1 files changed, 64 insertions, 0 deletions
diff --git a/dbg.d b/dbg.d
new file mode 100644
index 0000000..4af02a6
--- /dev/null
+++ b/dbg.d
@@ -0,0 +1,64 @@
+import std.stdio;
+import std.string;
+
+import chunk;
+import parser : Value, Atom, ValueType;
+//import parser;
+//import dbg;
+//import value;
+
+string printableValue(Value val) {
+    switch (val.type) {
+        case ValueType.STRING:
+            return val.as.str;
+        case ValueType.NUMBER:
+            return format("%g", val.as.number);
+        case ValueType.BOOLEAN:
+            if (val.as.boolean) {
+                return "true";
+            } else {
+                return "false";
+            }
+        default:
+            return "! unknown value type !";
+    }
+}
+
+string atomAsString(Atom a) {
+    return printableValue(a.value);
+}
+
+int constantInstruction(string message, Chunk chunk, int offset) {
+    ubyte idx = chunk.code[offset + 1];
+    //writeln("dunno how to write a constant");
+    writefln("%-16s %4d '%s'", message, idx, printableValue(chunk.constants[idx]));
+    //writefln("%-16s %4d '%s'", message, idx, atomAsString(chunk.constants[idx]));
+    return offset + 2;
+}
+
+int simpleInstruction(string message, int offset) {
+    writeln(message);
+    return offset + 1;
+}
+
+int disassemble(Chunk chunk, int offset) {
+    writef("%04d %4d ", offset, chunk.lines[offset]);
+
+    ubyte inst = chunk.code[offset];
+    switch (inst) {
+        case OpCode.OP_ADD:
+            return simpleInstruction("OP_ADD", offset);
+        case OpCode.OP_CONSTANT:
+            return constantInstruction("OP_CONSTANT", chunk, offset);
+        case OpCode.OP_NEGATE:
+            return simpleInstruction("OP_NEGATE", offset);
+        case OpCode.OP_POP:
+            return simpleInstruction("OP_POP", offset);
+        case OpCode.OP_RETURN:
+            return simpleInstruction("OP_RETURN", offset);
+        default:
+            writeln("unknown opcode?");
+            return offset + 1;
+    }
+    return 0;
+}