Author: Michael R Sweet

# Mini-XML 3.3 Programming Manual

Michael R Sweet

Copyright © 2003-2022, All Rights Reserved.

## Contents

- Introduction
  - History
  - Resources
  - Legal Stuff
- Using Mini-XML
  - Loading an XML File
  - Nodes
  - Creating XML Documents
  - Saving an XML File
  - Memory Management
- More About Nodes
  - Element Nodes
  - CDATA Nodes
  - Comment Nodes
  - Processing Instruction Nodes
  - Integer Nodes
  - Opaque String Nodes
  - Text Nodes
  - Real Number Nodes
- Locating Data in an XML Document
  - Finding Nodes
  - Iterating Nodes
  - Indexing
- Custom Data Types
- SAX (Stream) Loading of Documents
- Functions
  - mxmlAdd
  - mxmlDelete
  - mxmlElementDeleteAttr
  - mxmlElementGetAttr
  - mxmlElementGetAttrByIndex
  - mxmlElementGetAttrCount
  - mxmlElementSetAttr
  - mxmlElementSetAttrf
  - mxmlEntityAddCallback
  - mxmlEntityGetName
  - mxmlEntityGetValue
  - mxmlEntityRemoveCallback
  - mxmlFindElement
  - mxmlFindPath
  - mxmlGetCDATA
  - mxmlGetCustom
  - mxmlGetElement
  - mxmlGetFirstChild
  - mxmlGetInteger
  - mxmlGetLastChild
  - mxmlGetNextSibling
  - mxmlGetOpaque
  - mxmlGetParent
  - mxmlGetPrevSibling
  - mxmlGetReal
  - mxmlGetRefCount
  - mxmlGetText
  - mxmlGetType
  - mxmlGetUserData
  - mxmlIndexDelete
  - mxmlIndexEnum
  - mxmlIndexFind
  - mxmlIndexGetCount
  - mxmlIndexNew
  - mxmlIndexReset
  - mxmlLoadFd
  - mxmlLoadFile
  - mxmlLoadString
  - mxmlNewCDATA
  - mxmlNewCustom
  - mxmlNewElement
  - mxmlNewInteger
  - mxmlNewOpaque
  - mxmlNewOpaquef
  - mxmlNewReal
  - mxmlNewText
  - mxmlNewTextf
  - mxmlNewXML
  - mxmlRelease
  - mxmlRemove
  - mxmlRetain
  - mxmlSAXLoadFd
  - mxmlSAXLoadFile
  - mxmlSAXLoadString
  - mxmlSaveAllocString
  - mxmlSaveFd
  - mxmlSaveFile
  - mxmlSaveString
  - mxmlSetCDATA
  - mxmlSetCustom
  - mxmlSetCustomHandlers
  - mxmlSetElement
  - mxmlSetErrorCallback
  - mxmlSetInteger
  - mxmlSetOpaque
  - mxmlSetOpaquef
  - mxmlSetReal
  - mxmlSetText
  - mxmlSetTextf
  - mxmlSetUserData
  - mxmlSetWrapMargin
  - mxmlWalkNext
  - mxmlWalkPrev
- Data Types
  - mxml_custom_destroy_cb_t
  - mxml_custom_load_cb_t
  - mxml_custom_save_cb_t
  - mxml_entity_cb_t
  - mxml_error_cb_t
  - mxml_index_t
  - mxml_load_cb_t
  - mxml_node_t
  - mxml_save_cb_t
  - mxml_sax_cb_t
  - mxml_sax_event_t
  - mxml_type_t
- Enumerations
  - mxml_sax_event_e
  - mxml_type_e

## Introduction

Mini-XML is a small XML parsing library that you can use to read XML data files or strings in your application without requiring large non-standard libraries. Mini-XML provides the following functionality:

- Reading of UTF-8 and UTF-16 and writing of UTF-8 encoded XML files and strings.

- Data is stored in a linked-list tree structure, preserving the XML data hierarchy.

- SAX (streamed) reading of XML files and strings to minimize memory usage.

- Supports arbitrary element names, attributes, and attribute values with no preset limits, just available memory.

- Supports integer, real, opaque ("cdata"), and text data types in "leaf" nodes.

- Functions for creating and managing trees of data.

- "Find" and "walk" functions for easily locating and navigating trees of data.

Mini-XML doesn't do validation or other types of processing on the data based upon schema files or other sources of definition information.

### History

Mini-XML was initially developed for the Gutenprint project to replace the rather large and unwieldy `libxml2` library with something substantially smaller and easier-to-use. It all began one morning in June of 2003 when Robert posted the following sentence to the developer's list:

> It's bad enough that we require libxml2, but rolling our own XML parser is a bit more than we can handle.

I then replied with:

> Given the limited scope of what you use in XML, it should be trivial to code a mini-XML API in a few hundred lines of code.

I took my own challenge and coded furiously for two days to produced the initial public release of Mini-XML, total lines of code: 696. Robert promptly integrated Mini-XML into Gutenprint and removed libxml2.

Thanks to lots of feedback and support from various developers, Mini-XML has evolved since then to provide a more complete XML implementation and now stands at a whopping 4,300 lines of code, compared to 196,141 lines of code for libxml2 version 2.9.9.

### Resources

The Mini-XML home page can be found at https://www.msweet.org/mxml. From there you can download the current version of Mini-XML, access the issue tracker, and find other resources.

### Legal Stuff

The Mini-XML library is copyright © 2003-2021 by Michael R Sweet and is provided under the Apache License Version 2.0 with an exception to allow linking against GPL2/LGPL2-only software. See the files "LICENSE" and "NOTICE" for more information.

## Using Mini-XML

Mini-XML provides a single header file which you include:

    #include <mxml.h>

The Mini-XML library is included with your program using the `-lmxml` option:

    gcc -o myprogram myprogram.c -lmxml

If you have the `pkg-config` software installed, you can use it to determine the proper compiler and linker options for your installation:

    gcc `pkg-config --cflags mxml` -o myprogram myprogram.c `pkg-config --libs mxml`

### Loading an XML File

You load an XML file using the `mxmlLoadFile` function:

    mxml_node_t *
    mxmlLoadFile(mxml_node_t *top, FILE *fp,
                 mxml_type_t (*cb)(mxml_node_t *));

The `cb` argument specifies a function that assigns child (value) node types for each element in the document. The callback can be a function you provide or one of the standard functions provided with Mini-XML. For example, to load the XML file "filename.xml" containing text strings you can use the `MXML_OPAQUE_CALLBACK` function:

    FILE *fp;
    mxml_node_t *tree;

    fp = fopen("filename.xml", "r");
    tree = mxmlLoadFile(NULL, fp, MXML_OPAQUE_CALLBACK);
    fclose(fp);

Mini-XML also provides functions to load from a file descriptor or string:

    mxml_node_t *
    mxmlLoadFd(mxml_node_t *top, int fd,
               mxml_type_t (*cb)(mxml_node_t *));

    mxml_node_t *
    mxmlLoadString(mxml_node_t *top, const char *s,
                   mxml_type_t (*cb)(mxml_node_t *));

#### Load Callbacks

The last argument to the `mxmlLoad` functions is a callback function which is used to determine the value type of each data node in an XML document. Mini-XML defines several standard callbacks for simple XML data files:

- `MXML_INTEGER_CALLBACK`: All data nodes contain whitespace-separated integers.

- `MXML_OPAQUE_CALLBACK`: All data nodes contain opaque strings with whitespace preserved.

- `MXML_REAL_CALLBACK` - All data nodes contain whitespace-separated floating-point numbers.

- `MXML_TEXT_CALLBACK` - All data nodes contain whitespace-separated strings.

You can provide your own callback functions for more complex XML documents. Your callback function will receive a pointer to the current element node and must return the value type of the immediate children for that element node: `MXML_CUSTOM`, `MXML_INTEGER`, `MXML_OPAQUE`, `MXML_REAL`, or `MXML_TEXT`. The function is called after the element and its attributes have been read, so you can look at the element name, attributes, and attribute values to determine the proper value type to return.

