Doc/tools/sgmlconv/latex2esis.py

#! /usr/bin/env python

"""Generate ESIS events based on a LaTeX source document and
configuration data.

The conversion is not strong enough to work with arbitrary LaTeX
documents; it has only been designed to work with the highly stylized
markup used in the standard Python documentation.  A lot of
information about specific markup is encoded in the control table
passed to the convert() function; changing this table can allow this
tool to support additional LaTeX markups.

The format of the table is largely undocumented; see the commented
headers where the table is specified in main().  There is no provision 
to load an alternate table from an external file.
"""
__version__ = '$Revision$'

import errno
import getopt
import os
import re
import string
import sys
import UserList
import xml.sax.saxutils

from types import ListType, StringType, TupleType

try:
    from xml.parsers.xmllib import XMLParser
except ImportError:
    from xmllib import XMLParser


DEBUG = 0


class LaTeXFormatError(Exception):
    pass


class LaTeXStackError(LaTeXFormatError):
    def __init__(self, found, stack):
        msg = "environment close for %s doesn't match;\n  stack = %s" \
              % (found, stack)
        self.found = found
        self.stack = stack[:]
        LaTeXFormatError.__init__(self, msg)

def encode(s):
    s = xml.sax.saxutils.escape(s)
    return s.replace("\n", "\\n\n-")


_begin_env_rx = re.compile(r"[\\]begin{([^}]*)}")
_end_env_rx = re.compile(r"[\\]end{([^}]*)}")
_begin_macro_rx = re.compile(r"[\\]([a-zA-Z]+[*]?) ?({|\s*\n?)")
_comment_rx = re.compile("%+ ?(.*)\n[ \t]*")
_text_rx = re.compile(r"[^]~%\\{}]+")
_optional_rx = re.compile(r"\s*[[]([^]]*)[]]")
# _parameter_rx is this complicated to allow {...} inside a parameter;
# this is useful to match tabular layout specifications like {c|p{24pt}}
_parameter_rx = re.compile("[ \n]*{(([^{}}]|{[^}]*})*)}")
_token_rx = re.compile(r"[a-zA-Z][a-zA-Z0-9.-]*$")
_start_group_rx = re.compile("[ \n]*{")
_start_optional_rx = re.compile("[ \n]*[[]")


ESCAPED_CHARS = "$%#^ {}&~"


def dbgmsg(msg):
    if DEBUG:
        sys.stderr.write(msg + "\n")

def pushing(name, point, depth):
    dbgmsg("pushing <%s> at %s" % (name, point))

def popping(name, point, depth):
    dbgmsg("popping </%s> at %s" % (name, point))


class _Stack(UserList.UserList):
    def append(self, entry):
        if type(entry) is not StringType:
            raise LaTeXFormatError("cannot push non-string on stack: "
                                   + `entry`)
        sys.stderr.write("%s<%s>\n" % (" "*len(self.data), entry))
        self.data.append(entry)

    def pop(self, index=-1):
        entry = self.data[index]
        del self.data[index]
        sys.stderr.write("%s</%s>\n" % (" "*len(self.data), entry))

    def __delitem__(self, index):
        entry = self.data[index]
        del self.data[index]
        sys.stderr.write("%s</%s>\n" % (" "*len(self.data), entry))


def new_stack():
    if DEBUG:
        return _Stack()
    return []


class Conversion:
    def __init__(self, ifp, ofp, table):
        self.write = ofp.write
        self.ofp = ofp
        self.table = table
        self.line = string.join(map(string.rstrip, ifp.readlines()), "\n")
        self.preamble = 1

    def write_ordinal(self, ordinal):
        self.write("-\\%%%d;\n" % ordinal)

    def err_write(self, msg):
        if DEBUG:
            sys.stderr.write(str(msg) + "\n")

    def convert(self):
        self.subconvert()

