/usr/share/gauche-0.9/0.9.4/lib/www/css.scm is in gauche 0.9.4-3.
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;;; css.scm - Generate and parse CSS
;;;
;;; Copyright (c) 2014 Shiro Kawai <shiro@acm.org>
;;;
;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:
;;;
;;; 1. Redistributions of source code must retain the above copyright
;;; notice, this list of conditions and the following disclaimer.
;;;
;;; 2. Redistributions in binary form must reproduce the above copyright
;;; notice, this list of conditions and the following disclaimer in the
;;; documentation and/or other materials provided with the distribution.
;;;
;;; 3. Neither the name of the authors nor the names of its contributors
;;; may be used to endorse or promote products derived from this
;;; software without specific prior written permission.
;;;
;;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
;;; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
;;; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;;; A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
;;; OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
;;; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
;;; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
;;; PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
;;; LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;;;
;; EXPERIMENTAL : API may change
(define-module www.css
(use gauche.generator)
(use gauche.lazy)
(use parser.peg)
(use util.match)
(use text.tree)
(use srfi-13)
(export construct-css simple-selector?
css-parse-file
css-parse-selector-string)
)
(select-module www.css)
;;;
;;; S-expression CSS
;;;
;;; <s-css> : {<ruleset> | <at-rule>} ...
;;; <style-rule> : (style-rule <pattern> <declaration> ...)
;;; | (style-decls <declaration> ...)
;;;
;;; <pattern> : <selector> | (or <selector> ...)
;;; <seletor> : <simple-selector>
;;; | <chained-selector>
;;; <chained-selector> : (<simple-selector> . (<op>? . <chained-selector>))
;;; <op> : > | + | ~
;;; <simple-selector> : <element-name>
;;; | (<element-name> <option> ...)
;;; <option> : (id <name>) ; E#id
;;; | (class <ident>) ; E.class
;;; | (has <ident>) ; E[attrib]
;;; | (= <ident> <attrib-value>) ; E[attrib=val]
;;; | (~= <ident> <attrib-value>) ; E[attrib~=val]
;;; | (:= <ident> <attrib-value>) ; E[attrib|=val]
;;; | (*= <ident> <attrib-value>) ; E[attrib*=val]
;;; | (^= <ident> <attrib-value>) ; E[attrib^=val]
;;; | ($= <ident> <attrib-value>) ; E[attrib$=val]
;;; | (:not <negation-arg>) ; E:not(s)
;;; | (: <ident>) ; E:pseudo-class
;;; | (: (<fn> <ident> ...)) ; E:pseudl-class(arg)
;;; | (:: <ident>) ; E::pseudo-element
;;; <element-name> : <ident> | *
;;; <attrib-value> : <ident> | <string>
;;; <negation-arg> | <element-name> | * | <option> ; except <negation-arg>
;;;
;;; <declaration> : (<ident> <expr> <expr2> ... <important>?)
;;; <important> : !important
;;; <expr> : <term>
;;; | (/ <term> <term> ...)
;;; | (or <term> <term> ...)
;;; | #(<term> <term> ...) ; juxtaposition
;;; <term> : <quantity> | (- <quantity>) | (+ <quantity>)
;;; | <string> | <ident> | <url> | <hexcolor> | <function>
;;; <quantity> : <number>
;;; | (<number> %)
;;; | (<number> <ident>)
;;; <url> | (url <string>)
;;; <hexcolor> | (color <string>) ; <string> must be hexdigits
;;; <function> | (<fn> <arg> ...)
;;; <arg> | <term> | #(<term> ...) | (/ <term> <term> ...)
;;;
;;;
;;; NB: style-decls shouldn't appear in a complete stylesheet, but can
;;; appear when the 'style' attribute of the document is parsed.
;;; It is also useful to render the value for the style attribute.
;;;
;;; NB: Negaton op is :not instead of not, since (not <negation-arg>)
;;; would be ambiguous from the simple node named "not" with one option.