The following callback function looks for an attribute named "type" or the element name to determine the value type for its child nodes:

    mxml_type_t
    type_cb(mxml_node_t *node)
    {
      const char *type;

     /*
      * You can lookup attributes and/or use the element name,
      * hierarchy, etc...
      */

      type = mxmlElementGetAttr(node, "type");
      if (type == NULL)
        type = mxmlGetElement(node);

      if (!strcmp(type, "integer"))
        return (MXML_INTEGER);
      else if (!strcmp(type, "opaque"))
        return (MXML_OPAQUE);
      else if (!strcmp(type, "real"))
        return (MXML_REAL);
      else
        return (MXML_TEXT);
    }

To use this callback function, simply use the name when you call any of the load functions:

    FILE *fp;
    mxml_node_t *tree;

    fp = fopen("filename.xml", "r");
    tree = mxmlLoadFile(NULL, fp, type_cb);
    fclose(fp);

### Nodes

Every piece of information in an XML file is stored in memory in "nodes". Nodes are defined by the `mxml_node_t` structure. Each node has a typed value, optional user data, a parent node, sibling nodes (previous and next), and potentially child nodes.

For example, if you have an XML file like the following:

    <?xml version="1.0" encoding="utf-8"?>
    <data>
        <node>val1</node>
        <node>val2</node>
        <node>val3</node>
        <group>
            <node>val4</node>
            <node>val5</node>
            <node>val6</node>
        </group>
        <node>val7</node>
        <node>val8</node>
    </data>

the node tree for the file would look like the following in memory:

    ?xml version="1.0" encoding="utf-8"?
      |
    data
      |
    node - node - node - group - node - node
      |      |      |      |       |      |
    val1   val2   val3     |     val7   val8
                           |
                         node - node - node
                           |      |      |
                         val4   val5   val6

where "-" is a pointer to the sibling node and "|" is a pointer to the first child or parent node.

The `mxmlGetType` function gets the type of a node:

    mxml_type_t
    mxmlGetType(mxml_node_t *node);

- `MXML_CUSTOM` : A custom value defined by your application,

- `MXML_ELEMENT` : An XML element, CDATA, comment, or processing instruction,

- `MXML_INTEGER` : A whitespace-delimited integer value,

- `MXML_OPAQUE` : An opaque string value that preserves all whitespace,

- `MXML_REAL` : A whitespace-delimited floating point value, or

- `MXML_TEXT` : A whitespace-delimited text (fragment) value.

> Note: CDATA, comment, and processing directive nodes are currently stored in memory as special elements. This will be changed in a future major release of Mini-XML.

The parent and sibling nodes are accessed using the `mxmlGetParent`, `mxmlGetNextSibling`, and `mxmlGetPreviousSibling` functions, while the children of an element node are accessed using the `mxmlGetFirstChild` or `mxmlGetLastChild` functions:

    mxml_node_t *
    mxmlGetFirstChild(mxml_node_t *node);

    mxml_node_t *
    mxmlGetLastChild(mxml_node_t *node);

    mxml_node_t *
    mxmlGetNextSibling(mxml_node_t *node);

    mxml_node_t *
    mxmlGetParent(mxml_node_t *node);

    mxml_node_t *
    mxmlGetPrevSibling(mxml_node_t *node);

The `mxmlGetUserData` function gets any user (application) data associated with the node:

    void *
    mxmlGetUserData(mxml_node_t *node);

### Creating XML Documents

You can create and update XML documents in memory using the various `mxmlNew` functions. The following code will create the XML document described in the previous section:

    mxml_node_t *xml;    /* <?xml ... ?> */
    mxml_node_t *data;   /* <data> */
    mxml_node_t *node;   /* <node> */
    mxml_node_t *group;  /* <group> */

    xml = mxmlNewXML("1.0");

    data = mxmlNewElement(xml, "data");

        node = mxmlNewElement(data, "node");
        mxmlNewText(node, 0, "val1");
        node = mxmlNewElement(data, "node");
        mxmlNewText(node, 0, "val2");
        node = mxmlNewElement(data, "node");
        mxmlNewText(node, 0, "val3");

        group = mxmlNewElement(data, "group");

            node = mxmlNewElement(group, "node");
            mxmlNewText(node, 0, "val4");
            node = mxmlNewElement(group, "node");
            mxmlNewText(node, 0, "val5");
            node = mxmlNewElement(group, "node");
            mxmlNewText(node, 0, "val6");

        node = mxmlNewElement(data, "node");
        mxmlNewText(node, 0, "val7");
        node = mxmlNewElement(data, "node");
        mxmlNewText(node, 0, "val8");

We start by creating the declaration node common to all XML files using the `mxmlNewXML` function:

    xml = mxmlNewXML("1.0");

We then create the `<data>` node used for this document using the `mxmlNewElement` function. The first argument specifies the parent node (`xml`) while the second specifies the element name (`data`):

    data = mxmlNewElement(xml, "data");

Each `<node>...</node>` in the file is created using the `mxmlNewElement` and `mxmlNewText` functions. The first argument of `mxmlNewText` specifies the parent node (`node`). The second argument specifies whether whitespace appears before the text - 0 or false in this case. The last argument specifies the actual text to add:

    node = mxmlNewElement(data, "node");
    mxmlNewText(node, 0, "val1");

The resulting in-memory XML document can then be saved or processed just like one loaded from disk or a string.

### Saving an XML File

You save an XML file using the `mxmlSaveFile` function:

    int
    mxmlSaveFile(mxml_node_t *node, FILE *fp,
                 mxml_save_cb_t cb);

The `cb` argument specifies a function that returns the whitespace (if any) that is inserted before and after each element node. The `MXML_NO_CALLBACK` constant tells Mini-XML to not include any extra whitespace. For example, so save an XML file to the file "filename.xml" with no extra whitespace:

    FILE *fp;

    fp = fopen("filename.xml", "w");
    mxmlSaveFile(xml, fp, MXML_NO_CALLBACK);
    fclose(fp);

Mini-XML also provides functions to save to a file descriptor or strings:

    char *
    mxmlSaveAllocString(mxml_node_t *node, mxml_save_cb_t cb);

    int
    mxmlSaveFd(mxml_node_t *node, int fd, mxml_save_cb_t cb);

    int
    mxmlSaveString(mxml_node_t *node, char *buffer, int bufsize,
                   mxml_save_cb_t cb);

#### Controlling Line Wrapping

When saving XML documents, Mini-XML normally wraps output lines at column 75 so that the text is readable in terminal windows. The `mxmlSetWrapMargin` function overrides the default wrap margin for the current thread:

    void mxmlSetWrapMargin(int column);

For example, the following code sets the margin to 132 columns:

    mxmlSetWrapMargin(132);

while the following code disables wrapping by setting the margin to 0:

    mxmlSetWrapMargin(0);

#### Save Callbacks

The last argument to the `mxmlSave` functions is a callback function which is used to automatically insert whitespace in an XML document. Your callback function will be called up to four times for each element node with a pointer to the node and a "where" value of `MXML_WS_BEFORE_OPEN`, `MXML_WS_AFTER_OPEN`, `MXML_WS_BEFORE_CLOSE`, or `MXML_WS_AFTER_CLOSE`. The callback function should return `NULL` if no whitespace should be added or the string to insert (spaces, tabs, carriage returns, and newlines) otherwise.

The following whitespace callback can be used to add whitespace to XHTML output to make it more readable in a standard text editor:

    const char *
    whitespace_cb(mxml_node_t *node, int where)
    {
      const char *element;

     /*
      * We can conditionally break to a new line before or after
      * any element.  These are just common HTML elements...
      */

      element = mxmlGetElement(node);

      if (!strcmp(element, "html") ||
          !strcmp(element, "head") ||
          !strcmp(element, "body") ||
          !strcmp(element, "pre") ||
          !strcmp(element, "p") ||
          !strcmp(element, "h1") ||
          !strcmp(element, "h2") ||
          !strcmp(element, "h3") ||
          !strcmp(element, "h4") ||
          !strcmp(element, "h5") ||
          !strcmp(element, "h6"))
      {
       /*
        * Newlines before open and after close...
        */

        if (where == MXML_WS_BEFORE_OPEN ||
            where == MXML_WS_AFTER_CLOSE)
          return ("\n");
      }
      else if (!strcmp(element, "dl") ||
               !strcmp(element, "ol") ||
               !strcmp(element, "ul"))
      {
       /*
        * Put a newline before and after list elements...
        */

        return ("\n");
      }
      else if (!strcmp(element, "dd") ||
               !strcmp(element, "dt") ||
               !strcmp(element, "li"))
      {
       /*
        * Put a tab before <li>'s, <dd>'s, and <dt>'s, and a
        * newline after them...
        */

        if (where == MXML_WS_BEFORE_OPEN)
          return ("\t");
        else if (where == MXML_WS_AFTER_CLOSE)
          return ("\n");
      }

     /*
      * Otherwise return NULL for no added whitespace...
      */

      return (NULL);
    }

To use this callback function, simply use the name when you call any of the save functions:

    FILE *fp;
    mxml_node_t *tree;

    fp = fopen("filename.xml", "w");
    mxmlSaveFile(tree, fp, whitespace_cb);
    fclose(fp);

### Memory Management

Once you are done with the XML data, use the `mxmlDelete` function to recursively free the memory that is used for a particular node or the entire tree:

    void
    mxmlDelete(mxml_node_t *tree);

You can also use reference counting to manage memory usage. The `mxmlRetain` and `mxmlRelease` functions increment and decrement a node's use count, respectively. When the use count goes to zero, `mxmlRelease` automatically calls `mxmlDelete` to actually free the memory used by the node tree. New nodes start with a use count of 1.

