mirror of
https://github.com/python/cpython.git
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09bcf8c031
<leonard@dstc.edu.au>; allows hyphen and period in the middle of attribute names. Still not allowed as first character; as first character these are illegal in the Reference Concrete Syntax, and we've not identified any use of these characters as the first char in an attribute name in deployment on the web.
447 lines
12 KiB
Python
447 lines
12 KiB
Python
# A parser for SGML, using the derived class as static DTD.
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# XXX This only supports those SGML features used by HTML.
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# XXX There should be a way to distinguish between PCDATA (parsed
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# character data -- the normal case), RCDATA (replaceable character
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# data -- only char and entity references and end tags are special)
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# and CDATA (character data -- only end tags are special).
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import regex
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import string
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# Regular expressions used for parsing
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interesting = regex.compile('[&<]')
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incomplete = regex.compile('&\([a-zA-Z][a-zA-Z0-9]*\|#[0-9]*\)?\|'
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'<\([a-zA-Z][^<>]*\|'
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'/\([a-zA-Z][^<>]*\)?\|'
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'![^<>]*\)?')
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entityref = regex.compile('&\([a-zA-Z][a-zA-Z0-9]*\)[^a-zA-Z0-9]')
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charref = regex.compile('&#\([0-9]+\)[^0-9]')
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starttagopen = regex.compile('<[>a-zA-Z]')
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shorttagopen = regex.compile('<[a-zA-Z][a-zA-Z0-9]*/')
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shorttag = regex.compile('<\([a-zA-Z][a-zA-Z0-9]*\)/\([^/]*\)/')
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endtagopen = regex.compile('</[<>a-zA-Z]')
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endbracket = regex.compile('[<>]')
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special = regex.compile('<![^<>]*>')
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commentopen = regex.compile('<!--')
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commentclose = regex.compile('--[ \t\n]*>')
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tagfind = regex.compile('[a-zA-Z][a-zA-Z0-9]*')
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attrfind = regex.compile(
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'[ \t\n]+\([a-zA-Z_][-.a-zA-Z_0-9]*\)'
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'\([ \t\n]*=[ \t\n]*'
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'\(\'[^\']*\'\|"[^"]*"\|[-a-zA-Z0-9./:+*%?!()_#=~]*\)\)?')
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# SGML parser base class -- find tags and call handler functions.
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# Usage: p = SGMLParser(); p.feed(data); ...; p.close().
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# The dtd is defined by deriving a class which defines methods
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# with special names to handle tags: start_foo and end_foo to handle
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# <foo> and </foo>, respectively, or do_foo to handle <foo> by itself.
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# (Tags are converted to lower case for this purpose.) The data
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# between tags is passed to the parser by calling self.handle_data()
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# with some data as argument (the data may be split up in arbutrary
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# chunks). Entity references are passed by calling
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# self.handle_entityref() with the entity reference as argument.
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class SGMLParser:
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# Interface -- initialize and reset this instance
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def __init__(self, verbose=0):
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self.verbose = verbose
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self.reset()
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# Interface -- reset this instance. Loses all unprocessed data
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def reset(self):
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self.rawdata = ''
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self.stack = []
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self.lasttag = '???'
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self.nomoretags = 0
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self.literal = 0
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# For derived classes only -- enter literal mode (CDATA) till EOF
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def setnomoretags(self):
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self.nomoretags = self.literal = 1
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# For derived classes only -- enter literal mode (CDATA)
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def setliteral(self, *args):
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self.literal = 1
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# Interface -- feed some data to the parser. Call this as
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# often as you want, with as little or as much text as you
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# want (may include '\n'). (This just saves the text, all the
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# processing is done by goahead().)
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def feed(self, data):
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self.rawdata = self.rawdata + data
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self.goahead(0)
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# Interface -- handle the remaining data
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def close(self):
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self.goahead(1)
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# Internal -- handle data as far as reasonable. May leave state
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# and data to be processed by a subsequent call. If 'end' is
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# true, force handling all data as if followed by EOF marker.
