Class: OvirtSDK4::XmlReader

Inherits:

Object

• Object
• OvirtSDK4::XmlReader

Defined in:

ext/ovirtsdk4c/ov_xml_reader.c

Instance Method Summary

• #close ⇒ Object
• #empty_element? ⇒ Boolean
• #forward ⇒ Object

  Define the methods:.

• #get_attribute(name) ⇒ Object
• #initialize(io) ⇒ Object constructor
• #next_element ⇒ Object
• #node_name ⇒ Object
• #read ⇒ Object
• #read_element ⇒ Object
• #read_elements ⇒ Object

Constructor Details

#initialize(io) ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 124

static VALUE ov_xml_reader_initialize(VALUE self, VALUE io) {
    VALUE io_class;
    int rc;
    ov_xml_reader_object* ptr;

    /* Get the pointer to the object: */
    ov_xml_reader_ptr(self, ptr);

    /* The parameter of the constructor can be a string or an IO object. If it is a string then we need to create aa
       IO object to read from it. */
    io_class = rb_class_of(io);
    if (io_class == rb_cString) {
        ptr->io = ov_xml_reader_create_string_io(io);
    }
    else if (io_class == rb_cIO) {
        ptr->io = io;
    }
    else {
        rb_raise(
            ov_error_class,
            "The type of the 'io' parameter must be 'String' or 'IO', but it is '%"PRIsVALUE"'",
            io_class
        );
    }

    /* Clear the closed flag: */
    ptr->closed = false;

    /* Create the libxml reader: */
    ptr->reader = xmlReaderForIO(ov_xml_reader_callback, NULL, ptr, NULL, NULL, 0);
    if (ptr->reader == NULL) {
        rb_raise(ov_error_class, "Can't create reader");
    }

    /* Move the cursor to the first node: */
    rc = xmlTextReaderRead(ptr->reader);
    if (rc == -1) {
        rb_raise(ov_error_class, "Can't read first node");
    }

    return self;
}

Instance Method Details

#close ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 417

static VALUE ov_xml_reader_close(VALUE self) {
    ov_xml_reader_object* ptr;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);
    xmlFreeTextReader(ptr->reader);
    ptr->reader = NULL;
    ptr->closed = true;
    return Qnil;
}

#empty_element? ⇒ Boolean

Returns:

• (Boolean)

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 227

static VALUE ov_xml_reader_empty_element(VALUE self) {
    int c_empty;
    ov_xml_reader_object* ptr;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);
    c_empty = xmlTextReaderIsEmptyElement(ptr->reader);
    if (c_empty == -1) {
        rb_raise(ov_error_class, "Can't check if current element is empty");
    }
    return c_empty? Qtrue: Qfalse;
}

#forward ⇒ Object

Define the methods:

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 184

static VALUE ov_xml_reader_forward(VALUE self) {
    int c_type = 0;
    int rc = 0;
    ov_xml_reader_object* ptr;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);

    for (;;) {
        c_type = xmlTextReaderNodeType(ptr->reader);
        if (c_type == -1) {
            rb_raise(ov_error_class, "Can't get current node type");
        }
        else if (c_type == XML_READER_TYPE_ELEMENT) {
            return Qtrue;
        }
        else if (c_type == XML_READER_TYPE_END_ELEMENT || c_type == XML_READER_TYPE_NONE) {
            return Qfalse;
        }
        else {
            rc = xmlTextReaderRead(ptr->reader);
            if (rc == -1) {
                rb_raise(ov_error_class, "Can't move to next node");
            }
        }
    }
}

#get_attribute(name) ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 240

static VALUE ov_xml_reader_get_attribute(VALUE self, VALUE name) {
    VALUE value;
    ov_xml_reader_object* ptr;
    xmlChar* c_name;
    xmlChar* c_value;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);
    c_name = (xmlChar*) StringValueCStr(name);
    c_value = xmlTextReaderGetAttribute(ptr->reader, c_name);
    if (c_value == NULL) {
        return Qnil;
    }
    value = rb_str_new_cstr((char*) c_value);
    xmlFree(c_value);
    return value;
}

#next_element ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 401

static VALUE ov_xml_reader_next_element(VALUE self) {
    int rc;
    ov_xml_reader_object* ptr;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);
    rc = xmlTextReaderNext(ptr->reader);
    if (rc == 0) {
        return Qfalse;
    }
    if (rc == 1) {
        return Qtrue;
    }
    rb_raise(ov_error_class, "Can't move to next element");
}

#node_name ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 212

static VALUE ov_xml_reader_node_name(VALUE self) {
    VALUE name;
    const xmlChar* c_name;
    ov_xml_reader_object* ptr;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);
    c_name = xmlTextReaderConstName(ptr->reader);
    if (c_name == NULL) {
        return Qnil;
    }
    name = rb_str_new_cstr((char*) c_name);
    return name;
}