;;
;; Some utilities on S-expr CSS
;;
;; API
;; Returns canonicalized simple selector (element . options) or #f
(define (simple-selector? sel)
(define (option? x)
(match x
[(a b . _) (memq a '(id class has = ~= := *= ^= $= :not : ::))]
[_ #f]))
(match sel
[(? symbol?) (list sel)]
[((? symbol?) (? option?) ...) sel]
[_ #f]))
;;
;; S-expr CSS -> CSS
;;
;; API
(define (construct-css sexpr :optional (oport (current-output-port)))
(define (render top)
(match top
[('style-rule pattern . decls)
(write-tree (render-style-rule pattern decls) oport)
(newline oport)]
[('style-decls . decls)
(write-tree (intersperse ";" (map render-decl decls)))]
[_ (error "invalid or unsupported sexpr css:" top)]))
(define (render-style-rule pattern decls)
`(,(render-pattern pattern) "{"
,(intersperse ";" (map render-decl decls))
"}\n"))
(define (render-pattern pattern)
(match pattern
[('or selector ...) (intersperse "," (map render-selector selector))]
[_ (render-selector pattern)]))
(define (render-selector selector)
(if-let1 s (simple-selector? selector)
(render-simple-selector s)
(let loop ([sels selector])
(cond [(null? sels) '()]
[(simple-selector? (car sels))
=> (^s `(,(render-simple-selector s)" " ,@(loop (cdr sels))))]
[(memq (car sels) '(> + ~)) `(,(car sels) ,@(loop (cdr sels)))]
[else (error "invalid selector in sexpr css:" selector)]))))
(define (render-simple-selector s)
`(,(car s) ,@(map render-options (cdr s))))
(define (render-options op)
(match op
[('id name) `("#" ,name)]
[('class name) `("." ,name)]
[('has name) `("[" ,name "]")]
[((and (or '= '~= '^= '$= '*=) op) ident value)
`("[" ,ident ,op ,(render-attrval value) "]")]
[(':= ident value) `("[" ,ident "|=" ,(render-attrval value) "]")]
[(':not not-arg) `(":(" ,(if (symbol? not-arg)
not-arg
(render-options not-arg)) ")")]
[(': (fn arg ...)) `(":" ,(render-fn fn arg))]
[(': ident) `(":" ,ident)]
[(':: ident) `("::" ,ident)]
[_ (error "invalid selector option:" op)]))
(define (render-attrval val) (if (string? val) (escape-string val) val))
(define (escape-string val)
(if (string-index val #\')
`(#\",(regexp-replace-all* val #/\"/ "\\22") #\")
`(#\',val #\')))
(define (render-fn fn args)
`(,fn "(" ,@(intersperse "," (map render-arg args)) ")"))
(define (render-arg arg)
(match arg
[#(v ...) (intersperse " " (map render-attrval v))]
[(/ v ...) (intersperse "/" (map render-attrval v))]
[v (render-attrval v)]))
(define (render-decl decl)
(match decl
[(ident expr . exprs)
(if (and (pair? exprs)
(eq? (last exprs) '!important))
`(,ident ":" ,@($ intersperse " " $ map render-expr
$ cons expr (drop-right exprs 1))
" !important")
`(,ident ":" ,@($ intersperse " " $ map render-expr
$ cons expr exprs)))]
[_ (error "invalid declaration:" decl)]))
(define (render-expr expr)
(match expr
[('/ term ...) (intersperse "/" (map render-term term))]
[('or term ...) (intersperse "," (map render-expr term))]
[#(term ...) (intersperse " " (map render-expr term))]
[term (render-term term)]))
(define (render-term term)
(match term
[('- quantity) `(- ,(render-quantity quantity))]
[('+ quantity) `(+ ,(render-quantity quantity))]
[('color digs) `("#" ,digs)]
[#(expr ...) (intersperse " " (map render-expr expr))]
[((? number?) x) (render-quantity term)]
[((? symbol? fn) expr ...)
`(,fn "(" ,@(intersperse "," (map render-expr expr)) ")")] ;also url
[(? string?) (escape-string term)]
[(? symbol?) term]
[(? number?) term]
[_ (error "invalid term:" term)]))
(define (render-quantity quant)
(match quant
[(num '%) `(,num "%")]
[(num unit) `(,num ,unit)]
[num num]))
(for-each render sexpr))
;; experimental
(define ($/ parser . parsers)
(if (null? parsers)
parser
($or ($try parser) (apply $/ parsers))))
;;
;; CSS -> S-expr CSS
;;
;; Core syntax
;; http://www.w3.org/TR/css3-syntax/
;; CSS grammar definition is layered in order to allow different support
;; levels of the client. It's conceptually parallel to Lisp syntax---
;; the S-expression defines the core syntax, and more complex syntax is
;; defined on top of S-expr.