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def goahead(self, end):
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rawdata = self.rawdata
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i = 0
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n = len(rawdata)
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while i < n:
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if self.nomoretags:
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self.handle_data(rawdata[i:n])
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i = n
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break
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j = interesting.search(rawdata, i)
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if j < 0: j = n
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if i < j: self.handle_data(rawdata[i:j])
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i = j
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if i == n: break
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if rawdata[i] == '<':
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if starttagopen.match(rawdata, i) >= 0:
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if self.literal:
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self.handle_data(rawdata[i])
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i = i+1
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continue
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k = self.parse_starttag(i)
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if k < 0: break
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i = k
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continue
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if endtagopen.match(rawdata, i) >= 0:
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k = self.parse_endtag(i)
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if k < 0: break
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i = k
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self.literal = 0
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continue
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if commentopen.match(rawdata, i) >= 0:
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if self.literal:
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self.handle_data(rawdata[i])
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i = i+1
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continue
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k = self.parse_comment(i)
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if k < 0: break
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i = i+k
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continue
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k = special.match(rawdata, i)
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if k >= 0:
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if self.literal:
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self.handle_data(rawdata[i])
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i = i+1
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continue
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i = i+k
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continue
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elif rawdata[i] == '&':
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k = charref.match(rawdata, i)
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if k >= 0:
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k = i+k
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if rawdata[k-1] != ';': k = k-1
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name = charref.group(1)
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self.handle_charref(name)
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i = k
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continue
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k = entityref.match(rawdata, i)
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if k >= 0:
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k = i+k
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if rawdata[k-1] != ';': k = k-1
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name = entityref.group(1)
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self.handle_entityref(name)
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i = k
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continue
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else:
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raise RuntimeError, 'neither < nor & ??'
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# We get here only if incomplete matches but
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# nothing else
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k = incomplete.match(rawdata, i)
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if k < 0:
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self.handle_data(rawdata[i])
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i = i+1
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continue
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j = i+k
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if j == n:
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break # Really incomplete
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self.handle_data(rawdata[i:j])
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i = j
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# end while
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if end and i < n:
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self.handle_data(rawdata[i:n])
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i = n
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self.rawdata = rawdata[i:]
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# XXX if end: check for empty stack
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# Internal -- parse comment, return length or -1 if not terminated
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def parse_comment(self, i):
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rawdata = self.rawdata
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if rawdata[i:i+4] <> '<!--':
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raise RuntimeError, 'unexpected call to handle_comment'
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j = commentclose.search(rawdata, i+4)
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if j < 0:
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return -1
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self.handle_comment(rawdata[i+4: j])
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j = j+commentclose.match(rawdata, j)
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return j-i
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# Internal -- handle starttag, return length or -1 if not terminated
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def parse_starttag(self, i):
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rawdata = self.rawdata
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if shorttagopen.match(rawdata, i) >= 0:
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# SGML shorthand: <tag/data/ == <tag>data</tag>
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# XXX Can data contain &... (entity or char refs)?
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# XXX Can data contain < or > (tag characters)?
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# XXX Can there be whitespace before the first /?
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j = shorttag.match(rawdata, i)
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if j < 0:
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return -1
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tag, data = shorttag.group(1, 2)
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tag = string.lower(tag)
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self.finish_shorttag(tag, data)
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k = i+j
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if rawdata[k-1] == '<':
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k = k-1
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return k
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# XXX The following should skip matching quotes (' or ")
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j = endbracket.search(rawdata, i+1)
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if j < 0:
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return -1
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# Now parse the data between i+1 and j into a tag and attrs
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attrs = []
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if rawdata[i:i+2] == '<>':
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# SGML shorthand: <> == <last open tag seen>
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k = j
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tag = self.lasttag
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else:
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k = tagfind.match(rawdata, i+1)
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if k < 0:
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raise RuntimeError, 'unexpected call to parse_starttag'
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k = i+1+k
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tag = string.lower(rawdata[i+1:k])
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self.lasttag = tag
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while k < j:
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l = attrfind.match(rawdata, k)
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if l < 0: break
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attrname, rest, attrvalue = attrfind.group(1, 2, 3)
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if not rest:
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attrvalue = attrname
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elif attrvalue[:1] == '\'' == attrvalue[-1:] or \
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attrvalue[:1] == '"' == attrvalue[-1:]:
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attrvalue = attrvalue[1:-1]
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attrs.append((string.lower(attrname), attrvalue))
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k = k + l
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if rawdata[j] == '>':
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j = j+1
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self.finish_starttag(tag, attrs)
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return j
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# Internal -- parse endtag
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def parse_endtag(self, i):
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rawdata = self.rawdata
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j = endbracket.search(rawdata, i+1)
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if j < 0:
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return -1
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tag = string.lower(string.strip(rawdata[i+2:j]))
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if rawdata[j] == '>':
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j = j+1
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self.finish_endtag(tag)
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return j
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# Internal -- finish parsing of <tag/data/ (same as <tag>data</tag>)
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def finish_shorttag(self, tag, data):
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self.finish_starttag(tag, [])
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self.handle_data(data)
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self.finish_endtag(tag)
