blah.diff

diff --git a/cclox.cc b/cclox.cc
index 0e9d3c5..f736492 100644
--- a/cclox.cc
+++ b/cclox.cc
@@ -59,7 +59,7 @@ struct Value {
   }
 
 
-  auto copy() -> Value {
+  [[nodiscard]] auto copy() const -> Value {
     auto result = Value(Nil());
     result.data = data;
     return result;
@@ -157,12 +157,6 @@ enum class Op : uint8_t {
 
 
 struct Chunk {
-  std::vector<uint8_t> code;
-  std::vector<int> lines;
-  std::vector<Value> constants;
-  std::vector<std::unique_ptr<std::string>> strings;
-
-
   auto write(uint8_t byte, int line) -> void {
     code.push_back(byte);
     lines.push_back(line);
@@ -182,6 +176,34 @@ struct Chunk {
     constants.emplace_back(std::forward<Args>(args)...);
     return int(constants.size() - 1);
   }
+
+
+  [[nodiscard]] auto size() const -> int {
+    return int(code.size());
+  }
+
+  [[nodiscard]] auto start() const -> const uint8_t * {
+    return code.data();
+  }
+
+  [[nodiscard]] auto read(int offset) const -> uint8_t {
+    return code[offset];
+  }
+
+  [[nodiscard]] auto line(int offset) const -> int {
+    return lines[offset];
+  }
+
+  [[nodiscard]] auto constant(int id) const -> const Value & {
+    return constants[id];
+  }
+
+
+private:
+  std::vector<uint8_t> code;
+  std::vector<int> lines;
+  std::vector<Value> constants;
+  std::vector<std::unique_ptr<std::string>> strings;
 };
 
 
@@ -198,13 +220,13 @@ struct Disassembly {
   auto instruction(int offset) -> int {
     std::printf("%04d ", offset);
 
-    if (offset > 0 && chunk.lines[offset] == chunk.lines[offset - 1]) {
+    if (offset > 0 && chunk.line(offset) == chunk.line(offset - 1)) {
       std::printf("   | ");
     } else {
-      std::printf("%4d ", chunk.lines[offset]);
+      std::printf("%4d ", chunk.line(offset));
     }
 
-    switch (auto opCode = Op(chunk.code[offset])) {
+    switch (auto opCode = Op(chunk.read(offset))) {
     case Op::Constant:
       return constant("OP_CONSTANT", offset);
     case Op::Nil:
@@ -242,7 +264,7 @@ struct Disassembly {
   auto all(std::string_view name) {
     std::printf("== %.*s ==\n", int(name.size()), name.data());
 
-    for (auto offset = 0; offset < chunk.code.size();) {
+    for (auto offset = 0; offset < chunk.size();) {
       offset = instruction(offset);
     }
   }
@@ -258,9 +280,9 @@ private:
   }
 
   auto constant(std::string_view name, int offset) -> int {
-    auto constant = chunk.code[offset + 1];
+    auto constant = chunk.read(offset + 1);
     std::printf("%-16.*s %4d '", int(name.size()), name.data(), constant);
-    chunk.constants[constant].print();
+    chunk.constant(constant).print();
     std::printf("'\n");
     return offset + 2;
   }
@@ -858,14 +880,14 @@ struct VM {
     };
 
 
-    auto ip = chunk.code.data();
+    auto ip = chunk.start();
 
     const auto readByte = [&]() -> uint8_t {
       return *ip++;
     };
 
     const auto readConstant = [&]() -> Value {
-      return chunk.constants[readByte()].copy();
+      return chunk.constant(readByte()).copy();
     };
 
 
@@ -877,8 +899,8 @@ struct VM {
       fprintf(stderr, fmt, args...);
 #pragma clang diagnostic pop
 
-      auto instruction = ip - chunk.code.data() - 1;
-      auto line = chunk.lines[instruction];
+      auto offset = ip - chunk.start() - 1;
+      auto line = chunk.line(offset);
       fprintf(stderr, "\n[line %d] in script\n", line);
 
       clear();
@@ -908,7 +930,7 @@ struct VM {
           std::printf(" ]");
         }
         std::printf("\n");
-        Disassembly(chunk).instruction(int(ip - chunk.code.data()));
+        Disassembly(chunk).instruction(int(ip - chunk.start()));
       }
 
       switch (auto instruction = Op(readByte())) {