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#############################################################################
##
#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);
#############################################################################
#E
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