leptris (Python) — lxml-shaped bindings for libleptris
leptris wraps the libleptris
C API (XML 1.0 parsing, XPath 1.0) using cffi in ABI mode, with a
required C accelerator for Element allocation and the hot accessors
(tag, text, attrib, get, indexing, sibling navigation and
plain-path XPath evaluation). Wheels ship it compiled; sdist builds
require a C compiler.
The pinned libleptris version lives in libleptris-version.txt
(lockstep releases); CI builds it from the release tarball. The
binding loads the shared library from LEPTRIS_LIB_PATH or the
loader path.
Requirements
- Python 3.9+
cffi(installed automatically)- libleptris 1.9.3+ as a shared library (1.9.1 has an options-struct ABI break — leptris/leptris#568)
- libleptris as a shared library (
libleptris.dylib/.so/.dll) on the loader path, or pointed to byLEPTRIS_LIB_PATH(which must name the library file — the loaderdlopens it verbatim). For a development checkout:
cmake -B build -S /path/to/leptris -DLEPTRIS_BUILD_SHARED=ON
cmake --build build --target leptris_shared
export LEPTRIS_LIB_PATH=/path/to/leptris/build/src/libleptris.dylib
Quick start
from leptris import fromstring, tostring
root = fromstring("<library><book id='1' lang='en'>Ulysses</book></library>")
root.tag # "library"
root[0].get("id") # "1"
root[0].attrib # {"id": "1", "lang": "en"}
root[0].text # "Ulysses"
root.xpath("count(//book)") # 1.0
[b.text for b in root.findall("book")] # ["Ulysses"]
tostring(root[0], encoding="unicode") # "<book id=\"1\" lang=\"en\">Ulysses</book>"
Documents own the tree; use the context manager or close():
from leptris import parse
with parse("catalog.xml") as doc:
doc.xpath("//book[@lang='en']")
Namespaces, variables, canonical XML and streaming:
root.xpath("//x:item", namespaces={"x": "urn:ex"})
root.xpath("//book[@id=$id]", variables={"id": "2"})
c14n(root, exclusive=True)
from leptris import sax
sax.parse(xml, handler) # one-shot
with sax.StreamingParser(handler) as parser: # push, constant memory
parser.feed(chunk, final=last)
XSLT and XPath version support
leptris.XSLT(stylesheet) compiles once, applies to any Document, and
returns a Document; leptris.XPath(expression) compiles an XPath for
repeated evaluation. Which language constructs work is decided by the
engine — the matrix below is measured against libleptris 1.9.32
(audited through this binding; the upstream gap ledger is
leptris/leptris#685).
| language | status | notes |
|---|---|---|
| XSLT 1.0 | full | libxslt conformance suite 205/205 upstream; EXSLT math/set/str/date included |
| XSLT 2.0 | partial | ✓ for-each-group, analyze-string + regex-group(), xsl:number formats, xsl:assert, xsl:sequence (multi-item), xsl:perform-sort · ✗ xsl:function, tunnel parameters, shadow attributes, xsl:result-document, @separator |
| XSLT 3.0 | increments | ✓ try/catch (with $err:description), accumulator (gated by xsl:mode use-accumulators), iterate + break + on-completion, on-empty, evaluate, grouping, modes, where-populated, on-non-empty, next-match, fork, @start-at, composite keys, tunnel params, copy/@select, xsl:namespace, xsl:document, @default, merge, result-document (writes the href target), character maps · ✗ package, xsl:map, xsl:evaluate with-params, next-iteration chaining |
| XPath 1.0 | full | complete core function library |
| XPath 2.0 | grammar complete | ✓ quantified (some/every), set algebra (union/intersect/except), node comparisons (is, <<, >>), (), ends-with, deep-equal, value comparisons, cast/castable/treat/instance of, function items + HOFs (1.9.73+) · function slices by group (sequences, regex, math:, strings/QNames/URIs, dates, xs: constructors); remaining: format-date/format-time, JSON, map:/array: constructors · format-number works in plain XPath since 1.9.80 |
| XPath 3.1 | lane 0 | ✓ let, simple map !, arrow =>, string concat || — through both XPath() and XSLT · ✗ function items, inline functions, maps, arrays, string constructors |
| XQuery | 1.0 core + 3.x increments | leptris.XQuery(query) — FLWOR (for/let/where/order by/return/group by, positional at, tumbling/sliding windows), prolog (declare variable/namespace/function local:*), constructors, doc()/collection(), try/catch, typeswitch — libleptris 1.9.68+; 3.1 remainder (maps/arrays, modules) tracked in #684 |
XQuery 1.0 core is a first-class API since libleptris 1.9.64:
from leptris import Document, XQuery
with Document.parse("<r><item v='1'>alpha</item><item v='5'>beta</item></r>") as doc:
XQuery("for $i in //item where $i/@v > 1 return string($i)")(doc) # ['beta']
XQuery("declare variable $n := 3; <out>{$n * 2}</out>")(doc) # '<out>6</out>'
