1 files changed, 42 insertions, 2 deletions

diff --git a/vm.d b/vm.d
index 6011928..7955963 100644
--- a/vm.d
+++ b/vm.d
@@ -1,5 +1,6 @@
 import std.stdio;
 import std.string;
+import std.conv;
 
 import chunk;
 import parser;
@@ -19,6 +20,7 @@ class VM {
     Value[] stack;
     //ObjFunction func;
     Function func;
+    Value[string] globals;
 
     this(Function func) {
         this.func = func;
@@ -26,6 +28,7 @@ class VM {
     
     Value peek(int offset) {
         if (offset >= this.topOffset) {
+        //if (offset > this.topOffset) {
             writefln("offset of %d greater than stack size %d", offset, topOffset);
         }
         return this.stack[topOffset - offset - 1];
@@ -58,22 +61,55 @@ class VM {
         return value.type == ValueType.NUMBER;
     }
 
+    bool isString(Value value) {
+        return value.type == ValueType.STRING;
+    }
+
     double asNumber(Value value) {
         return value.as.number;
     }
 
+    string asString(Value value) {
+        return value.as.str;
+    }
+
     InterpretResult run() {
         //int ip = 0;  // TODO this is wrong
         while (true) {
             write("          ");
-            //foreach (Value val; this.stack) {
             for (int i = 0; i < this.topOffset; i++) {
                 writef("[ %s ]", printableValue(this.stack[i]));
             }
             writeln("\n--");
+
             disassemble(this.func.chunk, this.ip);
             ubyte inst;
             switch (inst = this.readByte()) {
+                case OpCode.OP_DEFINE_GLOBAL:
+                    Value name = func.chunk.constants[readByte()];
+                    if (!isString(name)) {
+                        writefln("variables must be strings, got %s", printableValue(name));
+                        return InterpretResult.RUNTIME_ERROR;  // TODO error
+                    }
+                    Value val = pop();
+                    globals[asString(name)] = val;
+                    break;
+                case OpCode.OP_GET_GLOBAL:
+                    writeln("in OP_GET_GLOBAL");
+                    Value name = func.chunk.constants[readByte()];
+                    writefln(asString(name));
+                    if (!isString(name)) {
+                        writefln("variables must be strings, got %s", printableValue(name));
+                        return InterpretResult.RUNTIME_ERROR;  // TODO error
+                    }
+                    writefln(asString(name));
+                    Value* member = asString(name) in globals;
+                    if (member is null) {
+                        writefln("no such variable: %s", printableValue(name));
+                        return InterpretResult.RUNTIME_ERROR;  // TODO error
+                    }
+                    push(*member);  // do i need to dereference?
+                    break;
                 case OpCode.OP_CONSTANT:
                     Value constant = this.func.chunk.constants[this.readByte()];
                     this.push(constant);
@@ -142,5 +178,9 @@ class VM {
         }
 
     }
-
 }
+
+/*
+InterpretResult interpret(string source) {
+    Parser parser = new Parser(source);
+*/