;; The API provides access for the lower layer, with the option to hook
;; a translator for certain syntax units.
;; NB: @charset rule is not handled here; we need to switch port encodings
;; 4.3 Tokenizer
;; css-token-generator :: [Char] -> ( () -> Token )
;; Token = (IDENT . name) | (FUNCTION . name) | (AT-KEYWORD . name)
;; | (HASH name flag) | (STRING . value) | (BAD-STRING)
;; | (URL . value) | (BAD-URL)
;; | (DELIM . char) | (NUMBER . value) | (PERCENTAGE . value)
;; | (DIMENSION value unit)
;; | (UNICODE-RANGE start end)
;; | (INCLUDE-MATCH) | (DASH-MATCH) | (PREFIX-MATCH) | (SUFFIX-MATCH)
;; | (SUBSTRING-MATCH) | (COLUMN) | (WHITESPACE) | (CDO) | (CDC)
;; | (COLON) | (SEMICOLON) | (COMMA) | (OPEN-BRACKET) | (CLOSE-BRACKET)
;; | (OPEN-PAREN) | (CLOSE-PAREN) | (OPEN-BRACE) | (CLOSE-BRACE)
(define %w ($skip-many ($one-of #[ \t\r\n\f])))
(define %s ($skip-many1 ($one-of #[ \t\r\n\f])))
(define %nl ($/ ($s "\n") ($s "\r\n") ($s "\n") ($s "\f")))
;; comment => vlid
(define %comment
($seq ($s "/*")
($skip-many ($none-of #[*]))
($skip-many1 ($c #\*))
($skip-many ($seq ($none-of #[/*])
($skip-many ($none-of #[*]))
($skip-many1 ($c #\*))))
($c #\/)))
;; nonascii [^\0-\237] => char
(define %nonascii ($none-of #[\x00-\x9f]))
;; unicode \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])? => char
(define %unicode ($do [ ($c #\\) ]
[code ($many ($one-of #[0-9a-fA-F]) 1 6)]
[ ($optional ($/ ($s "\r\n") ($one-of #[ \n\r\t\f]))) ]
($return ($ integer->char
$ (cut string->number <> 16)
$ list->string code))))
;; escape {unicode}|\\[^\n\r\f0-9a-f] => char
(define %escape ($/ %unicode ($seq ($c #\\) ($none-of #[\n\r\f0-9a-f]))))
;; nmstart [_a-z]|{nonascii}|{escape} => char
(define %nmstart ($/ ($one-of #[_a-zA-Z]) %nonascii %escape))
;; nonascii [^\0-\237] => char
(define %nonascii ($none-of #[\x00-\x9f]))
;; unicode \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])? => char
(define %unicode ($do [ ($c #\\) ]
[code ($many ($one-of #[0-9a-fA-F]) 1 6)]
[ ($optional ($/ ($s "\r\n") ($one-of #[ \n\r\t\f]))) ]
($return ($ integer->char
$ (cut string->number <> 16)
$ list->string code))))
;; escape {unicode}|\\[^\n\r\f0-9a-f] => char
(define %escape ($/ %unicode
($seq ($c #\\) ($none-of #[\n\r\f0-9a-f]))))
;; nmstart [_a-z]|{nonascii}|{escape} => char
(define %nmstart ($/ ($one-of #[_a-zA-Z]) %nonascii %escape))
;; nmchar [_a-z0-9-]|{nonascii}|{escape} => char
(define %nmchar ($/ ($one-of #[_a-zA-Z0-9-]) %nonascii %escape))
;; name {nmchar}+ => string
(define %name ($->string ($many1 %nmchar)))
;; ident [-]?{nmstart}{nmchar}* => string
(define %ident ($->symbol ($optional ($c #\-)) %nmstart ($many %nmchar)))
(define %hexdigit ($one-of #[0-9a-fA-F]))
;; num [0-9]+|[0-9]*\.[0-9]+
(define %num
(let* ([digs ($many1 ($one-of #[0-9]))]
[frac ($->rope ($c #\.) digs)])
($lift ($ string->number $ rope->string $)
($/ ($->rope digs ($optional frac))
($->rope frac)))))
;; string {string1}|{string2}
