From f1fd15171cf6a98983b7c51c2cfce38b1f7fade0 Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Sat, 10 Aug 2024 18:46:20 +0100
Subject: [PATCH] Add const qualifiers where necessary

---
 src/arena.hpp    |   6 +-
 src/common.cpp   |  10 +--
 src/common.hpp   | 184 +++++++++++++++++++++++++++++------------------
 src/compiler.cpp |  28 ++++++--
 4 files changed, 144 insertions(+), 84 deletions(-)

diff --git a/src/arena.hpp b/src/arena.hpp
index 800831b..f21c009 100644
--- a/src/arena.hpp
+++ b/src/arena.hpp
@@ -44,9 +44,9 @@ class GcRoot : public GcRootBase {
   static Result<GcRoot<T>> create(T* ptr);
   Result<GcRoot<T>> copy() const { return GcRoot<T>::create((T*)_ptr); }
 
-  T* get() { return (T*)_ptr; }
-  T& operator*() { return *(T*)_ptr; }
-  T* operator->() { return (T*)_ptr; }
+  T* get() const { return (T*)_ptr; }
+  T& operator*() const { return *(T*)_ptr; }
+  T* operator->() const { return (T*)_ptr; }
 };
 
 template <class T>
diff --git a/src/common.cpp b/src/common.cpp
index cea7659..e143760 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -199,7 +199,7 @@ Result<Value> Dict::get(Value& key) {
   return TRY(Value::create(_value->data[pos * 2 + 1].get()));
 }
 
-Result<Dict> Dict::insert(Value& key, Value& value) {
+Result<Dict> Dict::insert(const Value& key, const Value& value) {
   auto pos = TRY(find(key));
   auto s = size();
   if (pos >= s) {
@@ -232,7 +232,7 @@ Result<Dict> Dict::insert(Value& key, Value& value) {
   return Dict(TRY(MkGcRoot(pod)));
 }
 
-Result<uint64_t> Dict::find(Value& key) {
+Result<uint64_t> Dict::find(const Value& key) {
   uint64_t left = 0;
   uint64_t right = size();
   uint64_t pos = (left + right) / 2;
@@ -253,17 +253,17 @@ Result<uint64_t> Dict::find(Value& key) {
   return left;
 }
 
-Result<short> Int64::cmp(Float& rhs) {
+Result<short> Int64::cmp(const Float& rhs) const {
   return (_value->value > rhs._value->value) -
          (_value->value < rhs._value->value);
 }
 
-Result<short> Float::cmp(Int64& rhs) {
+Result<short> Float::cmp(const Int64& rhs) const {
   return (_value->value > rhs._value->value) -
          (_value->value < rhs._value->value);
 }
 
-Result<short> Dict::cmp(Dict& rhs) {
+Result<short> Dict::cmp(const Dict& rhs) const {
   auto lsize = size() * 2;
   auto rsize = rhs.size() * 2;
   uint64_t i = 0;
diff --git a/src/common.hpp b/src/common.hpp
index 1b41a8d..7e02f79 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -31,23 +31,41 @@ short cmp_tag(Tag lhs, Tag rhs);
 
 class Object {
  public:
-  virtual Tag tag() = 0;
+  virtual Tag tag() const = 0;
   virtual Result<Value> copy() const = 0;
-  virtual PodObject* pod() = 0;
+  virtual PodObject* pod() const = 0;
   virtual void move(Object*) = 0;
   virtual ~Object() = default;
 