## More About Nodes

### Element Nodes

Element (`MXML_ELEMENT`) nodes are created using the `mxmlNewElement` function. Element attributes are set using the `mxmlElementSetAttr` and `mxmlElementSetAttrf` functions and cleared using the `mxmlElementDeleteAttr` function:

    mxml_node_t *
    mxmlNewElement(mxml_node_t *parent, const char *name);

    void
    mxmlElementDeleteAttr(mxml_node_t *node, const char *name);

    void
    mxmlElementSetAttr(mxml_node_t *node, const char *name,
                       const char *value);

    void
    mxmlElementSetAttrf(mxml_node_t *node, const char *name,
                        const char *format, ...);

Child nodes are added using the various `mxmlNew` functions. The top (root) node must be an element, usually created by the `mxmlNewXML` function:

    mxml_node_t *
    mxmlNewXML(const char *version);

The `mxmlGetElement` function retrieves the element name, the `mxmlElementGetAttr` function retrieves the value string for a named attribute associated with the element. The `mxmlElementGetAttrByIndex` and `mxmlElementGetAttrCount` functions retrieve attributes by index:

    const char *
    mxmlGetElement(mxml_node_t *node);

    const char *
    mxmlElementGetAttr(mxml_node_t *node, const char *name);

    const char *
    mxmlElementGetAttrByIndex(mxml_node_t *node, int idx,
                              const char **name);

    int
    mxmlElementGetAttrCount(mxml_node_t *node);

### CDATA Nodes

CDATA (`MXML_ELEMENT`) nodes are created using the `mxmlNewCDATA` function:

    mxml_node_t *mxmlNewCDATA(mxml_node_t *parent, const char *string);

The `mxmlGetCDATA` function retrieves the CDATA string pointer for a node:

    const char *mxmlGetCDATA(mxml_node_t *node);

### Comment Nodes

Because comments are currently stored as element nodes, comment (`MXML_ELEMENT`) nodes are created using the `mxmlNewElement` function by including the surrounding "!--" and "--" characters in the element name, for example:

    mxml_node_t *node = mxmlNewElement("!-- This is a comment --");

Similarly, the `mxmlGetElement` function retrieves the comment string pointer for a node, which includes the surrounding "!--" and "--" characters.

    const char *comment = mxmlGetElement(node);
    /* returns "!-- This is a comment --" */

### Processing Instruction Nodes

Because processing instructions are currently stored as element nodes, processing instruction (`MXML_ELEMENT`) nodes are created using the `mxmlNewElement` function including the surrounding "?" characters:

    mxml_node_t *node = mxmlNewElement("?xml-stylesheet type=\"text/css\" href=\"style.css\"?");

The `mxmlGetElement` function retrieves the processing instruction string for a node, including the surrounding "?" characters:

    const char *instr = mxmlGetElement(node);
    /* returned "?xml-stylesheet type=\"text/css\" href=\"style.css\"?" */

### Integer Nodes

Integer (`MXML_INTEGER`) nodes are created using the `mxmlNewInteger` function:

    mxml_node_t *
    mxmlNewInteger(mxml_node_t *parent, int integer);

The `mxmlGetInteger` function retrieves the integer value for a node:

    int
    mxmlGetInteger(mxml_node_t *node);

### Opaque String Nodes

Opaque string (`MXML_OPAQUE`) nodes are created using the `mxmlNewOpaque` function:

    mxml_node_t *
    mxmlNewOpaque(mxml_node_t *parent, const char *opaque);

The `mxmlGetOpaque` function retrieves the opaque string pointer for a node:

    const char *
    mxmlGetOpaque(mxml_node_t *node);

### Text Nodes

Whitespace-delimited text string (`MXML_TEXT`) nodes are created using the `mxmlNewText` and `mxmlNewTextf` functions. Each text node consists of a text string and (leading) whitespace flag value.

    mxml_node_t *
    mxmlNewText(mxml_node_t *parent, int whitespace,
                const char *string);

    mxml_node_t *
    mxmlNewTextf(mxml_node_t *parent, int whitespace,
                 const char *format, ...);

The `mxmlGetText` function retrieves the text string pointer and whitespace flag value for a node:

     const char *
     mxmlGetText(mxml_node_t *node, int *whitespace);

### Real Number Nodes

Real number (`MXML_REAL`) nodes are created using the `mxmlNewReal` function:

    mxml_node_t *
    mxmlNewReal(mxml_node_t *parent, double real);

The `mxmlGetReal` function retrieves the real number for a node:

    double
    mxmlGetReal(mxml_node_t *node);

## Locating Data in an XML Document

Mini-XML provides many functions for enumerating, searching, and indexing XML documents.

### Finding Nodes

The `mxmlFindPath` function finds the (first) value node under a specific element using a "path":

    mxml_node_t *
    mxmlFindPath(mxml_node_t *node, const char *path);

The `path` string can contain the "*" wildcard to match a single element node in the hierarchy. For example, the following code will find the first "node" element under the "group" element, first using an explicit path and then using a wildcard:

    mxml_node_t *value = mxmlFindPath(xml, "data/group/node");

    mxml_node_t *value = mxmlFindPath(xml, "data/*/node");

The `mxmlFindElement` function can be used to find a named element, optionally matching an attribute and value:

    mxml_node_t *
    mxmlFindElement(mxml_node_t *node, mxml_node_t *top,
                    const char *element, const char *attr,
                    const char *value, int descend);

The "element", "attr", and "value" arguments can be passed as `NULL` to act as wildcards, e.g.:

    /* Find the first "a" element */
    node = mxmlFindElement(tree, tree, "a", NULL, NULL,
                           MXML_DESCEND);

    /* Find the first "a" element with "href" attribute */
    node = mxmlFindElement(tree, tree, "a", "href", NULL,
                           MXML_DESCEND);

    /* Find the first "a" element with "href" to a URL */
    node = mxmlFindElement(tree, tree, "a", "href",
                           "http://michaelrsweet.github.io/",
                           MXML_DESCEND);

    /* Find the first element with a "src" attribute*/
    node = mxmlFindElement(tree, tree, NULL, "src", NULL,
                           MXML_DESCEND);

    /* Find the first element with a "src" = "foo.jpg" */
    node = mxmlFindElement(tree, tree, NULL, "src", "foo.jpg",
                           MXML_DESCEND);

You can also iterate with the same function:

    mxml_node_t *node;

    for (node = mxmlFindElement(tree, tree, "element", NULL,
                                NULL, MXML_DESCEND);
         node != NULL;
         node = mxmlFindElement(node, tree, "element", NULL,
                                NULL, MXML_DESCEND))
    {
      ... do something ...
    }

The `descend` argument (`MXML_DESCEND` in the examples above) can be one of three constants:

- `MXML_NO_DESCEND`: ignore child nodes in the element hierarchy, instead using siblings (same level) or parent nodes (above) until the top (root) node is reached.

- `MXML_DESCEND_FIRST`: start the search with the first child of the node, and then search siblings. 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 previous example.

- `MXML_DESCEND`: search child nodes first, then sibling nodes, and then parent nodes.

### Iterating Nodes

While the `mxmlFindNode` and `mxmlFindPath` functions will find a particular element node, sometimes you need to iterate over all nodes. The `mxmlWalkNext` and `mxmlWalkPrev` functions can be used to iterate through the XML node tree:

    mxml_node_t *
    mxmlWalkNext(mxml_node_t *node, mxml_node_t *top,
                 int descend);

    mxml_node_t *
    mxmlWalkPrev(mxml_node_t *node, mxml_node_t *top,
                 int descend);

Depending on the value of the `descend` argument, these functions will automatically traverse child, sibling, and parent nodes until the `top` node is reached. For example, the following code will iterate over all of the nodes in the sample XML document in the previous section:

    mxml_node_t *node;

    for (node = xml;
         node != NULL;
         node = mxmlWalkNext(node, xml, MXML_DESCEND))
    {
      ... do something ...
    }

The nodes will be returned in the following order:

    <?xml version="1.0" encoding="utf-8"?>
    <data>
    <node>
    val1
    <node>
    val2
    <node>
    val3
    <group>
    <node>
    val4
    <node>
    val5
    <node>
    val6
    <node>
    val7
    <node>
    val8

### Indexing

The `mxmlIndexNew` function allows you to create an index of nodes for faster searching and enumeration:

    mxml_index_t *
    mxmlIndexNew(mxml_node_t *node, const char *element,
                 const char *attr);

The `element` and `attr` arguments control which elements are included in the index. If `element` is not `NULL` then only elements with the specified name are added to the index. Similarly, if `attr` is not `NULL` then only elements containing the specified attribute are added to the index. The nodes are sorted in the index.