;; string1 \"([^\n\r\f\\"]|\\{nl}|{escape})*\"
;; string2 \'([^\n\r\f\\']|\\{nl}|{escape})*\'
(define %string
($->rope
($/ ($between ($char #\")
($many ($/ ($none-of #[\n\r\f\"\\])
($try ($seq ($char #\\) %nl))
%escape))
($or ($char #\") eof))
($between ($char #\')
($many ($/ ($none-of #[\n\r\f\'\\])
($try ($seq ($char #\\) %nl))
%escape))
($or ($char #\') eof)))))
(define %bad-string
($/ ($seq ($char #\")
($skip-many ($/ ($none-of #[\n\r\f\"])
($try ($seq ($char #\\) %nl))
%escape))
($char #\newline))
($seq ($char #\')
($skip-many ($/ ($none-of #[\n\r\f\'])
($try ($seq ($char #\\) %nl))
%escape))
($char #\newline))))
(define %url
($lift (^[_ _ r _ _] (rope->string r))
($string "url(") %w
($->rope ($/ %string
($many ($/ ($one-of #[!#$%&*-~])
%nonascii
%escape))))
%w ($char #\))))
(define %unicode-range
(letrec [(code (^[cs] (string->number (list->string cs) 16)))]
($seq ($one-of #[Uu]) ($c #\+)
($/ ($lift (^[cs1 _ cs2] `(UNICODE-RANGE ,(code cs1) ,(code cs2)))
($many %hexdigit 1 6) ($c #\-) ($many %hexdigit 1 6))
($do [ds ($many %hexdigit 1 5)]
[ws ($many ($c #\?) 1 (- 6 (length ds)))]
($return
`(UNICODE-RANGE ,(code (append ds (map (^_ #\0) ws)))
,(max (code (append ds (map (^_ #\f) ws)))
#x10ffff))))
($lift (^[cs] `(UNICODE-RANGE ,(code cs) ,(code cs)))
($many %hexdigit 1 6))))))
;; Tokenizer
;; comment returns :comment, which is ignored by the token generator
;; note that this parser never fails except at the end of input.
(define %tokenize
($/ ($seq %comment ($return :comment))
($seq %s ($return '(WHITESPACE)))
%unicode-range
($seq ($s "~=") ($return '(INCLUDE-MATCH)))
($seq ($s "|=") ($return '(DASH-MATCH)))
($seq ($s "^=") ($return '(PREFIX-MATCH)))
($seq ($s "$=") ($return '(SUFFIX-MATCH)))
($seq ($s "*=") ($return '(SUBSTRING-MATCH)))
($seq ($s "||") ($return '(COLUMN)))
($seq ($s "<!--") ($return '(CDO)))
($seq ($s "-->") ($return '(CDC)))
($seq ($c #\:) ($return '(COLON)))
($seq ($c #\;) ($return '(SEMICOLON)))
($seq ($c #\,) ($return '(COMMA)))
($seq ($c #\[) ($return '(OPEN-BRACKET)))
($seq ($c #\]) ($return '(CLOSE-BRACKET)))
($seq ($c #\() ($return '(OPEN-PAREN)))
($seq ($c #\)) ($return '(CLOSE-PAREN)))
($seq ($c #\{) ($return '(OPEN-BRACE)))
($seq ($c #\}) ($return '(CLOSE-BRACE)))
($lift (^[val] `(URL . ,val)) %url)
($lift (^[ident _] `(FUNCTION . ,ident)) %ident ($c #\())
($lift (^[ident] `(IDENT . ,ident)) %ident)
($lift (^[_ ident] `(AT-KEYWORD . ,ident)) ($c #\@) %ident)
($lift (^[_ val] `(HASH ,val #t)) ($c #\#) %ident)
($lift (^[_ val] `(HASH ,val #f)) ($c #\#) %name)
($lift (^[val] `(STRING . ,val)) %string)
($lift (^[_] '(BAD-STRING)) %bad-string)
($lift (^[val _] `(PERCENTAGE . ,val)) %num ($c #\%))
($lift (^[val unit] `(DIMENSION ,val ,unit)) %num %ident)
($lift (^[val] `(NUMBER . ,val)) %num)
($do [c anychar] ($return `(DELIM . ,c)))))
(define (css-token-generator chars)
(define cs chars)
(rec (gen)
(if (null? cs)
(eof-object)
