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	var.c - 9base - revived minimalist port of Plan 9 userland to Unix
	git clone git://git.suckless.org/9base
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	---
	var.c (2561B)
	---
	1 #include "rc.h"
	2 #include "exec.h"
	3 #include "fns.h"
	4
	5 int
	6 hash(char *s, int n)
	7 {
	8 int h = 0, i = 1;
	9 while(s) h+=s++*i++;
	10 h%=n;
	11 return h<0?h+n:h;
	12 }
	13 #define NKW 30
	14 struct kw{
	15 char *name;
	16 int type;
	17 struct kw *next;
	18 }*kw[NKW];
	19
	20 void
	21 kenter(int type, char *name)
	22 {
	23 int h = hash(name, NKW);
	24 struct kw *p = new(struct kw);
	25 p->type = type;
	26 p->name = name;
	27 p->next = kw[h];
	28 kw[h] = p;
	29 }
	30
	31 void
	32 kinit(void)
	33 {
	34 kenter(FOR, "for");
	35 kenter(IN, "in");
	36 kenter(WHILE, "while");
	37 kenter(IF, "if");
	38 kenter(NOT, "not");
	39 kenter(TWIDDLE, "~");
	40 kenter(BANG, "!");
	41 kenter(SUBSHELL, "@");
	42 kenter(SWITCH, "switch");
	43 kenter(FN, "fn");
	44 }
	45
	46 tree*
	47 klook(char *name)
	48 {
	49 struct kw *p;
	50 tree *t = token(name, WORD);
	51 for(p = kw[hash(name, NKW)];p;p = p->next)
	52 if(strcmp(p->name, name)==0){
	53 t->type = p->type;
	54 t->iskw = 1;
	55 break;
	56 }
	57 return t;
	58 }
	59
	60 var*
	61 gvlook(char *name)
	62 {
	63 int h = hash(name, NVAR);
	64 var *v;
	65 for(v = gvar[h];v;v = v->next) if(strcmp(v->name, name)==0) retu…
	66 return gvar[h] = newvar(strdup(name), gvar[h]);
	67 }
	68
	69 var*
	70 vlook(char *name)
	71 {
	72 var *v;
	73 if(runq)
	74 for(v = runq->local;v;v = v->next)
	75 if(strcmp(v->name, name)==0) return v;
	76 return gvlook(name);
	77 }
	78
	79 void
	80 _setvar(char name, word val, int callfn)
	81 {
	82 struct var *v = vlook(name);
	83 freewords(v->val);
	84 v->val=val;
	85 v->changed=1;
	86 if(callfn && v->changefn)
	87 v->changefn(v);
	88 }
	89
	90 void
	91 setvar(char name, word val)
	92 {
	93 _setvar(name, val, 1);
	94 }
	95
	96 void
	97 bigpath(var *v)
	98 {
	99 /* convert $PATH to $path */
	100 char p, q;
	101 word *l, w;
	102
	103 if(v->val == nil){
	104 _setvar("path", nil, 0);
	105 return;
	106 }
	107 p = v->val->word;
	108 w = nil;
	109 l = &w;
	110 /*
	111 * Doesn't handle escaped colon nonsense.
	112 */
	113 if(p[0] == 0)
	114 p = nil;
	115 while(p){
	116 q = strchr(p, ':');
	117 if(q)
	118 *q = 0;
	119 *l = newword(p[0] ? p : ".", nil);
	120 l = &(*l)->next;
	121 if(q){
	122 *q = ':';
	123 p = q+1;
	124 }else
	125 p = nil;
	126 }
	127 _setvar("path", w, 0);
	128 }
	129
	130 char*
	131 list2strcolon(word *words)
	132 {
	133 char value, s, *t;
	134 int len = 0;
	135 word *ap;
	136 for(ap = words;ap;ap = ap->next)
	137 len+=1+strlen(ap->word);
	138 value = emalloc(len+1);
	139 s = value;
	140 for(ap = words;ap;ap = ap->next){
	141 for(t = ap->word;t;) s++=*t++;
	142 *s++=':';
	143 }
	144 if(s==value)
	145 *s='\0';
	146 else s[-1]='\0';
	147 return value;
	148 }
	149 void
	150 littlepath(var *v)
	151 {
	152 /* convert $path to $PATH */
	153 char *p;
	154 word *w;
	155
	156 p = list2strcolon(v->val);
	157 w = new(word);
	158 w->word = p;
	159 w->next = nil;
	160 _setvar("PATH", w, 1); /* 1: recompute $path to expose co…
	161 }
	162
	163 void
	164 pathinit(void)
	165 {
	166 var *v;
	167
	168 v = gvlook("path");
	169 v->changefn = littlepath;
	170 v = gvlook("PATH");
	171 v->changefn = bigpath;
	172 bigpath(v);
	173 }