For example, the following code creates an index of all "id" values in an XML document:

    mxml_index_t *ind = mxmlIndexNew(xml, NULL, "id");

Once the index is created, the `mxmlIndexFind` function can be used to find a matching node:

    mxml_node_t *
    mxmlIndexFind(mxml_index_t *ind, const char *element,
                  const char *value);

For example, the following code will find the element whose "id" string is "42":

    mxml_node_t *node = mxmlIndexFind(ind, NULL, "42");

Alternately, the `mxmlIndexReset` and `mxmlIndexEnum` functions can be used to enumerate the nodes in the index:

    mxml_node_t *
    mxmlIndexReset(mxml_index_t *ind);

    mxml_node_t *
    mxmlIndexEnum(mxml_index_t *ind);

Typically these functions will be used in a `for` loop:

    mxml_node_t *node;

    for (node = mxmlIndexReset(ind);
         node != NULL;
         node = mxmlIndexEnum(ind))
    {
      ... do something ...
    }

The `mxmlIndexCount` function returns the number of nodes in the index:

    int
    mxmlIndexGetCount(mxml_index_t *ind);

Finally, the `mxmlIndexDelete` function frees all memory associated with the index:

    void
    mxmlIndexDelete(mxml_index_t *ind);

## Custom Data Types

Mini-XML supports custom data types via per-thread load and save callbacks. Only a single set of callbacks can be active at any time for the current thread, however your callbacks can store additional information in order to support multiple custom data types as needed. The `MXML_CUSTOM` node type identifies custom data nodes.

The `mxmlGetCustom` function retrieves the custom value pointer for a node.

    const void *
    mxmlGetCustom(mxml_node_t *node);

Custom (`MXML_CUSTOM`) nodes are created using the `mxmlNewCustom` function or using a custom per-thread load callbacks specified using the `mxmlSetCustomHandlers` function:

    typedef void (*mxml_custom_destroy_cb_t)(void *);
    typedef int (*mxml_custom_load_cb_t)(mxml_node_t *, const char *);
    typedef char *(*mxml_custom_save_cb_t)(mxml_node_t *);

    mxml_node_t *
    mxmlNewCustom(mxml_node_t *parent, void *data,
                  mxml_custom_destroy_cb_t destroy);

    int
    mxmlSetCustom(mxml_node_t *node, void *data,
                  mxml_custom_destroy_cb_t destroy);

    void
    mxmlSetCustomHandlers(mxml_custom_load_cb_t load,
                          mxml_custom_save_cb_t save);

The load callback receives a pointer to the current data node and a string of opaque character data from the XML source with character entities converted to the corresponding UTF-8 characters. For example, if we wanted to support a custom date/time type whose value is encoded as "yyyy-mm-ddThh:mm:ssZ" (ISO format), the load callback would look like the following:

    typedef struct
    {
      unsigned year,    /* Year */
               month,   /* Month */
               day,     /* Day */
               hour,    /* Hour */
               minute,  /* Minute */
               second;  /* Second */
      time_t   unix;    /* UNIX time */
    } iso_date_time_t;

    int
    load_custom(mxml_node_t *node, const char *data)
    {
      iso_date_time_t *dt;
      struct tm tmdata;

     /*
      * Allocate data structure...
      */

      dt = calloc(1, sizeof(iso_date_time_t));

     /*
      * Try reading 6 unsigned integers from the data string...
      */

      if (sscanf(data, "%u-%u-%uT%u:%u:%uZ", &(dt->year),
                 &(dt->month), &(dt->day), &(dt->hour),
                 &(dt->minute), &(dt->second)) != 6)
      {
       /*
        * Unable to read numbers, free the data structure and
        * return an error...
        */

        free(dt);

        return (-1);
      }

     /*
      * Range check values...
      */

      if (dt->month < 1 || dt->month > 12 ||
          dt->day < 1 || dt->day > 31 ||
          dt->hour < 0 || dt->hour > 23 ||
          dt->minute < 0 || dt->minute > 59 ||
          dt->second < 0 || dt->second > 60)
      {
       /*
        * Date information is out of range...
        */

        free(dt);

        return (-1);
      }

     /*
      * Convert ISO time to UNIX time in seconds...
      */

      tmdata.tm_year = dt->year - 1900;
      tmdata.tm_mon  = dt->month - 1;
      tmdata.tm_day  = dt->day;
      tmdata.tm_hour = dt->hour;
      tmdata.tm_min  = dt->minute;
      tmdata.tm_sec  = dt->second;

      dt->unix = gmtime(&tmdata);

     /*
      * Assign custom node data and destroy (free) function
      * pointers...
      */

      mxmlSetCustom(node, data, free);

     /*
      * Return with no errors...
      */

      return (0);
    }

The function itself can return 0 on success or -1 if it is unable to decode the custom data or the data contains an error. Custom data nodes contain a `void` pointer to the allocated custom data for the node and a pointer to a destructor function which will free the custom data when the node is deleted. In this example, we use the standard `free` function since everything is contained in a single calloc'd block.

The save callback receives the node pointer and returns an allocated string containing the custom data value. The following save callback could be used for our ISO date/time type:

    char *
    save_custom(mxml_node_t *node)
    {
      char data[255];
      iso_date_time_t *dt;

      dt = (iso_date_time_t *)mxmlGetCustom(node);

      snprintf(data, sizeof(data),
               "%04u-%02u-%02uT%02u:%02u:%02uZ",
               dt->year, dt->month, dt->day, dt->hour,
               dt->minute, dt->second);

      return (strdup(data));
    }

You register the callback functions using the `mxmlSetCustomHandlers` function:

    mxmlSetCustomHandlers(load_custom, save_custom);

## SAX (Stream) Loading of Documents

Mini-XML supports an implementation of the Simple API for XML (SAX) which allows you to load and process an XML document as a stream of nodes. Aside from allowing you to process XML documents of any size, the Mini-XML implementation also allows you to retain portions of the document in memory for later processing.

The `mxmlSAXLoadFd`, `mxmlSAXLoadFile`, and `mxmlSAXLoadString` functions provide the SAX loading APIs:

    mxml_node_t *
    mxmlSAXLoadFd(mxml_node_t *top, int fd,
                  mxml_type_t (*cb)(mxml_node_t *),
                  mxml_sax_cb_t sax, void *sax_data);

    mxml_node_t *
    mxmlSAXLoadFile(mxml_node_t *top, FILE *fp,
                    mxml_type_t (*cb)(mxml_node_t *),
                    mxml_sax_cb_t sax, void *sax_data);

    mxml_node_t *
    mxmlSAXLoadString(mxml_node_t *top, const char *s,
                      mxml_type_t (*cb)(mxml_node_t *),
                      mxml_sax_cb_t sax, void *sax_data);

Each function works like the corresponding `mxmlLoad` function but uses a callback to process each node as it is read. The callback function receives the node, an event code, and a user data pointer you supply:

    void
    sax_cb(mxml_node_t *node, mxml_sax_event_t event,
           void *data)
    {
      ... do something ...
    }

The event will be one of the following:

- `MXML_SAX_CDATA`: CDATA was just read.

- `MXML_SAX_COMMENT`: A comment was just read.

- `MXML_SAX_DATA`: Data (custom, integer, opaque, real, or text) was just read.

- `MXML_SAX_DIRECTIVE`: A processing directive/instruction was just read.

