224 lines
		
	
	
	
		
			6.1 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			224 lines
		
	
	
	
		
			6.1 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
diff -rc aterm-1142707243.10633/aterm/aterm.c aterm/aterm/aterm.c
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*** aterm-1142707243.10633/aterm/aterm.c	2006-02-08 11:35:28.000000000 +0100
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--- aterm/aterm/aterm.c	2006-04-25 17:10:52.000000000 +0200
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***************
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*** 193,198 ****
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--- 193,199 ----
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    /* that have char == 2 bytes, and sizeof(header_type) == 2 */
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    assert(sizeof(header_type) == sizeof(ATerm *));
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    assert(sizeof(header_type) >= 4);
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+   assert(sizeof(ATerm) == sizeof(MachineWord));
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    /*}}}  */
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    /*{{{  Initialize buffer */
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diff -rc aterm-1142707243.10633/aterm/memory.c aterm/aterm/memory.c
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*** aterm-1142707243.10633/aterm/memory.c	2006-03-09 15:02:56.000000000 +0100
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--- aterm/aterm/memory.c	2006-04-25 18:22:00.000000000 +0200
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***************
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*** 119,130 ****
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                          hash_number(tmp,3)) 
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  */
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  #define HASHNUMBER3(t)\
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! FINISH(COMBINE(START(((MachineWord*)t)[0]), ((MachineWord*)t)[2]))
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  #define HASHNUMBER4(t)\
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! FINISH(COMBINE(COMBINE(START(((MachineWord*)t)[0]), \
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! 		       ((MachineWord*)t)[2]),((MachineWord*)t)[3]))
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  #define HASHINT(val) \
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  FINISH(COMBINE(START( (AT_INT<<SHIFT_TYPE) ), val))
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--- 119,171 ----
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                          hash_number(tmp,3)) 
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  */
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+ /* The ATerm library use some heavy aliasing.  For instance, the
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+    various ATermXXX structures are referenced through MachineWord
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+    arrays.  This is not generally allowed by the C standard --- see
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+    C99, section 6.5, clause 7.  In particular, this means that you
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+    cannot assign something through an ATermXXX pointer, e.g.,
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+ 
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+      protoAppl->header = header;
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+ 
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+    and then read it through a MachineWord*, e.g.,
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+ 
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+      hnr = hash_number((ATerm) protoAppl, 2);
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+ 
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+    (hash_number walks over the term by casting it to a MachineWord*).
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+ 
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+    However, the same clause of the C standard also specifies that you
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+    *can* read the memory location through a union type that contains
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+    both the original type (e.g. ATermAppl) and the type used to read
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+    the memory location (e.g. MachineWord).  That's what we do
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+    below: we have a union of all the types that occur in the various
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+    ATerm types.  We then read the "w" element of the union.  The
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+    compiler is not allowed to assume absence of aliasing with the
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+    other types in the union.
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+ 
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+    A better solution would be to hash the term through a character
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+    pointer (since *any* memory location can be legally read as a
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+    character), but I'm too lazy right now.  Performance might also
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+    suffer if we do that. */
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+ 
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+ typedef union 
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+ {
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+     MachineWord w;
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+     header_type header;
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+     ATerm term;
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+     ATermList list;
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+     int i;
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+     double d;
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+     void* p;
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+ } Aliaser;
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+ 
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+ #define GET_WORD(t, n) (((Aliaser*) (((MachineWord*) t) + n))->w)
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+ 
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  #define HASHNUMBER3(t)\
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! FINISH(COMBINE(START(GET_WORD(t, 0)), GET_WORD(t, 2)))
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  #define HASHNUMBER4(t)\
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! FINISH(COMBINE(COMBINE(START(GET_WORD(t, 0)), \
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! 		       GET_WORD(t, 2)), GET_WORD(t, 3)))
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  #define HASHINT(val) \
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  FINISH(COMBINE(START( (AT_INT<<SHIFT_TYPE) ), val))
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***************
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*** 132,144 ****
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  #endif /* HASHPEM */
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! #define PROTO_APPL_ARGS ((ATerm *) (protoTerm + ARG_OFFSET))
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  #define SET_PROTO_APPL_ARG(i, a) \
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!   (PROTO_APPL_ARGS[(i)] = (a))
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  #define GET_PROTO_APPL_ARG(i) \
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!   (PROTO_APPL_ARGS[(i)])
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  #define CHECK_TERM(t) \
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    assert((t) != NULL \
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--- 173,185 ----
