Quelle parse.gi Sprache: unbekannt

#############################################################################
##
#W  parse.gi           OpenMath Package         Andrew Solomon
#W                                                     Marco Costantini
##
#Y    Copyright (C) 1999, 2000, 2001, 2006
#Y    School Math and Comp. Sci., University of St.  Andrews, Scotland
#Y    Copyright (C) 2004, 2005, 2006 Marco Costantini
##
##  The parser reads token/values off the stream and builds GAP objects.
##

InstallGlobalFunction(OMgetObjectByteStream, function(inputstream)
local stream, obj;

# assumes there is at least one byte on stream.
stream := rec(next := ReadByte(inputstream), stream := inputstream);

# Start -> OMtokenObject object OMtokenEndObject

# get the OMtokenObject
OMgetToken(stream, OMtokenObject);

# parse the object
obj := OMparseObject(stream);

OMgetToken(stream, OMtokenEndObject);

return obj;
end);

InstallGlobalFunction(OMparseApplication, function(stream)
  local head, rest, nextob;

  # first get the OMtokenApp off the stream
  OMgetToken(stream, OMtokenApp);

  #
  # 1. Get the "head" object
  # the possibilities are:
  #
  # 2. Apply the head to the rest
  #

  # 1.1 If it's a symbol, look it up and see what it translates to in GAP
  if OMnextToken(stream) = OMtokenSymbol then
   head := OMsymLookup(OMgetSymbol(stream));
  else
   head := OMparseObject(stream);
  fi;

  # get the rest
  rest := [];
  while OMnextToken(stream) <> OMtokenEndApp do
   nextob := OMparseObject(stream);
   Append(rest, [nextob]);
  od;

  # finally get the OMtokenEndApp off the stream
  OMgetToken(stream, OMtokenEndApp);

  return head( rest );
end);

# just ignore everything but the object
InstallGlobalFunction(OMparseAttribution, function(stream)
  local nextob, ob;

  # first get the OMtokenAttr off the stream
  OMgetToken(stream, OMtokenAttr);

  # now get the OMtokenAtp off the stream
  OMgetToken(stream, OMtokenAtp);

  # just read all the objects until the end of attribution
  while OMnextToken(stream) <> OMtokenEndAtp do
   nextob := OMparseObject(stream);
  od;

  # get the OMtokenEndAtp off the stream
  OMgetToken(stream, OMtokenEndAtp);

  # finally, the only thing we don't ignore - the unattributed object
  ob :=  OMparseObject(stream);

  OMgetToken(stream, OMtokenEndAttr);

  return ob;
end);

InstallGlobalFunction(OMparseBind, function(stream)
Error("Binding is unimplemented");
end);

InstallGlobalFunction(OMparseObject, function(stream)
##
## Object -> symbol | variable | integer | float | string | bytearray |
##           application | binding | error | attribution

# first the basic objects

if OMnextToken(stream) = OMtokenSymbol then
  # this is just a nullary symbol
  return OMsymLookup(OMgetSymbol(stream));
elif OMnextToken(stream) = OMtokenVar then
  return OMgetVar(stream);
elif  OMnextToken(stream) = OMtokenInteger then
  return OMgetInteger(stream);
elif OMnextToken(stream) = OMtokenFloat then
  Error("GAP doesn't support floating point numbers.");
elif OMnextToken(stream) = OMtokenString then
  return OMgetString(stream);
elif OMnextToken(stream) = OMtokenByteArray then
  Error("GAP doesn't support byte arrays.");

# now the compound objects
elif OMnextToken(stream) = OMtokenApp then
  return OMparseApplication(stream);
elif OMnextToken(stream) = OMtokenBind then
  return OMparseBind(stream);
elif OMnextToken(stream) = OMtokenError then
  Error("OMtokenError encountered");
elif OMnextToken(stream) = OMtokenAttr then
  return OMparseAttribution(stream);


else
  Error("unrecognized token ", OMnextToken(stream));
fi;
end);

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#E

Quelle parse.gi Sprache: unbekannt

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