- `MXML_SAX_ELEMENT_CLOSE` - A close element was just read (`</element>`)

- `MXML_SAX_ELEMENT_OPEN` - An open element was just read (`<element>`)

Elements are released after the close element is processed. All other nodes are released after they are processed. The SAX callback can retain the node using the `mxmlRetain` function. For example, the following SAX callback will retain all nodes, effectively simulating a normal in-memory load:

    void
    sax_cb(mxml_node_t *node, mxml_sax_event_t event,
           void *data)
    {
      if (event != MXML_SAX_ELEMENT_CLOSE)
        mxmlRetain(node);
    }

More typically the SAX callback will only retain a small portion of the document that is needed for post-processing. For example, the following SAX callback will retain the title and headings in an XHTML file. It also retains the (parent) elements like `<html>`, `<head>`, and `<body>`, and processing directives like `<?xml ... ?>` and `<!DOCTYPE ... >`:

    void
    sax_cb(mxml_node_t *node, mxml_sax_event_t event,
           void *data)
    {
      if (event == MXML_SAX_ELEMENT_OPEN)
      {
       /*
        * Retain headings and titles...
        */

        const char *element = mxmlGetElement(node);

        if (!strcmp(element, "html") ||
            !strcmp(element, "head") ||
            !strcmp(element, "title") ||
            !strcmp(element, "body") ||
            !strcmp(element, "h1") ||
            !strcmp(element, "h2") ||
            !strcmp(element, "h3") ||
            !strcmp(element, "h4") ||
            !strcmp(element, "h5") ||
            !strcmp(element, "h6"))
          mxmlRetain(node);
      }
      else if (event == MXML_SAX_DIRECTIVE)
        mxmlRetain(node);
      else if (event == MXML_SAX_DATA)
      {
        if (mxmlGetRefCount(mxmlGetParent(node)) > 1)
        {
         /*
          * If the parent was retained, then retain this data
          * node as well.
          */

          mxmlRetain(node);
        }
      }
    }

The resulting skeleton document tree can then be searched just like one loaded using the `mxmlLoad` functions. For example, a filter that reads an XHTML document from stdin and then shows the title and headings in the document would look like:

    mxml_node_t *doc, *title, *body, *heading;

    doc = mxmlSAXLoadFd(NULL, 0, MXML_TEXT_CALLBACK, sax_cb,
                        NULL);

    title = mxmlFindElement(doc, doc, "title", NULL, NULL,
                            MXML_DESCEND);

    if (title)
      print_children(title);

    body = mxmlFindElement(doc, doc, "body", NULL, NULL,
                           MXML_DESCEND);

    if (body)
    {
      for (heading = mxmlGetFirstChild(body);
           heading;
           heading = mxmlGetNextSibling(heading))
        print_children(heading);
    }

The `print_children` function is:

    void
    print_children(mxml_node_t *parent)
    {
      mxml_node_t *node;
      const char *text;
      int whitespace;

      for (node = mxmlGetFirstChild(parent);
           node != NULL;
           node = mxmlGetNextSibling(node))
      {
        text = mxmlGetText(node, &whitespace);

        if (whitespace)
          putchar(' ');

        fputs(text, stdout);
      }

      putchar('\n');
    }

## Functions

### mxmlAdd

Add a node to a tree.

void mxmlAdd(mxml_node_t *parent, int where, mxml_node_t *child, mxml_node_t *node);

#### Parameters

parent | Parent node
where | Where to add, `MXML_ADD_BEFORE` or `MXML_ADD_AFTER`
child | Child node for where or `MXML_ADD_TO_PARENT`
node | Node to add

#### Discussion

Adds the specified node to the parent. If the child argument is not `NULL`, puts the new node before or after the specified child depending on the value of the where argument. If the child argument is `NULL`, puts the new node at the beginning of the child list (`MXML_ADD_BEFORE`) or at the end of the child list (`MXML_ADD_AFTER`). The constant `MXML_ADD_TO_PARENT` can be used to specify a `NULL` child pointer.

### mxmlDelete

Delete a node and all of its children.

void mxmlDelete(mxml_node_t *node);

#### Parameters

node | Node to delete

#### Discussion

If the specified node has a parent, this function first removes the node from its parent using the `mxmlRemove` function.

### Mini-XML 2.4 mxmlElementDeleteAttr

Delete an attribute.

void mxmlElementDeleteAttr(mxml_node_t *node, const char *name);

#### Parameters

node | Element
name | Attribute name

### mxmlElementGetAttr

Get an attribute.

const char *mxmlElementGetAttr(mxml_node_t *node, const char *name);

#### Parameters

node | Element node
name | Name of attribute

#### Return Value

Attribute value or `NULL`

#### Discussion

This function returns `NULL` if the node is not an element or the named attribute does not exist.

### Mini-XML 2.11 mxmlElementGetAttrByIndex

Get an element attribute by index.

const char *mxmlElementGetAttrByIndex(mxml_node_t *node, int idx, const char **name);

#### Parameters

node | Node
idx | Attribute index, starting at 0
name | Attribute name

#### Return Value

Attribute value

#### Discussion

The index ("idx") is 0-based. `NULL` is returned if the specified index is out of range.

### Mini-XML 2.11 mxmlElementGetAttrCount

Get the number of element attributes.

int mxmlElementGetAttrCount(mxml_node_t *node);

#### Parameters

node | Node

#### Return Value

Number of attributes

### mxmlElementSetAttr

Set an attribute.

void mxmlElementSetAttr(mxml_node_t *node, const char *name, const char *value);

#### Parameters

node | Element node
name | Name of attribute
value | Attribute value

#### Discussion

If the named attribute already exists, the value of the attribute is replaced by the new string value. The string value is copied into the element node. This function does nothing if the node is not an element.

### Mini-XML 2.3 mxmlElementSetAttrf

Set an attribute with a formatted value.

void mxmlElementSetAttrf(mxml_node_t *node, const char *name, const char *format, ...);

#### Parameters

node | Element node
name | Name of attribute
format | Printf-style attribute value
... | Additional arguments as needed

#### Discussion

If the named attribute already exists, the value of the attribute is replaced by the new formatted string. The formatted string value is copied into the element node. This function does nothing if the node is not an element.

### mxmlEntityAddCallback

Add a callback to convert entities to Unicode.

int mxmlEntityAddCallback(mxml_entity_cb_t cb);

#### Parameters

cb | Callback function to add

#### Return Value

0 on success, -1 on failure

### mxmlEntityGetName

Get the name that corresponds to the character value.

const char *mxmlEntityGetName(int val);

#### Parameters

val | Character value

#### Return Value

Entity name or `NULL`

#### Discussion

If val does not need to be represented by a named entity, `NULL` is returned.

### mxmlEntityGetValue

Get the character corresponding to a named entity.

int mxmlEntityGetValue(const char *name);

#### Parameters

name | Entity name

#### Return Value

Character value or -1 on error

#### Discussion

The entity name can also be a numeric constant. -1 is returned if the name is not known.

### mxmlEntityRemoveCallback

Remove a callback.

void mxmlEntityRemoveCallback(mxml_entity_cb_t cb);

#### Parameters

cb | Callback function to remove

### mxmlFindElement

Find the named element.

mxml_node_t *mxmlFindElement(mxml_node_t *node, mxml_node_t *top, const char *element, const char *attr, const char *value, int descend);

#### Parameters

node | Current node
top | Top node
element | Element name or `NULL` for any
attr | Attribute name, or `NULL` for none
value | Attribute value, or `NULL` for any
descend | Descend into tree - `MXML_DESCEND`, `MXML_NO_DESCEND`, or `MXML_DESCEND_FIRST`

#### Return Value

Element node or `NULL`

#### Discussion

The search is constrained by the name, attribute name, and value; any `NULL` names or values are treated as wildcards, so different kinds of searches can be implemented by looking for all elements of a given name or all elements with a specific attribute. The descend argument determines whether the search descends into child nodes; normally you will use `MXML_DESCEND_FIRST` for the initial search and `MXML_NO_DESCEND` to find additional direct descendents of the node. The top node argument constrains the search to a particular node's children.

### Mini-XML 2.7 mxmlFindPath

Find a node with the given path.

mxml_node_t *mxmlFindPath(mxml_node_t *top, const char *path);

#### Parameters

top | Top node
path | Path to element

#### Return Value

Found node or `NULL`

#### Discussion

The "path" is a slash-separated list of element names. The name "" is considered a wildcard for one or more levels of elements. For example, "foo/one/two", "bar/two/one", "/one", and so forth.
The first child node of the found node is returned if the given node has children and the first child is a value node.

### Mini-XML 2.7 mxmlGetCDATA

Get the value for a CDATA node.

const char *mxmlGetCDATA(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

CDATA value or `NULL`

#### Discussion

`NULL` is returned if the node is not a CDATA element.

### Mini-XML 2.7 mxmlGetCustom

Get the value for a custom node.

const void *mxmlGetCustom(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Custom value or `NULL`

#### Discussion

`NULL` is returned if the node (or its first child) is not a custom value node.

