sgmllib.py

在 linux平台上的网页编程的模板

# A parser for SGML, using the derived class as static DTD.

# XXX This only supports those SGML features used by HTML.

# XXX There should be a way to distinguish between PCDATA (parsed
# character data -- the normal case), RCDATA (replaceable character
# data -- only char and entity references and end tags are special)
# and CDATA (character data -- only end tags are special).

# sgmlop support added by [e-mail] (April 6, 1998)

import re
import string
import sys

try:
    from xml.parsers import sgmlop
except ImportError:
    sgmlop = None

# standard entity defs

ENTITYDEFS = {
    'lt': '<',
    'gt': '>',
    'amp': '&',
    'quot': '"',
    'apos': '\''
    }

# SGML parser base class -- find tags and call handler functions.
# Usage: p = SGMLParser(); p.feed(data); ...; p.close().
# The dtd is defined by deriving a class which defines methods
# with special names to handle tags: start_foo and end_foo to handle
# <foo> and </foo>, respectively, or do_foo to handle <foo> by itself.
# (Tags are converted to lower case for this purpose.)  The data
# between tags is passed to the parser by calling self.handle_data()
# with some data as argument (the data may be split up in arbutrary
# chunks).  Entity references are passed by calling
# self.handle_entityref() with the entity reference as argument.

# --------------------------------------------------------------------
# original re-based SGML parser

interesting = re.compile('[&<]')
incomplete = re.compile('&([a-zA-Z][a-zA-Z0-9]*|#[0-9]*)?|'
                           '<([a-zA-Z][^<>]*|'
                              '/([a-zA-Z][^<>]*)?|'
                              '![^<>]*)?')

entityref = re.compile('&([a-zA-Z][a-zA-Z0-9]*)[^a-zA-Z0-9]')
charref = re.compile('&#([0-9]+)[^0-9]')

starttagopen = re.compile('<[>a-zA-Z]')
shorttagopen = re.compile('<[a-zA-Z][a-zA-Z0-9]*/')
shorttag = re.compile('<([a-zA-Z][a-zA-Z0-9]*)/([^/]*)/')
endtagopen = re.compile('</[<>a-zA-Z]')
endbracket = re.compile('[<>]')
special = re.compile('<![^<>]*>')
commentopen = re.compile('<!--')
commentclose = re.compile('--[ \t\n]*>')
tagfind = re.compile('[a-zA-Z][a-zA-Z0-9]*')
attrfind = re.compile(
    '[ \t\n]*([a-zA-Z_][-.a-zA-Z_0-9]*)'
    '([ \t\n]*=[ \t\n]*'
    r'(\'[^\']*\'|"[^"]*"|[^ \t\n]*))?')


class SlowSGMLParser:

    # Interface -- initialize and reset this instance
    def __init__(self, verbose=0):
        self.verbose = verbose
        self.reset()

    # Interface -- reset this instance.  Loses all unprocessed data
    def reset(self):
        self.rawdata = ''
        self.stack = []
        self.lasttag = '???'
        self.nomoretags = 0
        self.literal = 0

    # For derived classes only -- enter literal mode (CDATA) till EOF
    def setnomoretags(self):
        self.nomoretags = self.literal = 1

    # For derived classes only -- enter literal mode (CDATA)
    def setliteral(self, *args):
        self.literal = 1

    # Interface -- feed some data to the parser.  Call this as
    # often as you want, with as little or as much text as you
    # want (may include '\n').  (This just saves the text, all the
    # processing is done by goahead().)
    def feed(self, data):
        self.rawdata = self.rawdata + data
        self.goahead(0)

    # Interface -- handle the remaining data
    def close(self):
        self.goahead(1)

    # Internal -- handle data as far as reasonable.  May leave state
    # and data to be processed by a subsequent call.  If 'end' is
    # true, force handling all data as if followed by EOF marker.
    def goahead(self, end):
        rawdata = self.rawdata
        i = 0
        n = len(rawdata)
        while i < n:
            if self.nomoretags:
                self.handle_data(rawdata[i:n])
                i = n
                break
            match = interesting.search(rawdata, i)
            if match: j = match.start(0)
            else: j = n
            if i < j: self.handle_data(rawdata[i:j])
            i = j
            if i == n: break
            if rawdata[i] == '<':
                if starttagopen.match(rawdata, i):
                    if self.literal:
                        self.handle_data(rawdata[i])
                        i = i+1
                        continue
                    k = self.parse_starttag(i)
                    if k < 0: break
                    i = k
                    continue
                if endtagopen.match(rawdata, i):
                    k = self.parse_endtag(i)
                    if k < 0: break
                    i =  k
                    self.literal = 0
                    continue
                if commentopen.match(rawdata, i):
                    if self.literal:
                        self.handle_data(rawdata[i])
                        i = i+1
                        continue
                    k = self.parse_comment(i)
                    if k < 0: break
                    i = i+k
                    continue
                match = special.match(rawdata, i)
                if match:
                    if self.literal:
                        self.handle_data(rawdata[i])
                        i = i+1
                        continue
                    i = match.end(0)
                    continue
            elif rawdata[i] == '&':
                match = charref.match(rawdata, i)
                if match:
                    name = match.group(1)
                    self.handle_charref(name)
                    i = match.end(0)
                    if rawdata[i-1] != ';': i = i-1
                    continue
                match = entityref.match(rawdata, i)
                if match:
                    name = match.group(1)
                    self.handle_entityref(name)
                    i = match.end(0)
                    if rawdata[i-1] != ';': i = i-1
                    continue
            else:
                raise RuntimeError, 'neither < nor & ??'
            # We get here only if incomplete matches but
            # nothing else
            match = incomplete.match(rawdata, i)
            if not match:
                self.handle_data(rawdata[i])
                i = i+1
                continue
            j = match.end(0)
            if j == n:
                break # Really incomplete
            self.handle_data(rawdata[i:j])
            i = j
        # end while
        if end and i < n:
            self.handle_data(rawdata[i:n])
            i = n
        self.rawdata = rawdata[i:]
        # XXX if end: check for empty stack

