通过标签定制BeautifulSoup的美化

Question

I was wondering if it would be possible to make it so that prettify did not create new lines on specific tags.

I would like to make it so that span and a tags do not split up, for example:

doc="""<div><div><span>a</span><span>b</span>
<a>link</a></div><a>link1</a><a>link2</a></div>"""

from bs4 import BeautifulSoup as BS
soup = BS(doc)
print soup.prettify()

below is what I want to print:

<div>
    <div>
        <span>a</span><span>b</span>
        <a>link</a>
    </div>
    <a>link1</a><a>link2</a>
</div>

But this is what will actually print:

<div>
    <div>
        <span>
            a
        </span>
        <span>
            b
        </span>
        <a>
            link
        </a>
    </div>
    <a>
        link1
    </a>
    <a>
        link2
    </a>
</div>

Placing inline styled tags on new lines like that actually will add space between them, slightly altering how the actual page looks. I will link you to two jsfiddles displaying the difference:

anchor tags on new lines

anchor tags next to eachother

If you're wondering why that matters for BeautifulSoup, it is because I am writing a web-page debugger, and the prettify function would be very useful (along with other things in bs4). But if I prettify the document, then I risk altering some things.

So, is there any way to customize the prettify function so that I can set it to not break up certain tags?

Answer 1

I'm posting a quick hack while I don't find a better solution.

I'm actually using it on my project to avoid breaking textareas and pre tags. Replace ['span', 'a'] with the tags on which you want to prevent indentation.

markup = """<div><div><span>a</span><span>b</span>
<a>link</a></div><a>link1</a><a>link2</a></div>"""

# Double curly brackets to avoid problems with .format()
stripped_markup = markup.replace('{','{{').replace('}','}}')

stripped_markup = BeautifulSoup(stripped_markup)

unformatted_tag_list = []

for i, tag in enumerate(stripped_markup.find_all(['span', 'a'])):
    unformatted_tag_list.append(str(tag))
    tag.replace_with('{' + 'unformatted_tag_list[{0}]'.format(i) + '}')

pretty_markup = stripped_markup.prettify().format(unformatted_tag_list=unformatted_tag_list)

print pretty_markup

Answer 2

The short answer is no.

The longer answer is not easily.

I'm still using bs3, so this is a hack is for bs3. I'm partway through porting this to bs4.

It essentially involves subclassing Tag and BeautifulSoup and overloading the prettify (and related) methods.

Code:

import sys
import BeautifulSoup

class Tag(BeautifulSoup.Tag):
    def __str__(self, encoding=BeautifulSoup.DEFAULT_OUTPUT_ENCODING,
            prettyPrint=False, indentLevel=0, pprint_exs=[]):
        """Returns a string or Unicode representation of this tag and
        its contents. To get Unicode, pass None for encoding.

        NOTE: since Python's HTML parser consumes whitespace, this
        method is not certain to reproduce the whitespace present in
        the original string."""

        encodedName = self.toEncoding(self.name, encoding)

        unflatten_here = (not self.name in pprint_exs)

        attrs = []
        if self.attrs:
            for key, val in self.attrs:
                fmt = '%s="%s"'
                if isinstance(val, basestring):
                    if self.containsSubstitutions and '%SOUP-ENCODING%' in val:
                        val = self.substituteEncoding(val, encoding)

                    # The attribute value either:
                    #
                    # * Contains no embedded double quotes or single quotes.
                    #   No problem: we enclose it in double quotes.
                    # * Contains embedded single quotes. No problem:
                    #   double quotes work here too.
                    # * Contains embedded double quotes. No problem:
                    #   we enclose it in single quotes.
                    # * Embeds both single _and_ double quotes. This
                    #   can't happen naturally, but it can happen if
                    #   you modify an attribute value after parsing
                    #   the document. Now we have a bit of a
                    #   problem. We solve it by enclosing the
                    #   attribute in single quotes, and escaping any
                    #   embedded single quotes to XML entities.
                    if '"' in val:
                        fmt = "%s='%s'"
                        if "'" in val:
                            # TODO: replace with apos when
                            # appropriate.
                            val = val.replace("'", "&squot;")