#read ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 167

static VALUE ov_xml_reader_read(VALUE self) {
    int rc = 0;
    ov_xml_reader_object* ptr;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);
    rc = xmlTextReaderRead(ptr->reader);
    if (rc == 0) {
        return Qfalse;
    }
    if (rc == 1) {
        return Qtrue;
    }
    rb_raise(ov_error_class, "Can't move to next node");
    return Qnil;
}

#read_element ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 258

static VALUE ov_xml_reader_read_element(VALUE self) {
    VALUE value;
    int c_empty;
    int c_type;
    int rc;
    ov_xml_reader_object* ptr;
    xmlChar* c_value;

    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);

    /* Check the type of the current node: */
    c_type = xmlTextReaderNodeType(ptr->reader);
    if (c_type == -1) {
        rb_raise(ov_error_class, "Can't get current node type");
    }
    if (c_type != XML_READER_TYPE_ELEMENT) {
        rb_raise(ov_error_class, "Current node isn't the start of an element");
    }

    /* Check if the current node is empty: */
    c_empty = xmlTextReaderIsEmptyElement(ptr->reader);
    if (c_empty == -1) {
        rb_raise(ov_error_class, "Can't check if current element is empty");
    }

    /* For empty values elements there is no need to read the value. For non empty values we need to read the value, and
       check if it is NULL, as that means that the value is an empty string. */
    if (c_empty) {
        c_value = NULL;
    }
    else {
        c_value = xmlTextReaderReadString(ptr->reader);
        if (c_value == NULL) {
            c_value = xmlCharStrdup("");
            if (c_value == NULL) {
                rb_raise(ov_error_class, "Can't allocate XML string");
            }
        }
    }

    /* Move to the next element: */
    rc = xmlTextReaderNext(ptr->reader);
    if (rc == -1) {
        if (c_value != NULL) {
            xmlFree(c_value);
        }
        rb_raise(ov_error_class, "Can't move to the next element");
    }

    /* Return the result: */
    if (c_value == NULL) {
       return Qnil;
    }
    value = rb_str_new_cstr((char*) c_value);
    xmlFree(c_value);
    return value;
}

#read_elements ⇒ Object

# File 'ext/ovirtsdk4c/ov_xml_reader.c', line 317

static VALUE ov_xml_reader_read_elements(VALUE self) {
    VALUE element;
    VALUE list;
    int c_empty;
    int c_type;
    int rc;
    ov_xml_reader_object* ptr;

    /* Get the pointer to the object and check that it isn't closed: */
    ov_xml_reader_ptr(self, ptr);
    ov_xml_reader_check_closed(ptr);

    /* This method assumes that the reader is positioned at the element that contains the values to read. For example
       if the XML document is the following:

       <list>
         <value>first</value>
         <value>second</value>
       </list>

       The reader should be positioned at the <list> element. The first thing we need to do is to check: */
    c_type = xmlTextReaderNodeType(ptr->reader);
    if (c_type == -1) {
        rb_raise(ov_error_class, "Can't get current node type");
    }
    if (c_type != XML_READER_TYPE_ELEMENT) {
        rb_raise(ov_error_class, "Current node isn't the start of an element");
    }

    /* If we are indeed positioned at the first element, then we need to check if it is empty, <list/>, as we will
       need this lter, after discarding the element: */
    c_empty = xmlTextReaderIsEmptyElement(ptr->reader);
    if (c_empty == -1) {
        rb_raise(ov_error_class, "Can't check if current element is empty");
    }

    /* Now we need to discard the current element, as we are interested only in the nested <value>...</value>
       elements: */
    rc = xmlTextReaderRead(ptr->reader);
    if (rc == -1) {
        rb_raise(ov_error_class, "Can't move to next node");
    }

    /* Create the list that will contain the result: */
    list = rb_ary_new();

    /* At this point, if the start element was empty, we don't need to do anything else: */
    if (c_empty) {
        return list;
    }

    /* Process the nested elements: */
    for (;;) {
        c_type = xmlTextReaderNodeType(ptr->reader);
        if (c_type == -1) {
            rb_raise(ov_error_class, "Can't get current node type");
        }
        else if (c_type == XML_READER_TYPE_ELEMENT) {
            element = ov_xml_reader_read_element(self);
            rb_ary_push(list, element);
        }
        else if (c_type == XML_READER_TYPE_END_ELEMENT || c_type == XML_READER_TYPE_NONE) {
            break;
        }
        else {
            rc = xmlTextReaderNext(ptr->reader);
            if (rc == -1) {
                rb_raise(ov_error_class, "Can't move to the next node");
            }
        }
    }

    /* Once all the nested <value>...</value> elements are processed the reader will be positioned at the closing
       </list> element, or at the end of the document. If it is the closing element then we need to discard it. */
    if (c_type == XML_READER_TYPE_END_ELEMENT) {
        rc = xmlTextReaderRead(ptr->reader);
        if (rc == -1) {
            rb_raise(ov_error_class, "Can't move to next node");
        }
    }

    return list;
}