    # Internal -- parse comment, return length or -1 if not terminated
    def parse_comment(self, i):
        rawdata = self.rawdata
        if rawdata[i:i+4] <> '<!--':
            raise RuntimeError, 'unexpected call to handle_comment'
        match = commentclose.search(rawdata, i+4)
        if not match:
            return -1
        j = match.start(0)
        self.handle_comment(rawdata[i+4: j])
        j = match.end(0)
        return j-i

    # Internal -- handle starttag, return length or -1 if not terminated
    def parse_starttag(self, i):
        rawdata = self.rawdata
        if shorttagopen.match(rawdata, i):
            # SGML shorthand: <tag/data/ == <tag>data</tag>
            # XXX Can data contain &... (entity or char refs)?
            # XXX Can data contain < or > (tag characters)?
            # XXX Can there be whitespace before the first /?
            match = shorttag.match(rawdata, i)
            if not match:
                return -1
            tag, data = match.group(1, 2)
            tag = string.lower(tag)
            self.finish_shorttag(tag, data)
            k = match.end(0)
            return k
        # XXX The following should skip matching quotes (' or ")
        match = endbracket.search(rawdata, i+1)
        if not match:
            return -1
        j = match.start(0)
        # Now parse the data between i+1 and j into a tag and attrs
        attrs = []
        if rawdata[i:i+2] == '<>':
            # SGML shorthand: <> == <last open tag seen>
            k = j
            tag = self.lasttag
        else:
            match = tagfind.match(rawdata, i+1)
            if not match:
                raise RuntimeError, 'unexpected call to parse_starttag'
            k = match.end(0)
            tag = string.lower(rawdata[i+1:k])
            self.lasttag = tag
        while k < j:
            match = attrfind.match(rawdata, k)
            if not match: break
            attrname, rest, attrvalue = match.group(1, 2, 3)
            if not rest:
                attrvalue = attrname
            elif attrvalue[:1] == '\'' == attrvalue[-1:] or \
                 attrvalue[:1] == '"' == attrvalue[-1:]:
                attrvalue = attrvalue[1:-1]
            attrs.append((string.lower(attrname), attrvalue))
            k = match.end(0)
        if rawdata[j] == '>':
            j = j+1
        self.finish_starttag(tag, attrs)
        return j

    # Internal -- parse endtag
    def parse_endtag(self, i):
        rawdata = self.rawdata
        match = endbracket.search(rawdata, i+1)
        if not match:
            return -1
        j = match.start(0)
        tag = string.lower(string.strip(rawdata[i+2:j]))
        if rawdata[j] == '>':
            j = j+1
        self.finish_endtag(tag)
        return j

    # Internal -- finish parsing of <tag/data/ (same as <tag>data</tag>)
    def finish_shorttag(self, tag, data):
        self.finish_starttag(tag, [])
        self.handle_data(data)
        self.finish_endtag(tag)

    # Internal -- finish processing of start tag
    # Return -1 for unknown tag, 0 for open-only tag, 1 for balanced tag
    def finish_starttag(self, tag, attrs):
        try:
            method = getattr(self, 'start_' + tag)
        except AttributeError:
            try:
                method = getattr(self, 'do_' + tag)
            except AttributeError:
                self.unknown_starttag(tag, attrs)
                return -1
            else:
                self.handle_starttag(tag, method, attrs)
                return 0
        else:
            self.stack.append(tag)
            self.handle_starttag(tag, method, attrs)
            return 1

    # Internal -- finish processing of end tag
    def finish_endtag(self, tag):
        if not tag:
            found = len(self.stack) - 1
            if found < 0:
                self.unknown_endtag(tag)
                return
        else:
            if tag not in self.stack:
                try:
                    method = getattr(self, 'end_' + tag)
                except AttributeError:
                    self.unknown_endtag(tag)
                return
            found = len(self.stack)
            for i in range(found):
                if self.stack[i] == tag: found = i