From 31befca0138b5f3284ff50ee69b30798ef945de5 Mon Sep 17 00:00:00 2001
From: Dan King <daniel.zidan.king@gmail.com>
Date: Thu, 22 Aug 2024 16:00:04 +0100
Subject: [PATCH] impl Display for Utf8Scalar and BinaryScalar (#678)

Partially addresses #670.

---------

Co-authored-by: Daniel King <dan@spiraldb.com>
Co-authored-by: Robert Kruszewski <github@robertk.io>
---
 vortex-scalar/src/display.rs | 87 ++++++++++++++++++++++++++++++------
 1 file changed, 74 insertions(+), 13 deletions(-)

diff --git a/vortex-scalar/src/display.rs b/vortex-scalar/src/display.rs
index 2fa4bd62a1..39d20e28c8 100644
--- a/vortex-scalar/src/display.rs
+++ b/vortex-scalar/src/display.rs
@@ -1,9 +1,12 @@
 use std::fmt::{Display, Formatter};
 
+use itertools::Itertools;
 use vortex_dtype::{match_each_native_ptype, DType};
 
+use crate::binary::BinaryScalar;
 use crate::bool::BoolScalar;
 use crate::primitive::PrimitiveScalar;
+use crate::utf8::Utf8Scalar;
 use crate::Scalar;
 
 impl Display for Scalar {
@@ -11,14 +14,7 @@ impl Display for Scalar {
         match self.dtype() {
             DType::Null => write!(f, "null"),
             DType::Bool(_) => match BoolScalar::try_from(self)
-                .map_err(|err| {
-                    debug_assert!(
-                        false,
-                        "Failed to parse bool from scalar with DType Bool: {}",
-                        err
-                    );
-                    std::fmt::Error
-                })?
+                .map_err(|_| std::fmt::Error)?
                 .value()
             {
                 None => write!(f, "null"),
@@ -30,8 +26,30 @@ impl Display for Scalar {
                     Some(v) => write!(f, "{}", v),
                 }
             }),
-            DType::Utf8(_) => todo!(),
-            DType::Binary(_) => todo!(),
+            DType::Utf8(_) => {
+                match Utf8Scalar::try_from(self)
+                    .map_err(|_| std::fmt::Error)?
+                    .value()
+                {
+                    None => write!(f, "null"),
+                    Some(bs) => write!(f, "{}", bs.as_str()),
+                }
+            }
+            DType::Binary(_) => {
+                match BinaryScalar::try_from(self)
+                    .map_err(|_| std::fmt::Error)?
+                    .value()
+                {
+                    None => write!(f, "null"),
+                    Some(buf) => {
+                        write!(
+                            f,
+                            "{}",
+                            buf.as_slice().iter().map(|b| format!("{b:x}")).format(",")
+                        )
+                    }
+                }
+            }
             DType::Struct(..) => todo!(),
             DType::List(..) => todo!(),
             DType::Extension(..) => todo!(),
@@ -41,11 +59,54 @@ impl Display for Scalar {
 
 #[cfg(test)]
 mod tests {
+    use vortex_buffer::Buffer;
+    use vortex_dtype::Nullability::{NonNullable, Nullable};
+    use vortex_dtype::{DType, PType};
+
     use crate::Scalar;
 
     #[test]
-    fn display() {
-        let scalar = Scalar::from(false);
-        assert_eq!(format!("{}", scalar), "false");
+    fn display_bool() {
+        assert_eq!(format!("{}", Scalar::from(false)), "false");
+        assert_eq!(format!("{}", Scalar::from(true)), "true");
+        assert_eq!(format!("{}", Scalar::null(DType::Bool(Nullable))), "null");
+    }
+
+    #[test]
+    fn display_primitive() {
+        assert_eq!(format!("{}", Scalar::from(0_u8)), "0");
+        assert_eq!(format!("{}", Scalar::from(255_u8)), "255");
+
+        assert_eq!(format!("{}", Scalar::from(0_u16)), "0");
+        assert_eq!(format!("{}", Scalar::from(!0_u16)), "65535");
+
+        assert_eq!(format!("{}", Scalar::from(0_u32)), "0");
+        assert_eq!(format!("{}", Scalar::from(!0_u32)), "4294967295");
+
+        assert_eq!(format!("{}", Scalar::from(0_u64)), "0");
+        assert_eq!(format!("{}", Scalar::from(!0_u64)), "18446744073709551615");
+
+        assert_eq!(
+            format!("{}", Scalar::null(DType::Primitive(PType::U8, Nullable))),
+            "null"
+        );
+    }
+
+    #[test]
+    fn display_utf8() {
+        assert_eq!(format!("{}", Scalar::from("Hello World!")), "Hello World!");
+        assert_eq!(format!("{}", Scalar::null(DType::Utf8(Nullable))), "null");
+    }
+
+    #[test]
+    fn display_binary() {
+        assert_eq!(
+            format!(
+                "{}",
+                Scalar::binary(Buffer::from("Hello World!".as_bytes()), NonNullable)
+            ),
+            "48,65,6c,6c,6f,20,57,6f,72,6c,64,21"
+        );
+        assert_eq!(format!("{}", Scalar::null(DType::Binary(Nullable))), "null");
     }
 }