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	tree.c - 9base - revived minimalist port of Plan 9 userland to Unix
	git clone git://git.suckless.org/9base
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	---
	tree.c (2071B)
	---
	1 #include "rc.h"
	2 #include "exec.h"
	3 #include "io.h"
	4 #include "fns.h"
	5 tree *treenodes;
	6 /*
	7 * create and clear a new tree node, and add it
	8 * to the node list.
	9 */
	10
	11 tree*
	12 newtree(void)
	13 {
	14 tree *t = new(tree);
	15 t->iskw = 0;
	16 t->str = 0;
	17 t->child[0] = t->child[1] = t->child[2] = 0;
	18 t->next = treenodes;
	19 treenodes = t;
	20 return t;
	21 }
	22
	23 void
	24 freenodes(void)
	25 {
	26 tree t, u;
	27 for(t = treenodes;t;t = u){
	28 u = t->next;
	29 if(t->str)
	30 efree(t->str);
	31 efree((char *)t);
	32 }
	33 treenodes = 0;
	34 }
	35
	36 tree*
	37 tree1(int type, tree *c0)
	38 {
	39 return tree3(type, c0, (tree )0, (tree )0);
	40 }
	41
	42 tree*
	43 tree2(int type, tree c0, tree c1)
	44 {
	45 return tree3(type, c0, c1, (tree *)0);
	46 }
	47
	48 tree*
	49 tree3(int type, tree c0, tree c1, tree *c2)
	50 {
	51 tree *t;
	52 if(type==';'){
	53 if(c0==0)
	54 return c1;
	55 if(c1==0)
	56 return c0;
	57 }
	58 t = newtree();
	59 t->type = type;
	60 t->child[0] = c0;
	61 t->child[1] = c1;
	62 t->child[2] = c2;
	63 return t;
	64 }
	65
	66 tree*
	67 mung1(tree t, tree c0)
	68 {
	69 t->child[0] = c0;
	70 return t;
	71 }
	72
	73 tree*
	74 mung2(tree t, tree c0, tree *c1)
	75 {
	76 t->child[0] = c0;
	77 t->child[1] = c1;
	78 return t;
	79 }
	80
	81 tree*
	82 mung3(tree t, tree c0, tree c1, tree c2)
	83 {
	84 t->child[0] = c0;
	85 t->child[1] = c1;
	86 t->child[2] = c2;
	87 return t;
	88 }
	89
	90 tree*
	91 epimung(tree comp, tree epi)
	92 {
	93 tree *p;
	94 if(epi==0)
	95 return comp;
	96 for(p = epi;p->child[1];p = p->child[1]);
	97 p->child[1] = comp;
	98 return epi;
	99 }
	100 /*
	101 * Add a SIMPLE node at the root of t and percolate all the redirections
	102 * up to the root.
	103 */
	104
	105 tree*
	106 simplemung(tree *t)
	107 {
	108 tree *u;
	109 struct io *s;
	110 t = tree1(SIMPLE, t);
	111 s = openstr();
	112 pfmt(s, "%t", t);
	113 t->str = strdup(s->strp);
	114 closeio(s);
	115 for(u = t->child[0];u->type==ARGLIST;u = u->child[0]){
	116 if(u->child[1]->type==DUP
	117 \|\| u->child[1]->type==REDIR){
	118 u->child[1]->child[1] = t;
	119 t = u->child[1];
	120 u->child[1] = 0;
	121 }
	122 }
	123 return t;
	124 }
	125
	126 tree*
	127 token(char *str, int type)
	128 {
	129 tree *t = newtree();
	130 t->type = type;
	131 t->str = strdup(str);
	132 return t;
	133 }
	134
	135 void
	136 freetree(tree *p)
	137 {
	138 if(p==0)
	139 return;
	140 freetree(p->child[0]);
	141 freetree(p->child[1]);
	142 freetree(p->child[2]);
	143 if(p->str)
	144 efree(p->str);
	145 efree((char *)p);
	146 }