XQuery("declare function local:dbl($x) { $x * 2 }; local:dbl(4)")(doc) # 8.0
XPath 3.1 composition and XSLT 3.0 instructions flow through the existing API with zero binding change:
from leptris import Document, XPath, XSLT, tostring
with Document.parse("<r><item v='1'>alpha</item><item v='5'>beta</item></r>") as doc:
doc.getroot().xpath("let $n := //item[2] return $n/@v") # ['5']
doc.getroot().xpath("(//item ! string(.)) => count()") # 2.0
style = XSLT("""<xsl:stylesheet version="3.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:mode use-accumulators="depth"/>
<xsl:accumulator name="depth" initial-value="0">
<xsl:accumulator-rule match="*" phase="start" select="$value + 1"/>
<xsl:accumulator-rule match="*" phase="end" select="$value - 1"/>
</xsl:accumulator>
<xsl:template match="/"><o>
<xsl:iterate select="//item">
<i d="{accumulator-before('depth')}"/>
</xsl:iterate>
</o></xsl:template>
</xsl:stylesheet>""")
print(tostring(style(doc), encoding="unicode"))
# <o><i d="2"/><i d="2"/></o> # items sit at depth 2 (r → item)
Unsupported constructs fail at XSLT() compile time or at evaluation
with LeptrisError — except two instructions that still produce
empty output instead of an error (xsl:map/xsl:map-entry, and
xsl:value-of/@separator is ignored); tracked in the
#685/#690 ledgers above.
HTML parsing
leptris.html (libleptris 1.9.75+) — tolerant HTML in the shape of
lxml's etree.HTMLParser: implied end tags, void elements,
case-insensitive names, unquoted attributes, the named-entity
table, and a synthesized <html>/<head>/<body> wrapper:
from leptris import html
r = html.fromstring("<p>hello <b>world") # <html><head/><body><p>hello <b>world</b></p></body></html>
with html.document("<td>c") as doc:
doc.xpath("count(//td)") # 1.0
Since libleptris 1.9.76 the output is byte-exact with lxml's
etree.HTMLParser (minimized attributes are empty strings; no
empty <head/> is emitted) — leptris/leptris#813. One known
divergence (libleptris 1.9.104+): a leading script/style run
stays in body where lxml's libxml2 lifts it to head
(leptris/leptris#659).
Two modes (libleptris 1.9.104+): the default html4 keeps this
compatibility shape; mode="whatwg" selects the WHATWG-conformant
engine (leading script/style/noscript/template runs lift into the
implied head — not lxml byte-compatible).
Migrating from lxml
| lxml | leptris | Notes |
|---|---|---|
etree.fromstring / etree.XML |
fromstring / XML |
|
etree.parse |
parse |
paths and file-likes; no URLs |
etree.tostring(elem, …) |
tostring(elem, …) |
bytes by default, encoding="unicode" for str |
elem.tag / .text / .tail |
same | tag uses {uri}local Clark notation; CDATA merges into text (lxml's default parser behavior) |
elem.attrib / .get() / .keys() / .items() |
same | attrib is a read-only Mapping |
elem.getparent/getnext/getprevious |
same | |
elem[i], len(elem), iteration, slices |
same | indexing is child indexing, never attribute lookup |
elem.iter() / .iterdescendants() / .itertext() |
same | elements only (ElementTree semantics); lxml's iter() also yields comments/PIs |
elem.find/findall/findtext |
same | accepts full XPath 1.0 — a superset of ElementPath — including {uri}local names |
elem.xpath(expr, namespaces=…) |
same | plus variables={…} (leptris extension) |
etree.c14n / etree.XInclude |
c14n(…) / doc.process_xinclude() |
|
etree.XMLSyntaxError |
ParseError |
XPath failures raise XPathError; XSLT raises XSLTError, XQuery XQueryError — all subclass LeptrisError |
etree.Element, SubElement, append, set, remove |
not exposed | libleptris has partial mutation upstream (node content setters, set_root, remove_children) — not surfaced here; build trees elsewhere |
| document-level comments / PIs | doc.toplevel_comments() / doc.toplevel_pis() |
prolog then epilog; requires libleptris 1.9.3+ |
etree.iterparse |
leptris.iterparse(source, full_document=False) |
bounded by the largest subtree; yields ("end", element); elements borrowed until the next yield; tags resolve namespaces (Clark notation, libleptris 1.9.4+). Truncated or malformed input raises ParseError (both modes, libleptris 1.9.15+). full_document=True yields every element in completion order |
| smart strings | plain str |
XPath string/attribute results |
elem.nsmap |
absent | use elem.namespace / elem.prefix and xpath(namespaces=…) |
etree.XPath compiled objects |
leptris.XPath(expression) |
compile once, evaluate many; contexts, namespaces, and variables supported |
etree.XSLT |
leptris.XSLT(stylesheet) |
compile once, apply to any Document — see the version support matrix above |
parser options (resolve_entities, …) |
