/
value.go
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/
value.go
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/*
* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package sql
import (
"encoding/json"
"errors"
"fmt"
"math"
"reflect"
"strconv"
"strings"
"time"
"unicode/utf8"
)
var (
errArithMismatchedTypes = errors.New("cannot perform arithmetic on mismatched types")
errArithInvalidOperator = errors.New("invalid arithmetic operator")
errArithDivideByZero = errors.New("cannot divide by 0")
errCmpMismatchedTypes = errors.New("cannot compare values of different types")
errCmpInvalidBoolOperator = errors.New("invalid comparison operator for boolean arguments")
)
// Value represents a value of restricted type reduced from an
// expression represented by an ASTNode. Only one of the fields is
// non-nil.
//
// In cases where we are fetching data from a data source (like csv),
// the type may not be determined yet. In these cases, a byte-slice is
// used.
type Value struct {
value interface{}
}
// MarshalJSON provides json marshaling of values.
func (v Value) MarshalJSON() ([]byte, error) {
if b, ok := v.ToBytes(); ok {
return b, nil
}
return json.Marshal(v.value)
}
// GetTypeString returns a string representation for vType
func (v Value) GetTypeString() string {
switch v.value.(type) {
case nil:
return "NULL"
case bool:
return "BOOL"
case string:
return "STRING"
case int64:
return "INT"
case float64:
return "FLOAT"
case time.Time:
return "TIMESTAMP"
case []byte:
return "BYTES"
case []Value:
return "ARRAY"
}
return "--"
}
// Repr returns a string representation of value.
func (v Value) Repr() string {
switch x := v.value.(type) {
case nil:
return ":NULL"
case bool, int64, float64:
return fmt.Sprintf("%v:%s", v.value, v.GetTypeString())
case time.Time:
return fmt.Sprintf("%s:TIMESTAMP", x)
case string:
return fmt.Sprintf("\"%s\":%s", x, v.GetTypeString())
case []byte:
return fmt.Sprintf("\"%s\":BYTES", string(x))
case []Value:
var s strings.Builder
s.WriteByte('[')
for i, v := range x {
s.WriteString(v.Repr())
if i < len(x)-1 {
s.WriteByte(',')
}
}
s.WriteString("]:ARRAY")
return s.String()
default:
return fmt.Sprintf("%v:INVALID", v.value)
}
}
// FromFloat creates a Value from a number
func FromFloat(f float64) *Value {
return &Value{value: f}
}
// FromInt creates a Value from an int
func FromInt(f int64) *Value {
return &Value{value: f}
}
// FromString creates a Value from a string
func FromString(str string) *Value {
return &Value{value: str}
}
// FromBool creates a Value from a bool
func FromBool(b bool) *Value {
return &Value{value: b}
}
// FromTimestamp creates a Value from a timestamp
func FromTimestamp(t time.Time) *Value {
return &Value{value: t}
}
// FromNull creates a Value with Null value
func FromNull() *Value {
return &Value{value: nil}
}
// FromBytes creates a Value from a []byte
func FromBytes(b []byte) *Value {
return &Value{value: b}
}
// FromArray creates a Value from an array of values.
func FromArray(a []Value) *Value {
return &Value{value: a}
}
// ToFloat works for int and float values
func (v Value) ToFloat() (val float64, ok bool) {
switch x := v.value.(type) {
case float64:
return x, true
case int64:
return float64(x), true
}
return 0, false
}
// ToInt returns the value if int.
func (v Value) ToInt() (val int64, ok bool) {
val, ok = v.value.(int64)
return
}
// ToString returns the value if string.
func (v Value) ToString() (val string, ok bool) {
val, ok = v.value.(string)
return
}
// Equals returns whether the values strictly match.
