evalEngine: Implement string INSERT (#15201)

Signed-off-by: Noble Mittal <noblemittal@outlook.com>

Author: beingnoble03

go/vt/vtgate/evalengine/cached_size.go

@@ -327,6 +327,15 @@ func (c *compiler) compileNullCheck3(arg1, arg2, arg3 ctype) *jump {
 	return nil
 }
 
+func (c *compiler) compileNullCheck4(arg1, arg2, arg3, arg4 ctype) *jump {
+	if arg1.nullable() || arg2.nullable() || arg3.nullable() || arg4.nullable() {
+		j := c.asm.jumpFrom()
+		c.asm.NullCheck4(j)
+		return j
+	}
+	return nil
+}
+
 func (c *compiler) compileNullCheckArg(ct ctype, offset int) *jump {
 	if ct.nullable() {
 		j := c.asm.jumpFrom()

go/vt/vtgate/evalengine/compiler.go

@@ -2345,6 +2345,28 @@ func (asm *assembler) Fn_BIT_LENGTH() {
 	}, "FN BIT_LENGTH VARCHAR(SP-1)")
 }
 
+func (asm *assembler) Fn_INSERT(col collations.TypedCollation) {
+	asm.adjustStack(-3)
+
+	asm.emit(func(env *ExpressionEnv) int {
+		str := env.vm.stack[env.vm.sp-4].(*evalBytes)
+		pos := env.vm.stack[env.vm.sp-3].(*evalInt64).i
+		l := env.vm.stack[env.vm.sp-2].(*evalInt64).i
+		newstr := env.vm.stack[env.vm.sp-1].(*evalBytes)
+
+		res := insert(str, newstr, int(pos), int(l))
+		if !validMaxLength(int64(len(res)), 1) {
+			env.vm.stack[env.vm.sp-4] = nil
+			env.vm.sp -= 3
+			return 1
+		}
+
+		env.vm.stack[env.vm.sp-4] = env.vm.arena.newEvalText(res, col)
+		env.vm.sp -= 3
+		return 1
+	}, "FN INSERT VARCHAR(SP-4) INT64(SP-3) INT64(SP-2) VARCHAR(SP-1)")
+}
+
 func (asm *assembler) Fn_LUCASE(upcase bool) {
 	if upcase {
 		asm.emit(func(env *ExpressionEnv) int {
@@ -3147,6 +3169,17 @@ func (asm *assembler) NullCheck3(j *jump) {
 	}, "NULLCHECK SP-1, SP-2, SP-3")
 }
 
+func (asm *assembler) NullCheck4(j *jump) {
+	asm.emit(func(env *ExpressionEnv) int {
+		if env.vm.stack[env.vm.sp-4] == nil || env.vm.stack[env.vm.sp-3] == nil || env.vm.stack[env.vm.sp-2] == nil || env.vm.stack[env.vm.sp-1] == nil {
+			env.vm.stack[env.vm.sp-4] = nil
+			env.vm.sp -= 3
+			return j.offset()
+		}
+		return 1
+	}, "NULLCHECK SP-1, SP-2, SP-3, SP-4")
+}
+
 func (asm *assembler) NullCheckArg(j *jump, offset int) {
 	asm.emit(func(env *ExpressionEnv) int {
 		if env.vm.stack[env.vm.sp-1] == nil {

go/vt/vtgate/evalengine/compiler_asm.go

@@ -18,6 +18,7 @@ package evalengine
 
 import (
 	"bytes"
+	"math"
 
 	"vitess.io/vitess/go/mysql/collations"
 	"vitess.io/vitess/go/mysql/collations/charset"
@@ -29,6 +30,11 @@ import (
 )
 
 type (
+	builtinInsert struct {
+		CallExpr
+		collate collations.ID
+	}
+
 	builtinChangeCase struct {
 		CallExpr
 		upcase  bool
@@ -106,6 +112,7 @@ type (
 	}
 )
 
+var _ IR = (*builtinInsert)(nil)
 var _ IR = (*builtinChangeCase)(nil)
 var _ IR = (*builtinCharLength)(nil)
 var _ IR = (*builtinLength)(nil)
@@ -120,6 +127,122 @@ var _ IR = (*builtinLeftRight)(nil)
 var _ IR = (*builtinPad)(nil)
 var _ IR = (*builtinTrim)(nil)
 