(receive (val next) (peg-run-parser %tokenize cs)
(set! cs next)
(if (eq? val :comment) (gen) val)))))
(define (css-tokenize chars)
(generator->lseq (css-token-generator chars)))
;;
;; 5. Core parser
;;
;; Accept token of specific type
(define ($tok type)
(^s
(cond [(null? s) (return-failure/expect type s)]
[(eq? (caar s) type) (return-result (cdar s) (cdr s))]
[else (return-failure/expect type s)])))
(define ($delim char)
(^s
(cond [(null? s) (return-failure/expect char s)]
[(and (eqv? (caar s) 'DELIM) (eqv? (cdar s) char))
(return-result (cdar s) (cdr s))]
[else (return-failure/expect char s)])))
(define (%preserved-token s)
(if (null? s)
(return-failure/unexpect "EOF" s)
(return-result (car s) (cdr s))))
(define %WS* ($skip-many ($tok 'WHITESPACE)))
(define %component-value
($lazy
($between %WS*
($/ %brace-block %paren-block %bracket-block %function-call
%preserved-token)
%WS*)))
(define (block-parser opener closer tag)
($lift (^[_ _ v _] `(,tag ,@v))
($tok opener) %WS*
($many ($seq ($not ($tok closer)) %component-value))
($tok closer)))
(define %brace-block (block-parser 'OPEN-BRACE 'CLOSE-BRACE 'brace-block))
(define %paren-block (block-parser 'OPEN-PAREN 'CLOSE-PAREN 'paren-block))
(define %bracket-block (block-parser 'OPEN-BRACKET 'CLOSE-BRACKET 'bracket-block))
(define %function-call
($lift (^[fn args _] `(funcall ,fn ,@args))
($tok 'FUNCTION)
($many ($seq ($not ($tok 'CLOSE-PAREN)) %component-value))
($tok 'CLOSE-PAREN)))
(define %at-rule
($lift (^[keyword _ args block] `(,keyword ,args ,block))
($tok 'AT-KEYWORD) %WS*
($many ($seq ($not ($tok 'OPEN-BRACE))
($not ($tok 'SEMICOLON))
%component-value))
($/ %brace-block ($tok 'SEMICOLON))))
(define %qualified-rule
;; NB: We preserve whitespaces between qualifiers, for it is
;; required to parse selectors; see below.
($lift (^[_ words block _] (list words block))
%WS*
($many ($seq ($not ($tok 'OPEN-BRACE))
($/ %paren-block %bracket-block %function-call
%preserved-token ($tok 'WHITESPACE))))
%brace-block %WS*))
(define %important
($do [ ($delim #\!) ]
[ %WS* ]
[v ($tok 'IDENT)]
(if (string-ci=? (symbol->string v) "important")
($return '!important)
($fail "!important expected"))))
(define %declaration
($lift (^[name _ _ block important _] (list name block important))
($tok 'IDENT) %WS* ($tok 'COLON)
($many ($seq ($not ($tok 'SEMICOLON))
($not ($delim #\!))
%component-value))
($optional %important)
%WS*))
(define %declaration-list
($lazy
($seq %WS* ($/ ($sep-by ($optional %declaration) ($tok 'SEMICOLON))
($lift list %at-rule %declaration-list)))))
(define %inter-rule-spaces
($skip-many ($/ ($tok 'CDO) ($tok 'CDC) ($tok 'WHITESPACE))))
(define %rule-list
($many ($/ ($tok 'WHITESPACE) %qualified-rule %at-rule)))
;;
;; Higher-level parser
;;
;; The core syntax defined in section 5 of css3 spec is very tolerable---
;; it accepts variety of syntaxes that doesn't make sense at all. This
;; layer uses higher-level semantics to get a meaningful representation.
