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# xmerl (xmerl v2.1.9)

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Functions for exporting XML data to an external format.

# Summary

## Types

callback()

A callback module or a list of inherited callback modules.

element()

Normal, well-formed, XML content element.

simple_attribute()

"Simple-form" XML attribute.

simple_element()

"Simple-form" XML content element.

xmlAttribute()

Record `#xmlAttribute{}`.

xmlComment()

Record `#xmlComment{}`.

xmlDecl()

Record `#xmlDecl{}`.

xmlDocument()

Record `#xmlDocument{}`.

xmlElement()

Record `#xmlElement{}`.

xmlNamespace()

Record `#xmlNamespace{}`.

xmlNsNode()

Record `#xmlNsNode{}`.

xmlPI()

Record `#xmlPI{}`.

xmlText()

Record `#xmlText{}`.

## Functions

callbacks(Module)

Find the list of inherited callback modules for a given module.

export(Content, Callback)

Equivalent to `export(Content, Callback, [])`.

export(Content, Callback, RootAttributes)

Export XML content.

export_content(Content, Callbacks)

Export normal XML content directly, without further context.

export_element(Element, Callback)

Exports a normal XML element directly, without further context.

export_element(Element, Callback, CallbackState)

For on-the-fly exporting during parsing (SAX style) of the XML document.

export_simple(Content, Callback)

Equivalent to `export_simple(Content, Callback, [])`.

export_simple(Content, Callback, RootAttributes)

Export "simple-form" XML content.

export_simple_content(Content, Callback)

Exports simple XML content directly, without further context.

export_simple_element(Element, Callback)

Export a simple XML element directly, without further context.

# Types

# callback()

(not exported)

    -type callback() :: module() | [module()].

A callback module or a list of inherited callback modules.

# element()

    -type element() :: xmlText() | xmlElement() | xmlPI() | xmlComment() | xmlDecl().

Normal, well-formed, XML content element.

# simple_attribute()

(not exported)

    -type simple_attribute() :: xmlAttribute() | {fun((_) -> _), term()} | {Key :: atom(), Value :: term()}.

"Simple-form" XML attribute.

# simple_element()

(not exported)

    -type simple_element() ::
              {Tag :: atom(),
               Attributes :: [{Name :: atom(), Value :: iolist() | atom() | integer()}],
               Content :: [simple_element()]} |
              {Tag :: atom(), Content :: [simple_element()]} |
              (Tag :: atom() | (IOString :: iolist() | element())).

"Simple-form" XML content element.

# xmlAttribute()

    -type xmlAttribute() ::
              #xmlAttribute{name :: term(),
                            expanded_name :: term(),
                            nsinfo :: term(),
                            namespace :: term(),
                            parents :: term(),
                            pos :: term(),
                            language :: term(),
                            value :: term(),
                            normalized :: term()}.

Record `#xmlAttribute{}`.

# xmlComment()

    -type xmlComment() :: #xmlComment{parents :: term(), pos :: term(), language :: term(), value :: term()}.

Record `#xmlComment{}`.

# xmlDecl()

    -type xmlDecl() ::
              #xmlDecl{vsn :: term(), encoding :: term(), standalone :: term(), attributes :: term()}.

Record `#xmlDecl{}`.

# xmlDocument()

    -type xmlDocument() :: #xmlDocument{content :: term()}.

Record `#xmlDocument{}`.

# xmlElement()

    -type xmlElement() ::
              #xmlElement{name :: term(),
                          expanded_name :: term(),
                          nsinfo :: term(),
                          namespace :: term(),
                          parents :: term(),
                          pos :: term(),
                          attributes :: term(),
                          content :: term(),
                          language :: term(),
                          xmlbase :: term(),
                          elementdef :: term()}.

Record `#xmlElement{}`.

# xmlNamespace()

    -type xmlNamespace() :: #xmlNamespace{default :: term(), nodes :: term()}.

Record `#xmlNamespace{}`.

# xmlNsNode()

    -type xmlNsNode() :: #xmlNsNode{parents :: term(), pos :: term(), prefix :: term(), uri :: term()}.

Record `#xmlNsNode{}`.

# xmlPI()

    -type xmlPI() :: #xmlPI{name :: term(), parents :: term(), pos :: term(), value :: term()}.

Record `#xmlPI{}`.

# xmlText()

    -type xmlText() ::
              #xmlText{parents :: term(),
                       pos :: term(),
                       language :: term(),
                       value :: term(),
                       type :: term()}.

Record `#xmlText{}`.

# Functions

# callbacks(Module)

    -spec callbacks(Module :: module()) -> [module()].

