95 lines
1.6 KiB
C
95 lines
1.6 KiB
C
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/*
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* varbuf.c
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*
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* Operations on a variable substitutions buffer.
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* The type is actually defined in runs.h
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*/
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#include "memory.h"
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#include "runs.h"
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/*
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* create a new varbuffer from the current state of the system
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*/
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Varbuf
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varbufInit (System sys)
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{
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Varbuf vb;
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Termlist tl;
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Term termfrom, termto;
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vb = (Varbuf) memAlloc(sizeof(struct varbuf));
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vb->from = NULL;
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vb->to = NULL;
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vb->empty = NULL;
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tl = sys->variables;
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while (tl != NULL)
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{
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if (realTermVariable(tl->term))
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{
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/* this is actually a variable */
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if (tl->term->subst == NULL)
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{
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/* non-instantiated */
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vb->empty = termlistAdd (vb->empty, tl->term);
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}
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else
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{
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/* store instantiation */
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termfrom = tl->term;
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termto = termfrom->subst;
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termfrom->subst = NULL; // temp disable
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vb->from = termlistAdd (vb->from, termfrom);
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vb->to = termlistAdd (vb->to, termto);
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termfrom->subst = termto; // restore
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}
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}
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tl = tl->next;
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}
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return vb;
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}
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/*
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* copy the variable state back into the system
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*/
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void
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varbufSet (System sys, Varbuf vb)
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{
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Termlist tl1, tl2;
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tl1 = vb->from;
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tl2 = vb->to;
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while (tl1 != NULL && tl2 != NULL)
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{
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tl1->term->subst = tl2->term;
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tl1 = tl1->next;
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tl2 = tl2->next;
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}
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tl1 = vb->empty;
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while (tl1 != NULL)
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{
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tl1->term->subst = NULL;
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tl1 = tl1->next;
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}
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}
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/*
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* cleanup
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*/
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void
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varbufDone (Varbuf vb)
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{
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if (vb != NULL)
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{
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termlistDelete (vb->from);
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termlistDelete (vb->to);
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termlistDelete (vb->empty);
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memFree(vb, sizeof(struct varbuf));
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}
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}
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