HTML: Parsing Library

6.1

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HTML: Parsing Library

(require html)

package: html-lib

The html library provides functions to read html documents and structures to represent them.

procedure
(read-xhtml port) → html?
port : input-port?
procedure
(read-html port) → html?
port : input-port?

Reads (X)HTML from a port, producing an html instance.

procedure
(read-html-as-xml port) → (listof content/c)
port : input-port?

Reads HTML from a port, producing a list of XML content, each of which could be turned into an X-expression, if necessary, with xml->xexpr.

parameter
(read-html-comments) → boolean?
(read-html-comments v) → void?
v : any/c

If v is not #f, then comments are read and returned. Defaults to #f.

parameter
(use-html-spec) → boolean?
(use-html-spec v) → void?
v : any/c

If v is not #f, then the HTML must respect the HTML specification with regards to what elements are allowed to be the children of other elements. For example, the top-level "<html>" element may only contain a "<body>" and "<head>" element. Defaults to #t.

1 Example

(module html-example racket

 ; Some of the symbols in html and xml conflict with
 ; each other and with racket/base language, so we prefix
 ; to avoid namespace conflict.
 (require (prefix-in h: html)
 (prefix-in x: xml))

 (define an-html
 (h:read-xhtml
 (open-input-string
 (string-append
 "<html><head><title>My title</title></head><body>"
 "Hello worldTesting!"
 "</body></html>"))))

 ; extract-pcdata: html-content/c -> (listof string)
 ; Pulls out the pcdata strings from some-content.
 (define (extract-pcdata some-content)
 (cond [(x:pcdata? some-content)
 (list (x:pcdata-string some-content))]
 [(x:entity? some-content)
 (list)]
 [else
 (extract-pcdata-from-element some-content)]))

 ; extract-pcdata-from-element: html-element -> (listof string)
 ; Pulls out the pcdata strings from an-html-element.
 (define (extract-pcdata-from-element an-html-element)
 (match an-html-element
 [(struct h:html-full (attributes content))
 (apply append (map extract-pcdata content))]

 [(struct h:html-element (attributes))
 '()]))

 (printf "~s\n" (extract-pcdata an-html)))

> (require 'html-example)
("My title" "Hello world" "Testing" "!")

2 HTML Structures

pcdata, entity, and attribute are defined in the xml documentation.

value
html-content/c : contract?

A html-content/c is either

struct
(struct html-element (attributes)
#:extra-constructor-name make-html-element)
attributes : (listof attribute)

Any of the structures below inherits from html-element.

struct
(struct html-full struct:html-element (content)
#:extra-constructor-name make-html-full)
content : (listof html-content/c)

Any html tag that may include content also inherits from html-full without adding any additional fields.

struct
(struct mzscheme html-full ()
#:extra-constructor-name make-mzscheme)

A mzscheme is special legacy value for the old documentation system.

struct
(struct html html-full ()
#:extra-constructor-name make-html)

A html is (make-html (listof attribute) (listof Contents-of-html))

A Contents-of-html is either

body
head

struct
(struct div html-full ()
#:extra-constructor-name make-div)

A div is (make-div (listof attribute) (listof G2))

struct
(struct center html-full ()
#:extra-constructor-name make-center)

A center is (make-center (listof attribute) (listof G2))

struct
(struct blockquote html-full ()
#:extra-constructor-name make-blockquote)

A blockquote is (make-blockquote (listof attribute) (listof G2))

struct
(struct ins html-full ()
#:extra-constructor-name make-ins)

An Ins is (make-ins (listof attribute) (listof G2))

struct
(struct del html-full ()
#:extra-constructor-name make-del)

A del is (make-del (listof attribute) (listof G2))

struct
(struct dd html-full ()
#:extra-constructor-name make-dd)

A dd is (make-dd (listof attribute) (listof G2))

struct
(struct li html-full ()
#:extra-constructor-name make-li)

A li is (make-li (listof attribute) (listof G2))

struct
(struct th html-full ()
#:extra-constructor-name make-th)

