xsl:copy-of
Copies the value obtained by evaluating the mandatory select
attribute. It makes an exact copy.
Category: instruction
Content: none
Permitted parent elements:
any XSLT element whose content model is
sequence-constructor; any literal result element
Attributes
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Value to be copied (which may be any sequence of nodes, atomic values, and/or function items), given by an expression. If this expression is a string, a number, or a boolean, the effect is the same as using xsl:sequence. |
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New in XSLT 3.0. Used to copy the pre-descent and post-descent values of accumulators on source nodes to the new copies. |
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Controls whether the in-scope
namespaces of any element nodes copied by this instruction are automatically
copied to the result. The default is |
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Notes on the Saxon implementation
Earlier releases of Saxon supported an attribute saxon:read-once to control
streaming behaviour. This is now superseded by the streaming features of XSLT 3.0;
an error is reported if the attribute is used.
Details
Making a deep copy of an element is particularly useful during streaming. For
this reason XSLT 3.0 introduces an equivalent function, copy-of(). For example one can write
<xsl:for-each select="employee/copy-of()"> which
processes a sequence of copies of the selected <employee>
elements; the significance of using copies is that streaming constraints do not
apply, since each <employee> element will be represented as a
tree in memory, discarded as soon as that element has been processed.