;; Selector syntax
;; http://www.w3.org/TR/css3-selectors/
(define %attr-selector-internal
($lift (^[_ name _ opval _]
(if opval `(,(car opval) ,name ,(cdr opval)) `(has ,name)))
%WS* ($tok 'IDENT) %WS*
($optional
($lift (^[op _ val] (cons op val))
($/ ($seq ($delim #\=) ($return '=))
($seq ($tok 'INCLUDE-MATCH) ($return '~=))
($seq ($tok 'DASH-MATCH) ($return ':=))
($seq ($tok 'PREFIX-MATCH) ($return '^=))
($seq ($tok 'SUFFIX-MATCH) ($return '$=))
($seq ($tok 'SUBSTRING-MATCH) ($return '*=)))
%WS*
($/ ($tok 'IDENT) ($tok 'STRING))))
%WS*))
(define (%attr-selector s)
(match s
[(('bracket-block . content) . rest)
(receive (r v s) (%attr-selector-internal content)
(if (and (parse-success? r)
(null? s))
(return-result v rest)
(return-failure/message "attr-selector" s)))]
[_ (return-failure/message "attr-selector" s)]))
(define %class-selector
($lift (^[_ class] `(class ,class)) ($delim #\.) ($tok 'IDENT)))
(define %id-selector
($do [hashval ($tok 'HASH)]
(if (cadr hashval) ; hashval is ident
($return `(id ,(car hashval)))
($fail "identifier required for id selector"))))
(define %pseudo-fn-arg
;; NB: To support an+b syntax
($/ ($tok 'DIMENSION)
($tok 'NUMBER)
($tok 'STRING)
($tok 'IDENT)))
(define %negation-selector-arg
($lazy
($/ %type-selector %attr-selector %class-selector %id-selector
%pseudo-selector)))
;; NB: negation-selector is also treated in pseudo-fn
(define (%pseudo-fn s)
(match s
[(('funcall name . arg-tokens) . rest)
(receive (r v s) (if (eq? name 'not)
(%negation-selector-arg arg-tokens)
(%pseudo-fn-arg arg-tokens))
(if (and (parse-success? r)
(null? s))
(return-result (list name v) rest)
(return-failure/message "pseudo-fn" s)))]
[_ (return-failure/message "pseudo-fn" s)]))
(define %pseudo-selector
($lift (^[_ elem? sel]
(match sel
[('not not-arg) `(:not ,not-arg)]
[(? symbol?) `(,(if elem? ':: ':) ,sel)]
[_ `(,(if elem? ':: ':) ,@sel)]))
($tok 'COLON) ($optional ($tok 'COLON))
($/ ($tok 'IDENT) %pseudo-fn)))
(define %selector-option
($/ %attr-selector
%class-selector
%id-selector
%pseudo-selector))
(define %type-selector
;; TODO: namespace support & case conversion
($/ ($tok 'IDENT) ($seq ($delim #\*) ($return '*))))
(define %simple-selector
($/ ($lift (^[type opts] (if (null? opts) type (cons type opts)))
%type-selector ($many %selector-option))
($lift (^[ops] `(* ,@ops)) ($many1 %selector-option))))
(define %selector-seq
($lazy
($lift (^[sel rest] (if rest (cons sel rest) (list sel)))
%simple-selector
($optional
($try
($lift (^[op rest] (if op (cons op rest) rest))
($/ ($between %WS*
($/ ($seq ($delim #\>) ($return '>))
($seq ($delim #\+) ($return '+))
($seq ($delim #\~) ($return '~)))
%WS*)
($followed-by ($seq ($tok 'WHITESPACE) ($return #f))
%WS*))
%selector-seq))))))
(define %selector-group ;; section 5
($lift (^[sels] (cond [(null? sels) #f]
[(null? (cdr sels)) (car sels)]
[else (cons 'or sels)]))
($sep-by ($lift (^[_ seq _] (if (null? (cdr seq)) (car seq) seq))
%WS* %selector-seq %WS*)
($tok 'COMMA))))
;; TOKENS is the first item of the value of %qualified-rule. Interpret
;; it as a selector and returns <pattern> structure of S-expr CSS.
;; If it can't be parsed, returns #f.
(define (parse-selectors tokens)
(receive (val next) (peg-run-parser %selector-group tokens)
(and (null? next) val)))
;; default declaration value parser
;; This part roughly follows CSS2.1 spec appendix G.
;; The difficulty is in expression;
;; CSS spec dosn't define general precedence among juxtaposition, comma and
;; slash operators, leaving its interpretation to each property. However,
;; the current defined property seems to use this rule:
;; - A rule of thumb is that '/' > juxtaposition > ','
;; - For some shorthand properties, '/' > ',' > juxtaposition
;; TODO: We need another rule for the argument of 'calc'.
