Add symbol comparison and test for it

CMakeLists.txt

@@ -48,6 +48,7 @@ enable_testing()
 set(CPP_TESTS
   dict
   array
+  symbol
 )
 
 

src/common.hpp

@@ -480,8 +480,26 @@ class Symbol : public Object {
   virtual Result<short> cmp(Arena& arena, Object& rhs) final {
     return -TRY(rhs.cmp(arena, *this));
   }
-  virtual Result<short> cmp(Arena&, Symbol& rhs) final { return 0; }
+  virtual Result<short> cmp(Arena&, Symbol& rhs) final {
+    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;
+
+      char32_t lc = _value->data[i];
+      char32_t rc = rhs._value->data[j];
+      cmp = (lc > rc) - (lc < rc);
+      if (cmp != 0) return cmp;
+      i++;
+      j++;
+    }
+    return 0;
+  }
   virtual void move(Object* obj) final { new (obj) Symbol(std::move(_value)); }
 
   static Result<Symbol> create(Arena& arena, PodSymbol* obj) {
@@ -497,6 +515,17 @@ class Symbol : public Object {
     return Symbol(TRY(MkGcRoot(pod, arena)));
   }
 
+  static Result<Symbol> create(Arena& arena, const char* str) {
+    uint64_t size = strlen(str);
+    auto pod = TRY(arena.alloc<PodSymbol>(size * sizeof(char32_t)));
+    pod->header.tag = Tag::Symbol;
+
+    for (uint64_t i = 0; i < size; i++) pod->data[i] = str[i];
+    pod->size = size;
+
+    return Symbol(TRY(MkGcRoot(pod, arena)));
+  }
+
   static Result<Symbol> create(Arena& arena, String& rhs);
   virtual Result<Value> copy(Arena& arena) const final;
 

test/symbol.cpp

@@ -0,0 +1,20 @@
+#include "common.hpp"
+#include "die.hpp"
+#include "reader.hpp"
+#include "test.hpp"
+#include "writer.hpp"
+
+StaticArena<64 * 1024 * 1024> arena;
+
+TEST_CASE(array_append) {
+  auto a = DIEX(Symbol::create(arena, "foo"));
+  auto b = DIEX(Symbol::create(arena, "foo"));
+
+  ASSERT_EQUALS(a, b);
+
+  auto s = DIEX(write_one(arena, a));
+
+  DIEX(arena.gc());
+
+  ASSERT_EQUALS(s, "foo");
+}