XML code generator

This is a source code generator tool for xml parser in c. This application parses XML schema file and generates C source code that can be used for parsing XML file.

It generates xs_element_t data structure in C based on the XML schema file. This structure contains all the schema properties of XML elements such as element name, its child elements, attributes, content type, etc.. It also contains the tree structure of XML elements in the schema. The parser uses this xs_element_t structure for validating the input XML file against XML schema constraints (rules).

How to use

This is a command line tool, it takes XML schema file as input and generates c source code. The simplest way to use is,

xml_code_generator.exe food.xsd

The tool generates two files

• food.h : This file contains food_t structure created from schema to store the content of XML.
• food.c : This file contains xs_element_t tree structure generated from schema.

food.xsd

Input XML schema.

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
 <xs:element name="food">
    <xs:complexType>
      <xs:sequence>
        <xs:element type="xs:string" name="name"/>
        <xs:element type="xs:float" name="price"/>
        <xs:element type="xs:string" name="description"/>
        <xs:element type="xs:unsignedInt" name="calories"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

food.h

Header file contains the C structure food_t based on the data structure of input XML schema. This structure is useful to store the extracted content from the XML file by XML parser.

typedef struct
{
    char* name;
    float price;
    char* description;
    uint32_t calories;
}food_t;

food.c

Source file contains the xs_element_t for each element in the schema.

food_root is the xs_element_t variable for root element "food". It represents all the XML element properties of "food" element in schema. Also, it holds the address of its attributes (food_attribute) and child elements (food_descendant).

const xs_element_t food_root =
{
    .Name.String = "food",
    .Name.Length = 4,
    .MinOccur    = 1,
    .MaxOccur    = 1,
    .Target.Type    = EN_RELATIVE,
    .Target.Offset  = 0,
    .Content.Type   = EN_NO_XML_DATA_TYPE,
    .Attribute_Quantity = 2,
    .Attribute          = food_attribute,
    .Child_Quantity = 4,
    .Child_Order    = EN_SEQUENCE,
    .Child          = food_descendant,
};

food_descendant is an array of xs_element_t. It holds all the child elements of food element.

static const xs_element_t food_descendant[] =
{
    [0].Name.String = "name",
    [0].Name.Length = 4,
    [0].MinOccur    = 1,
    [0].MaxOccur    = 1,
    [0].Target.Type    = EN_RELATIVE,
    [0].Target.Offset  = offsetof(food_t, name),
    [0].Content.Type   = EN_STRING_DYNAMIC,
    [0].Content.Facet.String.MinLength = 0,
    [0].Content.Facet.String.MaxLength = 4294967295,

    ...

    [3].Name.String = "calories",
    [3].Name.Length = 8,
    [3].MinOccur    = 1,
    [3].MaxOccur    = 1,
    [3].Target.Type    = EN_RELATIVE,
    [3].Target.Offset  = offsetof(food_t, calories),
    [3].Content.Type   = EN_UNSIGNED,
    [3].Content.Facet.Uint.MinValue = 0,
    [3].Content.Facet.Uint.MaxValue = 4294967295,
};

food_attribute is an array of xs_attribute_t. It holds all the attributes of food element.

static const xs_attribute_t food_attribute[] =
{
    [0].Name.String = "xmlns:xsi",
    [0].Name.Length = 9,
    [0].Use         = EN_OPTIONAL,

    [1].Name.String = "xsi:noNamespaceSchemaLocation",
    [1].Name.Length = 29,
    [1].Use         = EN_OPTIONAL,
};

Address of food_root is passed to xml parser along with XML string to parse. For further information on how to use these food.c and food.h for parsing XML file refer food example

Command line options

Callback

-b or --callback

Code generator includes Callback member in each xs_element_t variables of generated code.

By default Callback member variable is disabled in the xs_element_t structure to save code space. Hence, to avoid compilation error, code generator also by default omits the Callback member in the generated code. Use this option in the command line when you have enabled Callback member in the XML parser.

Dynamic memory allocation

-d or --dynamic Code generator uses dynamic addressing method (EN_DYNAMIC) for XML element that can occur multiple times (maxOccurs > 1) in an XML file.

By default code generator uses relative addressing method (EN_RELATIVE) as a target addressing method for all the XML elements. The dynamic addressing method enables user to allocate memory at runtime to store the XML data.

Enable context

-c or --context

Code generator includes context argument in the signature of allocate callback function.

By default user defined context in the XML parser is disabled to save code space. Hence, to avoid compilation error, code generator also by default omits the context argument in the allocate callback function. Use this option in the command line when you have enabled the context argument in the XML parser.

More

• For reporting issues/bugs or requesting features use GitHub issue tracker