+func insert(str, newstr *evalBytes, pos, l int) []byte {
+	pos--
+
+	cs := colldata.Lookup(str.col.Collation).Charset()
+	strLen := charset.Length(cs, str.bytes)
+
+	if pos < 0 || strLen <= pos {
+		return str.bytes
+	}
+	if l < 0 {
+		l = strLen
+	}
+
+	front := charset.Slice(cs, str.bytes, 0, pos)
+	var back []byte
+	if pos <= math.MaxInt-l && pos+l < strLen {
+		back = charset.Slice(cs, str.bytes, pos+l, strLen)
+	}
+
+	res := make([]byte, len(front)+len(newstr.bytes)+len(back))
+
+	copy(res[:len(front)], front)
+	copy(res[len(front):], newstr.bytes)
+	copy(res[len(front)+len(newstr.bytes):], back)
+
+	return res
+}
+
+func (call *builtinInsert) eval(env *ExpressionEnv) (eval, error) {
+	args, err := call.args(env)
+	if err != nil {
+		return nil, err
+	}
+	if args[0] == nil || args[1] == nil || args[2] == nil || args[3] == nil {
+		return nil, nil
+	}
+
+	str, ok := args[0].(*evalBytes)
+	if !ok {
+		str, err = evalToVarchar(args[0], call.collate, true)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	pos := evalToInt64(args[1]).i
+	l := evalToInt64(args[2]).i
+
+	newstr, err := evalToVarchar(args[3], str.col.Collation, true)
+	if err != nil {
+		return nil, err
+	}
+
+	res := insert(str, newstr, int(pos), int(l))
+	if !validMaxLength(int64(len(res)), 1) {
+		return nil, nil
+	}
+	return newEvalText(res, str.col), nil
+}
+
+func (call *builtinInsert) compile(c *compiler) (ctype, error) {
+	str, err := call.Arguments[0].compile(c)
+	if err != nil {
+		return ctype{}, err
+	}
+
+	pos, err := call.Arguments[1].compile(c)
+	if err != nil {
+		return ctype{}, err
+	}
+
+	l, err := call.Arguments[2].compile(c)
+	if err != nil {
+		return ctype{}, err
+	}
+
+	newstr, err := call.Arguments[3].compile(c)
+	if err != nil {
+		return ctype{}, err
+	}
+
+	skip := c.compileNullCheck4(str, pos, l, newstr)
+
+	_ = c.compileToInt64(pos, 3)
+	_ = c.compileToInt64(l, 2)
+
+	if err != nil {
+		return ctype{}, nil
+	}
+
+	col := str.Col
+
+	switch {
+	case str.isTextual():
+	default:
+		c.asm.Convert_xce(4, sqltypes.VarChar, c.collation)
+		col = typedCoercionCollation(sqltypes.VarChar, c.collation)
+	}
+
+	switch {
+	case newstr.isTextual():
+		fromCharset := colldata.Lookup(newstr.Col.Collation).Charset()
+		toCharset := colldata.Lookup(col.Collation).Charset()
+		if fromCharset != toCharset && !toCharset.IsSuperset(fromCharset) {
+			c.asm.Convert_xce(1, sqltypes.VarChar, col.Collation)
+		}
+	default:
+		c.asm.Convert_xce(1, sqltypes.VarChar, col.Collation)
+	}
+
+	c.asm.Fn_INSERT(col)
+	c.asm.jumpDestination(skip)
+
+	return ctype{Type: sqltypes.VarChar, Col: col, Flag: flagNullable}, nil
+}
+
 func (call *builtinChangeCase) eval(env *ExpressionEnv) (eval, error) {
 	arg, err := call.arg1(env)
 	if err != nil {

go/vt/vtgate/evalengine/fn_string.go

@@ -63,6 +63,7 @@ var Cases = []TestCase{
 	{Run: TupleComparisons},
 	{Run: Comparisons},
 	{Run: InStatement},
+	{Run: FnInsert},
 	{Run: FnLower},
 	{Run: FnUpper},
 	{Run: FnCharLength},
@@ -1314,6 +1315,28 @@ var JSONExtract_Schema = []*querypb.Field{
 	},
 }
 
