From 95eff595f0e7a23c155a3ba5a3dafcf7b77ab1a9 Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Mon, 4 Dec 2023 12:38:34 -0800
Subject: [PATCH] Added cast from half to numeric [skip ci]

---
 sql/vector--0.5.1--0.6.0.sql |  6 ++++++
 sql/vector.sql               |  6 ++++++
 src/half.c                   | 14 ++++++++++++++
 test/expected/half.out       | 26 ++++++++++++++++++++++----
 test/sql/half.sql            |  6 +++++-
 5 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/sql/vector--0.5.1--0.6.0.sql b/sql/vector--0.5.1--0.6.0.sql
index 5687c0a..3b9115e 100644
--- a/sql/vector--0.5.1--0.6.0.sql
+++ b/sql/vector--0.5.1--0.6.0.sql
@@ -55,6 +55,9 @@ CREATE FUNCTION integer_to_half(integer, integer, boolean) RETURNS half
 CREATE FUNCTION numeric_to_half(numeric, integer, boolean) RETURNS half
 	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
+CREATE FUNCTION half_to_numeric(half, integer, boolean) RETURNS numeric
+	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
 CREATE CAST (real AS half)
 	WITH FUNCTION float4_to_half(real, integer, boolean) AS IMPLICIT;
 
@@ -67,6 +70,9 @@ CREATE CAST (integer AS half)
 CREATE CAST (numeric AS half)
 	WITH FUNCTION numeric_to_half(numeric, integer, boolean) AS IMPLICIT;
 
+CREATE CAST (half AS numeric)
+	WITH FUNCTION half_to_numeric(half, integer, boolean) AS IMPLICIT;
+
 CREATE OPERATOR <-> (
 	LEFTARG = half[], RIGHTARG = half[], PROCEDURE = l2_distance,
 	COMMUTATOR = '<->'
diff --git a/sql/vector.sql b/sql/vector.sql
index bdecf37..dfa1c7c 100644
--- a/sql/vector.sql
+++ b/sql/vector.sql
@@ -353,6 +353,9 @@ CREATE FUNCTION integer_to_half(integer, integer, boolean) RETURNS half
 CREATE FUNCTION numeric_to_half(numeric, integer, boolean) RETURNS half
 	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
+CREATE FUNCTION half_to_numeric(half, integer, boolean) RETURNS numeric
+	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
 -- half casts
 
 CREATE CAST (real AS half)
@@ -367,6 +370,9 @@ CREATE CAST (integer AS half)
 CREATE CAST (numeric AS half)
 	WITH FUNCTION numeric_to_half(numeric, integer, boolean) AS IMPLICIT;
 
+CREATE CAST (half AS numeric)
+	WITH FUNCTION half_to_numeric(half, integer, boolean) AS IMPLICIT;
+
 -- half operators
 
 CREATE OPERATOR <-> (
diff --git a/src/half.c b/src/half.c
index 3991ab0..5199eff 100644
--- a/src/half.c
+++ b/src/half.c
@@ -426,6 +426,20 @@ numeric_to_half(PG_FUNCTION_ARGS)
 	PG_RETURN_HALF(h);
 }
 
+/*
+ * Convert half to numeric
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(half_to_numeric);
+Datum
+half_to_numeric(PG_FUNCTION_ARGS)
+{
+	half		h = PG_GETARG_HALF(0);
+	float		f = HalfToFloat4(h);
+	Numeric		num = DatumGetNumeric(DirectFunctionCall1(float4_numeric, Float4GetDatum(f)));
+
+	PG_RETURN_NUMERIC(num);
+}
+
 /*
  * Convert float4 to half
  */
diff --git a/test/expected/half.out b/test/expected/half.out
index ae1e391..95f4439 100644
--- a/test/expected/half.out
+++ b/test/expected/half.out
@@ -58,6 +58,12 @@ SELECT '{1,2,3}'::half[];
  {1,2,3}
 (1 row)
 
+SELECT '{1,2,3}'::half[]::real[];
+ float4  
+---------
+ {1,2,3}
+(1 row)
+
 SELECT '65505'::integer::half;
  half  
 -------
@@ -82,10 +88,22 @@ SELECT '1.5'::half::real;
     1.5
 (1 row)
 
-SELECT '{1.5}'::half[]::real[];
- float4 
---------
- {1.5}
+SELECT '1.5'::real::half;
+ half 
+------
+ 1.5
+(1 row)
+
+SELECT '1.5'::half::numeric;
+ numeric 
+---------
+     1.5
+(1 row)
+
+SELECT '1.5'::numeric::half;
+ half 
+------
+ 1.5
 (1 row)
 
 SELECT l2_distance('{0,0}'::half[], '{3,4}'::half[]);
diff --git a/test/sql/half.sql b/test/sql/half.sql
index 166cd23..7b01e1c 100644
--- a/test/sql/half.sql
+++ b/test/sql/half.sql
@@ -12,13 +12,17 @@ SELECT '1.5 '::half;
 SELECT '1.5a'::half;
 
 SELECT '{1,2,3}'::half[];
+SELECT '{1,2,3}'::half[]::real[];
 
 SELECT '65505'::integer::half;
 SELECT 'NaN'::real::half;
 SELECT 'Infinity'::real::half;
 
 SELECT '1.5'::half::real;
-SELECT '{1.5}'::half[]::real[];
+SELECT '1.5'::real::half;
+
+SELECT '1.5'::half::numeric;
+SELECT '1.5'::numeric::half;
 
 SELECT l2_distance('{0,0}'::half[], '{3,4}'::half[]);
 SELECT l2_distance('{0,0}'::half[], '{0,1}'::half[]);