From 425ef692da7e74112f88f0b368f3286dba84f846 Mon Sep 17 00:00:00 2001
From: Nicholas Noll <nbnoll@eml.cc>
Date: Thu, 18 Jun 2020 19:45:40 -0700
Subject: feat: working parser for rc shell language

---
 sys/cmd/rc/tree.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 sys/cmd/rc/tree.c

(limited to 'sys/cmd/rc/tree.c')

diff --git a/sys/cmd/rc/tree.c b/sys/cmd/rc/tree.c
new file mode 100644
index 0000000..8dca67f
--- /dev/null
+++ b/sys/cmd/rc/tree.c
@@ -0,0 +1,144 @@
+#include "rc.h"
+
+// -----------------------------------------------------------------------
+// globals
+
+static Tree *nodes;
+
+// -----------------------------------------------------------------------
+// exported funcs
+
+Tree*
+newtree(void)
+{
+    Tree *t;
+
+    alloc(t);
+    t->str = nil;
+    t->child[0] = t->child[1] = t->child[2] = nil;
+    t->redir.fd[0] = t->redir.fd[1] = t->redir.type = 0;
+
+    t->link = nodes, nodes = t;
+    return t;
+}
+
+void
+freetree(Tree *t)
+{
+    if (!t)
+        return;
+
+    freetree(t->child[0]);
+    freetree(t->child[1]);
+    freetree(t->child[2]);
+
+    if (t->str)
+        efree(t->str);
+    efree(t);
+}
+
+void
+freenodes(void)
+{
+    Tree *t, *u;
+
+    for (t = nodes;t;t = u) {
+        u = t->link;
+        if (t->str)
+            efree(t->str);
+        efree(t);
+    }
+    nodes = nil;
+}
+
+/* tree creation */
+Tree*
+tree3(int type, Tree *c0, Tree *c1, Tree *c2)
+{
+    Tree *t;
+
+    t = newtree();
+    t->type = type;
+    t->child[0] = c0;
+    t->child[1] = c1;
+    t->child[2] = c2;
+
+    return t;
+}
+
+Tree*
+tree2(int type, Tree *c0, Tree *c1)
+{
+	return tree3(type, c0, c1, nil);
+}
+
+Tree*
+tree1(int type, Tree *c0)
+{
+	return tree3(type, c0, nil, nil);
+}
+
+/* tree hang */
+Tree*
+hang1(Tree *p, Tree *c0)
+{
+    p->child[0] = c0;
+    return p;
+}
+
+Tree*
+hang2(Tree *p, Tree *c0, Tree *c1)
+{
+    p->child[0] = c0;
+    p->child[1] = c1;
+    return p;
+}
+
+Tree*
+hang3(Tree *p, Tree *c0, Tree *c1, Tree *c2)
+{
+    p->child[0] = c0;
+    p->child[1] = c1;
+    p->child[2] = c2;
+    return p;
+}
+
+/* hangs the cmd underneath the epilogue */
+Tree*
+epihang(Tree *c, Tree *epi)
+{
+    Tree *p;
+    if(!epi)
+        return c;
+    for(p=epi;p->child[1];p = p->child[1])
+        ;
+    p->child[1] = c;
+    return epi;
+}
+
+/* hangs tree t from a new simple node. percolates redirections to root */
+Tree*
+simplehang(Tree *t)
+{
+    Tree *u;
+    t = tree1(Asimple, t);
+    for(u = t->child[0];u->type==Aargs;u=u->child[0]) {
+        if (u->child[1]->type==Adup
+        ||  u->child[1]->type==Aredir){
+            u->child[1]->child[1] = t;
+            t = u->child[1];
+            u->child[1] = nil;
+        }
+    }
+    return t;
+}
+
+Tree*
+wordnode(char *w)
+{
+    Tree *t = newtree();
+    t->type = Aword;
+    t->str  = strdup(w);
+
+    return t;
+}
-- 
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