+func FnInsert(yield Query) {
+	for _, s := range insertStrings {
+		for _, ns := range insertStrings {
+			for _, l := range inputBitwise {
+				for _, p := range inputBitwise {
+					yield(fmt.Sprintf("INSERT(%s, %s, %s, %s)", s, p, l, ns), nil)
+				}
+			}
+		}
+	}
+
+	mysqlDocSamples := []string{
+		"INSERT('Quadratic', 3, 4, 'What')",
+		"INSERT('Quadratic', -1, 4, 'What')",
+		"INSERT('Quadratic', 3, 100, 'What')",
+	}
+
+	for _, q := range mysqlDocSamples {
+		yield(q, nil)
+	}
+}
+
 func FnLower(yield Query) {
 	for _, str := range inputStrings {
 		yield(fmt.Sprintf("LOWER(%s)", str), nil)

go/vt/vtgate/evalengine/testcases/cases.go

@@ -199,6 +199,41 @@ var inputStrings = []string{
 	// "_ucs2 'AabcÅå'",
 }
 
+var insertStrings = []string{
+	"NULL",
+	"\"\"",
+	"\"a\"",
+	"\"abc\"",
+	"1",
+	"-1",
+	"0123",
+	"0xAACC",
+	"3.1415926",
+	// MySQL has broken behavior for these inputs,
+	// see https://github.com/mysql/mysql-server/pull/517
+	// "\"Å å\"",
+	// "\"中文测试\"",
+	// "\"日本語テスト\"",
+	// "\"한국어 시험\"",
+	// "\"😊😂🤢\"",
+	// "_utf8mb4 'abcABCÅå'",
+	"DATE '2022-10-11'",
+	"TIME '11:02:23'",
+	"'123'",
+	"9223372036854775807",
+	"-9223372036854775808",
+	"999999999999999999999999",
+	"-999999999999999999999999",
+	"_binary 'Müller' ",
+	"_latin1 0xFF",
+	// TODO: support other multibyte encodings
+	// "_dec8 'ÒòÅå'",
+	// "_utf8mb3 'abcABCÅå'",
+	// "_utf16 'AabcÅå'",
+	// "_utf32 'AabcÅå'",
+	// "_ucs2 'AabcÅå'",
+}
+
 var inputConversionTypes = []string{
 	"BINARY", "BINARY(1)", "BINARY(0)", "BINARY(16)", "BINARY(-1)",
 	"CHAR", "CHAR(1)", "CHAR(0)", "CHAR(16)", "CHAR(-1)",

go/vt/vtgate/evalengine/testcases/inputs.go

@@ -984,6 +984,35 @@ func (ast *astCompiler) translateCallable(call sqlparser.Callable) (IR, error) {
 		return &builtinRegexpReplace{
 			CallExpr: CallExpr{Arguments: args, Method: "REGEXP_REPLACE"},
 		}, nil
+
+	case *sqlparser.InsertExpr:
+		str, err := ast.translateExpr(call.Str)
+		if err != nil {
+			return nil, err
+		}
+
+		pos, err := ast.translateExpr(call.Pos)
+		if err != nil {
+			return nil, err
+		}
+
+		len, err := ast.translateExpr(call.Len)
+		if err != nil {
+			return nil, err
+		}
+
+		newstr, err := ast.translateExpr(call.NewStr)
+		if err != nil {
+			return nil, err
+		}
+
+		args := []IR{str, pos, len, newstr}
+
+		var cexpr = CallExpr{Arguments: args, Method: "INSERT"}
+		return &builtinInsert{
+			CallExpr: cexpr,
+			collate:  ast.cfg.Collation,
+		}, nil
 	default:
 		return nil, translateExprNotSupported(call)
 	}

go/vt/vtgate/evalengine/translate_builtin.go

@@ -3048,15 +3048,15 @@
       "QueryType": "SELECT",
       "Original": "select insert('Quadratic', 3, 4, 'What')",
       "Instructions": {
-        "OperatorType": "Route",
-        "Variant": "Reference",
-        "Keyspace": {
-          "Name": "main",
-          "Sharded": false
-        },
-        "FieldQuery": "select insert('Quadratic', 3, 4, 'What') from dual where 1 != 1",
-        "Query": "select insert('Quadratic', 3, 4, 'What') from dual",
-        "Table": "dual"
+        "OperatorType": "Projection",
+        "Expressions": [
+          "'QuWhattic' as insert('Quadratic', 3, 4, 'What')"
+        ],
+        "Inputs": [
+          {
+            "OperatorType": "SingleRow"
+          }
+        ]
       },
       "TablesUsed": [
         "main.dual"