On this page:
6.1 ssax.ss
ssax: read-markup-token
ssax: read-pi-body-as-string
ssax: skip-internal-dtd
ssax: read-cdata-body
ssax: read-char-ref
ssax: handle-parsed-entity
ssax: read-attributes
ssax: uri-string->symbol
ssax: complete-start-tag
ssax: read-external-id
ssax: read-char-data
ssax: assert-token
ssax: make-pi-parser
ssax: make-elem-parser
ssax: make-parser
ssax: reverse-collect-str
6.2 input-parse.ss
6.3 sxml-tree-trans.ss
SRV: send-reply
replace-range: :
6.4 sxml-to-html.ss
string->good HTML
6.5 sxml-to-html-ext.ss

6 Automatically Extracted Comments

The following "documentation" was generated automatically, using a script that I believe is due to Mike Sperber. This documentation has not been read or formatted for scribble, and should be considered only as raw material for use in creating actual documentation.

6.1 ssax.ss

(make-xml-token KIND HEAD)  ???
This creates an XML token.

(xml-token? THING)  ???
  THING : any/c
(xml-token-kind XML-TOKEN)  ???
  XML-TOKEN : symbol?
(xml-token-head XML-TOKEN)  ???
  XML-TOKEN : symbol?

(ssax:read-markup-token PORT)  ???
  PORT : port?
This procedure starts parsing of a markup token. The current position in the stream must be #\<. This procedure scans enough of the input stream to figure out what kind of a markup token it is seeing. The procedure returns an xml-token structure describing the token. Note, generally reading of the current markup is not finished! In particular, no attributes of the start-tag token are scanned.

Here’s a detailed break out of the return values and the position in the PORT when that particular value is returned: PI-token: only PI-target is read. To finish the Processing Instruction and disregard it, call ssax:skip-pi. ssax:read-attributes may be useful as well (for PIs whose content is attribute-value pairs) END-token: The end tag is read completely; the current position is right after the terminating #\> character. COMMENT is read and skipped completely. The current position is right after "–>" that terminates the comment. CDSECT The current position is right after "<!CDATA[" Use ssax:read-cdata-body to read the rest. DECL We have read the keyword (the one that follows "<!") identifying this declaration markup. The current position is after the keyword (usually a whitespace character)

START-token We have read the keyword (GI) of this start tag. No attributes are scanned yet. We don’t know if this tag has an empty content either. Use ssax:complete-start-tag to finish parsing of the token.

(ssax:read-pi-body-as-string PORT)  ???
  PORT : port?
The current position is right after reading the PITarget. We read the body of PI and return is as a string. The port will point to the character right after ’?>’ combination that terminates PI. [16] PI ::= ’<?’ PITarget (S (Char* - (Char* ’?>’ Char*)))? ’?>’

(ssax:skip-internal-dtd PORT)  ???
  PORT : port?
The current pos in the port is inside an internal DTD subset (e.g., after reading #\[ that begins an internal DTD subset) Skip until the "]>" combination that terminates this DTD

(ssax:read-cdata-body PORT STR-HANDLER SEED)  ???
  PORT : port?
  STR-HANDLER : procedure?
This procedure must be called after we have read a string "<![CDATA[" that begins a CDATA section. The current position must be the first position of the CDATA body. This function reads _lines_ of the CDATA body and passes them to a STR-HANDLER, a character data consumer.

The str-handler is a STR-HANDLER, a procedure STRING1 STRING2 SEED. The first STRING1 argument to STR-HANDLER never contains a newline. The second STRING2 argument often will. On the first invocation of the STR-HANDLER, the seed is the one passed to ssax:read-cdata-body as the third argument. The result of this first invocation will be passed as the seed argument to the second invocation of the line consumer, and so on. The result of the last invocation of the STR-HANDLER is returned by the ssax:read-cdata-body. Note a similarity to the fundamental ’fold’ iterator.

Within a CDATA section all characters are taken at their face value, with only three exceptions: CR, LF, and CRLF are treated as line delimiters, and passed as a single #\newline to the STR-HANDLER "]]>" combination is the end of the CDATA section. &gt; is treated as an embedded #\> character Note, &lt; and &amp; are not specially recognized (and are not expanded)!

