###########################################################################
##
#W  omput.gi                OpenMath Package                 Andrew Solomon
#W                                                         Marco Costantini
#W                                                      Alexander Konovalov
##
##
#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
##
##  Low-level methods for output in the OpenMath XML format
## 

    
###########################################################################
##  
#F  OMWriteLine( <stream>, <list> )
##
##  Input : List of arguments to print
##  Output: \t ^ OMIndent, arguments
##
InstallGlobalFunction(OMWriteLine, function(stream, alist)
	local i;

	# do the indentation
	AppendTo( stream, ListWithIdenticalEntries( OMIndent, '\t' ) );

	for i in alist do
		AppendTo(stream, i);
	od;
	AppendTo(stream, "\n");
end);


###########################################################################
## 
## Basic OpenMath objects and tags
##
###########################################################################


###########################################################################
##
#F  OMPutVar( <stream>, <name> )
##
##  Input : name as string
##  Output: <OMV name="<name>" />
##
InstallMethod( OMPutVar, "to write OMV in XML OpenMath", true,
[ IsOpenMathXMLWriter, IsObject ],0,
function( writer, name )
  OMWriteLine( writer![1], ["<OMV name=\"", String(name), "\"/>"] );
end);


###########################################################################
##
#F  OMPutSymbol( <stream>, <cd>, <name> )
##
##  Input : cd, name as strings
##  Output: <OMS cd="<cd>" name="<name>" />
##
InstallMethod( OMPutSymbol, "to write OMS in XML OpenMath", true,
[ IsOpenMathXMLWriter, IsString, IsString ],0,
function( writer, cd, name )
  OMWriteLine( writer![1], ["<OMS cd=\"", cd, "\" name=\"", name, "\"/>"] );
end);


###########################################################################
##
#M  OMPutOMAWithId( <OMWriter>, <reference> )
##
##
##
InstallMethod( OMPutOMAWithId, "to put Applications with Ids", true,
[IsOpenMathXMLWriter, IsString],0,
function(writer, reference)
  OMWriteLine( writer![1], [ "<OMA id=\"", reference, "\" >" ] );
end);


###########################################################################
##
#M  OMPutOMA
#M  OMPutEndOMA
##
InstallMethod(OMPutOMA, "to write OMA in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMWriteLine( writer![1], [ "<OMA>" ] );
    OMIndent := OMIndent + 1;
end);

InstallMethod(OMPutEndOMA, "to write /OMA in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OMA>" ] );
end);


###########################################################################
##
#M  OMPutOMATTR
#M  OMPutEndOMATTR
##
InstallMethod(OMPutOMATTR, "to write OMATTR in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMWriteLine( writer![1], [ "<OMATTR>" ] );
    OMIndent := OMIndent + 1;
end);

InstallMethod(OMPutEndOMATTR, "to write /OMATTR in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OMATTR>" ] );
end);

InstallMethod(OMPutOMATP, "to write OMATP in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMWriteLine( writer![1], [ "<OMATP>" ] );
    OMIndent := OMIndent + 1;
end);

InstallMethod(OMPutEndOMATP, "to write /OMATP in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OMATP>" ] );
end);


###########################################################################
##
#M  OMPutOMBIND
#M  OMPutEndOMBIND
##
InstallMethod(OMPutOMBIND, "to write OMBIND in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMWriteLine( writer![1], [ "<OMBIND>" ] );
    OMIndent := OMIndent + 1;
end);

InstallMethod(OMPutEndOMBIND, "to write /OMBIND in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OMBIND>" ] );
end);


###########################################################################
##
#M  OMPutOMBVAR
#M  OMPutEndOMBVAR
##
InstallMethod(OMPutOMBVAR, "to write OMBVAR in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMWriteLine( writer![1], [ "<OMBVAR>" ] );
    OMIndent := OMIndent + 1;
end);

InstallMethod(OMPutEndOMBVAR, "to write /OMBVAR in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OMBVAR>" ] );
end);


###########################################################################
##
#M  OMPutOME
#M  OMPutEndOME
##
InstallMethod(OMPutOME, "to write OME in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMWriteLine( writer![1], [ "<OME>" ] );
    OMIndent := OMIndent + 1;
end);

InstallMethod(OMPutEndOME, "to write /OME in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OME>" ] );
end);


###########################################################################
##
#M  OMPutOMOBJ
#M  OMPutEndOMOBJ
##

BindGlobal( "OMOBJ_TAG", "<OMOBJ xmlns=\"http://www.openmath.org/OpenMath\" version=\"2.0\">" );

InstallMethod(OMPutOMOBJ, "to write OMOBJ in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
	OMIndent := 0;
	OMWriteLine( writer![1], [ OMOBJ_TAG ] );
    OMIndent := 1;
end);