    def subconvert(self, endchar=None, depth=0):
        #
        # Parses content, including sub-structures, until the character
        # 'endchar' is found (with no open structures), or until the end
        # of the input data is endchar is None.
        #
        stack = new_stack()
        line = self.line
        while line:
            if line[0] == endchar and not stack:
                self.line = line
                return line
            m = _comment_rx.match(line)
            if m:
                text = m.group(1)
                if text:
                    self.write("(COMMENT\n- %s \n)COMMENT\n-\\n\n"
                               % encode(text))
                line = line[m.end():]
                continue
            m = _begin_env_rx.match(line)
            if m:
                name = m.group(1)
                entry = self.get_env_entry(name)
                # re-write to use the macro handler
                line = r"\%s %s" % (name, line[m.end():])
                continue
            m = _end_env_rx.match(line)
            if m:
                # end of environment
                envname = m.group(1)
                entry = self.get_entry(envname)
                while stack and envname != stack[-1] \
                      and stack[-1] in entry.endcloses:
                    self.write(")%s\n" % stack.pop())
                if stack and envname == stack[-1]:
                    self.write(")%s\n" % entry.outputname)
                    del stack[-1]
                else:
                    raise LaTeXStackError(envname, stack)
                line = line[m.end():]
                continue
            m = _begin_macro_rx.match(line)
            if m:
                # start of macro
                macroname = m.group(1)
                if macroname == "c":
                    # Ugh!  This is a combining character...
                    endpos = m.end()
                    self.combining_char("c", line[endpos])
                    line = line[endpos + 1:]
                    continue
                entry = self.get_entry(macroname)
                if entry.verbatim:
                    # magic case!
                    pos = string.find(line, "\\end{%s}" % macroname)
                    text = line[m.end(1):pos]
                    stack.append(entry.name)
                    self.write("(%s\n" % entry.outputname)
                    self.write("-%s\n" % encode(text))
                    self.write(")%s\n" % entry.outputname)
                    stack.pop()
                    line = line[pos + len("\\end{%s}" % macroname):]
                    continue
                while stack and stack[-1] in entry.closes:
                    top = stack.pop()
                    topentry = self.get_entry(top)
                    if topentry.outputname:
                        self.write(")%s\n-\\n\n" % topentry.outputname)
                #
                if entry.outputname:
                    if entry.empty:
                        self.write("e\n")
                #
                params, optional, empty, environ = self.start_macro(macroname)
                # rip off the macroname
                if params:
                    line = line[m.end(1):]
                elif empty:
                    line = line[m.end(1):]
                else:
                    line = line[m.end():]
                opened = 0
                implied_content = 0

