+++ /dev/null
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->The PXP user's guide</TH
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->Chapter 3. The objects representing the document</TD
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-ALIGN="LEFT"
-WIDTH="100%"></DIV
-><DIV
-CLASS="SECT1"
-><H1
-CLASS="SECT1"
-><A
-NAME="AEN939"
->3.2. The class type <TT
-CLASS="LITERAL"
->node</TT
-></A
-></H1
-><P
-> From <TT
-CLASS="LITERAL"
->Pxp_document</TT
->:
-
-<PRE
-CLASS="PROGRAMLISTING"
->type node_type =
- T_data
-| T_element of string
-| T_super_root
-| T_pinstr of string
-| T_comment
-<TT
-CLASS="REPLACEABLE"
-><I
->and some other, reserved types</I
-></TT
->
-;;
-
-class type [ 'ext ] node =
- object ('self)
- constraint 'ext = 'ext node #extension
-
- <A
-NAME="TYPE-NODE-GENERAL.SIG"
-></A
->(* <A
-HREF="x939.html#TYPE-NODE-GENERAL"
-><I
-><I
->General observers</I
-></I
-></A
-> *)
-
- method extension : 'ext
- method dtd : dtd
- method parent : 'ext node
- method root : 'ext node
- method sub_nodes : 'ext node list
- method iter_nodes : ('ext node -> unit) -> unit
- method iter_nodes_sibl :
- ('ext node option -> 'ext node -> 'ext node option -> unit) -> unit
- method node_type : node_type
- method encoding : Pxp_types.rep_encoding
- method data : string
- method position : (string * int * int)
- method comment : string option
- method pinstr : string -> proc_instruction list
- method pinstr_names : string list
- method write : Pxp_types.output_stream -> Pxp_types.encoding -> unit
-
- <A
-NAME="TYPE-NODE-ATTS.SIG"
-></A
->(* <A
-HREF="x939.html#TYPE-NODE-ATTS"
-><I
-><I
->Attribute observers</I
-></I
-></A
-> *)
-
- method attribute : string -> Pxp_types.att_value
- method required_string_attribute : string -> string
- method optional_string_attribute : string -> string option
- method required_list_attribute : string -> string list
- method optional_list_attribute : string -> string list
- method attribute_names : string list
- method attribute_type : string -> Pxp_types.att_type
- method attributes : (string * Pxp_types.att_value) list
- method id_attribute_name : string
- method id_attribute_value : string
- method idref_attribute_names : string
-
- <A
-NAME="TYPE-NODE-MODS.SIG"
-></A
->(* <A
-HREF="x939.html#TYPE-NODE-MODS"
-><I
-><I
->Modifying methods</I
-></I
-></A
-> *)
-
- method add_node : ?force:bool -> 'ext node -> unit
- method add_pinstr : proc_instruction -> unit
- method delete : unit
- method set_nodes : 'ext node list -> unit
- method quick_set_attributes : (string * Pxp_types.att_value) list -> unit
- method set_comment : string option -> unit
-
- <A
-NAME="TYPE-NODE-CLONING.SIG"
-></A
->(* <A
-HREF="x939.html#TYPE-NODE-CLONING"
-><I
-><I
->Cloning methods</I
-></I
-></A
-> *)
-
- method orphaned_clone : 'self
- method orphaned_flat_clone : 'self
- method create_element :
- ?position:(string * int * int) ->
- dtd -> node_type -> (string * string) list ->
- 'ext node
- method create_data : dtd -> string -> 'ext node
- method keep_always_whitespace_mode : unit
-
- <A
-NAME="TYPE-NODE-WEIRD.SIG"
-></A
->(* <A
-HREF="x939.html#TYPE-NODE-WEIRD"
-><I
-><I
->Validating methods</I
-></I
-></A
-> *)
-
- method local_validate : ?use_dfa:bool -> unit -> unit
-
- (* ... Internal methods are undocumented. *)
-
- end
-;;</PRE
->
-
-In the module <TT
-CLASS="LITERAL"
->Pxp_types</TT
-> you can find another type
-definition that is important in this context:
-
-<PRE
-CLASS="PROGRAMLISTING"
->type Pxp_types.att_value =
- Value of string
- | Valuelist of string list
- | Implied_value
-;;</PRE
-></P
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN958"
->3.2.1. The structure of document trees</A
-></H2
-><P
->A node represents either an element or a character data section. There are two
-classes implementing the two aspects of nodes: <TT
-CLASS="LITERAL"
->element_impl</TT
->
-and <TT
-CLASS="LITERAL"
->data_impl</TT
->. The latter class does not implement all
-methods because some methods do not make sense for data nodes.</P
-><P
->(Note: PXP also supports a mode which forces that processing instructions and
-comments are represented as nodes of the document tree. However, these nodes
-are instances of <TT
-CLASS="LITERAL"
->element_impl</TT
-> with node types
-<TT
-CLASS="LITERAL"
->T_pinstr</TT
-> and <TT
-CLASS="LITERAL"
->T_comment</TT
->,
-respectively. This mode must be explicitly configured; the basic representation
-knows only element and data nodes.)</P
-><P
->The following figure
-(<A
-HREF="x939.html#NODE-TERM"
-><I
-><I
->A tree with element nodes, data nodes, and attributes</I
-><I
-></I
-></I
-></A
->) shows an example how
-a tree is constructed from element and data nodes. The circular areas
-represent element nodes whereas the ovals denote data nodes. Only elements
-may have subnodes; data nodes are always leaves of the tree. The subnodes
-of an element can be either element or data nodes; in both cases the O'Caml
-objects storing the nodes have the class type <TT
-CLASS="LITERAL"
->node</TT
->.</P
-><P
->Attributes (the clouds in the picture) are not directly
-integrated into the tree; there is always an extra link to the attribute
-list. This is also true for processing instructions (not shown in the
-picture). This means that there are separated access methods for attributes and
-processing instructions.</P
-><DIV
-CLASS="FIGURE"
-><A
-NAME="NODE-TERM"
-></A
-><P
-><B
->Figure 3-1. A tree with element nodes, data nodes, and attributes</B
-></P
-><P
-><IMG
-SRC="pic/node_term.gif"></P
-></DIV
-><P
->Only elements, data sections, attributes and processing
