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269 lines
7.7 KiB
Python
269 lines
7.7 KiB
Python
"""Diagnostic functions, mainly for use when doing tech support."""
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# Use of this source code is governed by the MIT license.
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__license__ = "MIT"
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import cProfile
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from io import BytesIO
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from html.parser import HTMLParser
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import bs4
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from bs4 import BeautifulSoup, __version__
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from bs4.builder import builder_registry
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from typing import (
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Any,
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IO,
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List,
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Optional,
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Tuple,
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TYPE_CHECKING,
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)
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if TYPE_CHECKING:
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from bs4._typing import _IncomingMarkup
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import pstats
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import random
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import tempfile
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import time
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import traceback
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import sys
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def diagnose(data: "_IncomingMarkup") -> None:
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"""Diagnostic suite for isolating common problems.
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:param data: Some markup that needs to be explained.
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:return: None; diagnostics are printed to standard output.
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"""
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print(("Diagnostic running on Beautiful Soup %s" % __version__))
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print(("Python version %s" % sys.version))
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basic_parsers = ["html.parser", "html5lib", "lxml"]
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for name in basic_parsers:
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for builder in builder_registry.builders:
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if name in builder.features:
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break
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else:
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basic_parsers.remove(name)
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print(
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("I noticed that %s is not installed. Installing it may help." % name)
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)
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if "lxml" in basic_parsers:
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basic_parsers.append("lxml-xml")
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try:
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from lxml import etree # type:ignore
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print(("Found lxml version %s" % ".".join(map(str, etree.LXML_VERSION))))
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except ImportError:
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print("lxml is not installed or couldn't be imported.")
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if "html5lib" in basic_parsers:
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try:
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import html5lib
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print(("Found html5lib version %s" % html5lib.__version__))
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except ImportError:
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print("html5lib is not installed or couldn't be imported.")
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if hasattr(data, "read"):
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data = data.read()
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for parser in basic_parsers:
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print(("Trying to parse your markup with %s" % parser))
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success = False
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try:
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soup = BeautifulSoup(data, features=parser)
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success = True
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except Exception:
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print(("%s could not parse the markup." % parser))
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traceback.print_exc()
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if success:
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print(("Here's what %s did with the markup:" % parser))
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print((soup.prettify()))
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print(("-" * 80))
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def lxml_trace(data: "_IncomingMarkup", html: bool = True, **kwargs: Any) -> None:
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"""Print out the lxml events that occur during parsing.
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This lets you see how lxml parses a document when no Beautiful
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Soup code is running. You can use this to determine whether
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an lxml-specific problem is in Beautiful Soup's lxml tree builders
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or in lxml itself.
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:param data: Some markup.
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:param html: If True, markup will be parsed with lxml's HTML parser.
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if False, lxml's XML parser will be used.
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"""
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from lxml import etree
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recover = kwargs.pop("recover", True)
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if isinstance(data, str):
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data = data.encode("utf8")
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if not isinstance(data, IO):
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reader = BytesIO(data)
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for event, element in etree.iterparse(reader, html=html, recover=recover, **kwargs):
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print(("%s, %4s, %s" % (event, element.tag, element.text)))
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class AnnouncingParser(HTMLParser):
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"""Subclass of HTMLParser that announces parse events, without doing
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anything else.
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You can use this to get a picture of how html.parser sees a given
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document. The easiest way to do this is to call `htmlparser_trace`.
