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1 /** ===========================================================================
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2 ** R-Package: rdyncall
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3 ** File: src/rutils.c
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4 ** Description: misc utility functions to work with low-level data structures in R
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5 **/
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6
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7 // uses: DATAPTR macro
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8 #define USE_RINTERNALS
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9 #include <Rinternals.h>
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10 #include <stddef.h>
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11
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12 SEXP r_isnullptr(SEXP x)
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13 {
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14 return ScalarLogical( ( R_ExternalPtrAddr(x) == NULL ) ? TRUE : FALSE );
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15 }
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16
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17 SEXP r_asextptr(SEXP x)
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18 {
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19 if (isVector(x)) {
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20 return R_MakeExternalPtr( DATAPTR(x), R_NilValue, x );
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21 }
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22 error("expected a vector type");
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23 return R_NilValue; /* dummy */
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24 }
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25
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26 SEXP r_offsetPtr(SEXP x, SEXP offset)
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27 {
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28 if ( LENGTH(offset) == 0 ) error("offset is missing");
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29 ptrdiff_t offsetval = INTEGER(offset)[0];
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30 unsigned char* ptr = 0;
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31 if (isVector(x)) {
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32 ptr = (unsigned char*) DATAPTR(x);
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33 } else if (TYPEOF(x) == EXTPTRSXP ) {
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34 ptr = (unsigned char*) R_ExternalPtrAddr(x);
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35 } else {
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36 error("unsupported type");
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37 }
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38 return R_MakeExternalPtr( ptr + offsetval , R_NilValue, x );
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39 }
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40
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