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  #endif /* HASHPEM */
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! #define PROTO_APPL_ARGS (protoTerm + ARG_OFFSET)
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  #define SET_PROTO_APPL_ARG(i, a) \
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!   (PROTO_APPL_ARGS[(i)] = (MachineWord) (a))
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  #define GET_PROTO_APPL_ARG(i) \
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!   ((ATerm) PROTO_APPL_ARGS[(i)])
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  #define CHECK_TERM(t) \
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    assert((t) != NULL \
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***************
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*** 323,336 ****
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  #else
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  static HashNumber hash_number(ATerm t, int size)
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  {
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-   MachineWord *words = (MachineWord *) t;
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    int i;
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    HashNumber hnr;
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!   hnr = START(HIDE_AGE_MARK(words[0]));
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    for (i=2; i<size; i++) {
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!     hnr = COMBINE(hnr, words[i]);
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    }
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    return FINISH(hnr);
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--- 364,376 ----
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  #else
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  static HashNumber hash_number(ATerm t, int size)
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  {
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    int i;
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    HashNumber hnr;
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!   hnr = START(HIDE_AGE_MARK(GET_WORD(t, 0)));
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    for (i=2; i<size; i++) {
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!     hnr = COMBINE(hnr, GET_WORD(t, i));
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    }
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    return FINISH(hnr);
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***************
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*** 338,351 ****
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  static HashNumber hash_number_anno(ATerm t, int size, ATerm anno)
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  {
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-   MachineWord *words = (MachineWord *) t;
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    int i;
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    HashNumber hnr;
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!   hnr = START(HIDE_AGE_MARK(words[0]));
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    for (i=2; i<size; i++) {
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!     hnr = COMBINE(hnr, words[i]);
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    }
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    hnr = COMBINE(hnr, (MachineWord)anno);
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--- 378,390 ----
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  static HashNumber hash_number_anno(ATerm t, int size, ATerm anno)
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  {
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    int i;
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    HashNumber hnr;
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!   hnr = START(HIDE_AGE_MARK(GET_WORD(t, 0)));
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    for (i=2; i<size; i++) {
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!     hnr = COMBINE(hnr, GET_WORD(t, i));
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    }
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    hnr = COMBINE(hnr, (MachineWord)anno);
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***************
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*** 1639,1645 ****
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    protoAppl->header = header;
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    CHECK_HEADER(protoAppl->header);
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!   if (args != PROTO_APPL_ARGS) {
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      for (i=0; i<arity; i++) {
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        CHECK_TERM(args[i]);
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        SET_PROTO_APPL_ARG(i, args[i]);
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--- 1678,1684 ----
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    protoAppl->header = header;
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    CHECK_HEADER(protoAppl->header);
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!   if (args != (ATerm *) PROTO_APPL_ARGS) {
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      for (i=0; i<arity; i++) {
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        CHECK_TERM(args[i]);
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        SET_PROTO_APPL_ARG(i, args[i]);
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***************
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*** 1680,1686 ****
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      hashtable[hnr] = cur;
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    }
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!   if (args != PROTO_APPL_ARGS) {
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      for (i=0; i<arity; i++) {
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        protected_buffer[i] = NULL;
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      }
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--- 1719,1725 ----
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      hashtable[hnr] = cur;
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    }
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!   if (args != (ATerm *) PROTO_APPL_ARGS) {
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      for (i=0; i<arity; i++) {
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        protected_buffer[i] = NULL;
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      }
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***************
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*** 2144,2150 ****
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    }
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    SET_PROTO_APPL_ARG(n, arg);
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!   result = ATmakeApplArray(sym, PROTO_APPL_ARGS);
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    annos = AT_getAnnotations((ATerm)appl);
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    if (annos != NULL) {
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      result = (ATermAppl)AT_setAnnotations((ATerm)result, annos);
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--- 2183,2189 ----
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    }
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    SET_PROTO_APPL_ARG(n, arg);
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!   result = ATmakeApplArray(sym, (ATerm *) PROTO_APPL_ARGS);
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    annos = AT_getAnnotations((ATerm)appl);
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    if (annos != NULL) {
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      result = (ATermAppl)AT_setAnnotations((ATerm)result, annos);
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