Utility Modules

class ElementTreeContentHandler:
    """SAX ContentHandler that builds lxml ElementTree."""
    
    def __init__(self, makeelement=None):
        """
        Create SAX content handler for building ElementTree.
        
        Args:
            makeelement: Custom element factory function (optional)
        """
    
    def etree(self):
        """Get built ElementTree after parsing completes."""
    
    # SAX ContentHandler interface methods
    def setDocumentLocator(self, locator): ...
    def startDocument(self): ...
    def endDocument(self): ...
    def startPrefixMapping(self, prefix, uri): ...
    def endPrefixMapping(self, prefix): ...
    def startElement(self, name, attrs): ...
    def endElement(self, name): ...
    def startElementNS(self, name, qname, attrs): ...
    def endElementNS(self, name, qname): ...
    def characters(self, data): ...
    def ignorableWhitespace(self, whitespace): ...
    def processingInstruction(self, target, data): ...
    def skippedEntity(self, name): ...

class ElementTreeProducer:
    """Generate SAX events from lxml ElementTree."""
    
    def __init__(self, element_or_tree, content_handler):
        """
        Create SAX event producer.
        
        Args:
            element_or_tree: Element or ElementTree to process
            content_handler: SAX ContentHandler to receive events
        """
    
    def saxify(self):
        """Generate SAX events for the element tree."""

def saxify(element_or_tree, content_handler):
    """
    Generate SAX events from lxml tree.
    
    Args:
        element_or_tree: Element or ElementTree to process
        content_handler: SAX ContentHandler to receive events
    """

class SaxError(LxmlError):
    """SAX processing error."""

class CSSSelector:
    """CSS selector that compiles to XPath for element matching."""
    
    def __init__(self, css, namespaces=None, translator='xml'):
        """
        Create CSS selector.
        
        Args:
            css: CSS selector string
            namespaces: dict mapping prefixes to namespace URIs
            translator: Selector translator ('xml' or 'html')
        """
    
    def __call__(self, element):
        """
        Find elements matching CSS selector.
        
        Args:
            element: Element or ElementTree to search
        
        Returns:
            list: Matching elements
        """
    
    @property
    def css(self):
        """CSS selector string."""
    
    @property
    def path(self):
        """Compiled XPath expression."""

class LxmlTranslator:
    """CSS to XPath translator with lxml-specific extensions."""
    
    def css_to_xpath(self, css, prefix='descendant-or-self::'):
        """Convert CSS selector to XPath expression."""

class LxmlHTMLTranslator(LxmlTranslator):
    """HTML-specific CSS to XPath translator."""

# CSS selector error classes
class SelectorSyntaxError(Exception):
    """CSS selector syntax error."""

class ExpressionError(Exception):
    """CSS expression error."""

class SelectorError(Exception):
    """General CSS selector error."""

class ElementMaker:
    """Factory for creating XML elements with builder pattern."""
    
    def __init__(self, typemap=None, namespace=None, nsmap=None, 
                 makeelement=None, **default_attributes):
        """
        Create element factory.
        
        Args:
            typemap: dict mapping Python types to conversion functions
            namespace: Default namespace URI for created elements
            nsmap: Namespace prefix mapping
            makeelement: Custom element factory function
            **default_attributes: Default attributes for all elements
        """
    
    def __call__(self, tag, *children, **attributes):
        """
        Create element with tag, children, and attributes.
        
        Args:
            tag: Element tag name
            *children: Child elements, text, or other content
            **attributes: Element attributes
        
        Returns:
            Element: Created element with children and attributes
        """
    
    def __getattr__(self, tag):
        """Create element factory method for specific tag."""

# Default element maker instance
E = ElementMaker()

def include(elem, loader=None, base_url=None, max_depth=6):
    """
    Process XInclude directives in element tree.
    