(define (%function-expr s)
(match s
[(('funcall name . arg-tokens) . rest)
(receive (r v s) (%comma-separated-exprs arg-tokens)
(if (and (parse-success? r)
(null? s))
(return-result (cons name v) rest)
(return-failure/expect "list of function arguments" s)))]
[_ (return-failure/expect "list of function arguments" s)]))
(define %term
($/ ($lift (^[u qual] (if u `(,(string->symbol (string u)) ,qual) qual))
($optional ($/ ($delim #\+) ($delim #\-)))
($/ ($tok 'NUMBER)
($lift (^[val] `(,val %)) ($tok 'PERCENTAGE))
($tok 'DIMENSION)))
($tok 'STRING)
($tok 'IDENT)
($lift (^[v] `(url ,v)) ($tok 'URL))
($lift (^[v] `(color ,(x->string (car v)))) ($tok 'HASH))
%function-expr))
(define %term-/
($lift (^[a b] (if b `(/ ,a ,b) a))
%term ($optional ($seq ($delim #\/) %term))))
(define %comma-separated-exprs
($sep-by ($lift (^[v vs] (if (null? vs) v (list->vector (cons v vs))))
%term-/ ($many %term-/))
($tok 'COMMA)))
(define %juxtaposed-exprs
($lift (^[vs] (match vs [(x) x] [xs (list->vector xs)]))
($many ($/ ($lift (^[a _ b] `(/ ,a ,b))
%term ($delim #\/) %term)
($lift (^[v vs] (if (null? vs) v (cons v vs)))
%term ($many ($seq ($tok 'COMMA) %term)))))))
(define *juxta-properties*
'(margin padding
border border-top border-right border-bottom border-left
font list-style pause cue))
(define (%decl-value property)
(if (memq property *juxta-properties*)
%juxtaposed-exprs
($do [exprs %comma-separated-exprs]
($return (match exprs [(x) x] [(xs ...) `(or ,@xs)])))))
;; val :: (property-name . tokens)
(define (parse-declaration val)
(match val
[(name tokens important?)
(receive (r v s) ((%decl-value (car val)) tokens)
(if (and (parse-success? r)
(null? s))
`(,name ,v ,@(cond-list [important? '!important]))
(begin
(css-parser-warn "Ignored unparsable value for property ~s: ~s\n"
(car val) (cdr val))
#f)))]
[_ #f]))
(define (parse-declarations block)
(match block
[('brace-block . component-values)
(receive (vals next) (peg-run-parser %declaration-list component-values)
(and (null? next)
(filter-map parse-declaration vals)))]
[_ #f]))
;; Interpret %qualified-rule as a style-rule and returns <ruleset> structure of
;; S-expr CSS. (section 8.1 of CSS3 sytnax)
;; If it can't be parsed, returns #f.
(define (parse-style-rule selector-tokens block-token)
(let ([selector (parse-selectors selector-tokens)]
[decls (parse-declarations block-token)])
(if (and selector decls)
`(style-rule ,selector ,@decls)
(begin
(unless selector
(css-parser-warn "Ignored unparsable selector: ~s\n"
selector-tokens))
(unless decls
(css-parser-warn "Ignored unparsable declarations block: ~s\n"
block-token))
#f))))
;; Integrated stylesheet parser
(define (make-stylesheet-parser qualified-rule-handler)
($seq %inter-rule-spaces
($many ($followed-by
($/ ($lift (^[a]
(css-parser-warn "Ignored unsupported at-rule: ~s\n"
a)
#f)
%at-rule)
($lift (^[q] (qualified-rule-handler (car q) (cadr q)))
%qualified-rule))
%inter-rule-spaces))))
(define (parse-stylesheet tokens
:key (qualified-rule-handler parse-style-rule))
(receive (r rest)
(peg-run-parser (make-stylesheet-parser qualified-rule-handler) tokens)
(filter identity r)))
;; API
;; TODO: Handle @charset
(define (css-parse-file file :key (encoding #f))
(call-with-input-file file
(^p ($ parse-stylesheet
$ css-tokenize $ generator->lseq $ port->char-generator p))
:encoding (or encoding (gauche-character-encoding))))
;; API
;; A utility function to parse only selector part.
;; We can't simply use parse-selectors, for it assumes the tokens is
;; processed as %qualified-rule.
;; Returns #f if input is unparsable. It is ok that imput has extra
;; blocks; they're ignored.
(define (css-parse-selector-string s)
(receive (r v s) ($ %selector-only $ css-tokenize $ x->lseq s)
(and (parse-success? r)
(parse-selectors v))))
(define %selector-only
($seq %WS*
($many ($seq ($not ($tok 'OPEN-BRACE))
($/ %paren-block %bracket-block %function-call
%preserved-token ($tok 'WHITESPACE))))))
;; TODO: make this customizable
(define css-parser-warn warn)
|