-instructions (and comments, if configured) can, directly or indirectly, occur
-in the document tree. It is impossible to add entity references to the tree; if
-the parser finds such a reference, not the reference as such but the referenced
-text (i.e. the tree representing the structured text) is included in the
-tree.</P
-><P
->Note that the parser collapses as much data material into one
-data node as possible such that there are normally never two adjacent data
-nodes. This invariant is enforced even if data material is included by entity
-references or CDATA sections, or if a data sequence is interrupted by
-comments. So <TT
-CLASS="LITERAL"
->a &amp; b <-- comment --> c <![CDATA[
-<> d]]></TT
-> is represented by only one data node, for
-instance. However, you can create document trees manually which break this
-invariant; it is only the way the parser forms the tree.</P
-><DIV
-CLASS="FIGURE"
-><A
-NAME="NODE-GENERAL"
-></A
-><P
-><B
->Figure 3-2. Nodes are doubly linked trees</B
-></P
-><P
-><IMG
-SRC="pic/node_general.gif"></P
-></DIV
-><P
->The node tree has links in both directions: Every node has a link to its parent
-(if any), and it has links to the subnodes (see
-figure <A
-HREF="x939.html#NODE-GENERAL"
-><I
-><I
->Nodes are doubly linked trees</I
-><I
-></I
-></I
-></A
->). Obviously,
-this doubly-linked structure simplifies the navigation in the tree; but has
-also some consequences for the possible operations on trees.</P
-><P
->Because every node must have at most <I
-CLASS="EMPHASIS"
->one</I
-> parent node,
-operations are illegal if they violate this condition. The following figure
-(<A
-HREF="x939.html#NODE-ADD"
-><I
-><I
->A node can only be added if it is a root</I
-><I
-></I
-></I
-></A
->) shows on the left side
-that node <TT
-CLASS="LITERAL"
->y</TT
-> is added to <TT
-CLASS="LITERAL"
->x</TT
-> as new subnode
-which is allowed because <TT
-CLASS="LITERAL"
->y</TT
-> does not have a parent yet. The
-right side of the picture illustrates what would happen if <TT
-CLASS="LITERAL"
->y</TT
->
-had a parent node; this is illegal because <TT
-CLASS="LITERAL"
->y</TT
-> would have two
-parents after the operation.</P
-><DIV
-CLASS="FIGURE"
-><A
-NAME="NODE-ADD"
-></A
-><P
-><B
->Figure 3-3. A node can only be added if it is a root</B
-></P
-><P
-><IMG
-SRC="pic/node_add.gif"></P
-></DIV
-><P
->The "delete" operation simply removes the links between two nodes. In the
-picture (<A
-HREF="x939.html#NODE-DELETE"
-><I
-><I
->A deleted node becomes the root of the subtree</I
-><I
-></I
-></I
-></A
->) the node
-<TT
-CLASS="LITERAL"
->x</TT
-> is deleted from the list of subnodes of
-<TT
-CLASS="LITERAL"
->y</TT
->. After that, <TT
-CLASS="LITERAL"
->x</TT
-> becomes the root of the
-subtree starting at this node.</P
-><DIV
-CLASS="FIGURE"
-><A
-NAME="NODE-DELETE"
-></A
-><P
-><B
->Figure 3-4. A deleted node becomes the root of the subtree</B
-></P
-><P
-><IMG
-SRC="pic/node_delete.gif"></P
-></DIV
-><P
->It is also possible to make a clone of a subtree; illustrated in
-<A
-HREF="x939.html#NODE-CLONE"
-><I
-><I
->The clone of a subtree</I
-><I
-></I
-></I
-></A
->. In this case, the
-clone is a copy of the original subtree except that it is no longer a
-subnode. Because cloning never keeps the connection to the parent, the clones
-are called <I
-CLASS="EMPHASIS"
->orphaned</I
->.</P
-><DIV
-CLASS="FIGURE"
-><A
-NAME="NODE-CLONE"
-></A
-><P
-><B
->Figure 3-5. The clone of a subtree</B
-></P
-><P
-><IMG
-SRC="pic/node_clone.gif"></P
-></DIV
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN1007"
->3.2.2. The methods of the class type <TT
-CLASS="LITERAL"
->node</TT
-></A
-></H2
-><A
-NAME="TYPE-NODE-GENERAL"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
-> <A
-HREF="x939.html#TYPE-NODE-GENERAL.SIG"
->General observers</A
->
- . </B
-> <P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->extension</TT
->: The reference to the extension object which
-belongs to this node (see ...).</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->dtd</TT
->: Returns a reference to the global DTD. All nodes
-of a tree must share the same DTD.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->parent</TT
->: Get the father node. Raises
-<TT
-CLASS="LITERAL"
->Not_found</TT
-> in the case the node does not have a
-parent, i.e. the node is the root.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->root</TT
->: Gets the reference to the root node of the tree.
-Every node is contained in a tree with a root, so this method always
-succeeds. Note that this method <I
-CLASS="EMPHASIS"
->searches</I
-> the root,
-which costs time proportional to the length of the path to the root.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->sub_nodes</TT
->: Returns references to the children. The returned
-list reflects the order of the children. For data nodes, this method returns
-the empty list.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->iter_nodes f</TT
->: Iterates over the children, and calls
-<TT
-CLASS="LITERAL"
->f</TT
-> for every child in turn. </P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->iter_nodes_sibl f</TT
->: Iterates over the children, and calls
-<TT
-CLASS="LITERAL"
->f</TT
-> for every child in turn. <TT
-CLASS="LITERAL"
->f</TT
-> gets as
-arguments the previous node, the current node, and the next node.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->node_type</TT
->: Returns either <TT
-CLASS="LITERAL"
->T_data</TT
-> which
-means that the node is a data node, or <TT
-CLASS="LITERAL"
->T_element n</TT
->
-which means that the node is an element of type <TT
-CLASS="LITERAL"
->n</TT
->.