-  virtual Result<short> cmp(Object&) = 0;
-  virtual Result<short> cmp(Nil&) { return cmp_tag(tag(), Tag::Nil); }
-  virtual Result<short> cmp(Int64&) { return cmp_tag(tag(), Tag::Int64); }
-  virtual Result<short> cmp(Float&) { return cmp_tag(tag(), Tag::Float); }
-  virtual Result<short> cmp(Bool&) { return cmp_tag(tag(), Tag::Bool); }
-  virtual Result<short> cmp(String&) { return cmp_tag(tag(), Tag::String); }
-  virtual Result<short> cmp(Symbol&) { return cmp_tag(tag(), Tag::Symbol); }
-  virtual Result<short> cmp(Syntax&) { return cmp_tag(tag(), Tag::Syntax); }
-  virtual Result<short> cmp(Pair&) { return cmp_tag(tag(), Tag::Pair); }
-  virtual Result<short> cmp(Array&) { return cmp_tag(tag(), Tag::Array); }
-  virtual Result<short> cmp(ByteArray&) {
+  virtual Result<short> cmp(const Object&) const = 0;
+  virtual Result<short> cmp(const Nil&) const {
+    return cmp_tag(tag(), Tag::Nil);
+  }
+  virtual Result<short> cmp(const Int64&) const {
+    return cmp_tag(tag(), Tag::Int64);
+  }
+  virtual Result<short> cmp(const Float&) const {
+    return cmp_tag(tag(), Tag::Float);
+  }
+  virtual Result<short> cmp(const Bool&) const {
+    return cmp_tag(tag(), Tag::Bool);
+  }
+  virtual Result<short> cmp(const String&) const {
+    return cmp_tag(tag(), Tag::String);
+  }
+  virtual Result<short> cmp(const Symbol&) const {
+    return cmp_tag(tag(), Tag::Symbol);
+  }
+  virtual Result<short> cmp(const Syntax&) const {
+    return cmp_tag(tag(), Tag::Syntax);
+  }
+  virtual Result<short> cmp(const Pair&) const {
+    return cmp_tag(tag(), Tag::Pair);
+  }
+  virtual Result<short> cmp(const Array&) const {
+    return cmp_tag(tag(), Tag::Array);
+  }
+  virtual Result<short> cmp(const ByteArray&) const {
     return cmp_tag(tag(), Tag::ByteArray);
   }
   virtual Result<Value> get(Value& key);
@@ -62,11 +80,13 @@ class Nil : public Object {
   Nil(Nil&& rhs) : _value(std::move(rhs._value)) {}
   Nil(GcRoot<PodNil>&& val) : _value(std::move(val)) {}
 
-  virtual Tag tag() final { return Tag::Nil; }
-  virtual PodObject* pod() final { return _value.get(); }
+  virtual Tag tag() const final { return Tag::Nil; }
+  virtual PodObject* pod() const final { return _value.get(); }
 
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Nil& rhs) final { return 0; }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Nil& rhs) const final { return 0; }
 
   static Result<Nil> create(PodNil* obj) { return Nil(TRY(MkGcRoot(obj))); }
 
@@ -96,10 +116,12 @@ class Array : public Object {
     return *this;
   }
 
-  virtual Tag tag() final { return Tag::Array; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Array& rhs) final { return 0; }
+  virtual Tag tag() const final { return Tag::Array; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Array& rhs) const final { return 0; }
 
   virtual void move(Object* obj) final { new (obj) Array(std::move(_value)); }
 
@@ -170,10 +192,12 @@ class ByteArray : public Object {
     return *this;
   }
 
-  virtual Tag tag() final { return Tag::ByteArray; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(ByteArray& rhs) final { return 0; }
+  virtual Tag tag() const final { return Tag::ByteArray; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const ByteArray& rhs) const final { return 0; }
 
   virtual void move(Object* obj) final {
     new (obj) ByteArray(std::move(_value));
@@ -277,10 +301,12 @@ class Dict : public Object {
     return *this;
   }
 
-  virtual Tag tag() final { return Tag::Dict; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Dict& rhs) final;
+  virtual Tag tag() const final { return Tag::Dict; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Dict& rhs) const final;
 
   virtual void move(Object* obj) final { new (obj) Dict(std::move(_value)); }
 
@@ -299,7 +325,7 @@ class Dict : public Object {
 
   virtual Result<Value> get(Value& key) final;
 
-  Result<Dict> insert(Value& key, Value& value);
+  Result<Dict> insert(const Value& key, const Value& value);
 
   template <class K, class V>
   Result<Dict> insert(const K& key, const V& value);
@@ -323,9 +349,9 @@ class Dict : public Object {
   }
 
  private:
-  Result<uint64_t> find(Value& key);
+  Result<uint64_t> find(const Value& key);
 
-  uint64_t size() { return _value->size; }
+  uint64_t size() const { return _value->size; }
   GcRoot<PodDict> _value;
 };
 