### Mini-XML 2.7 mxmlGetElement

Get the name for an element node.

const char *mxmlGetElement(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Element name or `NULL`

#### Discussion

`NULL` is returned if the node is not an element node.

### Mini-XML 2.7 mxmlGetFirstChild

Get the first child of an element node.

mxml_node_t *mxmlGetFirstChild(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

First child or `NULL`

#### Discussion

`NULL` is returned if the node is not an element node or if the node has no children.

### Mini-XML 2.7 mxmlGetInteger

Get the integer value from the specified node or its first child.

int mxmlGetInteger(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Integer value or 0

#### Discussion

0 is returned if the node (or its first child) is not an integer value node.

### Mini-XML 2.7 mxmlGetLastChild

Get the last child of an element node.

mxml_node_t *mxmlGetLastChild(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Last child or `NULL`

#### Discussion

`NULL` is returned if the node is not an element node or if the node has no children.

### mxmlGetNextSibling

mxml_node_t *mxmlGetNextSibling(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Get the next node for the current parent.

`NULL` is returned if this is the last child for the current parent.

### Mini-XML 2.7 mxmlGetOpaque

Get an opaque string value for a node or its first child.

const char *mxmlGetOpaque(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Opaque string or `NULL`

#### Discussion

`NULL` is returned if the node (or its first child) is not an opaque value node.

### Mini-XML 2.7 mxmlGetParent

Get the parent node.

mxml_node_t *mxmlGetParent(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Parent node or `NULL`

#### Discussion

`NULL` is returned for a root node.

### Mini-XML 2.7 mxmlGetPrevSibling

Get the previous node for the current parent.

mxml_node_t *mxmlGetPrevSibling(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Previous node or `NULL`

#### Discussion

`NULL` is returned if this is the first child for the current parent.

### Mini-XML 2.7 mxmlGetReal

Get the real value for a node or its first child.

double mxmlGetReal(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Real value or 0.0

#### Discussion

0.0 is returned if the node (or its first child) is not a real value node.

### Mini-XML 2.7 mxmlGetRefCount

Get the current reference (use) count for a node.

int mxmlGetRefCount(mxml_node_t *node);

#### Parameters

node | Node

#### Return Value

Reference count

#### Discussion

The initial reference count of new nodes is 1. Use the `mxmlRetain` and `mxmlRelease` functions to increment and decrement a node's reference count. .

### Mini-XML 2.7 mxmlGetText

Get the text value for a node or its first child.

const char *mxmlGetText(mxml_node_t *node, int *whitespace);

#### Parameters

node | Node to get
whitespace | 1 if string is preceded by whitespace, 0 otherwise

#### Return Value

Text string or `NULL`

#### Discussion

`NULL` is returned if the node (or its first child) is not a text node. The "whitespace" argument can be `NULL`.
Note: Text nodes consist of whitespace-delimited words. You will only get single words of text when reading an XML file with `MXML_TEXT` nodes. If you want the entire string between elements in the XML file, you MUST read the XML file with `MXML_OPAQUE` nodes and get the resulting strings using the `mxmlGetOpaque` function instead.

### Mini-XML 2.7 mxmlGetType

Get the node type.

mxml_type_t mxmlGetType(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

Type of node

#### Discussion

`MXML_IGNORE` is returned if "node" is `NULL`.

### Mini-XML 2.7 mxmlGetUserData

Get the user data pointer for a node.

void *mxmlGetUserData(mxml_node_t *node);

#### Parameters

node | Node to get

#### Return Value

User data pointer

### mxmlIndexDelete

Delete an index.

void mxmlIndexDelete(mxml_index_t *ind);

#### Parameters

ind | Index to delete

### mxmlIndexEnum

Return the next node in the index.

mxml_node_t *mxmlIndexEnum(mxml_index_t *ind);

#### Parameters

ind | Index to enumerate

#### Return Value

Next node or `NULL` if there is none

#### Discussion

You should call `mxmlIndexReset` prior to using this function to get the first node in the index. Nodes are returned in the sorted order of the index.

### mxmlIndexFind

Find the next matching node.

mxml_node_t *mxmlIndexFind(mxml_index_t *ind, const char *element, const char *value);

#### Parameters

ind | Index to search
element | Element name to find, if any
value | Attribute value, if any

#### Return Value

Node or `NULL` if none found

#### Discussion

You should call `mxmlIndexReset` prior to using this function for the first time with a particular set of "element" and "value" strings. Passing `NULL` for both "element" and "value" is equivalent to calling `mxmlIndexEnum`.

### Mini-XML 2.7 mxmlIndexGetCount

Get the number of nodes in an index.

int mxmlIndexGetCount(mxml_index_t *ind);

#### Parameters

ind | Index of nodes

#### Return Value

Number of nodes in index

### mxmlIndexNew

Create a new index.

mxml_index_t *mxmlIndexNew(mxml_node_t *node, const char *element, const char *attr);

#### Parameters

node | XML node tree
element | Element to index or `NULL` for all
attr | Attribute to index or `NULL` for none

#### Return Value

New index

#### Discussion

The index will contain all nodes that contain the named element and/or attribute. If both "element" and "attr" are `NULL`, then the index will contain a sorted list of the elements in the node tree. Nodes are sorted by element name and optionally by attribute value if the "attr" argument is not NULL.

### mxmlIndexReset

Reset the enumeration/find pointer in the index and return the first node in the index.

mxml_node_t *mxmlIndexReset(mxml_index_t *ind);

#### Parameters

ind | Index to reset

#### Return Value

First node or `NULL` if there is none

#### Discussion

This function should be called prior to using `mxmlIndexEnum` or `mxmlIndexFind` for the first time.

### mxmlLoadFd

Load a file descriptor into an XML node tree.

mxml_node_t *mxmlLoadFd(mxml_node_t *top, int fd, mxml_load_cb_t cb);

#### Parameters

top | Top node
fd | File descriptor to read from
cb | Callback function or constant

#### Return Value

First node or `NULL` if the file could not be read.

#### Discussion

The nodes in the specified file are added to the specified top node. If no top node is provided, the XML file MUST be well-formed with a single parent node like ?xml for the entire file. The callback function returns the value type that should be used for child nodes. The constants `MXML_INTEGER_CALLBACK`, `MXML_OPAQUE_CALLBACK`, `MXML_REAL_CALLBACK`, and `MXML_TEXT_CALLBACK` are defined for loading child (data) nodes of the specified type.
Note: The most common programming error when using the Mini-XML library is to load an XML file using the `MXML_TEXT_CALLBACK`, which returns inline text as a series of whitespace-delimited words, instead of using the `MXML_OPAQUE_CALLBACK` which returns the inline text as a single string (including whitespace).

### mxmlLoadFile

Load a file into an XML node tree.

mxml_node_t *mxmlLoadFile(mxml_node_t *top, FILE *fp, mxml_load_cb_t cb);

#### Parameters

top | Top node
fp | File to read from
cb | Callback function or constant

#### Return Value

First node or `NULL` if the file could not be read.

#### Discussion

The nodes in the specified file are added to the specified top node. If no top node is provided, the XML file MUST be well-formed with a single parent node like ?xml for the entire file. The callback function returns the value type that should be used for child nodes. The constants `MXML_INTEGER_CALLBACK`, `MXML_OPAQUE_CALLBACK`, `MXML_REAL_CALLBACK`, and `MXML_TEXT_CALLBACK` are defined for loading child (data) nodes of the specified type.
Note: The most common programming error when using the Mini-XML library is to load an XML file using the `MXML_TEXT_CALLBACK`, which returns inline text as a series of whitespace-delimited words, instead of using the `MXML_OPAQUE_CALLBACK` which returns the inline text as a single string (including whitespace).

### mxmlLoadString

Load a string into an XML node tree.

mxml_node_t *mxmlLoadString(mxml_node_t *top, const char *s, mxml_load_cb_t cb);

#### Parameters

top | Top node
s | String to load
cb | Callback function or constant

#### Return Value

First node or `NULL` if the string has errors.

#### Discussion

The nodes in the specified string are added to the specified top node. If no top node is provided, the XML string MUST be well-formed with a single parent node like ?xml for the entire string. The callback function returns the value type that should be used for child nodes. The constants `MXML_INTEGER_CALLBACK`, `MXML_OPAQUE_CALLBACK`, `MXML_REAL_CALLBACK`, and `MXML_TEXT_CALLBACK` are defined for loading child (data) nodes of the specified type.
Note: The most common programming error when using the Mini-XML library is to load an XML file using the `MXML_TEXT_CALLBACK`, which returns inline text as a series of whitespace-delimited words, instead of using the `MXML_OPAQUE_CALLBACK` which returns the inline text as a single string (including whitespace).