-If configured, possible node types are also <TT
-CLASS="LITERAL"
->T_pinstr t</TT
->
-indicating that the node represents a processing instruction with target
-<TT
-CLASS="LITERAL"
->t</TT
->, and <TT
-CLASS="LITERAL"
->T_comment</TT
-> in which case the node
-is a comment.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->encoding</TT
->: Returns the encoding of the strings.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->data</TT
->: Returns the character data of this node and all
-children, concatenated as one string. The encoding of the string is what
-the method <TT
-CLASS="LITERAL"
->encoding</TT
-> returns.
-- For data nodes, this method simply returns the represented characters.
-For elements, the meaning of the method has been extended such that it
-returns something useful, i.e. the effectively contained characters, without
-markup. (For <TT
-CLASS="LITERAL"
->T_pinstr</TT
-> and <TT
-CLASS="LITERAL"
->T_comment</TT
->
-nodes, the method returns the empty string.)</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->position</TT
->: If configured, this method returns the position of
-the element as triple (entity, line, byteposition). For data nodes, the
-position is not stored. If the position is not available the triple
-<TT
-CLASS="LITERAL"
->"?", 0, 0</TT
-> is returned.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->comment</TT
->: Returns <TT
-CLASS="LITERAL"
->Some text</TT
-> for comment
-nodes, and <TT
-CLASS="LITERAL"
->None</TT
-> for other nodes. The <TT
-CLASS="LITERAL"
->text</TT
->
-is everything between the comment delimiters <TT
-CLASS="LITERAL"
-><--</TT
-> and
-<TT
-CLASS="LITERAL"
->--></TT
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->pinstr n</TT
->: Returns all processing instructions that are
-directly contained in this element and that have a <I
-CLASS="EMPHASIS"
->target</I
->
-specification of <TT
-CLASS="LITERAL"
->n</TT
->. The target is the first word after
-the <TT
-CLASS="LITERAL"
-><?</TT
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->pinstr_names</TT
->: Returns the list of all targets of processing
-instructions directly contained in this element.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->write s enc</TT
->: Prints the node and all subnodes to the passed
-output stream as valid XML text, using the passed external encoding.</P
-></LI
-></UL
->
- </P
-></DIV
-><A
-NAME="TYPE-NODE-ATTS"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
-> <A
-HREF="x939.html#TYPE-NODE-ATTS.SIG"
->Attribute observers</A
->
- . </B
-> <P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->attribute n</TT
->: Returns the value of the attribute with name
-<TT
-CLASS="LITERAL"
->n</TT
->. This method returns a value for every declared
-attribute, and it raises <TT
-CLASS="LITERAL"
->Not_found</TT
-> for any undeclared
-attribute. Note that it even returns a value if the attribute is actually
-missing but is declared as <TT
-CLASS="LITERAL"
->#IMPLIED</TT
-> or has a default
-value. - Possible values are:
- <P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->Implied_value</TT
->: The attribute has been declared with the
-keyword <TT
-CLASS="LITERAL"
->#IMPLIED</TT
->, and the attribute is missing in the
-attribute list of this element.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->Value s</TT
->: The attribute has been declared as type
-<TT
-CLASS="LITERAL"
->CDATA</TT
->, as <TT
-CLASS="LITERAL"
->ID</TT
->, as
-<TT
-CLASS="LITERAL"
->IDREF</TT
->, as <TT
-CLASS="LITERAL"
->ENTITY</TT
->, or as
-<TT
-CLASS="LITERAL"
->NMTOKEN</TT
->, or as enumeration or notation, and one of the two
-conditions holds: (1) The attribute value is present in the attribute list in
-which case the value is returned in the string <TT
-CLASS="LITERAL"
->s</TT
->. (2) The
-attribute has been omitted, and the DTD declared the attribute with a default
-value. The default value is returned in <TT
-CLASS="LITERAL"
->s</TT
->.
-- Summarized, <TT
-CLASS="LITERAL"
->Value s</TT
-> is returned for non-implied, non-list
-attribute values.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->Valuelist l</TT
->: The attribute has been declared as type
-<TT
-CLASS="LITERAL"
->IDREFS</TT
->, as <TT
-CLASS="LITERAL"
->ENTITIES</TT
->, or
-as <TT
-CLASS="LITERAL"
->NMTOKENS</TT
->, and one of the two conditions holds: (1) The
-attribute value is present in the attribute list in which case the
-space-separated tokens of the value are returned in the string list
-<TT
-CLASS="LITERAL"
->l</TT
->. (2) The attribute has been omitted, and the DTD declared
-the attribute with a default value. The default value is returned in
-<TT
-CLASS="LITERAL"
->l</TT
->.
-- Summarized, <TT
-CLASS="LITERAL"
->Valuelist l</TT
-> is returned for all list-type
-attribute values.</P
-></LI
-></UL
->
-
-Note that before the attribute value is returned, the value is normalized. This
-means that newlines are converted to spaces, and that references to character
-entities (i.e. <TT
-CLASS="LITERAL"
->&#<TT
-CLASS="REPLACEABLE"
-><I
->n</I
-></TT
->;</TT
->) and
-general entities
-(i.e. <TT
-CLASS="LITERAL"
->&<TT
-CLASS="REPLACEABLE"
-><I
->name</I
-></TT
->;</TT
->) are expanded;
-if necessary, expansion is performed recursively.</P
-><P
->In well-formedness mode, there is no DTD which could declare an
-attribute. Because of this, every occuring attribute is considered as a CDATA
-attribute.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->required_string_attribute n</TT
->: returns the Value attribute
-called n, or the Valuelist attribute as a string where the list elements
-are separated by spaces. If the attribute value is implied, or if the
-attribute does not exists, the method will fail. - This method is convenient
-if you expect a non-implied and non-list attribute value.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->optional_string_attribute n</TT
->: returns the Value attribute
-called n, or the Valuelist attribute as a string where the list elements
-are separated by spaces. If the attribute value is implied, or if the
-attribute does not exists, the method returns None. - This method is
-convenient if you expect a non-list attribute value including the implied
-value.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->required_list_attribute n</TT
->: returns the Valuelist attribute
-called n, or the Value attribute as a list with a single element.