(ssax:read-char-ref PORT)  ???
  PORT : port?
[66] CharRef ::= ’&#’ [0-9]+ ’;’ | ’&#x’ [0-9a-fA-F]+ ’;’

This procedure must be called after we we have read "&#" that introduces a char reference. The procedure reads this reference and returns the corresponding char The current position in PORT will be after ";" that terminates the char reference Faults detected: WFC: XML-Spec.html#wf-Legalchar

According to Section "4.1 Character and Entity References" of the XML Recommendation: "[Definition: A character reference refers to a specific character in the ISO/IEC 10646 character set, for example one not directly accessible from available input devices.]" Therefore, we use a ucscode->char function to convert a character code into the character – *regardless* of the current character encoding of the input stream.

(ssax:handle-parsed-entity PORT    
  ENTITIES)  ???
  PORT : port?
  NAME : ???
  ENTITIES : ???

Expand and handle a parsed-entity reference port - a PORT name - the name of the parsed entity to expand, a symbol entities - see ENTITIES content-handler – procedure PORT ENTITIES SEED that is supposed to return a SEED str-handler - a STR-HANDLER. It is called if the entity in question turns out to be a pre-declared entity

The result is the one returned by CONTENT-HANDLER or STR-HANDLER Faults detected: WFC: XML-Spec.html#wf-entdeclared WFC: XML-Spec.html#norecursion

(make-empty-attlist)  ???
The ATTLIST Abstract Data Type Currently is implemented as an assoc list sorted in the ascending order of NAMES.

(attlist-add ATTLIST NAME-VALUE-PAIR)  ???
  ATTLIST : ???
Add a name-value pair to the existing attlist preserving the order Return the new list, in the sorted ascending order. Return #f if a pair with the same name already exists in the attlist

(attlist-null? ATTLIST)  ???
  ATTLIST : ???

(attlist-remove-top ATTLIST)  ???
  ATTLIST : ???
Given an non-null attlist, return a pair of values: the top and the rest

(attliast->alist)  ???
(attlist-fold)  ???

(ssax:read-attributes PORT ENTITIES)  ???
  PORT : port?
  ENTITIES : ???
This procedure reads and parses a production Attribute* [41] Attribute ::= Name Eq AttValue [10] AttValue ::= ’"’ ([^<&"] | Reference)* ’"’ | "’" ([^<&’] | Reference)* "’" [25] Eq ::= S? ’=’ S?

The procedure returns an ATTLIST, of Name (as UNRES-NAME), Value (as string) pairs. The current character on the PORT is a non-whitespace character that is not an ncname-starting character.

Note the following rules to keep in mind when reading an ’AttValue’ "Before the value of an attribute is passed to the application or checked for validity, the XML processor must normalize it as follows: - a character reference is processed by appending the referenced character to the attribute value - an entity reference is processed by recursively processing the replacement text of the entity [see ENTITIES] [named entities amp lt gt quot apos are assumed pre-declared] - a whitespace character (#x20, #xD, #xA, #x9) is processed by appending #x20 to the normalized value, except that only a single #x20 is appended for a "#xD#xA" sequence that is part of an external parsed entity or the literal entity value of an internal parsed entity - other characters are processed by appending them to the normalized value "

Faults detected: WFC: XML-Spec.html#CleanAttrVals WFC: XML-Spec.html#uniqattspec

(ssax:uri-string->symbol URI-STR)  ???
  URI-STR : string?
Convert a URI-STR to an appropriate symbol

(ssax:complete-start-tag TAG    
  TAG : symbol?
  PORT : port?
  ELEMS : ???
  ENTITIES : ???
This procedure is to complete parsing of a start-tag markup. The procedure must be called after the start tag token has been read. TAG is an UNRES-NAME. ELEMS is an instance of xml-decl::elems; it can be #f to tell the function to do _no_ validation of elements and their attributes.

This procedure returns several values: ELEM-GI: a RES-NAME. ATTRIBUTES: element’s attributes, an ATTLIST of (RES-NAME . STRING) pairs. The list does NOT include xmlns attributes. NAMESPACES: the input list of namespaces amended with namespace (re-)declarations contained within the start-tag under parsing ELEM-CONTENT-MODEL

On exit, the current position in PORT will be the first character after #\> that terminates the start-tag markup.

