HTML: Parsing Library

(require html)

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

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

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

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

(read-html-as-xml port) → (listof content?)

port : input-port?

Reads HTML from a port, producing an xexpr compatible with the xml library (which defines content?).

1 Example

(module html-example scheme

; Some of the symbols in html and xml conflict with

; each other and with scheme/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>"

"<p>Hello world</p><p><b>Testing</b>!</p>"

"</body></html>"))))

; extract-pcdata: html-content -> (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 (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.

A html-content is either

• html-element

• pcdata

• entity

(struct   html-element   (attributes))

attributes : (listof attribute)

Any of the structures below inherits from html-element.

(struct   (html-full struct:html-element)   (content))

content : (listof html-content)

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

(struct   (html html-full)   ())

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

A Contents-of-html is either

• body

• head

(struct   (div html-full)   ())

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

(struct   (center html-full)   ())

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

(struct   (blockquote html-full)   ())

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

(struct   (ins html-full)   ())

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

(struct   (del html-full)   ())

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

(struct   (dd html-full)   ())

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

(struct   (li html-full)   ())

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

(struct   (th html-full)   ())

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

(struct   (td html-full)   ())

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

(struct   (iframe html-full)   ())

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

(struct   (noframes html-full)   ())

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

(struct   (noscript html-full)   ())

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

(struct   (style html-full)   ())

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

(struct   (script html-full)   ())

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

(struct   (basefont html-element)   ())

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

(struct   (br html-element)   ())

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

(struct   (area html-element)   ())

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

(struct   (alink html-element)   ())

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

(struct   (img html-element)   ())

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

(struct   (param html-element)   ())

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

(struct   (hr html-element)   ())

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

(struct   (input html-element)   ())

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

(struct   (col html-element)   ())

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

(struct   (isindex html-element)   ())

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

(struct   (base html-element)   ())

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

(struct   (meta html-element)   ())

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

(struct   (option html-full)   ())

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

(struct   (textarea html-full)   ())

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

(struct   (title html-full)   ())

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

(struct   (head html-full)   ())

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

A Contents-of-head is either

• base

• isindex

• link

• meta

• object

• script

• style

• title

(struct   (tr html-full)   ())

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

A Contents-of-tr is either

• td

• th

(struct   (colgroup html-full)   ())

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

(struct   (thead html-full)   ())

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

(struct   (tfoot html-full)   ())

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

(struct   (tbody html-full)   ())

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

(struct   (tt html-full)   ())

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

(struct   (i html-full)   ())

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

(struct   (b html-full)   ())

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

(struct   (u html-full)   ())

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

(struct   (s html-full)   ())

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

(struct   (strike html-full)   ())

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

(struct   (big html-full)   ())

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

(struct   (small html-full)   ())

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

(struct   (em html-full)   ())

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

(struct   (strong html-full)   ())

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

(struct   (dfn html-full)   ())

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

(struct   (code html-full)   ())

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

(struct   (samp html-full)   ())

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

(struct   (kbd html-full)   ())

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

(struct   (var html-full)   ())

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

(struct   (cite html-full)   ())

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

(struct   (abbr html-full)   ())

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

(struct   (acronym html-full)   ())

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

(struct   (sub html-full)   ())

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

(struct   (sup html-full)   ())

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

(struct   (span html-full)   ())

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

(struct   (bdo html-full)   ())

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

(struct   (font html-full)   ())

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

(struct   (p html-full)   ())

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

(struct   (h1 html-full)   ())

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

(struct   (h2 html-full)   ())

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

(struct   (h3 html-full)   ())

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

(struct   (h4 html-full)   ())

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

(struct   (h5 html-full)   ())

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

(struct   (h6 html-full)   ())

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

(struct   (q html-full)   ())

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

(struct   (dt html-full)   ())

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

(struct   (legend html-full)   ())

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

(struct   (caption html-full)   ())

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

(struct   (table html-full)   ())

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

A Contents-of-table is either

• caption

• col

• colgroup

• tbody

• tfoot

• thead

(struct   (button html-full)   ())

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

(struct   (fieldset html-full)   ())

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

A Contents-of-fieldset is either

• legend

• G2

(struct   (optgroup html-full)   ())

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

(struct   (select html-full)   ())

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

A Contents-of-select is either

• optgroup

• option

(struct   (label html-full)   ())

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

(struct   (form html-full)   ())

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

(struct   (ol html-full)   ())

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

(struct   (ul html-full)   ())

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

(struct   (dir html-full)   ())

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

(struct   (menu html-full)   ())

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

(struct   (dl html-full)   ())

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

A Contents-of-dl is either

• dd

• dt

(struct   (pre html-full)   ())

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

A Contents-of-pre is either

• G9

• G11

(struct   (object html-full)   ())

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

(struct   (applet html-full)   ())

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

A Contents-of-object-applet is either

• param

• G2

(struct   (map html-full)   ())

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

A Contents-of-map is either

• area

• fieldset

• form

• isindex

• G10

(struct   (a html-full)   ())

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

A Contents-of-a is either

• label

• G7

(struct   (address html-full)   ())

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

A Contents-of-address is either

• p

• G5

(struct   (body html-full)   ())

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

A Contents-of-body is either

• del

• ins

• G2

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

• G8

• G12

A G6 is either

• a

• G7

A G5 is either

• label

• G6

A G4 is either

• G8

• G10

A G3 is either

• fieldset

• isindex

• G4

• G11

A G2 is either

• form

• G3