HTML: Parsing Library

Version: 4.2.1

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HTML: Parsing Library

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/c)

port : input-port?

Reads HTML from a port, producing an X-expression compatible with the xml library (which defines content/c).

(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.

(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 #f.

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 (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.

A html-content is either

(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

(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

(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

(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

(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

(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

A G11 is either

a
label
G12

A G10 is either

A G9 is either

A G8 is either

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

A G2 is either

form
G3

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