-If the attribute value is implied, or if the
-attribute does not exists, the method will fail. - This method is
-convenient if you expect a list attribute value.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->optional_list_attribute n</TT
->: returns the Valuelist attribute
-called n, or the Value attribute as a list with a single element.
-If the attribute value is implied, or if the
-attribute does not exists, an empty list will be returned. - This method
-is convenient if you expect a list attribute value or the implied value.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->attribute_names</TT
->: returns the list of all attribute names of
-this element. As this is a validating parser, this list is equal to the
-list of declared attributes.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->attribute_type n</TT
->: returns the type of the attribute called
-<TT
-CLASS="LITERAL"
->n</TT
->. See the module <TT
-CLASS="LITERAL"
->Pxp_types</TT
-> for a
-description of the encoding of the types.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->attributes</TT
->: returns the list of pairs of names and values
-for all attributes of
-this element.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->id_attribute_name</TT
->: returns the name of the attribute that is
-declared with type ID. There is at most one such attribute. The method raises
-<TT
-CLASS="LITERAL"
->Not_found</TT
-> if there is no declared ID attribute for the
-element type.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->id_attribute_value</TT
->: returns the value of the attribute that
-is declared with type ID. There is at most one such attribute. The method raises
-<TT
-CLASS="LITERAL"
->Not_found</TT
-> if there is no declared ID attribute for the
-element type.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->idref_attribute_names</TT
->: returns the list of attribute names
-that are declared as IDREF or IDREFS.</P
-></LI
-></UL
->
- </P
-></DIV
-><A
-NAME="TYPE-NODE-MODS"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
-> <A
-HREF="x939.html#TYPE-NODE-MODS.SIG"
->Modifying methods</A
->
- . </B
->The following methods are only defined for element nodes (more exactly:
-the methods are defined for data nodes, too, but fail always).
-
- <P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->add_node sn</TT
->: Adds sub node <TT
-CLASS="LITERAL"
->sn</TT
-> to the list
-of children. This operation is illustrated in the picture
-<A
-HREF="x939.html#NODE-ADD"
-><I
-><I
->A node can only be added if it is a root</I
-><I
-></I
-></I
-></A
->. This method expects that
-<TT
-CLASS="LITERAL"
->sn</TT
-> is a root, and it requires that <TT
-CLASS="LITERAL"
->sn</TT
-> and
-the current object share the same DTD.</P
-><P
->Because <TT
-CLASS="LITERAL"
->add_node</TT
-> is the method the parser itself uses
-to add new nodes to the tree, it performs by default some simple validation
-checks: If the content model is a regular expression, it is not allowed to add
-data nodes to this node unless the new nodes consist only of whitespace. In
-this case, the new data nodes are silently dropped (you can change this by
-invoking <TT
-CLASS="LITERAL"
->keep_always_whitespace_mode</TT
->).</P
-><P
->If the document is flagged as stand-alone, these data nodes only
-containing whitespace are even forbidden if the element declaration is
-contained in an external entity. This case is detected and rejected.</P
-><P
->If the content model is <TT
-CLASS="LITERAL"
->EMPTY</TT
->, it is not allowed to
-add any data node unless the data node is empty. In this case, the new data
-node is silently dropped.</P
-><P
->These checks only apply if there is a DTD. In well-formedness mode, it is
-assumed that every element is declared with content model
-<TT
-CLASS="LITERAL"
->ANY</TT
-> which prohibits any validation check. Furthermore, you
-turn these checks off by passing <TT
-CLASS="LITERAL"
->~force:true</TT
-> as first
-argument.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->add_pinstr pi</TT
->: Adds the processing instruction
-<TT
-CLASS="LITERAL"
->pi</TT
-> to the list of processing instructions.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->delete</TT
->: Deletes this node from the tree. After this
-operation, this node is no longer the child of the former father node; and the
-node loses the connection to the father as well. This operation is illustrated
-by the figure <A
-HREF="x939.html#NODE-DELETE"
-><I
-><I
->A deleted node becomes the root of the subtree</I
-><I
-></I
-></I
-></A
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->set_nodes nl</TT
->: Sets the list of children to
-<TT
-CLASS="LITERAL"
->nl</TT
->. It is required that every member of <TT
-CLASS="LITERAL"
->nl</TT
->
-is a root, and that all members and the current object share the same DTD.
