A Lisp Based HTML Parser
+ +Introduction/Simple Example
+LHTML parse output format
+Case mode notes
+Parsing HTML comments
+Parsing <SCRIPT> and <STYLE> tags
+Parsing SGML <! tags
+Parsing Illegal and Deprecated Tags
+Default Attribute Values
+Parsing Interleaved Character Formatting Tags
+parse-html reference
+ methods
+ phtml-internal
The parse-html generic function processes HTML
+input, returning a list of HTML tags, attributes, and text. Here is a simple example:
+
+(parse-html "<HTML>
+
+<HEAD>
+
+<TITLE>Example HTML input</TITLE>
+
+<BODY>
+
+<P>Here is some text with a <B>bold</B> word<br>and a <A
+HREF=\"help.html\">link</P>
+
+</HTML>")
generates:
+
+((:html (:head (:title "Example HTML input"))
+ (:body (:p "Here is some text with a " (:b "bold") "
+word" :br "and a "
+
+((:a :href "help.html") "link")))))
+
The output format is known as LHTML format; it is the same format that the
+aserve htmlgen macro accepts.
+
+LHTML format
+
+LHTML is a list representation of HTML tags and content.
+
+Each list member may be:
+
+
If excl:*current-case-mode* is :CASE-INSENSITIVE-UPPER, keyword package symbols will be
+in upper case; otherwise, they will be in lower case.
HTML comments are represented use a :comment symbol. For example,
+
+(parse-html "<!-- this is a comment-->")
+
+--> ((:comment " this is a comment"))
HTML <SCRIPT> and <STYLE> tags
+ +All <SCRIPT> and <STYLE> content is not parsed; it is returned as text
+content.
+
+For example,
+
+(parse-html "<SCRIPT>this <B>will not</B> be
+parsed</SCRIPT>")
+
+--> ((:script "this <B>will not</B> be parsed"))
Since, some HTML pages contain special XML/SGML tags, non-comment tags
+starting with '<!' are treated specially:
+
+(parse-html "<!doctype this is some text>")
+
+--> ((:!doctype " this is some text"))
There is plenty of illegal and deprecated HTML on the web that popular browsers
+nonetheless successfully display. The parse-html parser is generous - it will not
+raise an error condition upon encountering most input. In particular, it does not
+maintain a list of legal HTML tags and will successfully parse nonsense input.
+
+For example,
+
+(parse-html "<this> <is> <some> <nonsense>
+<input>")
+
+--> ((:this (:is (:some (:nonsense :input)))))
+
+In some situations, you may prefer a two-pass parse that results in a parse where
+deep nesting related to unrecognized tags is minimized:
+
+(let ((string "<this> <is> <some> <nonsense> </some>
+<input>"))
+ (multiple-value-bind (res rogues)
+ (parse-html string
+:collect-rogue-tags t)
+ (declare (ignorable
+res))
+ (parse-html string
+:no-body-tags rogues)))
+
+--> (:this :is (:some (:nonsense)) :input)
+
+See the :collect-rogue-tags and :no-body-tags argument
+descriptions in the reference
+section below for more information.
As per the HTML 4.0 specification, attributes without specified values are given a
+lower case
+string value that matches the attribute name.
+
+For example,
+
+(parse-html "<P here ARE some attributes>")
+
+--> (((:p :here "here" :are "are" :some "some"
+:attributes "attributes")))
Interleaved Character Formatting Tags
+ +Existing HTML pages often have character format tags that are interleaved among
+other tags. Such interleaving is removed in a manner consistent with the HTML 4.0
+specification.
+
+For example,
+
+(parse-html "<P>Here is <B>bold text<P>that spans</B>two
+paragraphs")
+
+--> ((:p "Here is " (:b "bold text")) (:p (:b "that
+spans") "two paragraphs"))
parse-html Reference
+
+parse-html [Generic function]
+
+Arguments: input-source &key callbacks callback-only
+ collect-rogue-tags
+no-body-tags parse-entities
+
+Returns LHTML output, as described above.
+
+The callbacks argument, if non-nil, should be an association list. Each list member's
+car (first) element specifies a keyword package symbol, and each list member's cdr (rest)
+element specifies a function object or a symbol naming a function. The function should
+expect one argument. The function will be invoked once for each time the HTML tag
+corresponding to the specified keyword package symbol is encountered in the HTML input;
+the
+argument will be an LHTML list containing the tag, along with associated attributes and
+content. The default callbacks argument value is nil.
+
+The callback-only argument, if non-nil, directs parse-html to not generate a complete
+LHTML
+output. Instead, LHTML lists will only be generated when necessary as arguments for
+functions
+specified in the callbacks association list. This results in faster parser execution. The
+default
+callback-only argument value is nil.
+
+The collect-rogue-tags argument, if non-nil, directs parse-html to return an additional
+value,
+a list containing any unrecognized tags closed by the end of input.
+
+The no-body-tags argument, if non-nil, should be a list containing unknown tags that, if
+encountered, will be treated as a tag with no body or content, and thus, no associated end
+tag. Typically, the argument is a list or modified list resulting from an earlier
+parse-html
+execution with the :collect-rogue-tags argument specified as non-nil.
If the parse-entities argument is true then entities are converted to the character
+they name. Thus for example the < entity is converted to the less than sign.
+
+parse-html Methods
+
+parse-html (p stream) &key callbacks callback-only
+ collect-rogue-tags
+no-body-tags parse-entities
+
+parse-html (str string) &key callbacks callback-only
+ collect-rogue-tags
+no-body-tags parse-entities
+
+parse-html (file t) &key callbacks callback-only
+ collect-rogue-tags
+no-body-tags parse-entities
+
+The t method assumes the argument is a pathname suitable
+for use with the with-open-file macro.
+
+
+phtml-internal [Function]
+
+Arguments: stream read-sequence-func callback-only callbacks
+collect-rogue-tags no-body-tags parse-entities
+
+This function may be used when more control is needed for supplying
+the HTML input. The read-sequence-func argument, if non-nil, should be a function
+object or a symbol naming a function. When phtml-internal requires another buffer
+of HTML input, it will invoke the read-sequence-func function with two arguments -
+the first argument is an internal buffer character array and the second argument is
+the phtml-internal stream argument. If read-sequence-fun is nil, phtml-internal
+will invoke read-sequence to fill the buffer. The read-sequence-func function must
+return the number of character array elements successfully stored in the buffer.
+
+
+
+
+
+
+
+