// Both type and value must match.
func (v Value) Equals(b Value) (ok bool) {
if !v.SameTypeAs(b) {
return false
}
return reflect.DeepEqual(v.value, b.value)
}
// SameTypeAs return whether the two types are strictly the same.
func (v Value) SameTypeAs(b Value) (ok bool) {
switch v.value.(type) {
case bool:
_, ok = b.value.(bool)
case string:
_, ok = b.value.(string)
case int64:
_, ok = b.value.(int64)
case float64:
_, ok = b.value.(float64)
case time.Time:
_, ok = b.value.(time.Time)
case []byte:
_, ok = b.value.([]byte)
case []Value:
_, ok = b.value.([]Value)
default:
ok = reflect.TypeOf(v.value) == reflect.TypeOf(b.value)
}
return ok
}
// ToBool returns the bool value; second return value refers to if the bool
// conversion succeeded.
func (v Value) ToBool() (val bool, ok bool) {
val, ok = v.value.(bool)
return
}
// ToTimestamp returns the timestamp value if present.
func (v Value) ToTimestamp() (t time.Time, ok bool) {
t, ok = v.value.(time.Time)
return
}
// ToBytes returns the value if byte-slice.
func (v Value) ToBytes() (val []byte, ok bool) {
val, ok = v.value.([]byte)
return
}
// ToArray returns the value if it is a slice of values.
func (v Value) ToArray() (val []Value, ok bool) {
val, ok = v.value.([]Value)
return
}
// IsNull - checks if value is missing.
func (v Value) IsNull() bool {
switch v.value.(type) {
case nil:
return true
}
return false
}
// IsArray returns whether the value is an array.
func (v Value) IsArray() (ok bool) {
_, ok = v.value.([]Value)
return ok
}
func (v Value) isNumeric() bool {
switch v.value.(type) {
case int64, float64:
return true
}
return false
}
// setters used internally to mutate values
func (v *Value) setInt(i int64) {
v.value = i
}
func (v *Value) setFloat(f float64) {
v.value = f
}
func (v *Value) setString(s string) {
v.value = s
}
func (v *Value) setBool(b bool) {
v.value = b
}
func (v *Value) setTimestamp(t time.Time) {
v.value = t
}
func (v Value) String() string {
return fmt.Sprintf("%#v", v.value)
}
// CSVString - convert to string for CSV serialization
func (v Value) CSVString() string {
switch x := v.value.(type) {
case nil:
return ""
case bool:
if x {
return "true"
}
return "false"
case string:
return x
case int64:
return strconv.FormatInt(x, 10)
case float64:
return strconv.FormatFloat(x, 'g', -1, 64)
case time.Time:
return FormatSQLTimestamp(x)
case []byte:
return string(x)
case []Value:
b, _ := json.Marshal(x)
return string(b)
default:
return "CSV serialization not implemented for this type"
}
}
// floatToValue converts a float into int representation if needed.
func floatToValue(f float64) *Value {
intPart, fracPart := math.Modf(f)
if fracPart == 0 && intPart < math.MaxInt64 && intPart > math.MinInt64 {
return FromInt(int64(intPart))
}
return FromFloat(f)
}
// negate negates a numeric value
func (v *Value) negate() {
switch x := v.value.(type) {
case float64:
v.value = -x
case int64:
v.value = -x
}
}
// Value comparison functions: we do not expose them outside the
// module. Logical operators "<", ">", ">=", "<=" work on strings and
// numbers. Equality operators "=", "!=" work on strings,
// numbers and booleans.
// Supported comparison operators
const (
opLt = "<"
opLte = "<="
opGt = ">"
opGte = ">="
opEq = "="
opIneq = "!="
)
// InferBytesType will attempt to infer the data type of bytes.
// Will fail if value type is not bytes or it would result in invalid utf8.
// ORDER: int, float, bool, JSON (object or array), timestamp, string
// If the content is valid JSON, the type will still be bytes.
func (v *Value) InferBytesType() (err error) {
b, ok := v.ToBytes()
if !ok {
return fmt.Errorf("InferByteType: Input is not bytes, but %v", v.GetTypeString())
}
// Check for numeric inference
if x, ok := v.bytesToInt(); ok {
v.setInt(x)
return nil
}
if x, ok := v.bytesToFloat(); ok {
v.setFloat(x)
return nil
}
if x, ok := v.bytesToBool(); ok {
v.setBool(x)
return nil
}
asString := strings.TrimSpace(v.bytesToString())
if len(b) > 0 &&
(strings.HasPrefix(asString, "{") || strings.HasPrefix(asString, "[")) {
return nil
}
if t, err := parseSQLTimestamp(asString); err == nil {
v.setTimestamp(t)
return nil
}
if !utf8.Valid(b) {
return errors.New("value is not valid utf-8")
}
// Fallback to string
v.setString(asString)
return
}
// When numeric types are compared, type promotions could happen. If
// values do not have types (e.g. when reading from CSV), for
// comparison operations, automatic type conversion happens by trying
// to check if the value is a number (first an integer, then a float),
// and falling back to string.