-Unlike <TT
-CLASS="LITERAL"
->add_node</TT
->, no validation checks are performed.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->quick_set_attributes atts</TT
->: sets the attributes of this
-element to <TT
-CLASS="LITERAL"
->atts</TT
->. It is <I
-CLASS="EMPHASIS"
->not</I
-> checked
-whether <TT
-CLASS="LITERAL"
->atts</TT
-> matches the DTD or not; it is up to the
-caller of this method to ensure this. (This method may be useful to transform
-the attribute values, i.e. apply a mapping to every attribute.)</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->set_comment text</TT
->: This method is only applicable to
-<TT
-CLASS="LITERAL"
->T_comment</TT
-> nodes; it sets the comment text contained by such
-nodes. </P
-></LI
-></UL
-></P
-></DIV
-><A
-NAME="TYPE-NODE-CLONING"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
-> <A
-HREF="x939.html#TYPE-NODE-CLONING.SIG"
->Cloning methods</A
->
- . </B
-> <P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->orphaned_clone</TT
->: Returns a clone of the node and the complete
-tree below this node (deep clone). The clone does not have a parent (i.e. the
-reference to the parent node is <I
-CLASS="EMPHASIS"
->not</I
-> cloned). While
-copying the subtree, strings are skipped; it is likely that the original tree
-and the copy tree share strings. Extension objects are cloned by invoking
-the <TT
-CLASS="LITERAL"
->clone</TT
-> method on the original objects; how much of
-the extension objects is cloned depends on the implemention of this method.</P
-><P
->This operation is illustrated by the figure
-<A
-HREF="x939.html#NODE-CLONE"
-><I
-><I
->The clone of a subtree</I
-><I
-></I
-></I
-></A
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->orphaned_flat_clone</TT
->: Returns a clone of the node,
-but sets the list of sub nodes to [], i.e. the sub nodes are not cloned.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><A
-NAME="TYPE-NODE-METH-CREATE-ELEMENT"
-></A
->
-<TT
-CLASS="LITERAL"
->create_element dtd nt al</TT
->: Returns a flat copy of this node
-(which must be an element) with the following modifications: The DTD is set to
-<TT
-CLASS="LITERAL"
->dtd</TT
->; the node type is set to <TT
-CLASS="LITERAL"
->nt</TT
->, and the
-new attribute list is set to <TT
-CLASS="LITERAL"
->al</TT
-> (given as list of
-(name,value) pairs). The copy does not have children nor a parent. It does not
-contain processing instructions. See
-<A
-HREF="x939.html#TYPE-NODE-EX-CREATE-ELEMENT"
->the example below</A
->.</P
-><P
->Note that you can specify the position of the new node
-by the optional argument <TT
-CLASS="LITERAL"
->~position</TT
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><A
-NAME="TYPE-NODE-METH-CREATE-DATA"
-></A
->
-<TT
-CLASS="LITERAL"
->create_data dtd cdata</TT
->: Returns a flat copy of this node
-(which must be a data node) with the following modifications: The DTD is set to
-<TT
-CLASS="LITERAL"
->dtd</TT
->; the node type is set to <TT
-CLASS="LITERAL"
->T_data</TT
->; the
-attribute list is empty (data nodes never have attributes); the list of
-children and PIs is empty, too (same reason). The new node does not have a
-parent. The value <TT
-CLASS="LITERAL"
->cdata</TT
-> is the new character content of the
-node. See
-<A
-HREF="x939.html#TYPE-NODE-EX-CREATE-DATA"
->the example below</A
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->keep_always_whitespace_mode</TT
->: Even data nodes which are
-normally dropped because they only contain ignorable whitespace, can added to
-this node once this mode is turned on. (This mode is useful to produce
-canonical XML.)</P
-></LI
-></UL
-></P
-></DIV
-><A
-NAME="TYPE-NODE-WEIRD"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
-> <A
-HREF="x939.html#TYPE-NODE-WEIRD.SIG"
->Validating methods</A
->
- . </B
->There is one method which locally validates the node, i.e. checks whether the
-subnodes match the content model of this node.
-
- <P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->local_validate</TT
->: Checks that this node conforms to the
-DTD by comparing the type of the subnodes with the content model for this
-node. (Applications need not call this method unless they add new nodes
-themselves to the tree.)</P
-></LI
-></UL
-></P
-></DIV
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN1252"
->3.2.3. The class <TT
-CLASS="LITERAL"
->element_impl</TT
-></A
-></H2
-><P
->This class is an implementation of <TT
-CLASS="LITERAL"
->node</TT
-> which
-realizes element nodes:
-
-<PRE
-CLASS="PROGRAMLISTING"
->class [ 'ext ] element_impl : 'ext -> [ 'ext ] node</PRE
-> </P
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Constructor. </B
->You can create a new instance by
-
-<PRE
-CLASS="PROGRAMLISTING"
->new element_impl <TT
-CLASS="REPLACEABLE"
-><I
->extension_object</I
-></TT
-></PRE
->
-
-which creates a special form of empty element which already contains a
-reference to the <TT
-CLASS="REPLACEABLE"
-><I
->extension_object</I
-></TT
->, but is
-otherwise empty. This special form is called an
-<I
-CLASS="EMPHASIS"
->exemplar</I
->. The purpose of exemplars is that they serve as
-patterns that can be duplicated and filled with data. The method
-<A
-HREF="x939.html#TYPE-NODE-METH-CREATE-ELEMENT"
-><TT
-CLASS="LITERAL"
->create_element</TT
-></A
-> is designed to perform this action.</P
-></DIV
-><A
-NAME="TYPE-NODE-EX-CREATE-ELEMENT"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Example. </B
->First, create an exemplar by
-
-<PRE
-CLASS="PROGRAMLISTING"
->let exemplar_ext = ... in
-let exemplar = new element_impl exemplar_ext in</PRE
->
-
-The <TT
-CLASS="LITERAL"
->exemplar</TT
-> is not used in node trees, but only as
-a pattern when the element nodes are created:
-
-<PRE
-CLASS="PROGRAMLISTING"
->let element = exemplar # <A
-HREF="x939.html#TYPE-NODE-METH-CREATE-ELEMENT"
->create_element</A
-> dtd (T_element name) attlist </PRE
->
-
-The <TT
-CLASS="LITERAL"
->element</TT
-> is a copy of <TT
-CLASS="LITERAL"
->exemplar</TT
->
-(even the extension <TT
-CLASS="LITERAL"
->exemplar_ext</TT
-> has been copied)
-which ensures that <TT
-CLASS="LITERAL"
->element</TT
-> and its extension are objects
-of the same class as the exemplars; note that you need not to pass a
-class name or other meta information. The copy is initially connected
-with the <TT
-CLASS="LITERAL"
->dtd</TT
->, it gets a node type, and the attribute list
-is filled. The <TT
-CLASS="LITERAL"
->element</TT
-> is now fully functional; it can
-be added to another element as child, and it can contain references to
-subnodes.</P
-></DIV
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN1281"
->3.2.4. The class <TT
-CLASS="LITERAL"
->data_impl</TT
-></A
-></H2
-><P
->This class is an implementation of <TT
-CLASS="LITERAL"
->node</TT
-> which
-should be used for all character data nodes:
-
-<PRE
-CLASS="PROGRAMLISTING"
->class [ 'ext ] data_impl : 'ext -> [ 'ext ] node</PRE
-> </P
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Constructor. </B
->You can create a new instance by
-
-<PRE
-CLASS="PROGRAMLISTING"
->new data_impl <TT
-CLASS="REPLACEABLE"
-><I
->extension_object</I
-></TT
-></PRE
->
-
-which creates an empty exemplar node which is connected to
-<TT
-CLASS="REPLACEABLE"
-><I
->extension_object</I
-></TT
->. The node does not contain a
-reference to any DTD, and because of this it cannot be added to node trees.</P
-></DIV
-><P
->To get a fully working data node, apply the method
-<A
-HREF="x939.html#TYPE-NODE-METH-CREATE-DATA"
-><TT
-CLASS="LITERAL"
->create_data</TT
-></A
-> to the exemplar (see example).</P
-><A
-NAME="TYPE-NODE-EX-CREATE-DATA"
-></A
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Example. </B
->First, create an exemplar by
-
-<PRE
-CLASS="PROGRAMLISTING"
->let exemplar_ext = ... in
-let exemplar = new exemplar_ext data_impl in</PRE
->
-
-The <TT
-CLASS="LITERAL"
->exemplar</TT
-> is not used in node trees, but only as
-a pattern when the data nodes are created:
-
-<PRE
-CLASS="PROGRAMLISTING"
->let data_node = exemplar # <A
-HREF="x939.html#TYPE-NODE-METH-CREATE-DATA"
->create_data</A
-> dtd "The characters contained in the data node" </PRE
->
-
-The <TT
-CLASS="LITERAL"
->data_node</TT
-> is a copy of <TT
-CLASS="LITERAL"
->exemplar</TT
->.