Find the list of inherited callback modules for a given module.

# export(Content, Callback)

    -spec export(Content :: term(), Callback :: term()) -> ExportedFormat :: term().

Equivalent to `export(Content, Callback, [])`.

# export(Content, Callback, RootAttributes)

    -spec export(Content, Callback, RootAttributes) -> ExportedFormat :: term()
                    when
                        Content :: [Element],
                        Element :: element(),
                        Callback :: callback(),
                        RootAttributes :: [simple_attribute()].

Export XML content.

Exports normal, well-formed XML content, using the specified callback module.

`Element` is any of:

- `#xmlText{}`
- `#xmlElement{}`
- `#xmlPI{}`
- `#xmlComment{}`
- `#xmlDecl{}`

(See `xmerl.hrl` for the record definitions.) Text in `#xmlText{}` elements can be deep lists of characters and/or binaries.

`RootAttributes` is a list of `#xmlAttribute{}` attributes for the `#root#` element, which implicitly becomes the parent of the given `Content`. The tag-handler function for `#root#` is thus called with the complete exported data of `Content`. Root attributes can be used to specify e.g. encoding or other metadata of an XML or HTML document.

The `Callback` module should contain hook functions for all tags present in the data structure. A hook function must have the following format:

        Tag(Data, Attributes, Parents, E)

where `E` is the corresponding `#xmlElement{}`, `Data` is the already-exported contents of `E` and `Attributes` is the list of `#xmlAttribute{}` records of `E`. Finally, `Parents` is the list of parent nodes of `E`, on the form `[{ParentTag::atom(), ParentPosition::integer()}]`.

The hook function should return either the data to be exported, or a tuple `{'#xml-alias#', NewTag::atom()}`, or a tuple `{'#xml-redefine#', Content}`, where `Content` is a content list (which can be on simple-form; see `export_simple/2` for details).

A callback module can inherit definitions from other callback modules, through the required function `'#xml-interitance#'() -> [ModuleName::atom()]`.

See also: `export/2`, `export_simple/3`.

# export_content(Content, Callbacks)

    -spec export_content(Content, Callbacks) -> _ when Content :: [element()], Callbacks :: [module()].

Export normal XML content directly, without further context.

# export_element(Element, Callback)

    -spec export_element(Element, Callback) -> _ when Element :: element(), Callback :: callback().

Exports a normal XML element directly, without further context.

# export_element(Element, Callback, CallbackState)

    -spec export_element(Element, Callback, CallbackState) -> ExportedFormat
                            when
                                Element :: element(),
                                Callback :: callback(),
                                CallbackState :: term(),
                                ExportedFormat :: term().

For on-the-fly exporting during parsing (SAX style) of the XML document.

# export_simple(Content, Callback)

    -spec export_simple(Content, Callback) -> ExportedFormat :: term()
                           when Content :: [Element], Element :: simple_element(), Callback :: callback().

Equivalent to `export_simple(Content, Callback, [])`.

# export_simple(Content, Callback, RootAttributes)

    -spec export_simple(Content, Callback, RootAttributes) -> ExportedFormat :: term()
                           when
                               Content :: [Element],
                               Element :: simple_element(),
                               Callback :: callback(),
                               RootAttributes :: [simple_attribute()].

Export "simple-form" XML content.

Exports "simple-form" XML content, using the specified callback-module.

`Element` is any of:

- `{Tag, Attributes, Content}`
- `{Tag, Content}`
- `Tag`
- `IOString`
- `#xmlText{}`
- `#xmlElement{}`
- `#xmlPI{}`
- `#xmlComment{}`
- `#xmlDecl{}`

where

- `Tag = atom()`
- `Attributes = [{Name, Value}]`
- `Name = atom()`

- `Value = IOString | atom() | integer()`

Normal-form XML elements can thus be included in the simple-form representation. Note that content lists must be flat. An `IOString` is a (possibly deep) list of characters and/or binaries.

`RootAttributes` is a list of:

- `XmlAttributes = #xmlAttribute{}`

See `export/3` for details on the callback module and the root attributes. The XML-data is always converted to normal form before being passed to the callback module.

See also: `export/3`, `export_simple/2`.

# export_simple_content(Content, Callback)

    -spec export_simple_content(Content, Callback) -> _
                                   when Content :: [simple_element()], Callback :: callback().

Exports simple XML content directly, without further context.

# export_simple_element(Element, Callback)

    -spec export_simple_element(Element, Callback) -> _
                                   when Element :: simple_element(), Callback :: callback().

Export a simple XML element directly, without further context.