parsing_combinators.txt revision 608:7e06bf1dcb09 
1Parsing
2
3- primtive types
4- lists of various sorts
5
6    Basic models
7
8	prefix		A,BCDF	    scans left-to-right
9	suffix		ABCD:F	    scans right-to-left
10
11    Model 1:
12    data is sep,op,next,combine
13
14	if (sep found in data)
15	    split data into prefix, rest
16	    return combine( op(prefix), next(rest) )
17	else
18	    return combine( default, next(data) )
19
20    pop = suffix1( ":", op3, op4, ++ )
21    op = prefix1( ",", op2, pop, ++ )
22
23    op( A,BDF.FGH:Z ) =
24
25	op2(A) ++ pop( BDF.FGH:Z ) =
26	op2(A) ++ op4( BDF.FGH ) ++ op3( Z )
27    
28    Model 2:
29    data is sep,op,next,combine
30
31	if (sep found in data)
32	    split data into prefix, rest
33	    return combine( op(prefix), next(rest) )
34	else
35	    return op(data)
36
37    example
38	op = prefix2( ":", op2, null, ++ ) 
39	op.setNext( op ) ;
40
41	op( A:B:C:D ) =
42
43	op2(A) ++ op2(B) ++ op2(C) ++ op2(D)
44
45
46
47reduce( sep, initial, op, combine )
48
49    operate( data )
50	if (sep in data)
51	    split data into prefix, rest
52	    return combine( op(prefix), operate( rest ))
53	else
54	    return combine( op(data), initial ) 
55
56reduce( sep, op1, op2, initial, combine )
57
58    operate(data)
59	if (sep in data)	// either first from left orfirst from right
60	    split data into prefix, rest
61	    return combine( op1( prefix ), op2( rest ) )
62	else
63	    return opx( data )
64
65type<X,Y>
66    class combine
67	init : X
68	add( X, Y )  : X
69    op1( String ) : X
70    op2( String ) : Y
71
72    reduce( sep, op1, op2, comb ) ( String ) : X 
73
74    operate(data)
75	if (sep in data)	// either first from left orfirst from right
76	    split data into prefix, rest
77	    return comb.add( op2.operate( rest ), op1.operate( prefix ) )
78	else
79	    return comb.add( comb.init(), op1.operate( data ) )
80
81    example
82
83	op = reduce( ":", op1, null, comb )
84	op.setop2( op ) 
85
86	op.operate( "A:B:C" ) =
87	comb.add( op.operate( "B:C" ), op1.operate( "A" ) ) = 
88	comb.add( comb.add( op.operate("C"), op1.operate("B") ), op1.operate( "A" ) =
89	comb.add( comb.add( comb.add( comb.init(), op1.operate("C") ), op1.operate("B") ),
90	    op1.operate("A") )
91
92
93Splitter interface
94
95interface Splitter {
96    List split( String str ) 
97}
98    
99variations:
100    - separated list		    SL
101    - first sep rest		    FSR
102	- fail if not present	    one arg
103	- default value		    two args
104    - rest sep last		    RSL
105	- fail if not present	    one arg
106	- default value		    two args
107
108Have we just pushed the real problem off a level?
109
110How do we combine:
111    op1 = FSR("@",v12)
112    op2 = LSR(":",9090)
113
114    str = 1.2@myhost:2345
115
116    op1(str) = ( "1.2" "myhost:2345" )
117
118    define splice( int index, Operator op ) on a list of strings, with op( String ) : (String)
119    to replace the indexth element of a list of strings with the list returned
120    from op( element ).
121
122    compose( op1, splice( 1, op2 )) is the correct parser.
123
124
125A grammar for parsers?
126
127parser	:	    simple_parser
128	|	    parser ":" simple_parser ;
129
130simple_parser :	    ident
131	      |	    ident "(" param_list ")" ;
132
133param_list    :	    param
134	      |	    param_list "," param ;
135
136param	      :	    constant
137	      |	    parser ;
138   
139constant is a Java constant
140ident x is interpreted as either a public static method on OperationFactory
141named xAction which takes as arguments the types of the param list, or as
142the fully qualified class name of a class that implements Operation and has
143a constructor which takes as arguments the types of the param list.
144
145From parser table:
146
147debugFlags		string
148ORBInitialHost		string
149ORBInitialPort		integer
150ORBServerHost		string
151ORBServerPort		integer
152orbId			string
153highWaterMark		integer
154lowWaterMark		integer
155etc.
156
157giopVersion		construct(GIOPVersion.class):map(integer):list('.')
158giopFragmentSize	mod(ORBConstants.GIOP_FRAGMENT_DIVISOR):min(ORBConstants.GIOP_FRAGMENT_SIZE):integer
159
160Lisp notation:
161    parse((mod ORBConstants.GIOP_FRAGMENT_DIVISOR) (min ...) (integer))
162
163giop11BuffMgr		makeMap(map) where map is constructed in java with
164			map.get("GROW") = Integer(0)
165			map.get("CLCT") = Integer(1)
166			map.get("STRM") = Integer(2)
167
168giopTargetAddressPreference	intToShort:integerRange(0,3)
169giopAddressDisposition		another map variant
170
171charData		construct(CodeSetComponentInfo.class):string
172
173
174What about corbaloc:?
175
176v12 = GIOPVersion.v12 ;
177
178giopVersion = construct( GIOPVersion.class ):mapSequence( [integer,integer] ):FSR(".") 
179
180iiopAddress =  mapSequence( [giopVersion,identity,integer] ):
181	       splice( 1, LSR( ":" 9090 )):
182	       FSR( "@", v12 )
183
184addressHandler = choice( 
185    "iiop:",	iiopAddress
186    ":",	iiopAddress 
187)
188
189addressList = map(addressHandler):SL(",")
190
191choice( 
192    "corbaloc:", mapSequence( [addressList,string] ):RSL("/", "NameService"),
193    "corbaname:", ...
194)
195