A th is (make-th (listof attribute) (listof G2))

struct
(struct td html-full ()
#:extra-constructor-name make-td)

A td is (make-td (listof attribute) (listof G2))

struct
(struct iframe html-full ()
#:extra-constructor-name make-iframe)

An iframe is (make-iframe (listof attribute) (listof G2))

struct
(struct noframes html-full ()
#:extra-constructor-name make-noframes)

A noframes is (make-noframes (listof attribute) (listof G2))

struct
(struct noscript html-full ()
#:extra-constructor-name make-noscript)

A noscript is (make-noscript (listof attribute) (listof G2))

struct
(struct style html-full ()
#:extra-constructor-name make-style)

A style is (make-style (listof attribute) (listof pcdata))

struct
(struct script html-full ()
#:extra-constructor-name make-script)

A script is (make-script (listof attribute) (listof pcdata))

struct
(struct basefont html-element ()
#:extra-constructor-name make-basefont)

A basefont is (make-basefont (listof attribute))

struct
(struct br html-element ()
#:extra-constructor-name make-br)

A br is (make-br (listof attribute))

struct
(struct area html-element ()
#:extra-constructor-name make-area)

An area is (make-area (listof attribute))

struct
(struct alink html-element ()
#:extra-constructor-name make-alink)

A alink is (make-alink (listof attribute))

struct
(struct img html-element ()
#:extra-constructor-name make-img)

An img is (make-img (listof attribute))

struct
(struct param html-element ()
#:extra-constructor-name make-param)

A param is (make-param (listof attribute))

struct
(struct hr html-element ()
#:extra-constructor-name make-hr)

A hr is (make-hr (listof attribute))

struct
(struct input html-element ()
#:extra-constructor-name make-input)

An input is (make-input (listof attribute))

struct
(struct col html-element ()
#:extra-constructor-name make-col)

A col is (make-col (listof attribute))

struct
(struct isindex html-element ()
#:extra-constructor-name make-isindex)

An isindex is (make-isindex (listof attribute))

struct
(struct base html-element ()
#:extra-constructor-name make-base)

A base is (make-base (listof attribute))

struct
(struct meta html-element ()
#:extra-constructor-name make-meta)

A meta is (make-meta (listof attribute))

struct
(struct option html-full ()
#:extra-constructor-name make-option)

An option is (make-option (listof attribute) (listof pcdata))

struct
(struct textarea html-full ()
#:extra-constructor-name make-textarea)

A textarea is (make-textarea (listof attribute) (listof pcdata))

struct
(struct title html-full ()
#:extra-constructor-name make-title)

A title is (make-title (listof attribute) (listof pcdata))

struct
(struct head html-full ()
#:extra-constructor-name make-head)

A head is (make-head (listof attribute) (listof Contents-of-head))

A Contents-of-head is either

base
isindex
alink
meta
object
script
style
title

struct
(struct tr html-full ()
#:extra-constructor-name make-tr)

A tr is (make-tr (listof attribute) (listof Contents-of-tr))

A Contents-of-tr is either

struct
(struct colgroup html-full ()
#:extra-constructor-name make-colgroup)

A colgroup is (make-colgroup (listof attribute) (listof col))

struct
(struct thead html-full ()
#:extra-constructor-name make-thead)

A thead is (make-thead (listof attribute) (listof tr))

struct
(struct tfoot html-full ()
#:extra-constructor-name make-tfoot)

A tfoot is (make-tfoot (listof attribute) (listof tr))

struct
(struct tbody html-full ()
#:extra-constructor-name make-tbody)

A tbody is (make-tbody (listof attribute) (listof tr))

struct
(struct tt html-full ()
#:extra-constructor-name make-tt)

A tt is (make-tt (listof attribute) (listof G5))

struct
(struct i html-full ()
#:extra-constructor-name make-i)

An i is (make-i (listof attribute) (listof G5))

struct
(struct b html-full ()
#:extra-constructor-name make-b)