-The copy is initially connected
-with the <TT
-CLASS="LITERAL"
->dtd</TT
->, and it is filled with character material.
-The <TT
-CLASS="LITERAL"
->data_node</TT
-> is now fully functional; it can
-be added to an element as child.</P
-></DIV
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN1308"
->3.2.5. The type <TT
-CLASS="LITERAL"
->spec</TT
-></A
-></H2
-><P
->The type <TT
-CLASS="LITERAL"
->spec</TT
-> defines a way to handle the details of
-creating nodes from exemplars.
-
-<PRE
-CLASS="PROGRAMLISTING"
->type 'ext spec
-constraint 'ext = 'ext node #extension
-
-val make_spec_from_mapping :
- ?super_root_exemplar : 'ext node ->
- ?comment_exemplar : 'ext node ->
- ?default_pinstr_exemplar : 'ext node ->
- ?pinstr_mapping : (string, 'ext node) Hashtbl.t ->
- data_exemplar: 'ext node ->
- default_element_exemplar: 'ext node ->
- element_mapping: (string, 'ext node) Hashtbl.t ->
- unit ->
- 'ext spec
-
-val make_spec_from_alist :
- ?super_root_exemplar : 'ext node ->
- ?comment_exemplar : 'ext node ->
- ?default_pinstr_exemplar : 'ext node ->
- ?pinstr_alist : (string * 'ext node) list ->
- data_exemplar: 'ext node ->
- default_element_exemplar: 'ext node ->
- element_alist: (string * 'ext node) list ->
- unit ->
- 'ext spec</PRE
->
-
-The two functions <TT
-CLASS="LITERAL"
->make_spec_from_mapping</TT
-> and
-<TT
-CLASS="LITERAL"
->make_spec_from_alist</TT
-> create <TT
-CLASS="LITERAL"
->spec</TT
->
-values. Both functions are functionally equivalent and the only difference is
-that the first function prefers hashtables and the latter associative lists to
-describe mappings from names to exemplars.</P
-><P
->You can specify exemplars for the various kinds of nodes that need to be
-generated when an XML document is parsed:
-
-<P
-></P
-><UL
-COMPACT="COMPACT"
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~super_root_exemplar</TT
->: This exemplar
-is used to create the super root. This special node is only created if the
-corresponding configuration option has been selected; it is the parent node of
-the root node which may be convenient if every working node must have a parent.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~comment_exemplar</TT
->: This exemplar is
-used when a comment node must be created. Note that such nodes are only created
-if the corresponding configuration option is "on".</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~default_pinstr_exemplar</TT
->: If a node
-for a processing instruction must be created, and the instruction is not listed
-in the table passed by <TT
-CLASS="LITERAL"
->~pinstr_mapping</TT
-> or
-<TT
-CLASS="LITERAL"
->~pinstr_alist</TT
->, this exemplar is used.
-Again the configuration option must be "on" in order to create such nodes at
-all. </P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~pinstr_mapping</TT
-> or
-<TT
-CLASS="LITERAL"
->~pinstr_alist</TT
->: Map the target names of processing
-instructions to exemplars. These mappings are only used when nodes for
-processing instructions are created.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~data_exemplar</TT
->: The exemplar for
-ordinary data nodes.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~default_element_exemplar</TT
->: This
-exemplar is used if an element node must be created, but the element type
-cannot be found in the tables <TT
-CLASS="LITERAL"
->element_mapping</TT
-> or
-<TT
-CLASS="LITERAL"
->element_alist</TT
->.</P
-></LI
-><LI
-STYLE="list-style-type: disc"
-><P
-><TT
-CLASS="LITERAL"
->~element_mapping</TT
-> or
-<TT
-CLASS="LITERAL"
->~element_alist</TT
->: Map the element types to exemplars. These
-mappings are used to create element nodes.</P
-></LI
-></UL
->
-
-In most cases, you only want to create <TT
-CLASS="LITERAL"
->spec</TT
-> values to pass
-them to the parser functions found in <TT
-CLASS="LITERAL"
->Pxp_yacc</TT
->. However, it
-might be useful to apply <TT
-CLASS="LITERAL"
->spec</TT
-> values directly.</P
-><P
->The following functions create various types of nodes by selecting the
-corresponding exemplar from the passed <TT
-CLASS="LITERAL"
->spec</TT
-> value, and by
-calling <TT
-CLASS="LITERAL"
->create_element</TT
-> or <TT
-CLASS="LITERAL"
->create_data</TT
-> on
-the exemplar.
