fb-1802 : Trim functionality (#2353)

* fb-1802 : Trim functionality

rebase

* fb-1802 : trim - updated as per review

sql3/planner/expression.go

@@ -1484,6 +1484,8 @@ func (n *callPlanExpression) Evaluate(currentRow []interface{}) (interface{}, er
 		return n.EvaluateSubstring(currentRow)
 	case "REPLACEALL":
 		return n.EvaluateReplaceAll(currentRow)
+	case "TRIM":
+		return n.EvaluateTrim(currentRow)
 	default:
 		return nil, sql3.NewErrInternalf("unhandled function name '%s'", n.name)
 	}

sql3/planner/expressionanalyzercall.go

@@ -249,6 +249,9 @@ func (p *ExecutionPlanner) analyzeCallExpression(call *parser.Call, scope parser
 		return p.analyseFunctionSubstring(call, scope)
 	case "REPLACEALL":
 		return p.analyseFunctionReplaceAll(call, scope)
+	case "TRIM":
+		return p.analyseFunctionTrim(call, scope)
+
 	default:
 		return nil, sql3.NewErrCallUnknownFunction(call.Name.NamePos.Line, call.Name.NamePos.Column, call.Name.Name)
 	}

sql3/planner/inbuiltfunctionsstring.go

@@ -170,7 +170,6 @@ func evaluateStringArg(n types.PlanExpression, currentRow []interface{}) (string
 	if err != nil {
 		return "", err
 	}
-
 	stringArgOne, ok := argOneEval.(string)
 	if !ok {
 		return "", sql3.NewErrInternalf("unexpected type converion %T", argOneEval)
@@ -178,3 +177,30 @@ func evaluateStringArg(n types.PlanExpression, currentRow []interface{}) (string
 
 	return stringArgOne, nil
 }
+
+//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 {
+		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
+}
+
+// Execute Trim function to remove whitespaces from string
+func (n *callPlanExpression) EvaluateTrim(currentRow []interface{}) (interface{}, error) {
+	stringArgOne, err := evaluateStringArg(n.args[0], currentRow)
+	if err != nil {
+		return nil, err
+	}
+
+	// Trim the whitespace from string
+	return strings.TrimSpace(stringArgOne), nil
+}

sql3/test/defs/defs_string_functions.go

@@ -188,5 +188,32 @@ var stringScalarFunctionsTests = TableTest{
 			),
 			ExpErr: "string expression expected",
 		},
+		{
+			name: "RemovingWhitespacefromStringusingTrim",
+			SQLs: sqls(
+				"select trim('  this  ')",
+			),
+			ExpHdrs: hdrs(
+				hdr("", fldTypeString),
+			),
+			ExpRows: rows(
+				row(string("this")),
+			),
+			Compare: CompareExactOrdered,
+		},
+		{
+			name: "IncorrectArgumentsforTrim",
+			SQLs: sqls(
+				"select trim('  a ','b')",
+			),
+			ExpErr: "'trim': count of formal parameters (1) does not match count of actual parameters (2)",
+		},
+		{
+			name: "IncorrectInputforTrim",
+			SQLs: sqls(
+				"select trim(1)",
+			),
+			ExpErr: "string expression expected",
+		},
 	},
 }