forked from cockroachdb/cockroach
/
datum.go
1066 lines (917 loc) · 22.7 KB
/
datum.go
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// Copyright 2015 The Cockroach Authors.
//
// 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.
//
// Author: Peter Mattis (peter@cockroachlabs.com)
package parser
import (
"bytes"
"fmt"
"math"
"reflect"
"sort"
"strconv"
"time"
"gopkg.in/inf.v0"
"github.com/cockroachdb/cockroach/roachpb"
)
var (
// DummyBool is a placeholder DBool value.
DummyBool Datum = DBool(false)
// DummyInt is a placeholder DInt value.
DummyInt Datum = DInt(0)
// DummyFloat is a placeholder DFloat value.
DummyFloat Datum = DFloat(0)
// DummyDecimal is a placeholder DDecimal value.
DummyDecimal Datum = &DDecimal{}
// DummyString is a placeholder DString value.
DummyString Datum = DString("")
// DummyBytes is a placeholder DBytes value.
DummyBytes Datum = DBytes("")
// DummyDate is a placeholder DDate value.
DummyDate Datum = DDate(0)
// DummyTimestamp is a placeholder DTimestamp value.
DummyTimestamp Datum = DTimestamp{}
// DummyInterval is a placeholder DInterval value.
DummyInterval Datum = DInterval{}
// dummyTuple is a placeholder DTuple value.
dummyTuple Datum = DTuple{}
// DNull is the NULL Datum.
DNull Datum = dNull{}
boolType = reflect.TypeOf(DummyBool)
intType = reflect.TypeOf(DummyInt)
floatType = reflect.TypeOf(DummyFloat)
decimalType = reflect.TypeOf(DummyDecimal)
stringType = reflect.TypeOf(DummyString)
bytesType = reflect.TypeOf(DummyBytes)
dateType = reflect.TypeOf(DummyDate)
timestampType = reflect.TypeOf(DummyTimestamp)
intervalType = reflect.TypeOf(DummyInterval)
tupleType = reflect.TypeOf(dummyTuple)
nullType = reflect.TypeOf(DNull)
valargType = reflect.TypeOf(DValArg{})
)
// A Datum holds either a bool, int64, float64, string or []Datum.
//
// TODO(nvanbenschoten) It might be worth it in the future to make all
// Datum implementations receive on pointer types to provide more control
// over memory allocations when packaging and unpackaging concrete types
// to and from their Datum interface. This would allow us to make
// optimizations in terms of shared buffer preallocations.
type Datum interface {
Expr
// Type returns the (user-friendly) name of the type.
Type() string
// TypeEqual determines if the receiver and the other Datum have the same
// type or not. This method should be used for asserting the type of all
// Datum, with the exception of DNull, where it is safe/encouraged to perform
// a direct equivalence check.
TypeEqual(other Datum) bool
// Compare returns -1 if the receiver is less than other, 0 if receiver is
// equal to other and +1 if receiver is greater than other.
// TODO(nvanbenschoten) Should we look into merging this with cmpOps?
Compare(other Datum) int
// HasPrev specifies if Prev() can be used to compute a previous value for
// a datum. For example, DBytes doesn't support it (the previous for BB is BAZZZ..).
HasPrev() bool
// Prev returns the previous datum. If the receiver is "b" and the returned datum
// is "a", then "a < b" and no other datum will compare such that "a < c <
// b".
// The return value is undefined if `IsMin()`.
Prev() Datum
// HasNext specifies if Next() can be used to compute a next value for a
// datum. For example, DDecimal doesn't support it (the next for 1.0 is 1.00..1).
HasNext() bool
// Next returns the next datum. If the receiver is "a" and the returned datum
// is "b", then "a < b" and no other datum will compare such that "a < c <
// b".
// The return value is undefined if `IsMax()`.
Next() Datum
// IsMax returns true if the datum is equal to the maximum value the datum
// type can hold.
IsMax() bool
// IsMin returns true if the datum is equal to the minimum value the datum
// type can hold.
IsMin() bool
}
// DBool is the boolean Datum.
type DBool bool
// GetBool gets DBool or an error (also treats NULL as false, not an error).
func GetBool(d Datum) (DBool, error) {
if v, ok := d.(DBool); ok {
return v, nil
}
if d == DNull {
return DBool(false), nil
}
return false, fmt.Errorf("cannot convert %s to bool", d.Type())
}
// Type implements the Datum interface.
func (d DBool) Type() string {
return "bool"
}
// TypeEqual implements the Datum interface.
func (d DBool) TypeEqual(other Datum) bool {
_, ok := other.(DBool)
return ok
}
// Compare implements the Datum interface.
func (d DBool) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DBool)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
if !d && v {
return -1
}
if d && !v {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DBool) HasPrev() bool {
return true
}
// Prev implements the Datum interface.
func (d DBool) Prev() Datum {
return DBool(false)
}
// HasNext implements the Datum interface.
func (d DBool) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DBool) Next() Datum {
return DBool(true)
}
// IsMax implements the Datum interface.
func (d DBool) IsMax() bool {
return d == true
}
// IsMin implements the Datum interface.
func (d DBool) IsMin() bool {
return d == false
}
func (d DBool) String() string {
return strconv.FormatBool(bool(d))
}
// DInt is the int Datum.
type DInt int64
// Type implements the Datum interface.
func (d DInt) Type() string {
return "int"
}
// TypeEqual implements the Datum interface.
