xref: /openjdk9/corba/src/java.corba/share/classes/com/sun/corba/se/impl/orb/parsing_combinators.txt

Parsing

- primtive types
- lists of various sorts

    Basic models

	prefix		A,BCDF	    scans left-to-right
	suffix		ABCD:F	    scans right-to-left

    Model 1:
    data is sep,op,next,combine

	if (sep found in data)
	    split data into prefix, rest
	    return combine( op(prefix), next(rest) )
	else
	    return combine( default, next(data) )

    pop = suffix1( ":", op3, op4, ++ )
    op = prefix1( ",", op2, pop, ++ )

    op( A,BDF.FGH:Z ) =

	op2(A) ++ pop( BDF.FGH:Z ) =
	op2(A) ++ op4( BDF.FGH ) ++ op3( Z )
    
    Model 2:
    data is sep,op,next,combine

	if (sep found in data)
	    split data into prefix, rest
	    return combine( op(prefix), next(rest) )
	else
	    return op(data)

    example
	op = prefix2( ":", op2, null, ++ ) 
	op.setNext( op ) ;

	op( A:B:C:D ) =

	op2(A) ++ op2(B) ++ op2(C) ++ op2(D)



reduce( sep, initial, op, combine )

    operate( data )
	if (sep in data)
	    split data into prefix, rest
	    return combine( op(prefix), operate( rest ))
	else
	    return combine( op(data), initial ) 

reduce( sep, op1, op2, initial, combine )

    operate(data)
	if (sep in data)	// either first from left orfirst from right
	    split data into prefix, rest
	    return combine( op1( prefix ), op2( rest ) )
	else
	    return opx( data )

type<X,Y>
    class combine
	init : X
	add( X, Y )  : X
    op1( String ) : X
    op2( String ) : Y

    reduce( sep, op1, op2, comb ) ( String ) : X 

    operate(data)
	if (sep in data)	// either first from left orfirst from right
	    split data into prefix, rest
	    return comb.add( op2.operate( rest ), op1.operate( prefix ) )
	else
	    return comb.add( comb.init(), op1.operate( data ) )

    example

	op = reduce( ":", op1, null, comb )
	op.setop2( op ) 

	op.operate( "A:B:C" ) =
	comb.add( op.operate( "B:C" ), op1.operate( "A" ) ) = 
	comb.add( comb.add( op.operate("C"), op1.operate("B") ), op1.operate( "A" ) =
	comb.add( comb.add( comb.add( comb.init(), op1.operate("C") ), op1.operate("B") ),
	    op1.operate("A") )


Splitter interface

interface Splitter {
    List split( String str ) 
}
    
variations:
    - separated list		    SL
    - first sep rest		    FSR
	- fail if not present	    one arg
	- default value		    two args
    - rest sep last		    RSL
	- fail if not present	    one arg
	- default value		    two args

Have we just pushed the real problem off a level?

How do we combine:
    op1 = FSR("@",v12)
    op2 = LSR(":",9090)

    str = 1.2@myhost:2345

    op1(str) = ( "1.2" "myhost:2345" )

    define splice( int index, Operator op ) on a list of strings, with op( String ) : (String)
    to replace the indexth element of a list of strings with the list returned
    from op( element ).

    compose( op1, splice( 1, op2 )) is the correct parser.


A grammar for parsers?

parser	:	    simple_parser
	|	    parser ":" simple_parser ;

simple_parser :	    ident
	      |	    ident "(" param_list ")" ;

param_list    :	    param
	      |	    param_list "," param ;

param	      :	    constant
	      |	    parser ;
   
constant is a Java constant
ident x is interpreted as either a public static method on OperationFactory
named xAction which takes as arguments the types of the param list, or as
the fully qualified class name of a class that implements Operation and has
a constructor which takes as arguments the types of the param list.

From parser table:

debugFlags		string
ORBInitialHost		string
ORBInitialPort		integer
ORBServerHost		string
ORBServerPort		integer
orbId			string
highWaterMark		integer
lowWaterMark		integer
etc.

giopVersion		construct(GIOPVersion.class):map(integer):list('.')
giopFragmentSize	mod(ORBConstants.GIOP_FRAGMENT_DIVISOR):min(ORBConstants.GIOP_FRAGMENT_SIZE):integer

Lisp notation:
    parse((mod ORBConstants.GIOP_FRAGMENT_DIVISOR) (min ...) (integer))

giop11BuffMgr		makeMap(map) where map is constructed in java with
			map.get("GROW") = Integer(0)
			map.get("CLCT") = Integer(1)
			map.get("STRM") = Integer(2)

giopTargetAddressPreference	intToShort:integerRange(0,3)
giopAddressDisposition		another map variant

charData		construct(CodeSetComponentInfo.class):string


What about corbaloc:?

v12 = GIOPVersion.v12 ;

giopVersion = construct( GIOPVersion.class ):mapSequence( [integer,integer] ):FSR(".") 

iiopAddress =  mapSequence( [giopVersion,identity,integer] ):
	       splice( 1, LSR( ":" 9090 )):
	       FSR( "@", v12 )

addressHandler = choice( 
    "iiop:",	iiopAddress
    ":",	iiopAddress 
)

addressList = map(addressHandler):SL(",")

choice( 
    "corbaloc:", mapSequence( [addressList,string] ):RSL("/", "NameService"),
    "corbaname:", ...
)