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Diffstat (limited to 'docs/manual/xpath.html')
| -rw-r--r-- | docs/manual/xpath.html | 44 |
1 files changed, 25 insertions, 19 deletions
diff --git a/docs/manual/xpath.html b/docs/manual/xpath.html index 731a969..513bb90 100644 --- a/docs/manual/xpath.html +++ b/docs/manual/xpath.html @@ -54,6 +54,9 @@ at tizag.com</a>, and <a href="http://www.w3.org/TR/xpath/" target="_top">the XPath 1.0 specification</a>. </p> +<p> + $$ + </p> <div class="note"><table border="0" summary="Note"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../images/note.png"></td> @@ -120,9 +123,11 @@ You can also create XPath nodes with one of tree constructors: the default constructor, the constructor that takes node argument, and the constructor that takes attribute and node arguments (in which case the attribute must - belong to the attribute list of the node). However, usually you don't need - to create your own XPath node objects, since they are returned to you via - selection functions. + belong to the attribute list of the node). The constructor from <code class="computeroutput"><span class="identifier">xml_node</span></code> is implicit, so you can usually + pass <code class="computeroutput"><span class="identifier">xml_node</span></code> to functions + that expect <code class="computeroutput"><span class="identifier">xpath_node</span></code>. Apart + from that you usually don't need to create your own XPath node objects, since + they are returned to you via selection functions. </p> <a name="xpath_node_set"></a><p> XPath expressions operate not on single nodes, but instead on node sets. @@ -309,20 +314,21 @@ <a name="xpath_query::evaluate_boolean"></a><a name="xpath_query::evaluate_number"></a><a name="xpath_query::evaluate_string"></a><a name="xpath_query::evaluate_node_set"></a><p> You can evaluate the query using one of the following functions: </p> -<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_boolean</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> -<span class="keyword">double</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_number</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> -<span class="identifier">string_t</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_string</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> -<span class="identifier">xpath_node_set</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_node_set</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> +<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_boolean</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xpath_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> +<span class="keyword">double</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_number</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xpath_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> +<span class="identifier">string_t</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_string</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xpath_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> +<span class="identifier">xpath_node_set</span> <span class="identifier">xpath_query</span><span class="special">::</span><span class="identifier">evaluate_node_set</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xpath_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> </pre> <p> - All functions take the context node as an argument, compute the expression - and return the result, converted to the requested type. By XPath specification, - value of any type can be converted to boolean, number or string value, but - no type other than node set can be converted to node set. Because of this, - <code class="computeroutput"><span class="identifier">evaluate_boolean</span></code>, <code class="computeroutput"><span class="identifier">evaluate_number</span></code> and <code class="computeroutput"><span class="identifier">evaluate_string</span></code> - always return a result, but <code class="computeroutput"><span class="identifier">evaluate_node_set</span></code> - throws an <code class="computeroutput"><span class="identifier">xpath_exception</span></code> - if the return type is not node set. + $$ exception, evaluate_string nostl All functions take the context node as + an argument, compute the expression and return the result, converted to the + requested type. By XPath specification, value of any type can be converted + to boolean, number or string value, but no type other than node set can be + converted to node set. Because of this, <code class="computeroutput"><span class="identifier">evaluate_boolean</span></code>, + <code class="computeroutput"><span class="identifier">evaluate_number</span></code> and <code class="computeroutput"><span class="identifier">evaluate_string</span></code> always return a result, + but <code class="computeroutput"><span class="identifier">evaluate_node_set</span></code> throws + an <code class="computeroutput"><span class="identifier">xpath_exception</span></code> if the + return type is not node set. </p> <div class="note"><table border="0" summary="Note"> <tr> @@ -370,7 +376,7 @@ <a name="manual.xpath.errors"></a><a class="link" href="xpath.html#manual.xpath.errors" title="Error handling"> Error handling</a> </h3></div></div></div> <a name="xpath_exception"></a><a name="xpath_exception::what"></a><p> - As of version 0.9, all XPath errors result in thrown exceptions. The errors + $$ As of version 0.9, all XPath errors result in thrown exceptions. The errors can arise during expression compilation or node set evaluation. In both cases, an <code class="computeroutput"><span class="identifier">xpath_exception</span></code> object is thrown. This is an exception object that implements <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception</span></code> @@ -379,8 +385,8 @@ <pre class="programlisting"><span class="keyword">virtual</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">xpath_exception</span><span class="special">::</span><span class="identifier">what</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">throw</span><span class="special">();</span> </pre> <p> - This function returns the error message. Currently it is impossible to get - the exact place where query compilation failed. This functionality, along + $$ This function returns the error message. Currently it is impossible to + get the exact place where query compilation failed. This functionality, along with optional error handling without exceptions, will be available in version 1.0. </p> @@ -464,7 +470,7 @@ </li> </ul></div> <p> - Some of these incompatibilities will be fixed in version 1.0. + $$ Some of these incompatibilities will be fixed in version 1.0. </p> </div> </div> |