### Mini-XML 2.3 mxmlNewCDATA

Create a new CDATA node.

mxml_node_t *mxmlNewCDATA(mxml_node_t *parent, const char *data);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
data | Data string

#### Return Value

New node

#### Discussion

The new CDATA node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new CDATA node has no parent. The data string must be nul-terminated and is copied into the new node. CDATA nodes currently use the `MXML_ELEMENT` type.

### Mini-XML 2.1 mxmlNewCustom

Create a new custom data node.

mxml_node_t *mxmlNewCustom(mxml_node_t *parent, void *data, mxml_custom_destroy_cb_t destroy);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
data | Pointer to data
destroy | Function to destroy data

#### Return Value

New node

#### Discussion

The new custom node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new element node has no parent. `NULL` can be passed when the data in the node is not dynamically allocated or is separately managed.

### mxmlNewElement

Create a new element node.

mxml_node_t *mxmlNewElement(mxml_node_t *parent, const char *name);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
name | Name of element

#### Return Value

New node

#### Discussion

The new element node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new element node has no parent.

### mxmlNewInteger

Create a new integer node.

mxml_node_t *mxmlNewInteger(mxml_node_t *parent, int integer);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
integer | Integer value

#### Return Value

New node

#### Discussion

The new integer node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new integer node has no parent.

### mxmlNewOpaque

Create a new opaque string.

mxml_node_t *mxmlNewOpaque(mxml_node_t *parent, const char *opaque);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
opaque | Opaque string

#### Return Value

New node

#### Discussion

The new opaque string node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new opaque string node has no parent. The opaque string must be nul- terminated and is copied into the new node.

### mxmlNewOpaquef

Create a new formatted opaque string node.

mxml_node_t *mxmlNewOpaquef(mxml_node_t *parent, const char *format, ...);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
format | Printf-style format string
... | Additional args as needed

#### Return Value

New node

#### Discussion

The new opaque string node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new opaque string node has no parent. The format string must be nul-terminated and is formatted into the new node.

### mxmlNewReal

Create a new real number node.

mxml_node_t *mxmlNewReal(mxml_node_t *parent, double real);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
real | Real number value

#### Return Value

New node

#### Discussion

The new real number node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new real number node has no parent.

### mxmlNewText

Create a new text fragment node.

mxml_node_t *mxmlNewText(mxml_node_t *parent, int whitespace, const char *string);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
whitespace | 1 = leading whitespace, 0 = no whitespace
string | String

#### Return Value

New node

#### Discussion

The new text node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new text node has no parent. The whitespace parameter is used to specify whether leading whitespace is present before the node. The text string must be nul-terminated and is copied into the new node.

### mxmlNewTextf

Create a new formatted text fragment node.

mxml_node_t *mxmlNewTextf(mxml_node_t *parent, int whitespace, const char *format, ...);

#### Parameters

parent | Parent node or `MXML_NO_PARENT`
whitespace | 1 = leading whitespace, 0 = no whitespace
format | Printf-style format string
... | Additional args as needed

#### Return Value

New node

#### Discussion

The new text node is added to the end of the specified parent's child list. The constant `MXML_NO_PARENT` can be used to specify that the new text node has no parent. The whitespace parameter is used to specify whether leading whitespace is present before the node. The format string must be nul-terminated and is formatted into the new node.

### Mini-XML 2.3 mxmlNewXML

Create a new XML document tree.

mxml_node_t *mxmlNewXML(const char *version);

#### Parameters

version | Version number to use

#### Return Value

New ?xml node

#### Discussion

The "version" argument specifies the version number to put in the ?xml element node. If `NULL`, version "1.0" is assumed.

### Mini-XML 2.3 mxmlRelease

Release a node.

int mxmlRelease(mxml_node_t *node);

#### Parameters

node | Node

#### Return Value

New reference count

#### Discussion

When the reference count reaches zero, the node (and any children) is deleted via `mxmlDelete`.

### mxmlRemove

Remove a node from its parent.

void mxmlRemove(mxml_node_t *node);

#### Parameters

node | Node to remove

#### Discussion

This function does not free memory used by the node - use `mxmlDelete` for that. This function does nothing if the node has no parent.

### Mini-XML 2.3 mxmlRetain

Retain a node.

int mxmlRetain(mxml_node_t *node);

#### Parameters

node | Node

#### Return Value

New reference count

### Mini-XML 2.3 mxmlSAXLoadFd

Load a file descriptor into an XML node tree using a SAX callback.

mxml_node_t *mxmlSAXLoadFd(mxml_node_t *top, int fd, mxml_load_cb_t cb, mxml_sax_cb_t sax_cb, void *sax_data);

#### Parameters

top | Top node
fd | File descriptor to read from
cb | Callback function or constant
sax_cb | SAX callback or `MXML_NO_CALLBACK`
sax_data | SAX user data

#### Return Value

First node or `NULL` if the file could not be read.

#### Discussion

The nodes in the specified file are added to the specified top node. If no top node is provided, the XML file MUST be well-formed with a single parent node like ?xml for the entire file. The callback function returns the value type that should be used for child nodes. The constants `MXML_INTEGER_CALLBACK`, `MXML_OPAQUE_CALLBACK`, `MXML_REAL_CALLBACK`, and `MXML_TEXT_CALLBACK` are defined for loading child nodes of the specified type.
The SAX callback must call `mxmlRetain` for any nodes that need to be kept for later use. Otherwise, nodes are deleted when the parent node is closed or after each data, comment, CDATA, or directive node.

### Mini-XML 2.3 mxmlSAXLoadFile

Load a file into an XML node tree using a SAX callback.

mxml_node_t *mxmlSAXLoadFile(mxml_node_t *top, FILE *fp, mxml_load_cb_t cb, mxml_sax_cb_t sax_cb, void *sax_data);

#### Parameters

top | Top node
fp | File to read from
cb | Callback function or constant
sax_cb | SAX callback or `MXML_NO_CALLBACK`
sax_data | SAX user data

#### Return Value

First node or `NULL` if the file could not be read.

#### Discussion

The nodes in the specified file are added to the specified top node. If no top node is provided, the XML file MUST be well-formed with a single parent node like ?xml for the entire file. The callback function returns the value type that should be used for child nodes. The constants `MXML_INTEGER_CALLBACK`, `MXML_OPAQUE_CALLBACK`, `MXML_REAL_CALLBACK`, and `MXML_TEXT_CALLBACK` are defined for loading child nodes of the specified type.
The SAX callback must call `mxmlRetain` for any nodes that need to be kept for later use. Otherwise, nodes are deleted when the parent node is closed or after each data, comment, CDATA, or directive node.

### Mini-XML 2.3 mxmlSAXLoadString

Load a string into an XML node tree using a SAX callback.

mxml_node_t *mxmlSAXLoadString(mxml_node_t *top, const char *s, mxml_load_cb_t cb, mxml_sax_cb_t sax_cb, void *sax_data);

#### Parameters

top | Top node
s | String to load
cb | Callback function or constant
sax_cb | SAX callback or `MXML_NO_CALLBACK`
sax_data | SAX user data

#### Return Value

First node or `NULL` if the string has errors.

#### Discussion

The nodes in the specified string are added to the specified top node. If no top node is provided, the XML string MUST be well-formed with a single parent node like ?xml for the entire string. The callback function returns the value type that should be used for child nodes. The constants `MXML_INTEGER_CALLBACK`, `MXML_OPAQUE_CALLBACK`, `MXML_REAL_CALLBACK`, and `MXML_TEXT_CALLBACK` are defined for loading child nodes of the specified type.
The SAX callback must call `mxmlRetain` for any nodes that need to be kept for later use. Otherwise, nodes are deleted when the parent node is closed or after each data, comment, CDATA, or directive node.

### mxmlSaveAllocString

Save an XML tree to an allocated string.

char *mxmlSaveAllocString(mxml_node_t *node, mxml_save_cb_t cb);

#### Parameters

node | Node to write
cb | Whitespace callback or `MXML_NO_CALLBACK`

#### Return Value

Allocated string or `NULL`

#### Discussion

This function returns a pointer to a string containing the textual representation of the XML node tree. The string should be freed using `free()` when you are done with it. `NULL` is returned if the node would produce an empty string or if the string cannot be allocated.
The callback argument specifies a function that returns a whitespace string or `NULL` before and after each element. If `MXML_NO_CALLBACK` is specified, whitespace will only be added before `MXML_TEXT` nodes with leading whitespace and before attribute names inside opening element tags.