absent | libleptris 1.2.0 has no per-parse options |
elem.sourceline |
same | requires libleptris 1.3.0+ |
| undeclared XPath prefix | raises in lxml | evaluates to an empty nodeset here |
| ATTLIST default attributes | applied by lxml's default parser | excluded by default (ElementTree-like; XML 1.0 §5 permits either) — Document.parse(xml, attribute_defaults=True) opts in |
| declared non-UTF-8 bytes (UTF-16, latin-1, …) | auto-detected | auto-detected — declared encodings route through the converter, others retry on failure (libleptris 1.9.15+) |
parser options (remove_blank_text, …) |
etree.XMLParser(remove_blank_text=True) |
Document.parse(xml, remove_blank_text=True) — ~35% faster on pretty-printed input; also attribute_defaults=True, recover=True |
Layout
leptris/_ffi.py— cdef mirror of the public headers + loader (the only place libleptris is declared)leptris/_engine.py— the compile-once lifecycle base shared by the compiled language objects (XSLT,XQuery, futureRelaxNG)leptris/_results.py— the result model: engine results to Python values (nodeset wrapping, scalar conversion), shared by every evaluation surfaceleptris/_leptrisaccel.c— the C accelerator (abi3): allocates Elements and runs the hot accessors, subtree iteration, the parse and serialization seams, and the per-document element registry; bound to libleptris by the positional protocol inelement.pyleptris/element.py,document.py,node.py,xpath.py— the Python surface: queries, walks, documents;node.pyexposes the full DOM (comments, CDATA, PIs) beneath the ElementTree shapeleptris/api.py—fromstring/parse/tostring/c14n/iterparseleptris/sax.py— SAX one-shot and streamingtests/— pytest suite (pytestwithLEPTRIS_LIB_PATHset)benchmarks/— matrix vs lxml/ElementTree/minidom (pip install .[bench], thenpython -m benchmarks.matrix)
Memory model
The Document owns the whole tree and its pool. Accessor strings
are copied into Python str at the boundary, so nothing depends on
document lifetime after a call returns. Elements keep a reference to
their Document, so the pool cannot be freed while any wrapper is
alive. Prefer explicit close() / the context manager; __del__ is
a refcounting safety net, not a contract. Using an element after its
document is closed raises LeptrisError.
Versioning
libleptris-version.txt pins the library release the binding is
built and tested against. Since 1.9.76.0 the package version is
{c-full-semver}.{patch} — the pinned libleptris version plus
a binding-local patch counter: lib 1.9.76 → 1.9.76.0, then
1.9.76.1 for binding-only fixes against the same pin, resetting
the patch whenever the pin moves. (1.2.0–1.27.1 were the interim
own-semver line.) pyproject.toml and leptris/__init__.py must
agree at release time.
Publishing
Releases publish to PyPI via .github/workflows/release.yml, using
PyPI trusted publishing (no stored credentials). The workflow
runs on manual dispatch (ships the version in pyproject.toml) and
is called by the libleptris release flow (publish: true), so every
libleptris release ships the wheel.
Local development
python3 -m venv .venv
./.venv/bin/pip install --upgrade build pytest cffi
./.venv/bin/pip install -e .[test,bench]
LEPTRIS_LIB_PATH=/path/to/libleptris.dylib ./.venv/bin/python -m pytest tests/ -q
Release files for leptris 1.9.107.0
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Source distribution (sdist)
| File | Size | Uploaded | |
|---|---|---|---|
| leptris-1.9.107.0.tar.gz | 75.3 kB | Details |
Built distributions (wheels)
| File | Reset | |||
|---|---|---|---|---|
| leptris-1.9.107.0-cp39-abi3-win_amd64.whl | CPython 3.9 | abi3 | Windows x86-64 | Details |
| leptris-1.9.107.0-cp39-abi3-manylinux_2_17_aarch64.manylinux2014_aarch64.whl | CPython 3.9 | abi3 | Linux glibc 2.17+ ARM64 | Details |
| leptris-1.9.107.0-cp39-abi3-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl | CPython 3.9 | abi3 | Linux glibc 2.5+ x86-64, Linux glibc 2.17+ x86-64 | Details |
| leptris-1.9.107.0-cp39-abi3-macosx_11_0_arm64.whl | CPython 3.9 | abi3 | macOS 11.0+ ARM64 | Details |
| leptris-1.9.107.0-cp39-abi3-macosx_10_9_x86_64.whl | CPython 3.9 | abi3 | macOS 10.9+ x86-64 | Details |
Total release size: 438.7 kB
Release files / leptris-1.9.107.0.tar.gz
| Download URL | leptris-1.9.107.0.tar.gz |
|---|---|
| Size | 75.3 kB |
| Tags | Source |
|
SHA-256 checksum How to use checksums |
294b98a27aaf02f3cf33105966c30cc47519d1b43c628b09a48b78515accc71b
|
|
BLAKE2b-256 checksum How to use checksums |
38ebb15e377ef811dabb6b6e6e4adf7e78799ea6da8db69eecd4cef076578477
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Sep 8, 2026.