-
-<PRE
-CLASS="PROGRAMLISTING"
->val create_data_node :
- 'ext spec ->
- dtd ->
- (* data material: *) string ->
- 'ext node
-
-val create_element_node :
- ?position:(string * int * int) ->
- 'ext spec ->
- dtd ->
- (* element type: *) string ->
- (* attributes: *) (string * string) list ->
- 'ext node
-
-val create_super_root_node :
- ?position:(string * int * int) ->
- 'ext spec ->
- dtd ->
- 'ext node
-
-val create_comment_node :
- ?position:(string * int * int) ->
- 'ext spec ->
- dtd ->
- (* comment text: *) string ->
- 'ext node
-
-val create_pinstr_node :
- ?position:(string * int * int) ->
- 'ext spec ->
- dtd ->
- proc_instruction ->
- 'ext node</PRE
-></P
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN1354"
->3.2.6. Examples</A
-></H2
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Building trees. </B
->Here is the piece of code that creates the tree of
-the figure <A
-HREF="x939.html#NODE-TERM"
-><I
-><I
->A tree with element nodes, data nodes, and attributes</I
-><I
-></I
-></I
-></A
->. The extension
-object and the DTD are beyond the scope of this example.
-
-<PRE
-CLASS="PROGRAMLISTING"
->let exemplar_ext = ... (* some extension *) in
-let dtd = ... (* some DTD *) in
-
-let element_exemplar = new element_impl exemplar_ext in
-let data_exemplar = new data_impl exemplar_ext in
-
-let a1 = element_exemplar # create_element dtd (T_element "a") ["att", "apple"]
-and b1 = element_exemplar # create_element dtd (T_element "b") []
-and c1 = element_exemplar # create_element dtd (T_element "c") []
-and a2 = element_exemplar # create_element dtd (T_element "a") ["att", "orange"]
-in
-
-let cherries = data_exemplar # create_data dtd "Cherries" in
-let orange = data_exemplar # create_data dtd "An orange" in
-
-a1 # add_node b1;
-a1 # add_node c1;
-b1 # add_node a2;
-b1 # add_node cherries;
-a2 # add_node orange;</PRE
->
-
-Alternatively, the last block of statements could also be written as:
-
-<PRE
-CLASS="PROGRAMLISTING"
->a1 # set_nodes [b1; c1];
-b1 # set_nodes [a2; cherries];
-a2 # set_nodes [orange];</PRE
->
-
-The root of the tree is <TT
-CLASS="LITERAL"
->a1</TT
->, i.e. it is true that
-
-<PRE
-CLASS="PROGRAMLISTING"
->x # root == a1</PRE
->
-
-for every x from { <TT
-CLASS="LITERAL"
->a1</TT
->, <TT
-CLASS="LITERAL"
->a2</TT
->,
-<TT
-CLASS="LITERAL"
->b1</TT
->, <TT
-CLASS="LITERAL"
->c1</TT
->, <TT
-CLASS="LITERAL"
->cherries</TT
->,
-<TT
-CLASS="LITERAL"
->orange</TT
-> }.</P
-></DIV
-><P
->Furthermore, the following properties hold:
-
-<PRE
-CLASS="PROGRAMLISTING"
-> a1 # attribute "att" = Value "apple"
-& a2 # attribute "att" = Value "orange"
-
-& cherries # data = "Cherries"
-& orange # data = "An orange"
-& a1 # data = "CherriesAn orange"
-
-& a1 # node_type = T_element "a"
-& a2 # node_type = T_element "a"
-& b1 # node_type = T_element "b"
-& c1 # node_type = T_element "c"
-& cherries # node_type = T_data
-& orange # node_type = T_data
-
-& a1 # sub_nodes = [ b1; c1 ]
-& a2 # sub_nodes = [ orange ]
-& b1 # sub_nodes = [ a2; cherries ]
-& c1 # sub_nodes = []
-& cherries # sub_nodes = []
-& orange # sub_nodes = []
-
-& a2 # parent == a1
-& b1 # parent == b1
-& c1 # parent == a1
-& cherries # parent == b1
-& orange # parent == a2</PRE
-></P
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Searching nodes. </B
->The following function searches all nodes of a tree
-for which a certain condition holds:
-
-<PRE
-CLASS="PROGRAMLISTING"
->let rec search p t =
- if p t then
- t :: search_list p (t # sub_nodes)
- else
- search_list p (t # sub_nodes)
-
-and search_list p l =
- match l with
- [] -> []
- | t :: l' -> (search p t) @ (search_list p l')
-;;</PRE
-></P
-></DIV
-><P
->For example, if you want to search all elements of a certain
-type <TT
-CLASS="LITERAL"
->et</TT
->, the function <TT
-CLASS="LITERAL"
->search</TT
-> can be
-applied as follows:
-
-<PRE
-CLASS="PROGRAMLISTING"
->let search_element_type et t =
- search (fun x -> x # node_type = T_element et) t
-;;</PRE
-></P
-><DIV
-CLASS="FORMALPARA"
-><P
-><B
->Getting attribute values. </B
->Suppose we have the declaration:
-
-<PRE
-CLASS="PROGRAMLISTING"
-><!ATTLIST e a CDATA #REQUIRED
- b CDATA #IMPLIED
- c CDATA "12345"></PRE
->
-
-In this case, every element <TT
-CLASS="LITERAL"
->e</TT
-> must have an attribute
-<TT
-CLASS="LITERAL"
->a</TT
->, otherwise the parser would indicate an error. If
-the O'Caml variable <TT
-CLASS="LITERAL"
->n</TT
-> holds the node of the tree
-corresponding to the element, you can get the value of the attribute
-<TT
-CLASS="LITERAL"
->a</TT
-> by
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_a = n # required_string_attribute "a"</PRE
->
-
-which is more or less an abbreviation for
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_a =
- match n # attribute "a" with
- Value s -> s
- | _ -> assert false</PRE
->
-
-- as the attribute is required, the <TT
-CLASS="LITERAL"
->attribute</TT
-> method always
-returns a <TT
-CLASS="LITERAL"
->Value</TT
->.</P
-></DIV
-><P
->In contrast to this, the attribute <TT
-CLASS="LITERAL"
->b</TT
-> can be
-omitted. In this case, the method <TT
-CLASS="LITERAL"
->required_string_attribute</TT
->
-works only if the attribute is there, and the method will fail if the attribute
