From bf03074e346b004659196b6c17eee04dbffd3ac2 Mon Sep 17 00:00:00 2001
From: Nicholas Noll <nbnoll@eml.cc>
Date: Fri, 15 Oct 2021 16:18:02 -0700
Subject: feat(rc): working prototype of input->compile->print loop

---
 sys/cmd/rc/code.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 sys/cmd/rc/code.c

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

diff --git a/sys/cmd/rc/code.c b/sys/cmd/rc/code.c
new file mode 100644
index 0000000..6deed89
--- /dev/null
+++ b/sys/cmd/rc/code.c
@@ -0,0 +1,164 @@
+#include "rc.h"
+#include "parse.h"
+#include "exec.h"
+
+// -----------------------------------------------------------------------
+// types
+
+struct Interpreter
+{
+    int i, cap;
+    Code  *code;
+};
+
+Code *compiled = nil;
+static struct Interpreter interpreter;
+#define	emiti(x) ((void)(interpreter.i != interpreter.cap || grow()), interpreter.code[interpreter.i].i = (x), interpreter.i++)
+#define	emitf(x) ((void)(interpreter.i != interpreter.cap || grow()), interpreter.code[interpreter.i].f = (x), interpreter.i++)
+#define	emits(x) ((void)(interpreter.i != interpreter.cap || grow()), interpreter.code[interpreter.i].s = (x), interpreter.i++)
+
+static
+int
+grow(void)
+{
+    interpreter.cap += 100;
+    interpreter.code = erealloc(interpreter.code, sizeof(*interpreter.code)*interpreter.cap);
+    memset(interpreter.code+interpreter.cap-100, 0, 100*sizeof(*interpreter.code));
+
+    return 0;
+}
+
+static
+void
+stashaddr(int a)
+{
+    if(interpreter.i <= a || a < 0)
+        fatal("bad address %d in interpreter", a);
+
+    interpreter.code[a].i = interpreter.i;
+}
+
+static
+void
+walk(Tree *node)
+{
+    int p;
+    Tree *n;
+
+    if(!node)
+        return;
+
+    switch(node->type){
+    default:
+        print(errio, "bad type %d in interpreter walk\n", node->type);
+        break;
+
+    case '$':
+        emitf(Xmark);
+        walk(node->child[0]);
+        emitf(Xdollar);
+        break;
+
+    case '&':
+        emitf(Xasync);
+        p = emiti(0);
+        emitf(Xexit);
+        stashaddr(p);
+        break;
+
+    case ';':
+        walk(node->child[0]);
+        walk(node->child[1]);
+        break;
+
+    case '^':
+        emitf(Xmark);
+        walk(node->child[1]);
+        emitf(Xmark);
+        walk(node->child[0]);
+        emitf(Xconcatenate);
+        break;
+
+    case Targs:
+        walk(node->child[1]);
+        walk(node->child[0]);
+        break;
+
+    case Tparen: case Tblock:
+        walk(node->child[0]);
+        break;
+
+    case Tbasic:
+        emitf(Xmark);
+        walk(node->child[0]);
+        emitf(Xbasic);
+        break;
+
+    case Tword:
+        emitf(Xword);
+        emits(strdup(node->str));
+        break;
+
+    case '=':
+        for(n=node; node && node->type == '='; node = node->child[2])
+            ;
+        if(node){
+            for(node=n; node->type=='='; node = node->child[2]){
+                emitf(Xmark);
+                walk(node->child[1]);
+                emitf(Xmark);
+                walk(node->child[0]);
+                emitf(Xlocal);
+            }
+            walk(node);
+            for(node=n; node->type=='='; node = node->child[2])
+                emitf(Xunlocal);
+        }else{
+            for(node=n; node; node=node->child[2]){
+                emitf(Xmark);
+                walk(node->child[1]);
+                emitf(Xmark);
+                walk(node->child[0]);
+                emitf(Xassign);
+            }
+        }
+        node = n;
+        break;
+    }
+}
+
+// -----------------------------------------------------------------------
+// main exports
+
+void
+freecode(Code *c)
+{
+    if(--c[0].i!=0)
+        return;
+    efree(c);
+}
+
+Code *
+copycode(Code *c)
+{
+    c[0].i++;
+    return c;
+}
+
+int
+compile(Tree *node)
+{
+    flush(errio);
+    print(errio, "%t\n", node);
+
+    interpreter.i = 0;
+    emiti(1); // reference count
+
+    walk(node);
+
+    emitf(Xreturn);
+    emitf(nil);
+
+    compiled =  interpreter.code;
+    return 0;
+}
-- 
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