From 10795782c674df12fc70ea3aeeaa2f62158b6cbd Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Thu, 12 Sep 2024 13:17:53 -0400
Subject: Implement optional hashing/equality/comparisons

---
 builtins/functions.c | 16 +++++++++++-----
 builtins/optionals.c |  2 +-
 builtins/optionals.h |  1 +
 test/optionals.tm    | 10 ++++++++++
 4 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/builtins/functions.c b/builtins/functions.c
index 3c01f678..a2b17807 100644
--- a/builtins/functions.c
+++ b/builtins/functions.c
@@ -115,9 +115,7 @@ PUREFUNC public uint64_t generic_hash(const void *obj, const TypeInfo *type)
     case ArrayInfo: return Array$hash(obj, type);
     case ChannelInfo: return Channel$hash((Channel_t**)obj, type);
     case TableInfo: return Table$hash(obj, type);
-    case OptionalInfo: {
-        errx(1, "Optional hash not implemented");
-    }
+    case OptionalInfo: return is_null(obj, type->OptionalInfo.type) ? 0 : generic_hash(obj, type->OptionalInfo.type);
     case EmptyStructInfo: return 0;
     case CustomInfo: case StructInfo: case EnumInfo: case CStringInfo: // These all share the same info
         if (!type->CustomInfo.hash)
@@ -141,7 +139,11 @@ PUREFUNC public int32_t generic_compare(const void *x, const void *y, const Type
     case ChannelInfo: return Channel$compare((Channel_t**)x, (Channel_t**)y, type);
     case TableInfo: return Table$compare(x, y, type);
     case OptionalInfo: {
-        errx(1, "Optional compare not implemented");
+        bool x_is_null = is_null(x, type->OptionalInfo.type);
+        bool y_is_null = is_null(y, type->OptionalInfo.type);
+        if (x_is_null && y_is_null) return 0;
+        else if (x_is_null != y_is_null) return (int32_t)y_is_null - (int32_t)x_is_null;
+        else return generic_compare(x, y, type->OptionalInfo.type);
     }
     case EmptyStructInfo: return 0;
     case CustomInfo: case StructInfo: case EnumInfo: case CStringInfo: // These all share the same info
@@ -166,7 +168,11 @@ PUREFUNC public bool generic_equal(const void *x, const void *y, const TypeInfo
     case TableInfo: return Table$equal(x, y, type);
     case EmptyStructInfo: return true;
     case OptionalInfo: {
-        errx(1, "Optional equal not implemented");
+        bool x_is_null = is_null(x, type->OptionalInfo.type);
+        bool y_is_null = is_null(y, type->OptionalInfo.type);
+        if (x_is_null && y_is_null) return true;
+        else if (x_is_null != y_is_null) return false;
+        else return generic_equal(x, y, type->OptionalInfo.type);
     }
     case CustomInfo: case StructInfo: case EnumInfo: case CStringInfo: // These all share the same info
         if (!type->CustomInfo.equal)
diff --git a/builtins/optionals.c b/builtins/optionals.c
index 8a1aaf99..8b890c97 100644
--- a/builtins/optionals.c
+++ b/builtins/optionals.c
@@ -14,7 +14,7 @@ public const Table_t NULL_TABLE = {.entries.length=-1};
 public const Closure_t NULL_CLOSURE = {.fn=NULL};
 public const Text_t NULL_TEXT = {.length=-1};
 
-static inline bool is_null(const void *obj, const TypeInfo *non_optional_type)
+public PUREFUNC bool is_null(const void *obj, const TypeInfo *non_optional_type)
 {
     if (non_optional_type == &Int$info)
         return ((Int_t*)obj)->small == 0;
diff --git a/builtins/optionals.h b/builtins/optionals.h
index 10599473..5f0a407f 100644
--- a/builtins/optionals.h
+++ b/builtins/optionals.h
@@ -18,6 +18,7 @@ extern const Int_t NULL_INT;
 extern const Closure_t NULL_CLOSURE;
 extern const Text_t NULL_TEXT;
 
+PUREFUNC bool is_null(const void *obj, const TypeInfo *non_optional_type);
 Text_t Optional$as_text(const void *obj, bool colorize, const TypeInfo *type);
 
 // vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/test/optionals.tm b/test/optionals.tm
index 5c18d58d..a3f33d6c 100644
--- a/test/optionals.tm
+++ b/test/optionals.tm
@@ -274,3 +274,13 @@ func main():
 
     >> maybe_int(yes)!
     = 123 : Int
+
+    # Test comparisons, hashing, equality:
+    >> (!Int == 5?)
+    = no
+    >> (5? == 5?)
+    = yes
+    >> {!Int, !Int}
+    = {!Int}
+    >> [5?, !Int, !Int, 6?]:sorted()
+    = [!Int, !Int, 5?, 6?]
-- 
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