A b is (make-b (listof attribute) (listof G5))

struct
(struct u html-full ()
#:extra-constructor-name make-u)

An u is (make-u (listof attribute) (listof G5))

struct
(struct s html-full ()
#:extra-constructor-name make-s)

A s is (make-s (listof attribute) (listof G5))

struct
(struct strike html-full ()
#:extra-constructor-name make-strike)

A strike is (make-strike (listof attribute) (listof G5))

struct
(struct big html-full ()
#:extra-constructor-name make-big)

A big is (make-big (listof attribute) (listof G5))

struct
(struct small html-full ()
#:extra-constructor-name make-small)

A small is (make-small (listof attribute) (listof G5))

struct
(struct em html-full ()
#:extra-constructor-name make-em)

An em is (make-em (listof attribute) (listof G5))

struct
(struct strong html-full ()
#:extra-constructor-name make-strong)

A strong is (make-strong (listof attribute) (listof G5))

struct
(struct dfn html-full ()
#:extra-constructor-name make-dfn)

A dfn is (make-dfn (listof attribute) (listof G5))

struct
(struct code html-full ()
#:extra-constructor-name make-code)

A code is (make-code (listof attribute) (listof G5))

struct
(struct samp html-full ()
#:extra-constructor-name make-samp)

A samp is (make-samp (listof attribute) (listof G5))

struct
(struct kbd html-full ()
#:extra-constructor-name make-kbd)

A kbd is (make-kbd (listof attribute) (listof G5))

struct
(struct var html-full ()
#:extra-constructor-name make-var)

A var is (make-var (listof attribute) (listof G5))

struct
(struct cite html-full ()
#:extra-constructor-name make-cite)

A cite is (make-cite (listof attribute) (listof G5))

struct
(struct abbr html-full ()
#:extra-constructor-name make-abbr)

An abbr is (make-abbr (listof attribute) (listof G5))

struct
(struct acronym html-full ()
#:extra-constructor-name make-acronym)

An acronym is (make-acronym (listof attribute) (listof G5))

struct
(struct sub html-full ()
#:extra-constructor-name make-sub)

A sub is (make-sub (listof attribute) (listof G5))

struct
(struct sup html-full ()
#:extra-constructor-name make-sup)

A sup is (make-sup (listof attribute) (listof G5))

struct
(struct span html-full ()
#:extra-constructor-name make-span)

A span is (make-span (listof attribute) (listof G5))

struct
(struct bdo html-full ()
#:extra-constructor-name make-bdo)

A bdo is (make-bdo (listof attribute) (listof G5))

struct
(struct font html-full ()
#:extra-constructor-name make-font)

A font is (make-font (listof attribute) (listof G5))

struct
(struct p html-full ()
#:extra-constructor-name make-p)

A p is (make-p (listof attribute) (listof G5))

struct
(struct h1 html-full ()
#:extra-constructor-name make-h1)

A h1 is (make-h1 (listof attribute) (listof G5))

struct
(struct h2 html-full ()
#:extra-constructor-name make-h2)

A h2 is (make-h2 (listof attribute) (listof G5))

struct
(struct h3 html-full ()
#:extra-constructor-name make-h3)

A h3 is (make-h3 (listof attribute) (listof G5))

struct
(struct h4 html-full ()
#:extra-constructor-name make-h4)

A h4 is (make-h4 (listof attribute) (listof G5))

struct
(struct h5 html-full ()
#:extra-constructor-name make-h5)

A h5 is (make-h5 (listof attribute) (listof G5))

struct
(struct h6 html-full ()
#:extra-constructor-name make-h6)

A h6 is (make-h6 (listof attribute) (listof G5))

struct
(struct q html-full ()
#:extra-constructor-name make-q)

A q is (make-q (listof attribute) (listof G5))

struct
(struct dt html-full ()
#:extra-constructor-name make-dt)

A dt is (make-dt (listof attribute) (listof G5))

struct
(struct legend html-full ()
#:extra-constructor-name make-legend)