    Args:
        elem: Element containing XInclude directives
        loader: Custom resource loader function
        base_url: Base URL for resolving relative hrefs
        max_depth: Maximum inclusion recursion depth
    
    Raises:
        FatalIncludeError: Fatal inclusion error
        LimitedRecursiveIncludeError: Recursion limit exceeded
    """

def default_loader(href, parse, encoding=None):
    """
    Default XInclude resource loader.
    
    Args:
        href: Resource URI to load
        parse: Parse mode ('xml' or 'text')
        encoding: Character encoding for text resources
    
    Returns:
        Element or str: Loaded resource content
    """

class FatalIncludeError(LxmlError):
    """Fatal XInclude processing error."""

class LimitedRecursiveIncludeError(FatalIncludeError):
    """XInclude recursion limit exceeded."""

# XInclude constants
DEFAULT_MAX_INCLUSION_DEPTH = 6
XINCLUDE_NAMESPACE = "http://www.w3.org/2001/XInclude"

def find(element, path, namespaces=None):
    """
    Find first element matching simple path expression.
    
    Args:
        element: Element to search from
        path: Simple path expression (e.g., 'child/grandchild')
        namespaces: Namespace prefix mapping
    
    Returns:
        Element or None: First matching element
    """

def findall(element, path, namespaces=None):
    """
    Find all elements matching simple path expression.
    
    Args:
        element: Element to search from
        path: Simple path expression
        namespaces: Namespace prefix mapping
    
    Returns:
        list: All matching elements
    """

def iterfind(element, path, namespaces=None):
    """
    Iterate over elements matching simple path expression.
    
    Args:
        element: Element to search from
        path: Simple path expression
        namespaces: Namespace prefix mapping
    
    Yields:
        Element: Matching elements
    """

def findtext(element, path, default=None, namespaces=None):
    """
    Find text content of first element matching path.
    
    Args:
        element: Element to search from
        path: Simple path expression
        default: Default value if no match found
        namespaces: Namespace prefix mapping
    
    Returns:
        str or default: Text content or default value
    """

# lxml.usedoctest - doctest support
def temp_install(modules=None, verbose=None):
    """Temporarily install lxml doctests."""

# lxml.doctestcompare - enhanced doctest comparison  
class LXMLOutputChecker:
    """Enhanced output checker for XML doctests."""
    
    def check_output(self, want, got, optionflags):
        """Compare expected and actual XML output."""

class LHTMLOutputChecker:
    """Enhanced output checker for HTML doctests."""

# Test options
PARSE_HTML = ...
PARSE_XML = ...
NOPARSE_MARKUP = ...

# lxml.pyclasslookup - Python-based element class lookup
class PythonElementClassLookup:
    """Element class lookup using Python callback functions."""
    
    def __init__(self, fallback=None):
        """
        Create Python-based class lookup.
        
        Args:
            fallback: Fallback class lookup for unhandled cases
        """
    
    def lookup(self, doc, element):
        """
        Lookup element class based on document and element.
        
        Args:
            doc: Document containing element
            element: Element to assign class for
        
        Returns:
            type or None: Element class or None for default
        """

def get_include():
    """
    Returns header include paths for compiling C code against lxml.
    
    Returns paths for lxml itself, libxml2, and libxslt headers when lxml
    was built with statically linked libraries.
    
    Returns:
        list: List of include directory paths
    """

from lxml import etree
from lxml.sax import ElementTreeContentHandler, saxify
from xml.sax import make_parser
import xml.sax.handler

# Build ElementTree from SAX events
class MyContentHandler(ElementTreeContentHandler):
    def __init__(self):
        super().__init__()
        self.elements_seen = []
    
    def startElement(self, name, attrs):
        super().startElement(name, attrs)
        self.elements_seen.append(name)

# Parse XML using SAX, build with lxml
xml_data = '''<?xml version="1.0"?>
<catalog>
    <book id="1">
        <title>Python Guide</title>
        <author>John Doe</author>
    </book>
    <book id="2">
        <title>XML Processing</title>
        <author>Jane Smith</author>
    </book>
</catalog>'''

handler = MyContentHandler()
parser = make_parser()
parser.setContentHandler(handler)

