Module xmlrat_mini_xslt

Description

Implements the "mxsl" subset/dialect of XSLT used for compiled XML templates.

Description

Implements the "mxsl" subset/dialect of XSLT used for compiled XML templates.

This template language is used in the -xml_record() attribute provided by xmlrat_parse_transform.

The MXSL language is designed to look and feel a lot like XSLT, but with some modifications (due to the fact that the input data is Erlang records and not XML/XPath), and some abbreviations to make templates easier to read and write.

As well as the normal XSLT-style use of namespaced elements to substitute values (e.g. <mxsl:value-of field='...'/>), MXSL also supports using XML entities named after each record field for substitution.

A short example of an MXSL template, showing both an XSLT-style substitution and an entity substitution:


  <KeyInfo>
    <mxsl:if defined='name'>
      <KeyName><mxsl:value-of field='name'/></KeyName>
    </mxsl:if>
    <KeyType Algorithm='&algorithm;'/>
  </KeyInfo>

The mxsl: namespace URI is https://cooperi.net/xmlrat/mini-xslt/. Templates can either use the pre-defined namespace prefix mxsl:, or define their own in the regular way using xmlns:* attributes.

MXSL element reference

<mxsl:value-of>

Substitutes with the value of a record field. The mxsl:value-of element will be deleted, replaced with the record field's type-coerced value.

Attributes:

field: specifies the name of the record field to substitute

Content:

none

<mxsl:attribute>

Adds an attribute to the parent element, with the new attribute's value set by a record field. Can also be nested inside a <mxsl:if> element (will add the attribute to the grandparent).

Attributes:

name: specifies the name of the attribute to add
namespace: specifies the namespace prefix of the attribute (optional)
field: specifies the name of the record field whose value will placed in the attribute

Content:

none

<mxsl:if>

Conditionally applies or includes some elements if a record field is set to a value other than undefined, or set to boolean true.

Attributes:

defined: specifies the record field whose value will checked for undefined
true: specifies the record field whose value will be checked for boolean true

Content:

<mxsl:attribute>
any content element

<mxsl:for-each>

Repeats a sub-tree of the document once for each element in a list. The current element is bound as a "fake" record field (and can be referenced by either <mxsl:value-of> etc or entities).

Attributes:

field: specifies the name of the record field whose value will be iterated over
as: specifies the name of the pseudo-field which will be bound to each individual element in the list

Content:

any content or MXSL element

<mxsl:tag>

Generates an element with a dynamic tag name based on a record field.

Attributes:

mxsl:field: specifies the record field whose contents will be used to rename this tag.

Content:

any content or MXSL element

The mxsl:field attribute will be elided from the output, but all other attributes of the tag will be inherited by the final output tag.

Entities

Within any element content or attribute value, entities may be used to refer to the value of record fields. The entity name matches the record field name exactly: e.g. &foobar; refers to the value of record field foobar.

When used in an attribute value, if the field is set to undefined, and the attribute value consists only of the field entity, the entire attribute will be elided from the output.

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