Transform

Apply an XSLT 1.0 stylesheet to a document, the job lxml’s etree.XSLT does. A stylesheet is an XML document, so it is read with turbohtml.parse_xml(); Transform holds the parsed stylesheet and is callable over source documents, the compile-once, apply-many shape. The whole transformation runs in the C extension, reusing turbohtml’s XPath 1.0 engine for every match pattern and select expression rather than growing a second path evaluator.

class turbohtml.transform.Transform(stylesheet, *, base_url=None)

A compiled XSLT 1.0 stylesheet, callable over source documents (lxml’s etree.XSLT).

Parameters:

• stylesheet (Node) – the stylesheet, a tree parsed with turbohtml.parse_xml().

• base_url (str | None) – the stylesheet’s path or file URL, against which xsl:import hrefs resolve; required only when the stylesheet imports.

__call__(source, /, **params)

Transform a source document and return the serialized result.

Parameters:

• source (Node) – the document to transform, a parsed tree.

• params (str) – top-level xsl:param values, each an XPath expression string (quote a string literal, as lxml does: convert(doc, title="'Report'")).

Raises:

• ValueError – if the stylesheet or an expression is malformed, or a referenced key or named template is undeclared.

• RuntimeError – on an xsl:message with terminate="yes".

Return type:

str

Returns:

the transformed document serialized under the stylesheet’s xsl:output method.

turbohtml.transform.transform(stylesheet, source, /, *, base_url=None, **params)

Apply an XSLT 1.0 stylesheet to a source document in one call.

Equivalent to Transform(stylesheet, base_url=base_url)(source, **params); use Transform to apply one stylesheet to many documents without re-reading it each time.

Parameters:

• stylesheet (Node) – the stylesheet, a tree parsed with turbohtml.parse_xml().

• source (Node) – the document to transform, a parsed tree.

• base_url (str | None) – the stylesheet’s path or file URL, against which xsl:import hrefs resolve; required only when the stylesheet imports.

• params (str) – top-level xsl:param values, each an XPath expression string.

Return type:

str

Returns:

the transformed document serialized under the stylesheet’s xsl:output method.

The engine covers the XSLT 1.0 core: xsl:template (match, name, mode, priority), xsl:apply-templates (select, mode, xsl:sort, xsl:with-param), xsl:call-template, xsl:for-each, xsl:if, xsl:choose/xsl:when/xsl:otherwise, xsl:value-of, xsl:copy and xsl:copy-of, xsl:element/xsl:attribute/xsl:text/xsl:comment/xsl:processing-instruction, xsl:variable/xsl:param (local and top-level), xsl:sort (data-type, order), xsl:number (value, format), xsl:key with the key() function, the built-in template rules, and the section 5.5 conflict resolution by priority then document order. It emits the xml, html, and text output methods, and adds the XSLT functions current(), key(), generate-id(), format-number(), system-property(), function-available(), and element-available().

External-document loading is limited. xsl:import resolves local paths and file URLs against base_url; the imported declarations join conflict resolution at lower import precedence. xsl:include and document() do not resolve, and document() returns an empty node-set.