Faults detected: VC: XML-Spec.html#enum VC: XML-Spec.html#RequiredAttr VC: XML-Spec.html#FixedAttr VC: XML-Spec.html#ValueType WFC: XML-Spec.html#uniqattspec (after namespaces prefixes are resolved) VC: XML-Spec.html#elementvalid WFC: REC-xml-names/#dt-NSName

Note, although XML Recommendation does not explicitly say it, xmlns and xmlns: attributes don’t have to be declared (although they can be declared, to specify their default value)

Procedure: ssax:complete-start-tag tag-head port elems entities namespaces

(ssax:read-external-id PORT)  ???
  PORT : port?
This procedure parses an ExternalID production:

[75] ExternalID ::= 'SYSTEM' S SystemLiteral

        | 'PUBLIC' S PubidLiteral S SystemLiteral

[11] SystemLiteral ::= ('"' [^"]* '"') | ("'" [^']* "'")

[12] PubidLiteral ::=  '"' PubidChar* '"' | "'" (PubidChar - "'")* "'"

[13] PubidChar ::=  #x20 | #xD | #xA | [a-zA-Z0-9]

                        | [-'()+,./:=?;!*#@$_%]

This procedure is supposed to be called when an ExternalID is expected; that is, the current character must be either #\S or #\P that start correspondingly a SYSTEM or PUBLIC token. This procedure returns the SystemLiteral as a string. A PubidLiteral is disregarded if present.

(ssax:read-char-data PORT    
  SEED)  ???
  PORT : port?
  EXPECT-EOF? : boolean?
  STR-HANDLER : procedure?
  SEED : ???
This procedure is to read the character content of an XML document or an XML element. [43] content ::= (element | CharData | Reference | CDSect | PI | Comment)* To be more precise, the procedure reads CharData, expands CDSect and character entities, and skips comments. The procedure stops at a named reference, EOF, at the beginning of a PI or a start/end tag.

port a PORT to read expect-eof? a boolean indicating if EOF is normal, i.e., the character data may be terminated by the EOF. EOF is normal while processing a parsed entity. str-handler a STR-HANDLER seed an argument passed to the first invocation of STR-HANDLER.

The procedure returns two results: SEED and TOKEN. The SEED is the result of the last invocation of STR-HANDLER, or the original seed if STR-HANDLER was never called.

TOKEN can be either an eof-object (this can happen only if expect-eof? was #t), or: - an xml-token describing a START tag or an END-tag; For a start token, the caller has to finish reading it. - an xml-token describing the beginning of a PI. It’s up to an application to read or skip through the rest of this PI; - an xml-token describing a named entity reference.

CDATA sections and character references are expanded inline and never returned. Comments are silently disregarded.

As the XML Recommendation requires, all whitespace in character data must be preserved. However, a CR character (#xD) must be disregarded if it appears before a LF character (#xA), or replaced by a #xA character otherwise. See Secs. 2.10 and 2.11 of the XML Recommendation. See also the canonical XML Recommendation.

(ssax:assert-token TOKEN KIND GI)  ???
  TOKEN : ???
  KIND : ???
  GI : ???
Make sure that TOKEN is of anticipated KIND and has anticipated GI Note GI argument may actually be a pair of two symbols, Namespace URI or the prefix, and of the localname. If the assertion fails, error-cont is evaluated by passing it three arguments: token kind gi. The result of error-cont is returned.

(ssax:make-pi-parser my-pi-handlers)  ???
  my-pi-handlers : ???
Create a parser to parse and process one Processing Element (PI).

my-pi-handlers An assoc list of pairs (PI-TAG . PI-HANDLER) where PI-TAG is an NCName symbol, the PI target, and PI-HANDLER is a procedure PORT PI-TAG SEED where PORT points to the first symbol after the PI target. The handler should read the rest of the PI up to and including the combination ’?>’ that terminates the PI. The handler should return a new seed. One of the PI-TAGs may be the symbol *DEFAULT*. The corresponding handler will handle PIs that no other handler will. If the *DEFAULT* PI-TAG is not specified, ssax:make-pi-parser will assume the default handler that skips the body of the PI

The output of the ssax:make-pi-parser is a procedure PORT PI-TAG SEED that will parse the current PI according to the user-specified handlers.

The previous version of ssax:make-pi-parser was a low-level macro:
(define-macro ssax:make-pi-parser
  (lambda (my-pi-handlers)
  `(lambda (port target seed)
    (case target
      ,@(let loop ((pi-handlers my-pi-handlers) (default #f))
          ((null? pi-handlers)
           (if default `((else (,default port target seed)))
                  (ssax:warn port "Skipping PI: " target nl)
                  (ssax:skip-pi port)
          ((eq? '*DEFAULT* (caar pi-handlers))
           (loop (cdr pi-handlers) (cdar pi-handlers)))
            `((,(caar pi-handlers)) (,(cdar pi-handlers) port target seed))
            (loop (cdr pi-handlers) default)))))))))

(ssax:make-elem-parser my-new-level-seed    
  my-finish-element)  ???
  my-new-level-seed : ???
  my-finish-element : ???
my-char-data-handler my-pi-handlers

