REBOL [
Title: "Attribute Values Extractor"
File: %ave.r
Author: [ "HY" ]
Date: 9-Jan-2006
Purpose: "Extract attribute values from (HTML) tags"
Library: [
level: 'intermediate
domain: [http web]
license: none
Platform: 'all
Tested-under: none
Type: 'function
Support: none
]
Comment: {
Here are two functions: ex-att1 and ex-att2. The first has some
limitations, and will return the worng text for the ACTION attribute
on the example tag herein. The second is usually a tiny bit faster
than the first, but in some cases much slower (like in the default
benchmark test further down in this document). But the ex-att2 function
RETURNS THE RIGHT ATTRIBUTE VALUE.
}
]
ex-att1: func [str attr /local a b] [
a: parse str "<> ='"
while [b: find a "" remove b] []
trim to-string select a attr
]
ex-att2: func [str attr /local ] [
; the following definition has to be inside this function since I do a comparison on 'attr
attr-value-pair: [copy a attr-name eq copy v attr-value (either all [dbq = first v dbq = last v] [v: trim-quotes v]
[if all [sgq = first v sgq = last v] [v: trim-quotes v]] if (trim attr) = (trim a) [return trim v]) any ws x: ]
parse/all str [thru-ws any [attr-only | attr-value-pair ] to end]
""
]
thru-ws: [thru #" " | thru tab | thru newline]
ws: [#" " | tab | newline]
to-ws: [to #" " | to newline | to tab]
not-eq: complement charset reduce "="
not-eq-or-ws: complement charset reduce [newline tab #" " #"="]
dbq: to-char {"}
sgq: #"'"
eq: [ any ws #"=" any ws ]
attr-value: [ [ dbq [ thru dbq | to end ] ] | [ sgq [ thru sgq | to end ] ] | [ to-ws any ws | to end ] ]
attr-name: [ some not-eq-or-ws ]
attr-only: [copy a attr-name any ws [not-eq x: (x: back x) :x | end] ]
trim-quotes: func [str] [
str: reverse next reverse str
str: next str
]
tag: