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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Generic parsing macros and utilities
(defmacro aif (test-form then-form &rest else-forms)
"Anaphoric if. Temporary variable `it' is the result of test-form."
`(let ((it ,test-form))
(if it ,then-form ,@else-forms)))
(defmacro pif (test-form then-form &rest else-forms)
"Parser anaphoric if. Temporary variable `it' is the result of test-form."
`(let ((it ,test-form))
(if (not (eq 'error (car it))) ,then-form ,@else-forms)))
(defmacro parse (regex nums label &rest body)
"Parse according to a regex and update the `input' variable."
`(aif (regex ,regex input ',(number-sequence 0 nums))
(let ((input (elt it ,nums)))
,@body)
`,`(error ,(concat "expected " ,label))))
(defmacro run (parser then-form &rest else-forms)
"Run a parser and update the input properly, extract the parsed
expression."
`(pif (,parser input)
(let ((input (cdr it))
(expr (car it)))
,then-form)
,@else-forms))
(defmacro por (parser1 parser2 then-form &rest else-forms)
"OR two parsers. Try one parser, if it fails try the next."
`(pif (,parser1 input)
(let ((input (cdr it))
(expr (car it)))
,then-form)
(pif (,parser2 input)
(let ((input (cdr it))
(expr (car it)))
,then-form)
,@else-forms)))
(defun regex (regexp string refs)
"Return a list of (`ref') matches for a `regex' on a `string' or nil."
(if (string-match (concat "^" regexp "\\(.*\\)$") string)
(mapcar (lambda (ref) (match-string ref string))
(if (sequencep refs) refs (list refs)))
nil))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Zen coding parsers
(defun expr (input)
"Parse a zen coding expression."
(run siblings
it
(run parent-child
it
(run pexpr
it
(run tag
it
'(error "no match, expecting ( or a-zA-Z0-9"))))))
(defun tag (input)
"Parse a tag."
(run tagname
(let ((result it)
(tagname (cdr expr)))
(run identifier
(tag-classes `(tag ,tagname ((id ,(cddr expr)))) input)
(tag-classes `(tag ,tagname ()) input)))
'(error "expected tagname")))
(defun tag-classes (tag input)
(run classes
(let ((tagname (cadr tag))
(props (caddr tag))
(classes `(class ,(mapconcat
(lambda (prop)
(cdadr prop))
(cdr expr)
" "))))
`((tag ,tagname ,(append props (list classes))) . ,input))
`(,tag . ,input)))
(defun tagname (input)
"Parse a tagname a-zA-Z0-9 tagname (e.g. html/head/xsl:if/br)."
(parse "\\([a-zA-Z0-9:-]+\\)" 2 "tagname, a-zA-Z0-9"
`((tagname . ,(elt it 1)) . ,input)))
(defun pexpr (input)
"A zen coding expression with parentheses around it."
(parse "(" 1 "("
(run expr
(aif (regex ")" input '(0 1))
`(,expr . ,(elt it 1))
'(error "expecting `)'")))))
(defun parent-child (input)
"Parse an tag>e expression, where `n' is an tag and `e' is any
expression."
(run tag
(let ((parent expr))
(parse ">" 1 ">"
(run expr
(let ((child expr))
`((parent-child ,parent ,child) . ,input))
'(error "expected child"))))
'(error "expected parent")))
(defun sibling (input)
(por pexpr tag
it
'(error "expected sibling")))
(defun siblings (input)
"Parse an e+e expression, where e is an tag or a pexpr."
(por pexpr tag
(let ((parent expr))
(parse "\\+" 1 "+"
(por siblings sibling
(let ((child expr))
`((siblings ,parent ,child) . ,input))
'(error "expected second sibling"))))
'(error "expected first sibling")))
(defun name (input)
"Parse a class or identifier name, e.g. news, footer, mainimage"
(parse "\\([a-zA-Z][a-zA-Z0-9-_]*\\)" 2 "class or identifer name"
`((name . ,(elt it 1)) . ,input)))
(defun class (input)
"Parse a classname expression, e.g. .foo"
(parse "\\." 1 "."
(run name
`((class ,expr) . ,input)
'(error "expected class name"))))
(defun identifier (input)
"Parse an identifier expression, e.g. #foo"
(parse "#" 1 "#"
(run name `((identifier . ,expr) . ,input))))
(defun classes (input)
"Parse many classes."
(run class
(pif (classes input)
`((classes . ,(cons expr (cdar it))) . ,(cdr it))
`((classes . ,(list expr)) . ,input))
'(error "expected class")))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Zen coding transformer from AST to HTML
(defun make-tag (tag &optional content)
(let ((name (car tag))
(props (apply 'concat (mapcar
(lambda (prop)
(concat " " (symbol-name (car prop))
"=\"" (cadr prop) "\""))
(cadr tag)))))
(concat "<" name props ">\n"
(if content content "")
"</" name ">\n")))
(defun transform (ast)
(let ((type (car ast)))
(cond
((eq type 'tag)
(make-tag (cdr ast)))
((eq type 'tagname) (make-tag (cdr ast)))
((eq type 'parent-child)
(let ((parent (cdadr ast))
(children (transform (caddr ast))))
(make-tag parent children)))
((eq type 'siblings)
(let ((sib1 (transform (cadr ast)))
(sib2 (transform (caddr ast))))
(concat sib1 sib2))))))
;; Demo
;; (transform (car (expr "a>b>c+d+e")))
;; => <a><b><c></c><d></d><e></e></b></a>
;; (transform (car (expr "html>head+(body>p)")))
;; => <html><head></head><body><p></p></body></html>
;; (transform (car (expr "html>head+(body>p+(ul>li))")))
;; => [indentation added with xml-mode]
;; <html>
;; <head>
;; </head>
;; <body>
;; <p>
;; </p>
;; <ul>
;; <li>
;; </li>
;; </ul>
;; </body>
;; </html>
;; (transform (car (expr "body.sub-page>div#news.content.a+div#news.content.a")))
;; => [indentation added with xml-mode]
;; <body class="sub-page">
;; <div id="news" class="content a">
;; </div>
;; <div id="news" class="content a">
;; </div>
;; </body>
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