From 5948bfa973954ff5af4ded3fc39aee86d4979ada Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Thu, 22 Aug 2024 17:21:05 +0100
Subject: [PATCH] First working implementation of closures

---
 example.vli      |  8 +++++++-
 src/common.cpp   | 21 +++++++++++++++++++++
 src/common.hpp   |  4 ++--
 src/compiler.cpp |  4 +++-
 src/vm.cpp       | 16 ++++++++++++++++
 src/vm.hpp       |  2 ++
 6 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/example.vli b/example.vli
index 84dc672..ca94781 100644
--- a/example.vli
+++ b/example.vli
@@ -1,3 +1,9 @@
 ;; Check that lambdas can be passed as arguments
 
-((lambda (f y) (f y)) (lambda (x) (* x x)) 2)
+((lambda (f y) (f y))
+ (lambda (x) (* x x))
+ 2)
+
+(((lambda (x)
+    (lambda () (* x x 2)))
+  2))
diff --git a/src/common.cpp b/src/common.cpp
index f64b55d..bc23705 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -448,6 +448,27 @@ Result<short> Dict::cmp(const Dict& rhs) const {
   return 0;
 }
 
+Result<short> Array::cmp(const Array& rhs) const {
+  auto lsize = size();
+  auto rsize = rhs.size();
+  uint64_t i = 0;
+  uint64_t j = 0;
+  while (1) {
+    if (i == lsize && j == lsize) return 0;
+
+    short cmp = short(i == lsize) - short(j == rsize);
+    if (cmp != 0) return cmp;
+
+    Value lc = TRY(Value::create(_value->data[i].get()));
+    Value rc = TRY(Value::create(rhs._value->data[j].get()));
+    cmp = TRY(lc.cmp(rc));
+    if (cmp != 0) return cmp;
+    i++;
+    j++;
+  }
+  return 0;
+}
+
 Result<Value> Object::get(const Value& key) const {
   return ERROR(TypeMismatch);
 }
diff --git a/src/common.hpp b/src/common.hpp
index a8710b7..b19ba0b 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -75,7 +75,7 @@ class Object {
     return cmp_tag(tag(), Tag::Opcode);
   }
   virtual Result<short> cmp(const Function& rhs) const {
-    return cmp_tag(tag(), Tag::Opcode);
+    return cmp_tag(tag(), Tag::Function);
   }
   virtual Result<short> cmp(const char* rhs) const {
     return ERROR(NotImplemented);
@@ -150,7 +150,7 @@ class Array : public Object {
   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 Result<short> cmp(const Array& rhs) const final;
 
   virtual void move(Object* obj) final { new (obj) Array(std::move(_value)); }
 
diff --git a/src/compiler.cpp b/src/compiler.cpp
index 757bc5a..58c28ca 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -373,6 +373,7 @@ Result<Expression> Compiler::compile_lambda(Context& context, Symbol& op,
     uint64_t reg = context.alloc_reg();
     TRY(ex_res.add_opcode(Oc::Mov, {0, (int64_t)reg}, {1, (int64_t)c}));
 
+    context.maxreg = reg + 1;
     ex_res.reg = reg;
 
     return ex_res;
@@ -393,7 +394,7 @@ Result<Expression> Compiler::compile_lambda(Context& context, Symbol& op,
   TRY(ex_res.add_opcode(Oc::MakeClosure, {0, (int64_t)reg},
                         {0, (int64_t)reg + (int64_t)ctx.closures.size() + 1}));
 
-  context.maxreg = reg;
+  context.maxreg = reg + 1;
   ex_res.reg = reg;
 
   return ex_res;
@@ -459,6 +460,7 @@ Result<Expression> Compiler::compile_function_call(Context& context,
                     {0, (int64_t)context.maxreg}));
 
   ex.reg = fun_ex.reg;
+  context.maxreg = maxreg;
   return ex;
 }
 
diff --git a/src/vm.cpp b/src/vm.cpp
index 6a9b38f..09166a4 100644
--- a/src/vm.cpp
+++ b/src/vm.cpp
@@ -96,6 +96,7 @@ Result<void> VM::vm_call(Opcode& oc) {
 
   _code = TRY(fun.code());
   _constants = TRY(fun.constants());
+  _closure = TRY(fun.closure());
   _fun = std::move(fun);
   _pc = 0;
   _base = reg_start;
@@ -123,6 +124,7 @@ Result<void> VM::vm_ret(Opcode& oc) {
 
   _code = TRY(fun.code());
   _constants = TRY(fun.constants());
+  _closure = TRY(fun.closure());
   _fun = std::move(fun);
   _pc = pc + 1;
   _base = oldbase;
@@ -155,11 +157,21 @@ Result<void> VM::vm_make_closure(Opcode& oc) {
   return Result<void>();
 }
 
+Result<void> VM::vm_closure_load(Opcode& oc) {
+  uint64_t acc = (uint64_t)oc.arg1().arg;
+  Value val = TRY(_closure.get((uint64_t)oc.arg2().arg));
+  setreg(acc, val);
+  _pc++;
+  return Result<void>();
+}
+
 Result<void> VM::step() {
   auto opcode = TRY(_code.get(_pc));
   if (!opcode.is<Opcode>()) return ERROR(TypeMismatch);
   Opcode& oc = *opcode.to<Opcode>();
 
+  // TRY(debug_print(TRY(oc.copy_value())));
+
   switch (oc.opcode()) {
     case Oc::Mov:
       TRY(vm_mov(oc));
@@ -191,6 +203,9 @@ Result<void> VM::step() {
     case Oc::MakeClosure:
       TRY(vm_make_closure(oc));
       break;
+    case Oc::ClosureLoad:
+      TRY(vm_closure_load(oc));
+      break;
     default:
       return ERROR(NotImplemented);
   }
@@ -206,6 +221,7 @@ Result<Value> VM::run(const Function& fun) {
   _base = 0;
   _code = TRY(fun.code());
   _constants = TRY(fun.constants());
+  _closure = TRY(fun.closure());
 
   while (true) {
     auto rc = step();
diff --git a/src/vm.hpp b/src/vm.hpp
index 6d78b8e..1cd82f4 100644
--- a/src/vm.hpp
+++ b/src/vm.hpp
@@ -32,6 +32,7 @@ class VM {
   Result<void> vm_jump(Opcode& oc);
 
   Result<void> vm_make_closure(Opcode& oc);
+  Result<void> vm_closure_load(Opcode& oc);
 
   Result<Value> get(bool is_const, uint64_t idx);
   Result<Value> getconst(uint64_t idx);
@@ -44,6 +45,7 @@ class VM {
   Function _fun;
   Array _code;
   Array _constants;
+  Array _closure;
   uint64_t _pc;
   uint64_t _base;
   Value _res;