InstallMethod(OMPutEndOMOBJ, "to write /OMOBJ in XML OpenMath", true,
[IsOpenMathXMLWriter],0,
function( writer )
    OMIndent := OMIndent - 1;
	OMWriteLine( writer![1], [ "</OMOBJ>" ] );
end);


###########################################################################
## 
## Various methods for OMPut
## 

BindGlobal( "OMINT_LIMIT", 2^15936 );

###########################################################################
##
#M  OMPut( <OMWriter>, <int> )  
##
##  Printing for integers: specified in the standard
## 
InstallMethod(OMPut, "for an integer to XML OpenMath", true,
[IsOpenMathXMLWriter, IsInt],0,
function(writer, x)
    if x >= OMINT_LIMIT then
  		OMWriteLine( writer![1], ["<OMI>", String(x), "</OMI>"] );
	else
  		OMWriteLine( writer![1], ["<OMI>", x, "</OMI>"] );
	fi;
end);


###########################################################################
##
#M  OMPut( <OMWriter>, <string> )  
##
##  specified in the standard
## 
InstallMethod(OMPut, "for a string to XML OpenMath", true,
[IsOpenMathXMLWriter, IsString],0,
function(writer, x)
	if IsEmpty(x) and not IsEmptyString(x) then
		TryNextMethod();
	fi;

  # convert XML escaped chars
  x := ReplacedString( x, "&", "&amp;" );
  x := ReplacedString( x, "<", "&lt;" );

	OMWriteLine(writer![1], ["<OMSTR>",x,"</OMSTR>"]);
end);


###########################################################################
##
#M  OMPut( <stream>, <float> )
##
##  Printing for floats: specified in the standard
##
InstallMethod(OMPut, "for a float", true,
[IsOpenMathXMLWriter, IsFloat],0,
function(writer, x)
    local  string;
    # treatment of x=0 separately was added when discovered
    # that Float("-0") returns -0, but it is also faster.
    if IsZero(x) then
    	OMWriteLine( writer![1], [ "<OMF dec=\"0\"/>" ] );
    else
    	string := String( x );
    	# the OpenMath standard requires floats encoded in this way, see
    	# section 3.1.2
    	string := ReplacedString( string, "e+", "e" );
    	string := ReplacedString( string, "inf", "INF" );
    	string := ReplacedString( string, "nan", "NaN" );
    	OMWriteLine( writer![1], [ "<OMF dec=\"", string, "\"/>" ] );
	fi;
end);


###########################################################################
#
# Functions and methods for OMPlainString
#
InstallGlobalFunction( OMPlainString, function( string )
if IsString( string ) then
    # note that we do not validate the string!
    return Objectify( OMPlainStringDefaultType, [ string ] );
else
    Error( "The argument of OMPlainString must be a string" );
fi;                    
end);


###########################################################################
##
#M  PrintObj( <IsOMPlainString> )
##
InstallMethod( PrintObj, "for IsOMPlainString",
[ IsOMPlainStringRep and IsOMPlainString ],
function( obj )
    Print( obj![1] );
end);


###########################################################################
##
#M  OMPut( <IsOMPlainString> )
##
InstallMethod( OMPut, "for IsOMPlainString",
true,
[ IsOpenMathXMLWriter, IsOMPlainString ],
0,
function( writer, s )
    OMWriteLine( writer![1], [ s ] );
end); 


###########################################################################
#
# OMPutReference( OMWriter, x );
#
# This method prints OpenMath references and can be used for printing complex 
# objects, for example, ideals of polynomial rings (the ideal will carry the
# ring R, and each polynomial generating the ideal will also refer to the 
# ring R). The method uses OMR, if the object x already has the attribute 
# OMReference, and prints the object x otherwise. 
#
# The concept of references implies that the author of the code is able to
# decide which objects needs references, and assign references to them, e.g.
# using
# SetOMReference( r, Concatenation("polyring", RandomString(16)));
#
# Once an object obtained a reference, it can not be changed, therefore, the
# same reference will be used in communication with all other CASs. 
#
# However, the reference will be not printed automatically for an object
# having it - otherwise, you will not be able to send the same object to
# multiple CASs. Instead of this, the reference will be printed only when
# this will be enforced by the usage of OMPutReference.
#
# If the SuppressOpenMathReferences is set to true, then 
# OMPutReference (lib/openmath.gi) will put the actual 
# OpenMath code for an object whenever it has id or not.
#
InstallMethod( OMPutReference, 
"for a stream and an object with reference",
true,
[ IsOpenMathWriter, IsObject ],
0,
function( writer, x )
if HasOMReference( x ) and not SuppressOpenMathReferences then
   OMWriteLine( writer![1], [ "<OMR href=\"\043", OMReference( x ), "\" />" ] );
else   
   OMPut( writer, x );
fi;
end);

###########################################################################
#E