A legend is (make-legend (listof attribute) (listof G5))

struct
(struct caption html-full ()
#:extra-constructor-name make-caption)

A caption is (make-caption (listof attribute) (listof G5))

struct
(struct table html-full ()
#:extra-constructor-name make-table)

A table is (make-table (listof attribute) (listof Contents-of-table))

A Contents-of-table is either

caption
col
colgroup
tbody
tfoot
thead

struct
(struct button html-full ()
#:extra-constructor-name make-button)

A button is (make-button (listof attribute) (listof G4))

struct
(struct fieldset html-full ()
#:extra-constructor-name make-fieldset)

A fieldset is (make-fieldset (listof attribute) (listof Contents-of-fieldset))

A Contents-of-fieldset is either

legend
G2

struct
(struct optgroup html-full ()
#:extra-constructor-name make-optgroup)

An optgroup is (make-optgroup (listof attribute) (listof option))

struct
(struct select html-full ()
#:extra-constructor-name make-select)

A select is (make-select (listof attribute) (listof Contents-of-select))

A Contents-of-select is either

optgroup
option

struct
(struct label html-full ()
#:extra-constructor-name make-label)

A label is (make-label (listof attribute) (listof G6))

struct
(struct form html-full ()
#:extra-constructor-name make-form)

A form is (make-form (listof attribute) (listof G3))

struct
(struct ol html-full ()
#:extra-constructor-name make-ol)

An ol is (make-ol (listof attribute) (listof li))

struct
(struct ul html-full ()
#:extra-constructor-name make-ul)

An ul is (make-ul (listof attribute) (listof li))

struct
(struct dir html-full ()
#:extra-constructor-name make-dir)

A dir is (make-dir (listof attribute) (listof li))

struct
(struct menu html-full ()
#:extra-constructor-name make-menu)

A menu is (make-menu (listof attribute) (listof li))

struct
(struct dl html-full ()
#:extra-constructor-name make-dl)

A dl is (make-dl (listof attribute) (listof Contents-of-dl))

A Contents-of-dl is either

struct
(struct pre html-full ()
#:extra-constructor-name make-pre)

A pre is (make-pre (listof attribute) (listof Contents-of-pre))

A Contents-of-pre is either

struct
(struct object html-full ()
#:extra-constructor-name make-object)

An object is (make-object (listof attribute) (listof Contents-of-object-applet))

struct
(struct applet html-full ()
#:extra-constructor-name make-applet)

An applet is (make-applet (listof attribute) (listof Contents-of-object-applet))

A Contents-of-object-applet is either

param
G2

struct
(struct -map html-full ()
#:extra-constructor-name make--map)

A Map is (make--map (listof attribute) (listof Contents-of-map))

A Contents-of-map is either

area
fieldset
form
isindex
G10

struct
(struct a html-full ()
#:extra-constructor-name make-a)

An a is (make-a (listof attribute) (listof Contents-of-a))

A Contents-of-a is either

label
G7

struct
(struct address html-full ()
#:extra-constructor-name make-address)

An address is (make-address (listof attribute) (listof Contents-of-address))

A Contents-of-address is either

struct
(struct body html-full ()
#:extra-constructor-name make-body)

A body is (make-body (listof attribute) (listof Contents-of-body))

A Contents-of-body is either

A G12 is either

button
iframe
input
select
textarea

A G11 is either

a
label
G12

A G10 is either

address
blockquote
center
dir
div
dl
h1
h2
h3
h4
h5
h6
hr
menu
noframes
noscript
ol
p
pre
table
ul

A G9 is either

abbr
acronym
b
bdo
br
cite
code
dfn
em
i
kbd
-map
pcdata
q
s
samp
script
span
strike
strong
tt
u
var

A G8 is either

applet
basefont
big
font
img
object
small
sub
sup
G9

A G7 is either

A G6 is either

A G5 is either

label
G6

A G4 is either

A G3 is either

fieldset
isindex
G4
G11

A G2 is either

form
G3

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