Create a parser to parse and process one element, including its character content or children elements. The parser is typically applied to the root element of a document.

my-new-level-seed procedure ELEM-GI ATTRIBUTES NAMESPACES EXPECTED-CONTENT SEED where ELEM-GI is a RES-NAME of the element about to be processed. This procedure is to generate the seed to be passed to handlers that process the content of the element. This is the function identified as ’fdown’ in the denotational semantics of the XML parser given in the title comments to this file.

my-finish-element procedure ELEM-GI ATTRIBUTES NAMESPACES PARENT-SEED SEED This procedure is called when parsing of ELEM-GI is finished. The SEED is the result from the last content parser (or from my-new-level-seed if the element has the empty content). PARENT-SEED is the same seed as was passed to my-new-level-seed. The procedure is to generate a seed that will be the result of the element parser. This is the function identified as ’fup’ in the denotational semantics of the XML parser given in the title comments to this file.

my-char-data-handler A STR-HANDLER

my-pi-handlers See ssax:make-pi-handler above

The generated parser is a procedure START-TAG-HEAD PORT ELEMS ENTITIES NAMESPACES PRESERVE-WS? SEED The procedure must be called after the start tag token has been read. START-TAG-HEAD is an UNRES-NAME from the start-element tag. ELEMS is an instance of xml-decl::elems. See ssax:complete-start-tag::preserve-ws?

Faults detected: VC: XML-Spec.html#elementvalid WFC: XML-Spec.html#GIMatch

(ssax:make-parser user-handler-tag    
  user-handler-proc ...)  ???
  user-handler-tag : ???
  user-handler-proc : ???
Create an XML parser, an instance of the XML parsing framework. This will be a SAX, a DOM, or a specialized parser depending on the supplied user-handlers.

user-handler-tag is a symbol that identifies a procedural expression that follows the tag. Given below are tags and signatures of the corresponding procedures. Not all tags have to be specified. If some are omitted, reasonable defaults will apply.

tag: DOCTYPE handler-procedure: PORT DOCNAME SYSTEMID INTERNAL-SUBSET? SEED If internal-subset? is #t, the current position in the port is right after we have read #\[ that begins the internal DTD subset. We must finish reading of this subset before we return (or must call skip-internal-subset if we aren’t interested in reading it). The port at exit must be at the first symbol after the whole DOCTYPE declaration. The handler-procedure must generate four values: ELEMS ENTITIES NAMESPACES SEED See xml-decl::elems for ELEMS. It may be #f to switch off the validation. NAMESPACES will typically contain USER-PREFIXes for selected URI-SYMBs. The default handler-procedure skips the internal subset, if any, and returns (values #f ’() ’() seed)

tag: UNDECL-ROOT handler-procedure: ELEM-GI SEED where ELEM-GI is an UNRES-NAME of the root element. This procedure is called when an XML document under parsing contains _no_ DOCTYPE declaration. The handler-procedure, as a DOCTYPE handler procedure above, must generate four values: ELEMS ENTITIES NAMESPACES SEED The default handler-procedure returns (values #f ’() ’() seed)

tag: DECL-ROOT handler-procedure: ELEM-GI SEED where ELEM-GI is an UNRES-NAME of the root element. This procedure is called when an XML document under parsing does contains the DOCTYPE declaration. The handler-procedure must generate a new SEED (and verify that the name of the root element matches the doctype, if the handler so wishes). The default handler-procedure is the identity function.

tag: NEW-LEVEL-SEED handler-procedure: see ssax:make-elem-parser, my-new-level-seed

tag: FINISH-ELEMENT handler-procedure: see ssax:make-elem-parser, my-finish-element

tag: CHAR-DATA-HANDLER handler-procedure: see ssax:make-elem-parser, my-char-data-handler

tag: PI handler-procedure: see ssax:make-pi-parser The default value is ’()

(ssax:reverse-collect-str LIST-OF-FRAGS)  ???
given the list of fragments (some of which are text strings) reverse the list and concatenate adjacent text strings. We can prove from the general case below that if LIST-OF-FRAGS has zero or one element, the result of the procedure is equal? to its argument. This fact justifies the shortcut evaluation below.

6.2 input-parse.ss

(parser-error PORT    
  PORT : port?
  MESSAGE : ???
Many procedures of this package call parser-error to report a parsing error. The first argument is a port, which typically points to the offending character or its neighborhood. Most of the Scheme systems let the user query a PORT for the current position. MESSAGE is the description of the error. Other arguments supply more details about the problem.

