( (read-char i)
(read-char i) (collect-fields (build-record head (read-sequence #\))))]
(collect-fields (build-record head (read-sequence #\))))] [#\[ (read-char i)
[_ (collect-fields (build-record head (list (read-sequence #\]))))]
head])) [#\{ (read-char i)
(collect-fields (build-record head (list (read-dictionary-or-set (hash)))))]
[_ head]))
(define (read-value) (define (read-value)
(skip-whitespace) (skip-whitespace)
(collect-fields (collect-fields
(match (peek-char i) (match (peek-char i)
[(? eof-object? o) o] [(? eof-object? o) o]
[#\{ (read-char i) (read-dictionary-or-set)] [#\{ (read-char i) (read-dictionary-or-set #f)]
[#\[ (read-char i) (read-sequence #\])] [#\[ (read-char i) (read-sequence #\])]
[(or #\- #\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9) (read-number)] [(or #\- #\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9) (read-number)]
[#\" (read-char i) (read-string #\")] [#\" (read-char i) (read-string #\")]

6
preserves.md
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@ -317,6 +317,12 @@ tokens `#set{` and `}`.[^printing-collections]
commas separating, and commas terminating elements or key/value commas separating, and commas terminating elements or key/value
pairs within a collection. pairs within a collection.
The special cases of records with a single field, which is in turn a
sequence or dictionary, may be written omitting the parentheses.
Record =/ Value Sequence
Record =/ Value Dictionary
`Boolean`s are the simple literal strings `#true` and `#false`. `Boolean`s are the simple literal strings `#true` and `#false`.
Boolean = %s"#true" / %s"#false" Boolean = %s"#true" / %s"#false"