Transparency logRelease files / leptris-1.9.107.0-cp39-abi3-win_amd64.whl
| Download URL | leptris-1.9.107.0-cp39-abi3-win_amd64.whl |
|---|---|
| Size | 51.8 kB |
| Tags | CPython 3.9 Windows x86-64 abi3 |
|
SHA-256 checksum How to use checksums |
775f0ee9916a1060424ad00128def90ef558d23a5f08adf4d8c9a9e75a0c88c4
|
|
BLAKE2b-256 checksum How to use checksums |
2c374b4ee23fa51d2dba45d2b2e105e1c9ac43da03ce59871a8b3b27e42510e2
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Sep 8, 2026.
Transparency logRelease files / leptris-1.9.107.0-cp39-abi3-manylinux_2_17_aarch64.manylinux2014_aarch64.whl
| Download URL | leptris-1.9.107.0-cp39-abi3-manylinux_2_17_aarch64.manylinux2014_aarch64.whl |
|---|---|
| Size | 108.0 kB |
| Tags | CPython 3.9 Linux glibc 2.17+ ARM64 abi3 |
|
SHA-256 checksum How to use checksums |
9fb36b1eb30da78183d32bb42a03ad421ca82269bada638b7dbceef15e1865f7
|
|
BLAKE2b-256 checksum How to use checksums |
271c977db6489a1c2c6e9e2d305c1020a47299380fa0469d941e862eaaabc2f6
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Sep 8, 2026.
Transparency logRelease files / leptris-1.9.107.0-cp39-abi3-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl
| Download URL | leptris-1.9.107.0-cp39-abi3-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl |
|---|---|
| Size | 103.9 kB |
| Tags | CPython 3.9 Linux glibc 2.17+ x86-64 Linux glibc 2.5+ x86-64 abi3 |
|
SHA-256 checksum How to use checksums |
d71950aa834958ca741c9fa7b076133dac5f20ad2cb3c964e94da28324c8915a
|
|
BLAKE2b-256 checksum How to use checksums |
188261acd0512b8bdcf0dada9c562e0eeb21b2eb52ff004d2f34beaf7fa74ec8
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Sep 8, 2026.
Transparency logRelease files / leptris-1.9.107.0-cp39-abi3-macosx_11_0_arm64.whl
| Download URL | leptris-1.9.107.0-cp39-abi3-macosx_11_0_arm64.whl |
|---|---|
| Size | 50.1 kB |
| Tags | CPython 3.9 abi3 macOS 11.0+ ARM64 |
|
SHA-256 checksum How to use checksums |
758b9606ca2845fd050c9f114ede2c3e8da9f87ecdfb3b2c67c46323dc5c4d88
|
|
BLAKE2b-256 checksum How to use checksums |
ed62d5a4ab729c6b61eabd7eb941682626e6e4eb920a919cb8b77f16e9af1434
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Sep 8, 2026.
Transparency logRelease files / leptris-1.9.107.0-cp39-abi3-macosx_10_9_x86_64.whl
| Download URL | leptris-1.9.107.0-cp39-abi3-macosx_10_9_x86_64.whl |
|---|---|
| Size | 49.5 kB |
| Tags | CPython 3.9 abi3 macOS 10.9+ x86-64 |
|
SHA-256 checksum How to use checksums |
2f0d1ea5af2088e206e284b10bf0c4f1ff68f74f4f2653184aeaad43fb343feb
|
|
BLAKE2b-256 checksum How to use checksums |
9998bc3ef66fc7c0fa508b930ca46e51722e1b2d8951df2467513188006240ac
|
| Upload date | |
|
Uploaded using Trusted Publishing? What is trusted publishing? |
Yes |
| Uploaded via |
twine/7.0.0 CPython/3.13.14
|
Provenance
Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.
PyPI Publish Attestation
PyPI verified that this artifact, at this checksum, originated from the publisher listed below.
Signed by GitHub Actions, verified by PyPI on Sep 8, 2026.
Transparency log