func (v *Value) compareOp(op string, a *Value) (res bool, err error) {
if !isValidComparisonOperator(op) {
return false, errArithInvalidOperator
}
// Check if type conversion/inference is needed - it is needed
// if the Value is a byte-slice.
err = inferTypesForCmp(v, a)
if err != nil {
return false, err
}
// Check if either is nil
if v.IsNull() || a.IsNull() {
// If one is, both must be.
return boolCompare(op, v.IsNull(), a.IsNull())
}
// Check array values
aArr, aOK := a.ToArray()
vArr, vOK := v.ToArray()
if aOK && vOK {
return arrayCompare(op, aArr, vArr)
}
isNumeric := v.isNumeric() && a.isNumeric()
if isNumeric {
intV, ok1i := v.ToInt()
intA, ok2i := a.ToInt()
if ok1i && ok2i {
return intCompare(op, intV, intA), nil
}
// If both values are numeric, then at least one is
// float since we got here, so we convert.
flV, _ := v.ToFloat()
flA, _ := a.ToFloat()
return floatCompare(op, flV, flA), nil
}
strV, ok1s := v.ToString()
strA, ok2s := a.ToString()
if ok1s && ok2s {
return stringCompare(op, strV, strA), nil
}
boolV, ok1b := v.ToBool()
boolA, ok2b := a.ToBool()
if ok1b && ok2b {
return boolCompare(op, boolV, boolA)
}
timestampV, ok1t := v.ToTimestamp()
timestampA, ok2t := a.ToTimestamp()
if ok1t && ok2t {
return timestampCompare(op, timestampV, timestampA), nil
}
// Types cannot be compared, they do not match.
switch op {
case opEq:
return false, nil
case opIneq:
return true, nil
}
return false, errCmpInvalidBoolOperator
}
func inferTypesForCmp(a *Value, b *Value) error {
_, okA := a.ToBytes()
_, okB := b.ToBytes()
switch {
case !okA && !okB:
// Both Values already have types
return nil
case okA && okB:
// Both Values are untyped so try the types in order:
// int, float, bool, string
// Check for numeric inference
iA, okAi := a.bytesToInt()
iB, okBi := b.bytesToInt()
if okAi && okBi {
a.setInt(iA)
b.setInt(iB)
return nil
}
fA, okAf := a.bytesToFloat()
fB, okBf := b.bytesToFloat()
if okAf && okBf {
a.setFloat(fA)
b.setFloat(fB)
return nil
}
// Check if they int and float combination.
if okAi && okBf {
a.setInt(iA)
b.setFloat(fA)
return nil
}
if okBi && okAf {
a.setFloat(fA)
b.setInt(iB)
return nil
}
// Not numeric types at this point.
// Check for bool inference
bA, okAb := a.bytesToBool()
bB, okBb := b.bytesToBool()
if okAb && okBb {
a.setBool(bA)
b.setBool(bB)
return nil
}
// Fallback to string
sA := a.bytesToString()
sB := b.bytesToString()
a.setString(sA)
b.setString(sB)
return nil
case okA && !okB:
// Here a has `a` is untyped, but `b` has a fixed
// type.
switch b.value.(type) {
case string:
s := a.bytesToString()
a.setString(s)
case int64, float64:
if iA, ok := a.bytesToInt(); ok {
a.setInt(iA)
} else if fA, ok := a.bytesToFloat(); ok {
a.setFloat(fA)
} else {
return fmt.Errorf("Could not convert %s to a number", a.String())
}
case bool:
if bA, ok := a.bytesToBool(); ok {
a.setBool(bA)
} else {
return fmt.Errorf("Could not convert %s to a boolean", a.String())
}
default:
return errCmpMismatchedTypes
}
return nil
case !okA && okB:
// swap arguments to avoid repeating code
return inferTypesForCmp(b, a)
default:
// Does not happen
return nil
}
}
// Value arithmetic functions: we do not expose them outside the
// module. All arithmetic works only on numeric values with automatic
// promotion to the "larger" type that can represent the value. TODO:
// Add support for large number arithmetic.
