From 0b62026d270d1198e696ea7657b7876d96b359e1 Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Sat, 7 Sep 2024 20:31:39 +0100
Subject: [PATCH] Implement simple quotation (no unquote yet though)

---
 src/common.cpp       | 22 ++++++++++++++++++++++
 src/common.hpp       |  1 +
 src/compiler.cpp     | 18 ++++++++++++++++++
 src/compiler.hpp     |  2 ++
 src/reader.cpp       | 22 ++++++++++++++++++++++
 src/reader.hpp       |  1 +
 test/collections.vli |  3 +++
 7 files changed, 69 insertions(+)

diff --git a/src/common.cpp b/src/common.cpp
index 014c51d..dd8d970 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -798,6 +798,28 @@ Result<Value> syntax_unwrap(const Value& value) {
   return TRY(value.to<Syntax>()->expression());
 }
 
+Result<Value> syntax_unwrap_all(const Value& value) {
+  if (value.is<Syntax>()) {
+    auto val = TRY(value.to<Syntax>()->expression());
+    return syntax_unwrap_all(val);
+  }
+
+  if (value.is<Pair>()) {
+    auto res = Value(TRY(Nil::create()));
+    auto cur = TRY(value.copy());
+
+    while (!cur.is<Nil>()) {
+      auto val = TRY(syntax_unwrap_all(TRY(cur.first())));
+      res = Value(TRY(Pair::create(val, res)));
+
+      cur = TRY(cur.rest());
+    }
+    return reverse(res);
+  }
+
+  return value.copy();
+}
+
 Result<Value> Syntax::first() const {
   auto val = TRY(expression());
   return val.first();
diff --git a/src/common.hpp b/src/common.hpp
index e28e3da..1bb340e 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -1298,3 +1298,4 @@ Result<Array> Array::append(const V& value) const {
 Result<bool> syntax_is_list(const Value& value);
 Result<bool> syntax_is_nil(const Value& value);
 Result<Value> syntax_unwrap(const Value& value);
+Result<Value> syntax_unwrap_all(const Value& value);
diff --git a/src/compiler.cpp b/src/compiler.cpp
index 523d35d..efe7583 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -584,6 +584,22 @@ Result<Expression> Compiler::compile_def(Context& context, Symbol& op,
   return std::move(ex);
 }
 
+Result<Expression> Compiler::compile_quote(Context& context, Symbol& op,
+                                           const Value& expr) {
+  auto quoted = TRY(expr.second());
+  quoted = TRY(syntax_unwrap_all(quoted));
+
+  uint64_t maxreg = context.maxreg;
+  Expression ex = TRY(Expression::create());
+
+  int64_t quoted_const = TRY(context.add_const(quoted));
+  TRY(ex.add_opcode(Oc::Mov, {0, (int64_t)maxreg}, {1, (int64_t)quoted_const}));
+
+  ex.reg = maxreg;
+  context.maxreg = maxreg + 1;
+
+  return std::move(ex);
+}
 Result<Expression> Compiler::compile_fn(Context& context, Symbol& op,
                                         const Value& expr) {
   Context ctx = TRY(Context::create(context));
@@ -880,6 +896,8 @@ Result<Expression> Compiler::compile_list(Context& context, const Value& expr) {
       return compile_fn(context, sym, expr);
     } else if (TRY(sym.cmp("let")) == 0) {
       return compile_let(context, sym, expr);
+    } else if (TRY(sym.cmp("quote")) == 0) {
+      return compile_quote(context, sym, expr);
     } else {
       return compile_function_call(context, expr);
     }
diff --git a/src/compiler.hpp b/src/compiler.hpp
index b4b611b..bdcd97a 100644
--- a/src/compiler.hpp
+++ b/src/compiler.hpp
@@ -47,6 +47,8 @@ class Compiler {
                                  const Value& expr);
   Result<Expression> compile_def(Context& context, Symbol& op,
                                  const Value& expr);
+  Result<Expression> compile_quote(Context& context, Symbol& op,
+                                   const Value& expr);
   Result<Expression> compile_fn(Context& context, Symbol& op,
                                 const Value& expr);
   Result<Expression> compile_let(Context& context, Symbol& op,
diff --git a/src/reader.cpp b/src/reader.cpp
index 9e9dbab..55ba9c2 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -63,6 +63,8 @@ Result<Value> Reader::read_one() {
     return read_array();
   } else if (match('{')) {
     return read_dict();
+  } else if (match('\'')) {
+    return read_quote();
   }
 
   position_ = saved_position;
@@ -351,6 +353,26 @@ Result<Value> Reader::read_nil() {
   return ERROR(ReadError);
 }
 
+Result<Value> Reader::read_quote() {
+  if (!match('\'')) return ERROR(ReadError);
+  SourcePosition start = position_;
+  forward();
+
+  auto sym = Value(TRY(Symbol::create("quote")));
+
+  auto subexpr = TRY(read_one());
+  SourcePosition end = position_;
+
+  auto res = Value(TRY(Pair::create(subexpr, TRY(Nil::create()))));
+  res = Value(TRY(Pair::create(sym, res)));
+
+  if (!_syntax) {
+    return res;
+  } else {
+    return Value(TRY(Syntax::create(_fname, start, end, res)));
+  }
+}
+
 Result<Value> Reader::read_string() {
   if (!match('"')) return ERROR(ReadError);
   size_t start = position_.offset + 1;
diff --git a/src/reader.hpp b/src/reader.hpp
index 23fb722..89f3314 100644
--- a/src/reader.hpp
+++ b/src/reader.hpp
@@ -41,6 +41,7 @@ class Reader {
   Result<Value> read_symbol();
   Result<Value> read_bool();
   Result<Value> read_nil();
+  Result<Value> read_quote();
 
   char32_t get(size_t offset = 0);
   bool match(const char* str);
diff --git a/test/collections.vli b/test/collections.vli
index 0f85575..1f0f616 100644
--- a/test/collections.vli
+++ b/test/collections.vli
@@ -13,3 +13,6 @@
 ;; Accessing collections by symbol
 (assert (= (get {:foo 1 :bar 2} :bar)
            2))
+
+;; quotes
+(assert (= '(1 2 3) (list 1 2 3)))