                # handle attribute mappings here:
                for pentry in params:
                    if pentry.type == "attribute":
                        if pentry.optional:
                            m = _optional_rx.match(line)
                            if m and entry.outputname:
                                line = line[m.end():]
                                self.dump_attr(pentry, m.group(1))
                        elif pentry.text and entry.outputname:
                            # value supplied by conversion spec:
                            self.dump_attr(pentry, pentry.text)
                        else:
                            m = _parameter_rx.match(line)
                            if not m:
                                raise LaTeXFormatError(
                                    "could not extract parameter %s for %s: %s"
                                    % (pentry.name, macroname, `line[:100]`))
                            if entry.outputname:
                                self.dump_attr(pentry, m.group(1))
                            line = line[m.end():]
                    elif pentry.type == "child":
                        if pentry.optional:
                            m = _optional_rx.match(line)
                            if m:
                                line = line[m.end():]
                                if entry.outputname and not opened:
                                    opened = 1
                                    self.write("(%s\n" % entry.outputname)
                                    stack.append(macroname)
                                stack.append(pentry.name)
                                self.write("(%s\n" % pentry.name)
                                self.write("-%s\n" % encode(m.group(1)))
                                self.write(")%s\n" % pentry.name)
                                stack.pop()
                        else:
                            if entry.outputname and not opened:
                                opened = 1
                                self.write("(%s\n" % entry.outputname)
                                stack.append(entry.name)
                            self.write("(%s\n" % pentry.name)
                            stack.append(pentry.name)
                            self.line = skip_white(line)[1:]
                            line = self.subconvert(
                                "}", len(stack) + depth + 1)[1:]
                            self.write(")%s\n" % stack.pop())
                    elif pentry.type == "content":
                        if pentry.implied:
                            implied_content = 1
                        else:
                            if entry.outputname and not opened:
                                opened = 1
                                self.write("(%s\n" % entry.outputname)
                                stack.append(entry.name)
                            line = skip_white(line)
                            if line[0] != "{":
                                raise LaTeXFormatError(
                                    "missing content for " + macroname)
                            self.line = line[1:]
                            line = self.subconvert("}", len(stack) + depth + 1)
                            if line and line[0] == "}":
                                line = line[1:]
                    elif pentry.type == "text" and pentry.text:
                        if entry.outputname and not opened:
                            opened = 1
                            stack.append(entry.name)
                            self.write("(%s\n" % entry.outputname)
                        self.err_write("--- text: %s\n" % `pentry.text`)
                        self.write("-%s\n" % encode(pentry.text))
                    elif pentry.type == "entityref":
                        self.write("&%s\n" % pentry.name)
                if entry.outputname:
                    if not opened:
                        self.write("(%s\n" % entry.outputname)
                        stack.append(entry.name)
                    if not implied_content:
                        self.write(")%s\n" % entry.outputname)
                        stack.pop()
                continue
            if line[0] == endchar and not stack:
                self.line = line[1:]
                return self.line
            if line[0] == "}":
                # end of macro or group
                macroname = stack[-1]
                if macroname:
                    conversion = self.table.get(macroname)
                    if conversion.outputname:
                        # otherwise, it was just a bare group
                        self.write(")%s\n" % conversion.outputname)
                del stack[-1]
                line = line[1:]
                continue
            if line[0] == "~":
                # don't worry about the "tie" aspect of this command
                line = line[1:]
                self.write("- \n")
                continue
            if line[0] == "{":
                stack.append("")
                line = line[1:]
                continue
            if line[0] == "\\" and line[1] in ESCAPED_CHARS:
                self.write("-%s\n" % encode(line[1]))
                line = line[2:]
                continue
            if line[:2] == r"\\":
                self.write("(BREAK\n)BREAK\n")
                line = line[2:]
                continue
            if line[:2] == r"\_":
                line = "_" + line[2:]
                continue
            if line[:2] in (r"\'", r'\"'):
                # combining characters...
                self.combining_char(line[1], line[2])
                line = line[3:]
                continue
            m = _text_rx.match(line)
            if m:
                text = encode(m.group())
                self.write("-%s\n" % text)
                line = line[m.end():]
                continue
            # special case because of \item[]
            # XXX can we axe this???
            if line[0] == "]":
                self.write("-]\n")
                line = line[1:]
                continue
            # avoid infinite loops
            extra = ""
            if len(line) > 100:
                extra = "..."
            raise LaTeXFormatError("could not identify markup: %s%s"
                                   % (`line[:100]`, extra))
        while stack:
            entry = self.get_entry(stack[-1])
            if entry.closes:
                self.write(")%s\n-%s\n" % (entry.outputname, encode("\n")))
                del stack[-1]
            else:
                break
        if stack:
            raise LaTeXFormatError("elements remain on stack: "
                                   + string.join(stack, ", "))
        # otherwise we just ran out of input here...

    # This is a really limited table of combinations, but it will have
    # to do for now.
    _combinations = {
        ("c", "c"): 0x00E7,
        ("'", "e"): 0x00E9,
        ('"', "o"): 0x00F6,
        }

    def combining_char(self, prefix, char):
        ordinal = self._combinations[(prefix, char)]
        self.write("-\\%%%d;\n" % ordinal)

    def start_macro(self, name):
        conversion = self.get_entry(name)
        parameters = conversion.parameters
        optional = parameters and parameters[0].optional
        return parameters, optional, conversion.empty, conversion.environment

    def get_entry(self, name):
        entry = self.table.get(name)
        if entry is None:
            self.err_write("get_entry(%s) failing; building default entry!"
                           % `name`)
            # not defined; build a default entry:
            entry = TableEntry(name)
            entry.has_content = 1
            entry.parameters.append(Parameter("content"))
            self.table[name] = entry
        return entry

    def get_env_entry(self, name):
        entry = self.table.get(name)
        if entry is None:
            # not defined; build a default entry:
            entry = TableEntry(name, 1)
            entry.has_content = 1
            entry.parameters.append(Parameter("content"))
            entry.parameters[-1].implied = 1
            self.table[name] = entry
        elif not entry.environment:
            raise LaTeXFormatError(
                name + " is defined as a macro; expected environment")
        return entry