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"""
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def _p(self, s: str) -> None:
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print(s)
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def handle_starttag(
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self,
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name: str,
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attrs: List[Tuple[str, Optional[str]]],
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handle_empty_element: bool = True,
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) -> None:
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self._p(f"{name} {attrs} START")
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def handle_endtag(self, name: str, check_already_closed: bool = True) -> None:
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self._p("%s END" % name)
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def handle_data(self, data: str) -> None:
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self._p("%s DATA" % data)
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def handle_charref(self, name: str) -> None:
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self._p("%s CHARREF" % name)
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def handle_entityref(self, name: str) -> None:
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self._p("%s ENTITYREF" % name)
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def handle_comment(self, data: str) -> None:
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self._p("%s COMMENT" % data)
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def handle_decl(self, data: str) -> None:
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self._p("%s DECL" % data)
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def unknown_decl(self, data: str) -> None:
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self._p("%s UNKNOWN-DECL" % data)
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def handle_pi(self, data: str) -> None:
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self._p("%s PI" % data)
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def htmlparser_trace(data: str) -> None:
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"""Print out the HTMLParser events that occur during parsing.
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This lets you see how HTMLParser parses a document when no
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Beautiful Soup code is running.
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:param data: Some markup.
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"""
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parser = AnnouncingParser()
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parser.feed(data)
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_vowels: str = "aeiou"
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_consonants: str = "bcdfghjklmnpqrstvwxyz"
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def rword(length: int = 5) -> str:
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"""Generate a random word-like string.
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:meta private:
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"""
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s = ""
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for i in range(length):
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if i % 2 == 0:
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t = _consonants
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else:
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t = _vowels
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s += random.choice(t)
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return s
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def rsentence(length: int = 4) -> str:
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"""Generate a random sentence-like string.
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:meta private:
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"""
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return " ".join(rword(random.randint(4, 9)) for i in range(length))
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def rdoc(num_elements: int = 1000) -> str:
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"""Randomly generate an invalid HTML document.
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:meta private:
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"""
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tag_names = ["p", "div", "span", "i", "b", "script", "table"]
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elements = []
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for i in range(num_elements):
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choice = random.randint(0, 3)
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if choice == 0:
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# New tag.
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tag_name = random.choice(tag_names)
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elements.append("<%s>" % tag_name)
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elif choice == 1:
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elements.append(rsentence(random.randint(1, 4)))
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elif choice == 2:
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# Close a tag.
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tag_name = random.choice(tag_names)
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elements.append("</%s>" % tag_name)
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return "<html>" + "\n".join(elements) + "</html>"
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def benchmark_parsers(num_elements: int = 100000) -> None:
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"""Very basic head-to-head performance benchmark."""
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print(("Comparative parser benchmark on Beautiful Soup %s" % __version__))
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data = rdoc(num_elements)
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print(("Generated a large invalid HTML document (%d bytes)." % len(data)))
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for parser_name in ["lxml", ["lxml", "html"], "html5lib", "html.parser"]:
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success = False
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try:
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a = time.time()
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BeautifulSoup(data, parser_name)
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b = time.time()
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success = True
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except Exception:
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print(("%s could not parse the markup." % parser_name))
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traceback.print_exc()
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if success:
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print(("BS4+%s parsed the markup in %.2fs." % (parser_name, b - a)))
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from lxml import etree
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a = time.time()
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etree.HTML(data)
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b = time.time()
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print(("Raw lxml parsed the markup in %.2fs." % (b - a)))
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import html5lib
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parser = html5lib.HTMLParser()
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a = time.time()
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parser.parse(data)
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b = time.time()
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print(("Raw html5lib parsed the markup in %.2fs." % (b - a)))
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def profile(num_elements: int = 100000, parser: str = "lxml") -> None:
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"""Use Python's profiler on a randomly generated document."""
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filehandle = tempfile.NamedTemporaryFile()
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filename = filehandle.name
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data = rdoc(num_elements)
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vars = dict(bs4=bs4, data=data, parser=parser)
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cProfile.runctx("bs4.BeautifulSoup(data, parser)", vars, vars, filename)
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stats = pstats.Stats(filename)
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# stats.strip_dirs()
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stats.sort_stats("cumulative")
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stats.print_stats("_html5lib|bs4", 50)
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# If this file is run as a script, standard input is diagnosed.
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if __name__ == "__main__":
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diagnose(sys.stdin.read())
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