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# Internal -- finish processing of start tag
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# Return -1 for unknown tag, 0 for open-only tag, 1 for balanced tag
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def finish_starttag(self, tag, attrs):
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try:
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method = getattr(self, 'start_' + tag)
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except AttributeError:
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try:
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method = getattr(self, 'do_' + tag)
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except AttributeError:
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self.unknown_starttag(tag, attrs)
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return -1
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else:
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self.handle_starttag(tag, method, attrs)
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return 0
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else:
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self.stack.append(tag)
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self.handle_starttag(tag, method, attrs)
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return 1
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# Internal -- finish processing of end tag
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def finish_endtag(self, tag):
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if not tag:
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found = len(self.stack) - 1
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if found < 0:
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self.unknown_endtag(tag)
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return
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else:
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if tag not in self.stack:
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try:
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method = getattr(self, 'end_' + tag)
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except AttributeError:
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self.unknown_endtag(tag)
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return
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found = len(self.stack)
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for i in range(found):
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if self.stack[i] == tag: found = i
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while len(self.stack) > found:
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tag = self.stack[-1]
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try:
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method = getattr(self, 'end_' + tag)
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except AttributeError:
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method = None
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if method:
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self.handle_endtag(tag, method)
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else:
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self.unknown_endtag(tag)
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del self.stack[-1]
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# Overridable -- handle start tag
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def handle_starttag(self, tag, method, attrs):
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method(attrs)
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# Overridable -- handle end tag
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def handle_endtag(self, tag, method):
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method()
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# Example -- report an unbalanced </...> tag.
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def report_unbalanced(self, tag):
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if self.verbose:
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print '*** Unbalanced </' + tag + '>'
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print '*** Stack:', self.stack
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# Example -- handle character reference, no need to override
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def handle_charref(self, name):
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try:
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n = string.atoi(name)
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except string.atoi_error:
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self.unknown_charref(name)
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return
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if not 0 <= n <= 255:
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self.unknown_charref(name)
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return
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self.handle_data(chr(n))
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# Definition of entities -- derived classes may override
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entitydefs = \
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{'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''}
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# Example -- handle entity reference, no need to override
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def handle_entityref(self, name):
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table = self.entitydefs
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if table.has_key(name):
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self.handle_data(table[name])
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else:
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self.unknown_entityref(name)
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return
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# Example -- handle data, should be overridden
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def handle_data(self, data):
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pass
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# Example -- handle comment, could be overridden
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def handle_comment(self, data):
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pass
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# To be overridden -- handlers for unknown objects
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def unknown_starttag(self, tag, attrs): pass
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def unknown_endtag(self, tag): pass
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def unknown_charref(self, ref): pass
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def unknown_entityref(self, ref): pass
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class TestSGMLParser(SGMLParser):
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def __init__(self, verbose=0):
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self.testdata = ""
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SGMLParser.__init__(self, verbose)
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def handle_data(self, data):
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self.testdata = self.testdata + data
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if len(`self.testdata`) >= 70:
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self.flush()
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def flush(self):
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data = self.testdata
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if data:
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self.testdata = ""
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print 'data:', `data`
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def handle_comment(self, data):
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self.flush()
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r = `data`
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if len(r) > 68:
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r = r[:32] + '...' + r[-32:]
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print 'comment:', r
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def unknown_starttag(self, tag, attrs):
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self.flush()
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if not attrs:
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print 'start tag: <' + tag + '>'
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else:
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print 'start tag: <' + tag,
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for name, value in attrs:
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print name + '=' + '"' + value + '"',
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print '>'
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def unknown_endtag(self, tag):
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self.flush()
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print 'end tag: </' + tag + '>'
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def unknown_entityref(self, ref):
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self.flush()
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print '*** unknown entity ref: &' + ref + ';'
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def unknown_charref(self, ref):
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self.flush()
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print '*** unknown char ref: &#' + ref + ';'
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def close(self):
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SGMLParser.close(self)
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self.flush()
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def test(args = None):
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import sys
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if not args:
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args = sys.argv[1:]
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if args and args[0] == '-s':
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args = args[1:]
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klass = SGMLParser
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else:
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klass = TestSGMLParser
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if args:
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file = args[0]
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else:
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file = 'test.html'
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if file == '-':
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f = sys.stdin
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else:
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try:
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f = open(file, 'r')
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except IOError, msg:
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print file, ":", msg
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sys.exit(1)
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data = f.read()
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if f is not sys.stdin:
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f.close()
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x = klass()
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for c in data:
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x.feed(c)
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x.close()
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if __name__ == '__main__':
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test()
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