@@ -340,10 +366,12 @@ class String : public Object {
     return *this;
   }
 
-  virtual Tag tag() final { return Tag::String; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(String& rhs) final {
+  virtual Tag tag() const final { return Tag::String; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const String& rhs) const final {
     auto lsize = size();
     auto rsize = rhs.size();
     uint64_t i = 0;
@@ -390,7 +418,7 @@ class String : public Object {
     return String(TRY(MkGcRoot(pod)));
   }
 
-  uint64_t size() { return _value->size; }
+  uint64_t size() const { return _value->size; }
   virtual Result<Value> copy() const final;
 
   Result<char32_t> operator[](uint64_t idx) {
@@ -461,10 +489,12 @@ class Symbol : public Object {
   Symbol() {}
   Symbol(Symbol&& rhs) : _value(std::move(rhs._value)) {}
   Symbol(GcRoot<PodSymbol>&& val) : _value(std::move(val)) {}
-  virtual Tag tag() final { return Tag::Symbol; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Symbol& rhs) final {
+  virtual Tag tag() const final { return Tag::Symbol; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Symbol& rhs) const final {
     auto lsize = size();
     auto rsize = rhs.size();
     uint64_t i = 0;
@@ -484,7 +514,7 @@ class Symbol : public Object {
     }
     return 0;
   }
-  virtual Result<short> cmp(const char* rhs) final {
+  virtual Result<short> cmp(const char* rhs) const final {
     auto lsize = size();
     auto rsize = strlen(rhs);
     uint64_t i = 0;
@@ -533,7 +563,7 @@ class Symbol : public Object {
   static Result<Symbol> create(String& rhs);
   virtual Result<Value> copy() const final;
 
-  uint64_t size() { return _value->size; }
+  uint64_t size() const { return _value->size; }
 
   Result<char32_t> operator[](uint64_t idx) {
     if (idx >= _value->size) return ERROR(IndexOutOfRange);
@@ -550,10 +580,12 @@ class Syntax : public Object {
   Syntax(Syntax&& rhs) : _value(std::move(rhs._value)) {}
   Syntax(GcRoot<PodSyntax>&& val) : _value(std::move(val)) {}
   Syntax(String filename, String modulename, Value expression);
-  virtual Tag tag() final { return Tag::Syntax; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Syntax& rhs) final { return 0; }
+  virtual Tag tag() const final { return Tag::Syntax; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Syntax& rhs) const final { return 0; }
 
   virtual void move(Object* obj) final { new (obj) Syntax(std::move(_value)); }
 
@@ -574,10 +606,12 @@ class Pair : public Object {
   Pair() {}
   Pair(Pair&& rhs) : _value(std::move(rhs._value)) {}
   Pair(GcRoot<PodPair>&& val) : _value(std::move(val)) {}
-  virtual Tag tag() final { return Tag::Pair; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Pair& rhs) final { return 0; }
+  virtual Tag tag() const final { return Tag::Pair; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Pair& rhs) const final { return 0; }
 
   virtual void move(Object* obj) final { new (obj) Pair(std::move(_value)); }
 
@@ -600,14 +634,16 @@ class Int64 : public Object {
   Int64() {}
   Int64(Int64&& rhs) : _value(std::move(rhs._value)) {}
   Int64(GcRoot<PodInt64>&& val) : _value(std::move(val)) {}
-  virtual Tag tag() final { return Tag::Int64; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Int64& rhs) final {
+  virtual Tag tag() const final { return Tag::Int64; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Int64& rhs) const final {
     return (_value->value > rhs._value->value) -
            (_value->value < rhs._value->value);
   }
-  virtual Result<short> cmp(Float& rhs) final;
+  virtual Result<short> cmp(const Float& rhs) const final;
 
   virtual void move(Object* obj) final { new (obj) Int64(std::move(_value)); }
 
@@ -638,14 +674,16 @@ class Float : public Object {
   Float() {}
   Float(Float&& rhs) : _value(std::move(rhs._value)) {}
   Float(GcRoot<PodFloat>&& val) : _value(std::move(val)) {}
-  virtual Tag tag() final { return Tag::Float; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Float& rhs) final {
+  virtual Tag tag() const final { return Tag::Float; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Float& rhs) const final {
     return (_value->value > rhs._value->value) -
            (_value->value < rhs._value->value);
   }
-  virtual Result<short> cmp(Int64& rhs) final;
+  virtual Result<short> cmp(const Int64& rhs) const final;
 
   virtual void move(Object* obj) final { new (obj) Float(std::move(_value)); }
 
@@ -675,10 +713,12 @@ class Bool : public Object {
   Bool(Bool&& rhs) : _value(std::move(rhs._value)) {}
   Bool(GcRoot<PodBool>&& val) : _value(std::move(val)) {}
 
