56 lines
921 B
C++
56 lines
921 B
C++
/* Substitute new expr for old expr in expr.
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Input: push expr
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push old expr
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push new expr
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Output: Result on stack
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*/
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#include "stdafx.h"
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#include "defs.h"
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void
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subst(void)
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{
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int i;
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save();
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p3 = pop(); // new expr
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p2 = pop(); // old expr
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if (p2 == symbol(NIL) || p3 == symbol(NIL)) {
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restore();
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return;
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}
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p1 = pop(); // expr
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if (istensor(p1)) {
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p4 = alloc_tensor(p1->u.tensor->nelem);
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p4->u.tensor->ndim = p1->u.tensor->ndim;
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for (i = 0; i < p1->u.tensor->ndim; i++)
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p4->u.tensor->dim[i] = p1->u.tensor->dim[i];
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for (i = 0; i < p1->u.tensor->nelem; i++) {
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push(p1->u.tensor->elem[i]);
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push(p2);
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push(p3);
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subst();
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p4->u.tensor->elem[i] = pop();
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}
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push(p4);
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} else if (equal(p1, p2))
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push(p3);
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else if (iscons(p1)) {
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push(car(p1));
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push(p2);
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push(p3);
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subst();
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push(cdr(p1));
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push(p2);
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push(p3);
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subst();
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cons();
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} else
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push(p1);
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restore();
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}
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