    def dump_attr(self, pentry, value):
        if not (pentry.name and value):
            return
        if _token_rx.match(value):
            dtype = "TOKEN"
        else:
            dtype = "CDATA"
        self.write("A%s %s %s\n" % (pentry.name, dtype, encode(value)))


def convert(ifp, ofp, table):
    c = Conversion(ifp, ofp, table)
    try:
        c.convert()
    except IOError, (err, msg):
        if err != errno.EPIPE:
            raise


def skip_white(line):
    while line and line[0] in " %\n\t\r":
        line = string.lstrip(line[1:])
    return line



class TableEntry:
    def __init__(self, name, environment=0):
        self.name = name
        self.outputname = name
        self.environment = environment
        self.empty = not environment
        self.has_content = 0
        self.verbatim = 0
        self.auto_close = 0
        self.parameters = []
        self.closes = []
        self.endcloses = []

class Parameter:
    def __init__(self, type, name=None, optional=0):
        self.type = type
        self.name = name
        self.optional = optional
        self.text = ''
        self.implied = 0


class TableParser(XMLParser):
    def __init__(self, table=None):
        if table is None:
            table = {}
        self.__table = table
        self.__current = None
        self.__buffer = ''
        XMLParser.__init__(self)

    def get_table(self):
        for entry in self.__table.values():
            if entry.environment and not entry.has_content:
                p = Parameter("content")
                p.implied = 1
                entry.parameters.append(p)
                entry.has_content = 1
        return self.__table

    def start_environment(self, attrs):
        name = attrs["name"]
        self.__current = TableEntry(name, environment=1)
        self.__current.verbatim = attrs.get("verbatim") == "yes"
        if attrs.has_key("outputname"):
            self.__current.outputname = attrs.get("outputname")
        self.__current.endcloses = string.split(attrs.get("endcloses", ""))
    def end_environment(self):
        self.end_macro()

    def start_macro(self, attrs):
        name = attrs["name"]
        self.__current = TableEntry(name)
        self.__current.closes = string.split(attrs.get("closes", ""))
        if attrs.has_key("outputname"):
            self.__current.outputname = attrs.get("outputname")
    def end_macro(self):
        self.__table[self.__current.name] = self.__current
        self.__current = None

    def start_attribute(self, attrs):
        name = attrs.get("name")
        optional = attrs.get("optional") == "yes"
        if name:
            p = Parameter("attribute", name, optional=optional)
        else:
            p = Parameter("attribute", optional=optional)
        self.__current.parameters.append(p)
        self.__buffer = ''
    def end_attribute(self):
        self.__current.parameters[-1].text = self.__buffer

    def start_entityref(self, attrs):
        name = attrs["name"]
        p = Parameter("entityref", name)
        self.__current.parameters.append(p)

    def start_child(self, attrs):
        name = attrs["name"]
        p = Parameter("child", name, attrs.get("optional") == "yes")
        self.__current.parameters.append(p)
        self.__current.empty = 0

    def start_content(self, attrs):
        p = Parameter("content")
        p.implied = attrs.get("implied") == "yes"
        if self.__current.environment:
            p.implied = 1
        self.__current.parameters.append(p)
        self.__current.has_content = 1
        self.__current.empty = 0

    def start_text(self, attrs):
        self.__current.empty = 0
        self.__buffer = ''
    def end_text(self):
        p = Parameter("text")
        p.text = self.__buffer
        self.__current.parameters.append(p)

    def handle_data(self, data):
        self.__buffer = self.__buffer + data


def load_table(fp, table=None):
    parser = TableParser(table=table)
    parser.feed(fp.read())
    parser.close()
    return parser.get_table()


def main():
    global DEBUG
    #
    opts, args = getopt.getopt(sys.argv[1:], "D", ["debug"])
    for opt, arg in opts:
        if opt in ("-D", "--debug"):
            DEBUG = DEBUG + 1
    if len(args) == 0:
        ifp = sys.stdin
        ofp = sys.stdout
    elif len(args) == 1:
        ifp = open(args)
        ofp = sys.stdout
    elif len(args) == 2:
        ifp = open(args[0])
        ofp = open(args[1], "w")
    else:
        usage()
        sys.exit(2)

    table = load_table(open(os.path.join(sys.path[0], 'conversion.xml')))
    convert(ifp, ofp, table)


if __name__ == "__main__":
    main()