-is missing. To get the value, you can apply the method
-<TT
-CLASS="LITERAL"
->optional_string_attribute</TT
->:
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_b = n # optional_string_attribute "b"</PRE
->
-
-Now, <TT
-CLASS="LITERAL"
->value_of_b</TT
-> is of type <TT
-CLASS="LITERAL"
->string option</TT
->,
-and <TT
-CLASS="LITERAL"
->None</TT
-> represents the omitted attribute. Alternatively,
-you could also use <TT
-CLASS="LITERAL"
->attribute</TT
->:
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_b =
- match n # attribute "b" with
- Value s -> Some s
- | Implied_value -> None
- | _ -> assert false</PRE
-></P
-><P
->The attribute <TT
-CLASS="LITERAL"
->c</TT
-> behaves much like
-<TT
-CLASS="LITERAL"
->a</TT
->, because it has always a value. If the attribute is
-omitted, the default, here "12345", will be returned instead. Because of this,
-you can again use <TT
-CLASS="LITERAL"
->required_string_attribute</TT
-> to get the
-value.</P
-><P
->The type <TT
-CLASS="LITERAL"
->CDATA</TT
-> is the most general string
-type. The types <TT
-CLASS="LITERAL"
->NMTOKEN</TT
->, <TT
-CLASS="LITERAL"
->ID</TT
->,
-<TT
-CLASS="LITERAL"
->IDREF</TT
->, <TT
-CLASS="LITERAL"
->ENTITY</TT
->, and all enumerators and
-notations are special forms of string types that restrict the possible
-values. From O'Caml, they behave like <TT
-CLASS="LITERAL"
->CDATA</TT
->, i.e. you can
-use the methods <TT
-CLASS="LITERAL"
->required_string_attribute</TT
-> and
-<TT
-CLASS="LITERAL"
->optional_string_attribute</TT
->, too.</P
-><P
->In contrast to this, the types <TT
-CLASS="LITERAL"
->NMTOKENS</TT
->,
-<TT
-CLASS="LITERAL"
->IDREFS</TT
->, and <TT
-CLASS="LITERAL"
->ENTITIES</TT
-> mean lists of
-strings. Suppose we have the declaration:
-
-<PRE
-CLASS="PROGRAMLISTING"
-><!ATTLIST f d NMTOKENS #REQUIRED
- e NMTOKENS #IMPLIED></PRE
->
-
-The type <TT
-CLASS="LITERAL"
->NMTOKENS</TT
-> stands for lists of space-separated
-tokens; for example the value <TT
-CLASS="LITERAL"
->"1 abc 23ef"</TT
-> means the list
-<TT
-CLASS="LITERAL"
->["1"; "abc"; "23ef"]</TT
->. (Again, <TT
-CLASS="LITERAL"
->IDREFS</TT
->
-and <TT
-CLASS="LITERAL"
->ENTITIES</TT
-> have more restricted values.) To get the
-value of attribute <TT
-CLASS="LITERAL"
->d</TT
->, one can use
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_d = n # required_list_attribute "d"</PRE
->
-
-or
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_d =
- match n # attribute "d" with
- Valuelist l -> l
- | _ -> assert false</PRE
->
-
-As <TT
-CLASS="LITERAL"
->d</TT
-> is required, the attribute cannot be omitted, and
-the <TT
-CLASS="LITERAL"
->attribute</TT
-> method returns always a
-<TT
-CLASS="LITERAL"
->Valuelist</TT
->. </P
-><P
->For optional attributes like <TT
-CLASS="LITERAL"
->e</TT
->, apply
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_e = n # optional_list_attribute "e"</PRE
->
-
-or
-
-<PRE
-CLASS="PROGRAMLISTING"
->let value_of_e =
- match n # attribute "e" with
- Valuelist l -> l
- | Implied_value -> []
- | _ -> assert false</PRE
->
-
-Here, the case that the attribute is missing counts like the empty list.</P
-></DIV
-><DIV
-CLASS="SECT2"
-><H2
-CLASS="SECT2"
-><A
-NAME="AEN1435"
->3.2.7. Iterators</A
-></H2
-><P
->There are also several iterators in Pxp_document; please see
-the mli file for details. You can find examples for them in the
-"simple_transformation" directory.
-
-<PRE
-CLASS="PROGRAMLISTING"
->val find : ?deeply:bool ->
- f:('ext node -> bool) -> 'ext node -> 'ext node
-
-val find_all : ?deeply:bool ->
- f:('ext node -> bool) -> 'ext node -> 'ext node list
-
-val find_element : ?deeply:bool ->
- string -> 'ext node -> 'ext node
-
-val find_all_elements : ?deeply:bool ->
- string -> 'ext node -> 'ext node list
-
-exception Skip
-val map_tree : pre:('exta node -> 'extb node) ->
- ?post:('extb node -> 'extb node) ->
- 'exta node ->
- 'extb node
-
-
-val map_tree_sibl :
- pre: ('exta node option -> 'exta node -> 'exta node option ->
- 'extb node) ->
- ?post:('extb node option -> 'extb node -> 'extb node option ->
- 'extb node) ->
- 'exta node ->
- 'extb node
-
-val iter_tree : ?pre:('ext node -> unit) ->
- ?post:('ext node -> unit) ->
- 'ext node ->
- unit
-
-val iter_tree_sibl :
- ?pre: ('ext node option -> 'ext node -> 'ext node option -> unit) ->
- ?post:('ext node option -> 'ext node -> 'ext node option -> unit) ->
- 'ext node ->
- unit</PRE
-></P
-></DIV
-></DIV
-><DIV
-CLASS="NAVFOOTER"
-><HR
-ALIGN="LEFT"
-WIDTH="100%"><TABLE
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
-><A
-HREF="c893.html"
->Prev</A
-></TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="index.html"
->Home</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
-><A
-HREF="x1439.html"
->Next</A
-></TD
-></TR
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
->The objects representing the document</TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="c893.html"
->Up</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
->The class type <TT
-CLASS="LITERAL"
->extension</TT
-></TD
-></TR
-></TABLE
-></DIV
-></BODY
-></HTML
->
\ No newline at end of file
projects / helm.git / blobdiff