-  virtual Tag tag() final { return Tag::Bool; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Bool& rhs) final { return 0; }
+  virtual Tag tag() const final { return Tag::Bool; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Bool& rhs) const final { return 0; }
 
   virtual void move(Object* obj) final { new (obj) Bool(std::move(_value)); }
 
@@ -706,10 +746,12 @@ class Opcode : public Object {
   Opcode(Opcode&& rhs) : _value(std::move(rhs._value)) {}
   Opcode(GcRoot<PodOpcode>&& val) : _value(std::move(val)) {}
 
-  virtual Tag tag() final { return Tag::Opcode; }
-  virtual PodObject* pod() final { return _value.get(); }
-  virtual Result<short> cmp(Object& rhs) final { return -TRY(rhs.cmp(*this)); }
-  virtual Result<short> cmp(Opcode& rhs) final { return 0; }
+  virtual Tag tag() const final { return Tag::Opcode; }
+  virtual PodObject* pod() const final { return _value.get(); }
+  virtual Result<short> cmp(const Object& rhs) const final {
+    return -TRY(rhs.cmp(*this));
+  }
+  virtual Result<short> cmp(const Opcode& rhs) const final { return 0; }
 
   virtual void move(Object* obj) final { new (obj) Opcode(std::move(_value)); }
 
@@ -787,13 +829,13 @@ class Value {
     return dynamic_cast<T*>((Object*)buf);
   }
 
-  PodObject* pod() { return ((Object*)buf)->pod(); }
+  PodObject* pod() const { return ((Object*)buf)->pod(); }
   Tag tag() { return ((Object*)buf)->tag(); }
 
   Object& operator*() { return *(Object*)(buf); }
   Object* operator->() { return (Object*)(buf); }
 
-  Result<short> cmp(Value& rhs) {
+  Result<short> cmp(const Value& rhs) const {
     return ((Object*)buf)->cmp(*(Object*)rhs.buf);
   }
 
diff --git a/src/compiler.cpp b/src/compiler.cpp
index da1bb1b..f0555d4 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -2,17 +2,19 @@
 
 struct Context {
   Context() {}
-  Context(Value&& env, Array&& constants)
+  Context(Value&& env, Array&& constants, Dict&& constants_dict)
       : env(std::move(env)),
         constants(std::move(constants)),
-        maxreg(0),
-        maxconst(0) {}
+        constants_dict(std::move(constants_dict)),
+        maxreg(0) {}
 
   static Result<Context> create() {
     auto env = TRY(Nil::create());
     auto constants = TRY(Array::create());
+    auto constants_dict = TRY(Dict::create());
 
-    return Context(std::move(env), std::move(constants));
+    return Context(std::move(env), std::move(constants),
+                   std::move(constants_dict));
   }
 
   uint64_t alloc_reg() {
@@ -21,10 +23,26 @@ struct Context {
     return reg;
   }
 
+  Result<int64_t> add_const(Value& val) {
+    auto idx = constants_dict.get(val);
+
+    if (idx.has_value()) {
+      if (!idx.value().is<Int64>()) return ERROR(TypeMismatch);
+
+      return idx.value().to<Int64>()->value();
+    }
+
+    int64_t i = constants.size();
+
+    constants = TRY(constants.append(val));
+    constants_dict = TRY(constants_dict.insert(val, TRY(Value::create(i))));
+    return i;
+  }
+
   Value env;
   Array constants;
+  Dict constants_dict;
   uint64_t maxreg;
-  uint64_t maxconst;
 };
 
 Result<Array> add_opcode(Array& opcodes, Oc opcode, OpArg arg1 = {0, 0},