basics.html

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    tree = mxmlLoadFile(NULL, fp,
                        MXML_TEXT_CALLBACK);
    fclose(fp);
</pre>

<p>The first argument specifies an existing XML parent node, if
any. Normally you will pass <tt>NULL</tt> for this argument
unless you are combining multiple XML sources. The XML file must
contain a complete XML document including the <tt>?xml</tt>
element if the parent node is <tt>NULL</tt>.</p>

<p>The second argument specifies the stdio file to read from, as
opened by <tt>fopen()</tt> or <tt>popen()</tt>. You can also use
<tt>stdin</tt> if you are implementing an XML filter
program.</p>

<p>The third argument specifies a callback function which returns
the value type of the immediate children for a new element node:
<tt>MXML_CUSTOM</tt>, <tt>MXML_IGNORE</tt>,
<tt>MXML_INTEGER</tt>, <tt>MXML_OPAQUE</tt>, <tt>MXML_REAL</tt>,
or <tt>MXML_TEXT</tt>. Load callbacks are described in detail in
<a href='#LOAD_CALLBACKS'>Chapter 3</a>. The example code uses
the <tt>MXML_TEXT_CALLBACK</tt> constant which specifies that all
data nodes in the document contain whitespace-separated text
values. Other standard callbacks include
<tt>MXML_IGNORE_CALLBACK</tt>, <tt>MXML_INTEGER_CALLBACK</tt>,
<tt>MXML_OPAQUE_CALLBACK</tt>, and 
<tt>MXML_REAL_CALLBACK</tt>.</p>

<p>The <a href='#mxmlLoadString'><tt>mxmlLoadString</tt></a>
function loads XML node trees from a string:</p>

<!-- NEED 10 -->
<pre>
    char buffer[8192];
    mxml_node_t *tree;

    ...
    tree = mxmlLoadString(NULL, buffer,
                          MXML_TEXT_CALLBACK);
</pre>

<p>The first and third arguments are the same as used for
<tt>mxmlLoadFile()</tt>. The second argument specifies the
string or character buffer to load and must be a complete XML
document including the <tt>?xml</tt> element if the parent node
is <tt>NULL</tt>.</p>


<!-- NEW PAGE -->
<h2>Saving XML</h2>

<p>You save an XML file using the <a
href='#mxmlSaveFile'><tt>mxmlSaveFile</tt></a> function:</p>

<pre>
    FILE *fp;
    mxml_node_t *tree;

    fp = fopen("filename.xml", "w");
    mxmlSaveFile(tree, fp, MXML_NO_CALLBACK);
    fclose(fp);
</pre>

<p>The first argument is the XML node tree to save. It should
normally be a pointer to the top-level <tt>?xml</tt> node in
your XML document.</p>

<p>The second argument is the stdio file to write to, as opened
by <tt>fopen()</tt> or <tt>popen()</tt>. You can also use
<tt>stdout</tt> if you are implementing an XML filter
program.</p>

<p>The third argument is the whitespace callback to use when
saving the file. Whitespace callbacks are covered in detail in <a
href='SAVE_CALLBACKS'>Chapter 3</a>. The previous example code
uses the <tt>MXML_NO_CALLBACK</tt> constant to specify that no
special whitespace handling is required.</p>

<p>The <a
href='#mxmlSaveAllocString'><tt>mxmlSaveAllocString</tt></a>,
and <a href='#mxmlSaveString'><tt>mxmlSaveString</tt></a>
functions save XML node trees to strings:</p>

<pre>
    char buffer[8192];
    char *ptr;
    mxml_node_t *tree;

    ...
    mxmlSaveString(tree, buffer, sizeof(buffer),
                   MXML_NO_CALLBACK);

    ...
    ptr = mxmlSaveAllocString(tree, MXML_NO_CALLBACK);
</pre>

<p>The first and last arguments are the same as used for
<tt>mxmlSaveFile()</tt>. The <tt>mxmlSaveString</tt> function
takes pointer and size arguments for saving the XML document to
a fixed-size buffer, while <tt>mxmlSaveAllocString()</tt>
returns a string buffer that was allocated using
<tt>malloc()</tt>.</p>

<h3>Controlling Line Wrapping</h3>

<p>When saving XML documents, Mini-XML normally wraps output
lines at column 75 so that the text is readable in terminal
windows. The <a
href='#mxmlSetWrapMargin'><tt>mxmlSetWrapMargin</tt></a> function
overrides the default wrap margin:</p>

