Question

XML:

    <mode>
        <submode>1</submode>
        <submode>2</submode>
        <submode>3</submode>
        <submode>4</submode>
        <submode>5</submode>
        <submode>6</submode>
        <submode>7</submode>
    </mode>
    <mode>
        <submode>7</submode>
        <submode>8</submode>
        <submode>9</submode>
        <submode>10</submode>
        <submode>11</submode>
        <submode>12</submode>
        <submode>13</submode>
    </mode>
    <mode>
        <submode>14</submode>
        <submode>15</submode>
        <submode>16</submode>
        <submode>17</submode>
        <submode>18</submode>
        <submode>19</submode>
        20</submode>
    </mode>   

How to test first <submode> from each <mode> (i need get numbers: 1, 7, 14) in such construction:

<xsl:template match="submode">
    <xsl:if test="(parent::mode) and (...what?...)">
        ...
    </xsl:if>
    ...
</xsl:template>

I do not understand how use position() here.

Answer 1

It is not generally true that

position() = 1

evaluates to true() if the current node has a parent mode and the current node is the first submode child of its parent.

position() specifies the position of the current node-list and this is defined in a different way, depending on how the select attribute of <xsl:apply-templates> is specified.

For example (assuming that the provided XML has a top element that is the parent of the mode elements), if the template was selected when processingthe following:

<xsl:apply-templates select="/*/mode/submode[. = 3]"/>

then

position() = 1

is true only for the 3rd submode child of the first mode element.

One correct answer:

parent::mode and not(preceding-sibling::submode)

Or, recommended:

Have a separate template:

<xsl:template match="mode/submode[1]">

In this case no code within template is necessary to check if the current node is the first submode child — this is already known to be so.