// Supported arithmetic operators
const (
opPlus = "+"
opMinus = "-"
opDivide = "/"
opMultiply = "*"
opModulo = "%"
)
// For arithmetic operations, if both values are numeric then the
// operation shall succeed. If the types are unknown automatic type
// conversion to a number is attempted.
func (v *Value) arithOp(op string, a *Value) error {
err := inferTypeForArithOp(v)
if err != nil {
return err
}
err = inferTypeForArithOp(a)
if err != nil {
return err
}
if !v.isNumeric() || !a.isNumeric() {
return errInvalidDataType(errArithMismatchedTypes)
}
if !isValidArithOperator(op) {
return errInvalidDataType(errArithMismatchedTypes)
}
intV, ok1i := v.ToInt()
intA, ok2i := a.ToInt()
switch {
case ok1i && ok2i:
res, err := intArithOp(op, intV, intA)
v.setInt(res)
return err
default:
// Convert arguments to float
flV, _ := v.ToFloat()
flA, _ := a.ToFloat()
res, err := floatArithOp(op, flV, flA)
v.setFloat(res)
return err
}
}
func inferTypeForArithOp(a *Value) error {
if _, ok := a.ToBytes(); !ok {
return nil
}
if i, ok := a.bytesToInt(); ok {
a.setInt(i)
return nil
}
if f, ok := a.bytesToFloat(); ok {
a.setFloat(f)
return nil
}
err := fmt.Errorf("Could not convert %q to a number", string(a.value.([]byte)))
return errInvalidDataType(err)
}
// All the bytesTo* functions defined below assume the value is a byte-slice.
// Converts untyped value into int. The bool return implies success -
// it returns false only if there is a conversion failure.
func (v Value) bytesToInt() (int64, bool) {
bytes, _ := v.ToBytes()
i, err := strconv.ParseInt(strings.TrimSpace(string(bytes)), 10, 64)
return i, err == nil
}
// Converts untyped value into float. The bool return implies success
// - it returns false only if there is a conversion failure.
func (v Value) bytesToFloat() (float64, bool) {
bytes, _ := v.ToBytes()
i, err := strconv.ParseFloat(strings.TrimSpace(string(bytes)), 64)
return i, err == nil
}
// Converts untyped value into bool. The second bool return implies
// success - it returns false in case of a conversion failure.
func (v Value) bytesToBool() (val bool, ok bool) {
bytes, _ := v.ToBytes()
ok = true
switch strings.ToLower(strings.TrimSpace(string(bytes))) {
case "t", "true", "1":
val = true
case "f", "false", "0":
val = false
default:
ok = false
}
return val, ok
}
// bytesToString - never fails, but returns empty string if value is not bytes.
func (v Value) bytesToString() string {
bytes, _ := v.ToBytes()
return string(bytes)
}
// Calculates minimum or maximum of v and a and assigns the result to
// v - it works only on numeric arguments, where `v` is already
// assumed to be numeric. Attempts conversion to numeric type for `a`
// (first int, then float) only if the underlying values do not have a
// type.
func (v *Value) minmax(a *Value, isMax, isFirstRow bool) error {
err := inferTypeForArithOp(a)
if err != nil {
return err
}
if !a.isNumeric() {
return errArithMismatchedTypes
}
// In case of first row, set v to a.