<pre>
    /* Set the margin to 132 columns */
    mxmlSetWrapMargin(132);

    /* Disable wrapping */
    mxmlSetWrapMargin(0);
</pre>


<!-- NEW PAGE-->
<h2>Finding and Iterating Nodes</h2>

<p>The <a
href='#mxmlWalkPrev'><tt>mxmlWalkPrev</tt></a>
and <a
href='#mxmlWalkNext'><tt>mxmlWalkNext</tt></a>functions
can be used to iterate through the XML node tree:</p>

<pre>
    mxml_node_t *node;
    
    node = mxmlWalkPrev(current, tree,
                        MXML_DESCEND);

    node = mxmlWalkNext(current, tree,
                        MXML_DESCEND);
</pre>

<p>In addition, you can find a named element/node using the <a
href='#mxmlFindElement'><tt>mxmlFindElement</tt></a>
function:</p>

<pre>
    mxml_node_t *node;
    
    node = mxmlFindElement(tree, tree, "name",
                           "attr", "value",
                           MXML_DESCEND);
</pre>

<p>The <tt>name</tt>, <tt>attr</tt>, and <tt>value</tt>
arguments can be passed as <tt>NULL</tt> to act as wildcards,
e.g.:</p>

<!-- NEED 4 -->
<pre>
    /* Find the first "a" element */
    node = mxmlFindElement(tree, tree, "a",
                           NULL, NULL,
                           MXML_DESCEND);
</pre>
<!-- NEED 5 -->
<pre>
    /* Find the first "a" element with "href"
       attribute */
    node = mxmlFindElement(tree, tree, "a",
                           "href", NULL,
                           MXML_DESCEND);
</pre>
<!-- NEED 6 -->
<pre>
    /* Find the first "a" element with "href"
       to a URL */
    node = mxmlFindElement(tree, tree, "a",
                           "href",
                           "http://www.easysw.com/",
                           MXML_DESCEND);
</pre>
<!-- NEED 5 -->
<pre>
    /* Find the first element with a "src"
       attribute */
    node = mxmlFindElement(tree, tree, NULL,
                           "src", NULL,
                           MXML_DESCEND);
</pre>
<!-- NEED 5 -->
<pre>
    /* Find the first element with a "src"
       = "foo.jpg" */
    node = mxmlFindElement(tree, tree, NULL,
                           "src", "foo.jpg",
                           MXML_DESCEND);
</pre>

<p>You can also iterate with the same function:</p>

<pre>
    mxml_node_t *node;

    for (node = mxmlFindElement(tree, tree,
                                "name",
                                NULL, NULL,
                                MXML_DESCEND);
         node != NULL;
         node = mxmlFindElement(node, tree,
                                "name",
                                NULL, NULL,
                                MXML_DESCEND))
    {
      ... do something ...
    }
</pre>

<!-- NEED 10 -->
<p>The <tt>MXML_DESCEND</tt> argument can actually be one of
three constants:</p>

<ul>

	<li><tt>MXML_NO_DESCEND</tt> means to not to look at any
	child nodes in the element hierarchy, just look at
	siblings at the same level or parent nodes until the top
	node or top-of-tree is reached.

        <p>The previous node from "group" would be the "node"
        element to the left, while the next node from "group" would
        be the "node" element to the right.<br><br></p></li>

        <li><tt>MXML_DESCEND_FIRST</tt> means that it is OK to
        descend to the first child of a node, but not to descend
        further when searching. You'll normally use this when
        iterating through direct children of a parent node, e.g. all
        of the "node" and "group" elements under the "?xml" parent
        node in the example above.

        <p>This mode is only applicable to the search function; the
        walk functions treat this as <tt>MXML_DESCEND</tt> since
        every call is a first time.<br><br></p></li>

        <li><tt>MXML_DESCEND</tt> means to keep descending until
        you hit the bottom of the tree. The previous node from
        "group" would be the "val3" node and the next node would
        be the first node element under "group".

        <p>If you were to walk from the root node "?xml" to the end
        of the tree with <tt>mxmlWalkNext()</tt>, the order would
        be:</p>

        <p><tt>?xml data node val1 node val2 node val3 group node
        val4 node val5 node val6 node val7 node val8</tt></p>

	<p>If you started at "val8" and walked using
	<tt>mxmlWalkPrev()</tt>, the order would be reversed,
	ending at "?xml".</p></li>

</ul>

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