6.3 sxml-tree-trans.ss

(SRV:send-reply FRAGMENT ...)  ???
  FRAGMENT : ???
Output the ’fragments’ The fragments are a list of strings, characters, numbers, thunks, #f, #t – and other fragments. The function traverses the tree depth-first, writes out strings and characters, executes thunks, and ignores #f and ’(). The function returns #t if anything was written at all; otherwise the result is #f If #t occurs among the fragments, it is not written out but causes the result of SRV:send-reply to be #t

(post-order TREE BINDINGS)  ???
  TREE : ???
  BINDINGS : ???
post-order is a strict subset of pre-post-order without *preorder* (let alone *macro*) traversals. Now pre-post-order is actually faster than the old post-order. The function post-order is deprecated and is aliased below for backward compatibility.

(replace-range:: BEG-PRED END-PRED FOREST)  ???
  BEG-PRED : ???
  END-PRED : ???
  FOREST : ???
Traverse a forest depth-first and cut/replace ranges of nodes.

The nodes that define a range don’t have to have the same immediate parent, don’t have to be on the same level, and the end node of a range doesn’t even have to exist. A replace-range procedure removes nodes from the beginning node of the range up to (but not including) the end node of the range. In addition, the beginning node of the range can be replaced by a node or a list of nodes. The range of nodes is cut while depth-first traversing the forest. If all branches of the node are cut a node is cut as well. The procedure can cut several non-overlapping ranges from a forest.

replace-range:: BEG-PRED x END-PRED x FOREST -> FOREST where type FOREST = (NODE ...) type NODE = Atom | (Name . FOREST) | FOREST

The range of nodes is specified by two predicates, beg-pred and end-pred. beg-pred:: NODE -> #f | FOREST end-pred:: NODE -> #f | FOREST The beg-pred predicate decides on the beginning of the range. The node for which the predicate yields non-#f marks the beginning of the range The non-#f value of the predicate replaces the node. The value can be a list of nodes. The replace-range procedure then traverses the tree and skips all the nodes, until the end-pred yields non-#f. The value of the end-pred replaces the end-range node. The new end node and its brothers will be re-scanned. The predicates are evaluated pre-order. We do not descend into a node that is marked as the beginning of the range.

6.4 sxml-to-html.ss

  TREE : ???
The following procedure is the most generic transformation of SXML into the corresponding HTML document. The SXML tree is traversed post-oder (depth-first) and transformed into another tree, which, written in a depth-first fashion, results in an HTML document.

(entag TAG ELEMS)  ???
  TAG : symbol?
  ELEMS : (listof sxml?)
Create the HTML markup for tags. This is used in the node handlers for the post-order function, see above.

(enattr ATTR-KEY VALUE)  ???
  ATTR-KEY : ???
  VALUE : ???
Create the HTML markup for attributes. This and entag are being used in the node handlers for the post-order function, see above.

(string->goodHTML STRING)  ???
  STRING : string?
Given a string, check to make sure it does not contain characters such as ’<’ or ’&’ that require encoding. Return either the original string, or a list of string fragments with special characters replaced by appropriate character entities.

6.5 sxml-to-html-ext.ss

(make-header HEAD-PARMS)  ???
  HEAD-PARMS : (listof (list/c symbol? any/c))
Create the ’head’ SXML/HTML tag. HEAD-PARMS is an assoc list of (h-key h-value), where h-value is a typically string; h-key is a symbol: title, description, AuthorAddress, keywords, Date-Revision-yyyymmdd, Date-Creation-yyyymmdd, long-title One of the h-key can be Links. In that case, h-value is a list of (l-key l-href (attr value) ...) where l-key is one of the following: start, contents, prev, next, top, home

(make-navbar: HEAD-PARMS)  ???
  HEAD-PARMS : ???
Create a navigational bar. The argument head-parms is the same as the one passed to make-header. We’re only concerned with the h-value Links

(make-footer HEAD-PARMS)  ???
  HEAD-PARMS : ???
Create a footer. The argument head-parms is the same as passed to make-header.

(universal-conversion-rules)  ???
Bindings for the post-order function, which traverses the SXML tree and converts it to a tree of fragments

The universal transformation from SXML to HTML. The following rules work for every HTML, present and future

(universal-protected-rules)  ???
A variation of universal-conversion-rules which keeps ’<’, ’>’, ’&’ and similar characters intact. The universal-protected-rules are useful when the tree of fragments has to be traversed one more time.

(alist-conv-rules)  ???
The following rules define the identity transformation