if isFirstRow {
intA, okI := a.ToInt()
if okI {
v.setInt(intA)
return nil
}
floatA, _ := a.ToFloat()
v.setFloat(floatA)
return nil
}
intV, ok1i := v.ToInt()
intA, ok2i := a.ToInt()
if ok1i && ok2i {
result := intV
if !isMax {
if intA < result {
result = intA
}
} else {
if intA > result {
result = intA
}
}
v.setInt(result)
return nil
}
floatV, _ := v.ToFloat()
floatA, _ := a.ToFloat()
var result float64
if !isMax {
result = math.Min(floatV, floatA)
} else {
result = math.Max(floatV, floatA)
}
v.setFloat(result)
return nil
}
func inferTypeAsTimestamp(v *Value) error {
if s, ok := v.ToString(); ok {
t, err := parseSQLTimestamp(s)
if err != nil {
return err
}
v.setTimestamp(t)
} else if b, ok := v.ToBytes(); ok {
s := string(b)
t, err := parseSQLTimestamp(s)
if err != nil {
return err
}
v.setTimestamp(t)
}
return nil
}
// inferTypeAsString is used to convert untyped values to string - it
// is called when the caller requires a string context to proceed.
func inferTypeAsString(v *Value) {
b, ok := v.ToBytes()
if !ok {
return
}
v.setString(string(b))
}
func isValidComparisonOperator(op string) bool {
switch op {
case opLt:
case opLte:
case opGt:
case opGte:
case opEq:
case opIneq:
default:
return false
}
return true
}
func intCompare(op string, left, right int64) bool {
switch op {
case opLt:
return left < right
case opLte:
return left <= right
case opGt:
return left > right
case opGte:
return left >= right
case opEq:
return left == right
case opIneq:
return left != right
}
// This case does not happen
return false
}
func floatCompare(op string, left, right float64) bool {
diff := math.Abs(left - right)
switch op {
case opLt:
return left < right
case opLte:
return left <= right
case opGt:
return left > right
case opGte:
return left >= right
case opEq:
return diff < floatCmpTolerance
case opIneq:
return diff > floatCmpTolerance
}
// This case does not happen
return false
}
func stringCompare(op string, left, right string) bool {
switch op {
case opLt:
return left < right
case opLte:
return left <= right
case opGt:
return left > right
case opGte:
return left >= right
case opEq:
return left == right
case opIneq:
return left != right
}
// This case does not happen
return false
}
func boolCompare(op string, left, right bool) (bool, error) {
switch op {
case opEq:
return left == right, nil
case opIneq:
return left != right, nil
default:
return false, errCmpInvalidBoolOperator
}
}
func arrayCompare(op string, left, right []Value) (bool, error) {
switch op {
case opEq:
if len(left) != len(right) {
return false, nil
}
for i, l := range left {
eq, err := l.compareOp(op, &right[i])
if !eq || err != nil {
return eq, err
}
}
return true, nil
case opIneq:
for i, l := range left {
eq, err := l.compareOp(op, &right[i])
if eq || err != nil {
return eq, err
}
}
return false, nil
default:
return false, errCmpInvalidBoolOperator
}
}
func timestampCompare(op string, left, right time.Time) bool {
switch op {
case opLt:
return left.Before(right)
case opLte:
return left.Before(right) || left.Equal(right)
case opGt:
return left.After(right)
case opGte:
return left.After(right) || left.Equal(right)
case opEq:
return left.Equal(right)
case opIneq:
return !left.Equal(right)
}
// This case does not happen
return false
}
func isValidArithOperator(op string) bool {
switch op {
case opPlus:
case opMinus:
case opDivide:
case opMultiply:
case opModulo:
default:
return false
}
return true
}
// Overflow errors are ignored.
func intArithOp(op string, left, right int64) (int64, error) {
switch op {
case opPlus:
return left + right, nil
case opMinus:
return left - right, nil
case opDivide:
if right == 0 {
return 0, errArithDivideByZero
}
return left / right, nil
case opMultiply:
return left * right, nil
case opModulo:
if right == 0 {
return 0, errArithDivideByZero
}
return left % right, nil
}
// This does not happen
return 0, nil
}
// Overflow errors are ignored.
func floatArithOp(op string, left, right float64) (float64, error) {
switch op {
case opPlus:
return left + right, nil
case opMinus:
return left - right, nil
case opDivide:
if right == 0 {
return 0, errArithDivideByZero
}
return left / right, nil
case opMultiply:
return left * right, nil
case opModulo:
if right == 0 {
return 0, errArithDivideByZero
}
return math.Mod(left, right), nil
}
// This does not happen
return 0, nil
}