                    # Now we're okay w/r/t quotes. But the attribute
                    # value might also contain angle brackets, or
                    # ampersands that aren't part of entities. We need
                    # to escape those to XML entities too.
                    val = self.BARE_AMPERSAND_OR_BRACKET.sub(self._sub_entity, val)

                attrs.append(fmt % (self.toEncoding(key, encoding),
                                    self.toEncoding(val, encoding)))
        close = ''
        closeTag = ''
        if self.isSelfClosing:
            close = ' /'
        else:
            closeTag = '</%s>' % encodedName

        prev = self.findPrevious(lambda x: isinstance(x, Tag))
        prev_sib = self.findPreviousSibling(lambda x: isinstance(x, Tag))
        ex_break_detected = (self.name != prev_sib.name) if(prev_sib and prev_sib.name in pprint_exs) else False
        break_detected = (self.name != prev.name) if(prev) else False

        indentTag, indentContents = 0, 0
        if prettyPrint:
            if(break_detected or unflatten_here):
                indentContents = indentLevel + 1
            indentTag = indentLevel
            space = (' ' * (indentTag-1))
        contents = self.renderContents(encoding, prettyPrint, indentContents, pprint_exs, unflatten_here)
        if self.hidden:
            s = contents
        else:
            s = []
            attributeString = ''
            if attrs:
                attributeString = ' ' + ' '.join(attrs)
            if prettyPrint and ex_break_detected and not unflatten_here:
                s.append("\n")
            if prettyPrint and (unflatten_here or break_detected):
                s.append(space)
            s.append('<%s%s%s>' % (encodedName, attributeString, close))
            if prettyPrint and unflatten_here:
                s.append("\n")
            s.append(contents)
            if prettyPrint and contents and contents[-1] != "\n" and unflatten_here:
                s.append("\n")
            if prettyPrint and closeTag and unflatten_here:
                s.append(space)
            s.append(closeTag)
            if prettyPrint and closeTag and self.nextSibling and unflatten_here:
                s.append("\n")
            if prettyPrint and isinstance(self.nextSibling, Tag) and self.nextSibling.name != self.name and not unflatten_here:
                s.append("\n")

            s = ''.join(s)
        return s

    def renderContents(self, encoding=BeautifulSoup.DEFAULT_OUTPUT_ENCODING,
                       prettyPrint=False, indentLevel=0, pprint_exs=[], unflatten=True):
        """Renders the contents of this tag as a string in the given
        encoding. If encoding is None, returns a Unicode string.."""
        s=[]
        for c in self:
            text = None
            if isinstance(c, BeautifulSoup.NavigableString):
                text = c.__str__(encoding)
            elif isinstance(c, Tag):
                s.append(c.__str__(encoding, prettyPrint, indentLevel, pprint_exs))
            if text and prettyPrint:
                text = text.strip()
            if text:
                if prettyPrint and unflatten:
                    s.append(" " * (indentLevel-1))
                s.append(text)
                if prettyPrint and unflatten:
                    s.append("\n")
        return ''.join(s)
BeautifulSoup.Tag = Tag

class BeautifulStoneSoup(Tag, BeautifulSoup.BeautifulStoneSoup):
    pass
BeautifulSoup.BeautifulStoneSoup = BeautifulStoneSoup

class PumpkinSoup(BeautifulStoneSoup, BeautifulSoup.BeautifulSoup):
    def __init__(self, *args, **kwargs):
        self.pprint_exs = kwargs.pop("pprint_exs", [])
        super(BeautifulSoup.BeautifulSoup, self).__init__(*args, **kwargs)
    def prettify(self, encoding=BeautifulSoup.DEFAULT_OUTPUT_ENCODING):
        return self.__str__(encoding, True, pprint_exs=self.pprint_exs)

doc = \
'''
<div>
 <div>
<span>a</span><span>b</span>
  <a>link1</a>
  <a>link2</a>
<span>c</span>
 </div>
<a>link3</a><a>link4</a>
</div>
'''

soup = PumpkinSoup(doc, pprint_exs = ["a", "span"])
print soup.prettify()