Inside Xslt

Part 1 of XPath Location Steps: Axes

In the location path ancestor :: NAME , which refers to a <NAME> element that is an ancestor of the context node, ancestor is the axis. XPath supports many different axes, and heres the complete list:

• The ancestor axis holds the ancestors of the context node; the ancestors of the context node are the parent of context node and the parents parent and so forth, back to and including the root node.

• The ancestor-or-self axis holds the context node and the ancestors of the context node.

• The attribute axis holds the attributes of the context node.

• The child axis holds the children of the context node.

• The descendant axis holds the descendants of the context node. A descendant is a child or a child of a child and so on.

• The descendant-or-self axis contains the context node and the descendants of the context node.

• The following axis holds all nodes in the same document as the context node that come after the context node.

• The following-sibling axis holds all the following siblings of the context node. A sibling is a node on the same level as the context node.

• The namespace axis holds the namespace nodes of the context node.

• The parent axis holds the parent of the context node.

• The preceding axis contains all nodes that come before the context node.

• The preceding-sibling axis contains all the preceding siblings of the context node. A sibling is a node on the same level as the context node.

• The self axis contains the context node.

In the following example template I use the descendant axis to indicate that I want to match descendants of the context node, which include child nodes, grandchild nodes, great-grandchild nodes, and so on:

<xsl:template match="PLANET"> <DATA> <NAME> <xsl:value-of select="descendant::NAME"/> </NAME> <MASS> <xsl:value-of select="descendant::MASS"/> </MASS> <DAY> <xsl:value-of select="descendant::DAY"/> </DAY> </DATA> </xsl:template>

This chapter looks at each of these axes. In this example, descendant is the axis, and the element names NAME , MASS , and DAY are node tests .