# Parse and get resulting ElementTree
from io import StringIO
parser.parse(StringIO(xml_data))
tree = handler.etree()

print(f"Elements seen: {handler.elements_seen}")
print(f"Root tag: {tree.getroot().tag}")

# Generate SAX events from lxml tree
class LoggingHandler(xml.sax.handler.ContentHandler):
    def startElement(self, name, attrs):
        print(f"Start: {name} {dict(attrs)}")
    
    def endElement(self, name):
        print(f"End: {name}")
    
    def characters(self, content):
        content = content.strip()
        if content:
            print(f"Text: {content}")

# Send lxml tree to SAX handler
root = etree.fromstring(xml_data)
logging_handler = LoggingHandler()
saxify(root, logging_handler)

from lxml import html
from lxml.cssselect import CSSSelector

# HTML document for CSS selection
html_content = '''
<html>
<head>
    <title>CSS Selector Example</title>
</head>
<body>
    <div id="header" class="main-header">
        <h1>Welcome</h1>
        <nav class="navigation">
            <a href="/home" class="nav-link active">Home</a>
            <a href="/about" class="nav-link">About</a>
            <a href="/contact" class="nav-link">Contact</a>
        </nav>
    </div>
    <div id="content" class="main-content">
        <article class="post featured">
            <h2>Featured Article</h2>
            <p>This is a featured article.</p>
        </article>
        <article class="post">
            <h2>Regular Article</h2>
            <p>This is a regular article.</p>
        </article>
    </div>
    <footer id="footer">
        <p>&copy; 2023 Example Site</p>
    </footer>
</body>
</html>
'''

doc = html.fromstring(html_content)

# Create CSS selectors
header_selector = CSSSelector('#header')
nav_links_selector = CSSSelector('nav.navigation a.nav-link')
featured_post_selector = CSSSelector('article.post.featured')
all_headings_selector = CSSSelector('h1, h2, h3, h4, h5, h6')

# Use selectors to find elements
header = header_selector(doc)
print(f"Header element: {header[0].get('class') if header else 'Not found'}")

nav_links = nav_links_selector(doc)
print(f"Navigation links: {len(nav_links)}")
for link in nav_links:
    print(f"  {link.text}: {link.get('href')}")

featured = featured_post_selector(doc)
if featured:
    print(f"Featured article title: {featured[0].find('.//h2').text}")

headings = all_headings_selector(doc)
print(f"All headings:")
for heading in headings:
    print(f"  {heading.tag}: {heading.text}")

# Advanced CSS selectors
active_link_selector = CSSSelector('a.nav-link.active')
first_paragraph_selector = CSSSelector('article p:first-child')
not_featured_selector = CSSSelector('article.post:not(.featured)')

active_links = active_link_selector(doc)
print(f"Active navigation links: {len(active_links)}")

first_paragraphs = first_paragraph_selector(doc)
print(f"First paragraphs in articles: {len(first_paragraphs)}")

regular_posts = not_featured_selector(doc)
print(f"Regular (non-featured) posts: {len(regular_posts)}")

from lxml import etree
from lxml.builder import ElementMaker

# Create element maker with namespace
E = ElementMaker(namespace="http://example.com/catalog",
                 nsmap={None: "http://example.com/catalog"})

# Build XML structure using element maker
catalog = E.catalog(
    E.metadata(
        E.title("Book Catalog"),
        E.created("2023-12-07"),
        E.version("1.0")
    ),
    E.books(
        E.book(
            E.title("Python Programming"),
            E.author("John Smith"),
            E.isbn("978-0123456789"),
            E.price("29.99", currency="USD"),
            E.categories(
                E.category("Programming"),
                E.category("Python"),
                E.category("Computers")
            ),
            id="1",
            available="true"
        ),
        E.book(
            E.title("Web Development"),
            E.author("Jane Doe"),
            E.isbn("978-0987654321"),
            E.price("34.95", currency="USD"),
            E.categories(
                E.category("Web"),
                E.category("HTML"),
                E.category("CSS")
            ),
            id="2",
            available="false"
        )
    )
)

print("Generated XML:")
print(etree.tostring(catalog, pretty_print=True, encoding='unicode'))