### mxmlSaveFd

Save an XML tree to a file descriptor.

int mxmlSaveFd(mxml_node_t *node, int fd, mxml_save_cb_t cb);

#### Parameters

node | Node to write
fd | File descriptor to write to
cb | Whitespace callback or `MXML_NO_CALLBACK`

#### Return Value

0 on success, -1 on error.

#### Discussion

The callback argument specifies a function that returns a whitespace string or NULL before and after each element. If `MXML_NO_CALLBACK` is specified, whitespace will only be added before `MXML_TEXT` nodes with leading whitespace and before attribute names inside opening element tags.

### mxmlSaveFile

Save an XML tree to a file.

int mxmlSaveFile(mxml_node_t *node, FILE *fp, mxml_save_cb_t cb);

#### Parameters

node | Node to write
fp | File to write to
cb | Whitespace callback or `MXML_NO_CALLBACK`

#### Return Value

0 on success, -1 on error.

#### Discussion

The callback argument specifies a function that returns a whitespace string or NULL before and after each element. If `MXML_NO_CALLBACK` is specified, whitespace will only be added before `MXML_TEXT` nodes with leading whitespace and before attribute names inside opening element tags.

### mxmlSaveString

Save an XML node tree to a string.

int mxmlSaveString(mxml_node_t *node, char *buffer, int bufsize, mxml_save_cb_t cb);

#### Parameters

node | Node to write
buffer | String buffer
bufsize | Size of string buffer
cb | Whitespace callback or `MXML_NO_CALLBACK`

#### Return Value

Size of string

#### Discussion

This function returns the total number of bytes that would be required for the string but only copies (bufsize - 1) characters into the specified buffer.
The callback argument specifies a function that returns a whitespace string or NULL before and after each element. If `MXML_NO_CALLBACK` is specified, whitespace will only be added before `MXML_TEXT` nodes with leading whitespace and before attribute names inside opening element tags.

### Mini-XML 2.3 mxmlSetCDATA

Set the element name of a CDATA node.

int mxmlSetCDATA(mxml_node_t *node, const char *data);

#### Parameters

node | Node to set
data | New data string

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not a CDATA element node.

### Mini-XML 2.1 mxmlSetCustom

Set the data and destructor of a custom data node.

int mxmlSetCustom(mxml_node_t *node, void *data, mxml_custom_destroy_cb_t destroy);

#### Parameters

node | Node to set
data | New data pointer
destroy | New destructor function

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not a custom node.

### mxmlSetCustomHandlers

Set the handling functions for custom data.

void mxmlSetCustomHandlers(mxml_custom_load_cb_t load, mxml_custom_save_cb_t save);

#### Parameters

load | Load function
save | Save function

#### Discussion

The load function accepts a node pointer and a data string and must return 0 on success and non-zero on error.
The save function accepts a node pointer and must return a malloc'd string on success and `NULL` on error.

### mxmlSetElement

Set the name of an element node.

int mxmlSetElement(mxml_node_t *node, const char *name);

#### Parameters

node | Node to set
name | New name string

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it is not an element node.

### mxmlSetErrorCallback

Set the error message callback.

void mxmlSetErrorCallback(mxml_error_cb_t cb);

#### Parameters

cb | Error callback function

### mxmlSetInteger

Set the value of an integer node.

int mxmlSetInteger(mxml_node_t *node, int integer);

#### Parameters

node | Node to set
integer | Integer value

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not an integer node.

### mxmlSetOpaque

Set the value of an opaque node.

int mxmlSetOpaque(mxml_node_t *node, const char *opaque);

#### Parameters

node | Node to set
opaque | Opaque string

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not an opaque node.

### Mini-XML 2.11 mxmlSetOpaquef

Set the value of an opaque string node to a formatted string.

int mxmlSetOpaquef(mxml_node_t *node, const char *format, ...);

#### Parameters

node | Node to set
format | Printf-style format string
... | Additional arguments as needed

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not an opaque node.

### mxmlSetReal

Set the value of a real number node.

int mxmlSetReal(mxml_node_t *node, double real);

#### Parameters

node | Node to set
real | Real number value

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not a real number node.

### mxmlSetText

Set the value of a text node.

int mxmlSetText(mxml_node_t *node, int whitespace, const char *string);

#### Parameters

node | Node to set
whitespace | 1 = leading whitespace, 0 = no whitespace
string | String

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not a text node.

### mxmlSetTextf

Set the value of a text node to a formatted string.

int mxmlSetTextf(mxml_node_t *node, int whitespace, const char *format, ...);

#### Parameters

node | Node to set
whitespace | 1 = leading whitespace, 0 = no whitespace
format | Printf-style format string
... | Additional arguments as needed

#### Return Value

0 on success, -1 on failure

#### Discussion

The node is not changed if it (or its first child) is not a text node.

### Mini-XML 2.7 mxmlSetUserData

Set the user data pointer for a node.

int mxmlSetUserData(mxml_node_t *node, void *data);

#### Parameters

node | Node to set
data | User data pointer

#### Return Value

0 on success, -1 on failure

### Mini-XML 2.3 mxmlSetWrapMargin

Set the wrap margin when saving XML data.

void mxmlSetWrapMargin(int column);

#### Parameters

column | Column for wrapping, 0 to disable wrapping

#### Discussion

Wrapping is disabled when "column" is 0.

### mxmlWalkNext

Walk to the next logical node in the tree.

mxml_node_t *mxmlWalkNext(mxml_node_t *node, mxml_node_t *top, int descend);

#### Parameters

node | Current node
top | Top node
descend | Descend into tree - `MXML_DESCEND`, `MXML_NO_DESCEND`, or `MXML_DESCEND_FIRST`

#### Return Value

Next node or `NULL`

#### Discussion

The descend argument controls whether the first child is considered to be the next node. The top node argument constrains the walk to the node's children.

### mxmlWalkPrev

Walk to the previous logical node in the tree.

mxml_node_t *mxmlWalkPrev(mxml_node_t *node, mxml_node_t *top, int descend);

#### Parameters

node | Current node
top | Top node
descend | Descend into tree - `MXML_DESCEND`, `MXML_NO_DESCEND`, or `MXML_DESCEND_FIRST`

#### Return Value

Previous node or `NULL`

#### Discussion

The descend argument controls whether the previous node's last child is considered to be the previous node. The top node argument constrains the walk to the node's children.

## Data Types

### mxml_custom_destroy_cb_t

Custom data destructor

typedef void (*mxml_custom_destroy_cb_t)(void *);

### mxml_custom_load_cb_t

Custom data load callback function

typedef int (*mxml_custom_load_cb_t)(mxml_node_t *, const char *);

### mxml_custom_save_cb_t

Custom data save callback function

typedef char *(*mxml_custom_save_cb_t)(mxml_node_t *);

### mxml_entity_cb_t

Entity callback function

typedef int (*mxml_entity_cb_t)(const char *);

### mxml_error_cb_t

Error callback function

typedef void (*mxml_error_cb_t)(const char *);

### mxml_index_t

An XML node index.

typedef struct _mxml_index_s mxml_index_t;

### mxml_load_cb_t

Load callback function

typedef mxml_type_t (*mxml_load_cb_t)(mxml_node_t *);

### mxml_node_t

An XML node.

typedef struct _mxml_node_s mxml_node_t;

### mxml_save_cb_t

Save callback function

typedef const char *(*mxml_save_cb_t)(mxml_node_t *, int);

### mxml_sax_cb_t

SAX callback function

typedef void (*mxml_sax_cb_t)(mxml_node_t *, mxml_sax_event_t, void *);

### mxml_sax_event_t

SAX event type.

typedef enum mxml_sax_event_e mxml_sax_event_t;

### mxml_type_t

The XML node type.

typedef enum mxml_type_e mxml_type_t;

## Constants

### mxml_sax_event_e

SAX event type.

#### Constants

MXML_SAX_CDATA | CDATA node
MXML_SAX_COMMENT | Comment node
MXML_SAX_DATA | Data node
MXML_SAX_DIRECTIVE | Processing directive node
MXML_SAX_ELEMENT_CLOSE | Element closed
MXML_SAX_ELEMENT_OPEN | Element opened

### mxml_type_e

The XML node type.

#### Constants

MXML_CUSTOM Mini-XML 2.1 | Custom data
MXML_ELEMENT | XML element with attributes
MXML_IGNORE Mini-XML 2.3 | Ignore/throw away node
MXML_INTEGER | Integer value
MXML_OPAQUE | Opaque string
MXML_REAL | Real value
MXML_TEXT | Text fragment