From e16c3e9b412762b85483f3831ee586a5e6631313 Mon Sep 17 00:00:00 2001
From: David Symonds <dsymonds@golang.org>
Date: Wed, 9 Dec 2020 20:54:10 +1100
Subject: [PATCH] feat(spanner/spannertest): implement ANY_VALUE aggregation
 function (#3428)

Fixes #3375.
---
 spanner/spannertest/funcs.go | 13 +++++++++++++
 spanner/spansql/keywords.go  |  1 +
 2 files changed, 14 insertions(+)

diff --git a/spanner/spannertest/funcs.go b/spanner/spannertest/funcs.go
index 3cfa53211e4..53c12c318f7 100644
--- a/spanner/spannertest/funcs.go
+++ b/spanner/spannertest/funcs.go
@@ -37,6 +37,19 @@ type aggregateFunc struct {
 
 // TODO: more aggregate funcs.
 var aggregateFuncs = map[string]aggregateFunc{
+	"ANY_VALUE": {
+		// https://cloud.google.com/spanner/docs/aggregate_functions#any_value
+		Eval: func(values []interface{}, typ spansql.Type) (interface{}, spansql.Type, error) {
+			// Return the first non-NULL value.
+			for _, v := range values {
+				if v != nil {
+					return v, typ, nil
+				}
+			}
+			// Either all values are NULL, or there are no values.
+			return nil, typ, nil
+		},
+	},
 	"ARRAY_AGG": {
 		// https://cloud.google.com/spanner/docs/aggregate_functions#array_agg
 		Eval: func(values []interface{}, typ spansql.Type) (interface{}, spansql.Type, error) {
diff --git a/spanner/spansql/keywords.go b/spanner/spansql/keywords.go
index 39a0493f1ac..7296b486155 100644
--- a/spanner/spansql/keywords.go
+++ b/spanner/spansql/keywords.go
@@ -129,6 +129,7 @@ var keywords = map[string]bool{
 // https://cloud.google.com/spanner/docs/functions-and-operators
 var funcs = map[string]bool{
 	// Aggregate functions.
+	"ANY_VALUE": true,
 	"ARRAY_AGG": true,
 	"AVG":       true,
 	"BIT_XOR":   true,