# Custom element maker with type mapping
def format_price(value):
    """Custom price formatter."""
    return f"${float(value):.2f}"

def bool_to_string(value):
    """Convert boolean to string."""
    return "yes" if value else "no"

custom_typemap = {
    float: format_price,
    bool: bool_to_string
}

CustomE = ElementMaker(typemap=custom_typemap)

# Use custom element maker
product = CustomE.product(
    CustomE.name("Widget"),
    CustomE.price(19.99),  # Will be formatted as currency
    CustomE.available(True),  # Will be converted to "yes"
    CustomE.features(
        CustomE.feature("Lightweight"),
        CustomE.feature("Durable"),
        CustomE.feature("Affordable")
    )
)

print("\nCustom formatted XML:")
print(etree.tostring(product, pretty_print=True, encoding='unicode'))

from lxml import etree
from lxml.ElementInclude import include, default_loader
import tempfile
import os

# Create temporary files for XInclude example
temp_dir = tempfile.mkdtemp()

# Create included content files
header_content = '''<?xml version="1.0"?>
<header>
    <title>Document Title</title>
    <author>John Doe</author>
    <date>2023-12-07</date>
</header>'''

footer_content = '''<?xml version="1.0"?>
<footer>
    <copyright>&copy; 2023 Example Corp</copyright>
    <contact>contact@example.com</contact>
</footer>'''

# Write include files
header_file = os.path.join(temp_dir, 'header.xml')
footer_file = os.path.join(temp_dir, 'footer.xml')

with open(header_file, 'w') as f:
    f.write(header_content)

with open(footer_file, 'w') as f:
    f.write(footer_content)

# Main document with XInclude directives
main_doc_content = f'''<?xml version="1.0"?>
<document xmlns:xi="http://www.w3.org/2001/XInclude">
    <xi:include href="{header_file}"/>
    
    <content>
        <section>
            <h1>Introduction</h1>
            <p>This is the main content of the document.</p>
        </section>
        <section>
            <h1>Details</h1>
            <p>More detailed information goes here.</p>
        </section>
    </content>
    
    <xi:include href="{footer_file}"/>
</document>'''

# Parse document with XInclude processing
root = etree.fromstring(main_doc_content)
print("Before XInclude processing:")
print(etree.tostring(root, pretty_print=True, encoding='unicode'))

# Process XInclude directives
include(root)
print("\nAfter XInclude processing:")
print(etree.tostring(root, pretty_print=True, encoding='unicode'))

# Custom loader for XInclude
def custom_loader(href, parse, encoding=None):
    """Custom XInclude loader with logging."""
    print(f"Loading: {href} (parse={parse}, encoding={encoding})")
    return default_loader(href, parse, encoding)

# Use custom loader
root2 = etree.fromstring(main_doc_content)
include(root2, loader=custom_loader)

# Clean up temporary files
os.unlink(header_file)
os.unlink(footer_file)
os.rmdir(temp_dir)

from lxml import etree
from lxml._elementpath import find, findall, iterfind, findtext

# XML document for path queries
xml_data = '''<?xml version="1.0"?>
<library>
    <section name="fiction">
        <book id="1">
            <title>The Great Gatsby</title>
            <author>F. Scott Fitzgerald</author>
            <metadata>
                <genre>Classic Literature</genre>
                <year>1925</year>
            </metadata>
        </book>
        <book id="2">
            <title>To Kill a Mockingbird</title>
            <author>Harper Lee</author>
            <metadata>
                <genre>Classic Literature</genre>
                <year>1960</year>
            </metadata>
        </book>
    </section>
    <section name="science">
        <book id="3">
            <title>A Brief History of Time</title>
            <author>Stephen Hawking</author>
            <metadata>
                <genre>Science</genre>
                <year>1988</year>
            </metadata>
        </book>
    </section>
</library>'''

root = etree.fromstring(xml_data)

