symbol.c

#include <stdlib.h>
#include <string.h>

#include "anicca.h"
#include "symbol.h"

A local;
A global;

I twprimes[NTWPRM]={31,61,103,241,523,883};

B symbinit(VO) {
    local=gsa(SYMB,1,twprimes[2],NULL);
    global=gsa(SYMB,1,twprimes[3],NULL);
    R 1;
}

B vldnm(I n, C *s) {
    R 1;
}

/*
  probe:  Hashing function. (Knuth, Algorithm L, pg 518).
  input:  (1)Symbol name, (2)Symbol table, (3)Assignment.
  output: Position in symbol table.
*/
static I probe(A y, A symb, B is) { A s; SY *tbl=SYAV(symb);
    C *nm=CAV(y); I n=AN(y), m=AN(symb);
    I k=256*(n+nm[0]+nm[n-1]);
    I i=k%m;
    if (is) { while (tbl[i].value) { i+=i>0?-1:m; } }
    else    { while ((s=tbl[i].name)&&(strncmp(nm,CAV(s),n))) { i+=i>0?-1:m; } }
    R i;
}

/*
  symbfind: Find name in symbol table.
  input:    (1)Name of symbol, (2)Symbol table.
  output:   Value of symbol.
*/
DYAD(symbfind) { SY *tbl=SYAV(y);
    A z=tbl[probe(x,y,0)].value;
    ASSERT(z,ERVALUE);
    R ca(z);
}

/*
  symblg: Find name in local or global symbol table.
  input:  Name of symbol.
  outout: Value of symbol.
*/
MONAD(symblg) { A z; R z; }

static I nmclr(A y, A symb) {
    I i=probe(y,symb,0);
    SY *sy=SYAV(symb)+i;
    B v=sy->value&&(sy->value!=mark);
    if (v) {
        freea(sy->name);  sy->name=NULL;
        freea(sy->value); sy->value=NULL;
    }
    R i;
}

/*
  symbis: Store a symbol in a given symbol table.
  input:  (1)Symbol name, (2)Symbol value, (3)Symbol table.
  output: Stored symbol.
*/
DDYAD(symbis) { A z; SY *sy; I i;
    if ((i=nmclr(x,self))>0) {
        /*i=probe(x,self,1);*/
        sy=SYAV(self)+i;
        sy->name=x;  refa(sy->name);
        sy->value=y; refa(sy->value);
    }
    else { a_signal(ERASGN); }
    R y;
}