Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 68K/cpm68k_pgms/snobol4/RSELECT.C

/* -*-c,save-*- */

/*

 * rselect.c - Random select function (Program 16.7 in Algorithms In SNOBOL4)

 * Robert Heller. Created: Sat Feb 22, 1986 11:46:53.85

 * Last Mod: 

 * 

 */



#include <stdio.h>



#include "patdef.h"



#define LOCAL static



/* #define DEBUG /* debug hackery */



typedef struct selelt {

    short int wts;

    char *strng;

    struct selelt *nxtelt;

    } SELELT;



#define MAXRSEL 100

LOCAL SELELT *rsel_tbl[MAXRSEL];

LOCAL int rsel_cnt = 0;



char *malloc(),*calloc();



LOCAL PATTERN_NODE *rsel_wt,*rsel_alt,*rsel_l1,*rsel_bc;

LOCAL STRING_DESCR BC,WT,ALT;

LOCAL int rsel_init = FALSE;



#define WTCHAR "#"



rselect(string,outbuff)

char *string,*outbuff;

{

    register SELELT *item;

    SELELT *fndrsel(),*newrsel();

    register int irnd;

    

    if (!rsel_init) rs_init();

    item = fndrsel(string);

    if (item == NULL) item = newrsel(string);

    if (item == NULL) {

	*outbuff = '\0';

	return;

	}

    irnd = (rand() % item->wts) + 1;

#ifdef DEBUG

    printf("***In rselect: irnd=%d\n",irnd);

#endif

    item = item->nxtelt;

    while ((item != NULL) && (irnd > item->wts)) {

#ifdef DEBUG

	printf("***            item->wts=%d\n",item->wts);

#endif

	item = item->nxtelt;

	}

    if (item == NULL) *outbuff = '\0';

    else strcpy(outbuff,item->strng);

    }

LOCAL rs_init()

{

    register PATTERN_NODE *temp1,*temp2,*temp3;

    ARG_DESCR *acons();



    temp1 = len(1);

    rsel_l1 = cassign(temp1,acons(STRING,&BC));

    rsel_bc = lit_string(&BC);

    temp1 = c_lit_string(WTCHAR);

    temp2 = breakk_c(WTCHAR);

    temp2 = cassign(temp2,acons(STRING,&WT));

    temp3 = concat(temp2,temp1);

    temp3 = concat(temp1,temp3);

    temp2 = pos(0);

    rsel_wt = concat(temp2,temp3);

    temp1 = alt(breakk(&BC),REM);

    rsel_alt = cassign(temp1,acons(STRING,&ALT));

    rsel_init = TRUE;

    }

SELELT *newrsel(string)

register char *string;

{

    STRING_DESCR matched;

    char *ssaved;

    register int wt,weights;

    register SELELT *code,**c1;

    SELELT *head;

    register char *altstr;

#ifdef DEBUG

    register int status;

#endif



#ifdef DEBUG

    printf("***In newrsel: string=%s\n",string);

#endif

    ssaved = string;

    weights = 0;

    head = malloc(sizeof(SELELT));

    c1 = (&head->nxtelt);

    if (pmatch(string,rsel_l1,&matched) == MATCH_FAIL) return(NULL);

    do {

	string += matched.length;

	wt = 1;

	if (pmatch(string,rsel_wt,&matched) == MATCH_SUCCESS) {

	    string += matched.length;

	    wt = atoi(WT.base+WT.offset);

	    }

#ifdef DEBUG

	printf("***            wt=%d\n",wt);

	printf("***            string=%s\n",string);

	status = 

#endif

	pmatch(string,rsel_alt,&matched);

	string += matched.length;

#ifdef DEBUG

	printf("***            match status is %d\n",status);

	printf("***            string=%s\n",string);

#endif

	weights += wt;

	code = malloc(sizeof(SELELT));

	altstr = malloc(ALT.length+1);

	code->wts = weights;

	code->strng = altstr;

	strncpy(altstr,ALT.base+ALT.offset,ALT.length);

	altstr[ALT.length] = '\0';

#ifdef DEBUG

	printf("***            code->wts=%d,code->strng=%s\n",code->wts,

	       code->strng);

#endif

	*c1 = code;

	c1 = (&code->nxtelt);

	} while(pmatch(string,rsel_bc,&matched) == MATCH_SUCCESS);

    *c1 = NULL;

    head->wts = weights;

    altstr = malloc(strlen(ssaved)+1);

    strcpy(altstr,ssaved);

    head->strng = altstr;

#ifdef DEBUG

    printf("***            head->wts=%d,head->strng=%s\n",head->wts,

	   head->strng);

#endif

    rselins(head);

    return(head);

    }

rselins(elt)

register SELELT *elt;

{

    int eltcmp();



    if (rsel_cnt >= MAXRSEL) {

	fprintf(stderr,"rselect: too many items (> %d)\n",MAXRSEL);

	abort();

	}

    rsel_tbl[rsel_cnt] = elt;

    rsel_cnt++;

    if (rsel_cnt > 1) qsort(rsel_tbl,rsel_cnt,sizeof(SELELT *),eltcmp);

    }

SELELT *fndrsel(str)

register char *str;

{

    register int first,last,indx,cmp;

    register SELELT *item;



    first = 0; last = rsel_cnt;

    while (first < last) {

	indx = ((last - first) >> 1) + first;

	item = rsel_tbl[indx];

	cmp = strcmp(str,item->strng);

	if (cmp == 0) return(item);

	else if (cmp < 0) last = indx;

	else first = indx+1;

	}

    return(NULL);

    }

LOCAL eltcmp(a,b)

SELELT **a,**b;

{

    register SELELT *aa,*bb;



    aa = *a; bb = *b;

    return(strcmp(aa->strng,bb->strng));

    }