# Simple path queries (ElementTree-style)
fiction_section = find(root, 'section[@name="fiction"]')
print(f"Fiction section: {fiction_section.get('name') if fiction_section else 'Not found'}")

# Find all books in any section
all_books = findall(root, './/book')
print(f"Total books: {len(all_books)}")

# Find specific book by ID
book1 = find(root, './/book[@id="1"]')
if book1:
    title = findtext(book1, 'title')
    author = findtext(book1, 'author') 
    print(f"Book 1: {title} by {author}")

# Iterate over books in fiction section
fiction_books = iterfind(root, 'section[@name="fiction"]/book')
print("Fiction books:")
for book in fiction_books:
    title = findtext(book, 'title')
    year = findtext(book, 'metadata/year')
    print(f"  {title} ({year})")

# Find text with default value
unknown_book = findtext(root, 'section/book[@id="999"]/title', 'Unknown Book')
print(f"Unknown book title: {unknown_book}")

# Complex paths
classic_books = findall(root, './/book[metadata/genre="Classic Literature"]')
print(f"Classic literature books: {len(classic_books)}")

recent_books = findall(root, './/book[metadata/year>"1950"]')
print(f"Books after 1950: {len(recent_books)}")

from lxml import etree

# Define custom element classes
class BookElement(etree.ElementBase):
    """Custom element class for book elements."""
    
    @property
    def title(self):
        """Get book title."""
        title_elem = self.find('title')
        return title_elem.text if title_elem is not None else None
    
    @property
    def author(self):
        """Get book author."""
        author_elem = self.find('author')
        return author_elem.text if author_elem is not None else None
    
    @property
    def year(self):
        """Get publication year as integer."""
        year_elem = self.find('metadata/year')
        if year_elem is not None:
            try:
                return int(year_elem.text)
            except (ValueError, TypeError):
                return None
        return None
    
    def is_classic(self):
        """Check if book is classic literature."""
        genre_elem = self.find('metadata/genre')
        return genre_elem is not None and genre_elem.text == 'Classic Literature'

class SectionElement(etree.ElementBase):
    """Custom element class for section elements."""
    
    @property
    def name(self):
        """Get section name."""
        return self.get('name', 'Unnamed Section')
    
    def get_books(self):
        """Get all books in this section."""
        return self.findall('book')
    
    def count_books(self):
        """Count books in this section."""
        return len(self.findall('book'))

# Create element class lookup
class CustomElementClassLookup(etree.PythonElementClassLookup):
    def lookup(self, document, element):
        if element.tag == 'book':
            return BookElement
        elif element.tag == 'section':
            return SectionElement
        return None

# Set up parser with custom lookup
lookup = CustomElementClassLookup()
parser = etree.XMLParser()
parser.set_element_class_lookup(lookup)

# Parse with custom element classes
xml_data = '''<?xml version="1.0"?>
<library>
    <section name="fiction">
        <book id="1">
            <title>The Great Gatsby</title>
            <author>F. Scott Fitzgerald</author>
            <metadata>
                <genre>Classic Literature</genre>
                <year>1925</year>
            </metadata>
        </book>
        <book id="2">
            <title>Modern Fiction</title>
            <author>Contemporary Author</author>
            <metadata>
                <genre>Modern Literature</genre>
                <year>2020</year>
            </metadata>
        </book>
    </section>
</library>'''

root = etree.fromstring(xml_data, parser)

# Use custom element methods
fiction_section = root.find('section')
print(f"Section: {fiction_section.name}")
print(f"Books in section: {fiction_section.count_books()}")

for book in fiction_section.get_books():
    print(f"  {book.title} by {book.author} ({book.year})")
    print(f"    Is classic: {book.is_classic()}")