From 838bc2dadb6fcbc04add7abc2d7fd8e60aeac30e Mon Sep 17 00:00:00 2001
From: Bruce Baranowski <92940816+bruce-b-molecula@users.noreply.github.com>
Date: Tue, 13 Dec 2022 14:59:05 -0500
Subject: [PATCH] FB-1719: implement SQL3 lower() (#2358)

* Implemented SQL3 LOWER()

(cherry picked from commit 4773aabc4ebe71e21e549fafb3d6ca6f4ba4e3e6)
---
 sql3/planner/expression.go              |  2 ++
 sql3/planner/expressionanalyzercall.go  |  2 ++
 sql3/planner/inbuiltfunctionsstring.go  | 25 ++++++++++++++++++++++-
 sql3/test/defs/defs_string_functions.go | 27 +++++++++++++++++++++++++
 4 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/sql3/planner/expression.go b/sql3/planner/expression.go
index ed6f4e087..617f3a9bf 100644
--- a/sql3/planner/expression.go
+++ b/sql3/planner/expression.go
@@ -1482,6 +1482,8 @@ func (n *callPlanExpression) Evaluate(currentRow []interface{}) (interface{}, er
 		return n.EvaluateUpper(currentRow)
 	case "SUBSTRING":
 		return n.EvaluateSubstring(currentRow)
+	case "LOWER":
+		return n.EvaluateLower(currentRow)
 	case "REPLACEALL":
 		return n.EvaluateReplaceAll(currentRow)
 	case "TRIM":
diff --git a/sql3/planner/expressionanalyzercall.go b/sql3/planner/expressionanalyzercall.go
index ad6dd991f..7e881c40f 100644
--- a/sql3/planner/expressionanalyzercall.go
+++ b/sql3/planner/expressionanalyzercall.go
@@ -247,6 +247,8 @@ func (p *ExecutionPlanner) analyzeCallExpression(call *parser.Call, scope parser
 		return p.analyzeFunctionUpper(call, scope)
 	case "SUBSTRING":
 		return p.analyseFunctionSubstring(call, scope)
+	case "LOWER":
+		return p.analyzeFunctionLower(call, scope)
 	case "REPLACEALL":
 		return p.analyseFunctionReplaceAll(call, scope)
 	case "TRIM":
diff --git a/sql3/planner/inbuiltfunctionsstring.go b/sql3/planner/inbuiltfunctionsstring.go
index 0718a542d..1cc63c863 100644
--- a/sql3/planner/inbuiltfunctionsstring.go
+++ b/sql3/planner/inbuiltfunctionsstring.go
@@ -44,6 +44,20 @@ func (p *ExecutionPlanner) analyseFunctionSubstring(call *parser.Call, scope par
 	return call, nil
 }
 
+func (p *ExecutionPlanner) analyzeFunctionLower(call *parser.Call, scope parser.Statement) (parser.Expr, error) {
+	if len(call.Args) != 1 {
+		return nil, sql3.NewErrCallParameterCountMismatch(call.Rparen.Line, call.Rparen.Column, call.Name.Name, 1, len(call.Args))
+	}
+
+	if !typeIsString(call.Args[0].DataType()) {
+		return nil, sql3.NewErrStringExpressionExpected(call.Args[0].Pos().Line, call.Args[0].Pos().Column)
+	}
+
+	call.ResultDataType = parser.NewDataTypeString()
+
+	return call, nil
+}
+
 func (p *ExecutionPlanner) analyseFunctionReplaceAll(call *parser.Call, scope parser.Statement) (parser.Expr, error) {
 	if len(call.Args) != 3 {
 		return nil, sql3.NewErrCallParameterCountMismatch(call.Rparen.Line, call.Rparen.Column, call.Name.Name, 3, len(call.Args))
@@ -146,6 +160,15 @@ func (n *callPlanExpression) EvaluateSubstring(currentRow []interface{}) (interf
 	return stringArgOne[startIndex:endIndex], nil
 }
 
+func (n *callPlanExpression) EvaluateLower(currentRow []interface{}) (interface{}, error) {
+	stringArgOne, err := evaluateStringArg(n.args[0], currentRow)
+	if err != nil {
+		return nil, err
+	}
+
+	return strings.ToLower(stringArgOne), nil
+}
+
 // takes string, findstring, replacestring.
 // replaces all occurances of findstring with replacestring
 func (n *callPlanExpression) EvaluateReplaceAll(currentRow []interface{}) (interface{}, error) {
@@ -177,7 +200,7 @@ func evaluateStringArg(n types.PlanExpression, currentRow []interface{}) (string
 	return stringArgOne, nil
 }
 
-//Analyze function for Trim
+// Analyze function for Trim
 func (p *ExecutionPlanner) analyseFunctionTrim(call *parser.Call, scope parser.Statement) (parser.Expr, error) {
 	//one argument for Trim Function
 	if len(call.Args) != 1 {
diff --git a/sql3/test/defs/defs_string_functions.go b/sql3/test/defs/defs_string_functions.go
index 1002597e0..5c1992242 100644
--- a/sql3/test/defs/defs_string_functions.go
+++ b/sql3/test/defs/defs_string_functions.go
@@ -135,6 +135,33 @@ var stringScalarFunctionsTests = TableTest{
 			),
 			ExpErr: "string expression expected",
 		},
+		{
+			name: "StringLower",
+			SQLs: sqls(
+				"select lower('AaBbCcDdEeFfGg-_0123')",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeString),
+			),
+			ExpRows: rows(
+				row(string("aabbccddeeffgg-_0123")),
+			),
+			Compare: CompareExactOrdered,
+		},
+		{
+			name: "IncorrectArgumentsforLower",
+			SQLs: sqls(
+				"select lower('LOWER','lower')",
+			),
+			ExpErr: "'lower': count of formal parameters (1) does not match count of actual parameters (2)",
+		},
+		{
+			name: "IncorrectInputforLower",
+			SQLs: sqls(
+				"select lower(1234)",
+			),
+			ExpErr: "string expression expected",
+		},
 		{
 			name: "ReplaceAllString",
 			SQLs: sqls(