func (d DInt) TypeEqual(other Datum) bool {
_, ok := other.(DInt)
return ok
}
// Compare implements the Datum interface.
func (d DInt) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DInt)
if !ok {
cmp, ok := mixedTypeCompare(d, other)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
return cmp
}
if d < v {
return -1
}
if d > v {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DInt) HasPrev() bool {
return true
}
// Prev implements the Datum interface.
func (d DInt) Prev() Datum {
return d - 1
}
// HasNext implements the Datum interface.
func (d DInt) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DInt) Next() Datum {
return d + 1
}
// IsMax implements the Datum interface.
func (d DInt) IsMax() bool {
return d == math.MaxInt64
}
// IsMin implements the Datum interface.
func (d DInt) IsMin() bool {
return d == math.MinInt64
}
func (d DInt) String() string {
return strconv.FormatInt(int64(d), 10)
}
// DFloat is the float Datum.
type DFloat float64
// Type implements the Datum interface.
func (d DFloat) Type() string {
return "float"
}
// TypeEqual implements the Datum interface.
func (d DFloat) TypeEqual(other Datum) bool {
_, ok := other.(DFloat)
return ok
}
// Compare implements the Datum interface.
func (d DFloat) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DFloat)
if !ok {
cmp, ok := mixedTypeCompare(d, other)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
return cmp
}
if d < v {
return -1
}
if d > v {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DFloat) HasPrev() bool {
return true
}
// Prev implements the Datum interface.
func (d DFloat) Prev() Datum {
return DFloat(math.Nextafter(float64(d), math.Inf(-1)))
}
// HasNext implements the Datum interface.
func (d DFloat) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DFloat) Next() Datum {
return DFloat(math.Nextafter(float64(d), math.Inf(1)))
}
// IsMax implements the Datum interface.
func (d DFloat) IsMax() bool {
// Using >= accounts for +inf as well.
return d >= math.MaxFloat64
}
// IsMin implements the Datum interface.
func (d DFloat) IsMin() bool {
// Using <= accounts for -inf as well.
return d <= -math.MaxFloat64
}
func (d DFloat) String() string {
fmt := byte('g')
prec := -1
if _, frac := math.Modf(float64(d)); frac == 0 {
// d is a whole number.
if -1000000 < d && d < 1000000 {
// Small whole numbers are printed without exponents, and with one
// digit of decimal precision to ensure they will parse as floats.
fmt = 'f'
prec = 1
} else {
// Large whole numbers are printed with exponents.
fmt = 'e'
}
}
return strconv.FormatFloat(float64(d), fmt, prec, 64)
}
// DDecimal is the decimal Datum.
type DDecimal struct {
inf.Dec
}
// Type implements the Datum interface.
func (d *DDecimal) Type() string {
return "decimal"
}
// TypeEqual implements the Datum interface.
func (d *DDecimal) TypeEqual(other Datum) bool {
_, ok := other.(*DDecimal)
return ok
}
// Compare implements the Datum interface.
func (d *DDecimal) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(*DDecimal)
if !ok {
cmp, ok := mixedTypeCompare(d, other)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
return cmp
}
return d.Cmp(&v.Dec)
}
// HasPrev implements the Datum interface.
func (d *DDecimal) HasPrev() bool {
return false
}
// Prev implements the Datum interface.
func (d *DDecimal) Prev() Datum {
panic(d.Type() + ".Prev() not supported")
}
// HasNext implements the Datum interface.
func (d *DDecimal) HasNext() bool {
return false
}
// Next implements the Datum interface.
func (d *DDecimal) Next() Datum {
panic(d.Type() + ".Next() not supported")
}
// IsMax implements the Datum interface.
func (d *DDecimal) IsMax() bool {
return false
}
// IsMin implements the Datum interface.
func (d *DDecimal) IsMin() bool {
return false
}
func (d *DDecimal) String() string {
return d.Dec.String()
}
// DString is the string Datum.
type DString string
// Type implements the Datum interface.
func (d DString) Type() string {
return "string"
}
// TypeEqual implements the Datum interface.
func (d DString) TypeEqual(other Datum) bool {
_, ok := other.(DString)
return ok
}
// Compare implements the Datum interface.
func (d DString) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DString)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
if d < v {
return -1
}
if d > v {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DString) HasPrev() bool {
return false
}
// Prev implements the Datum interface.
func (d DString) Prev() Datum {
panic(d.Type() + ".Prev() not supported")
}
// HasNext implements the Datum interface.
func (d DString) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DString) Next() Datum {
return DString(roachpb.Key(d).Next())
}
// IsMax implements the Datum interface.
func (d DString) IsMax() bool {
return false
}
// IsMin implements the Datum interface.
func (d DString) IsMin() bool {
return len(d) == 0
}
func (d DString) String() string {
return encodeSQLString(string(d))
}
// DBytes is the bytes Datum. The underlying type is a string because we want
// the immutability, but this may contain arbitrary bytes.
type DBytes string
// Type implements the Datum interface.
func (d DBytes) Type() string {
return "bytes"
}
// TypeEqual implements the Datum interface.
func (d DBytes) TypeEqual(other Datum) bool {
_, ok := other.(DBytes)
return ok
}
// Compare implements the Datum interface.
func (d DBytes) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DBytes)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
if d < v {
return -1
}
if d > v {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DBytes) HasPrev() bool {
return false
}
// Prev implements the Datum interface.
func (d DBytes) Prev() Datum {
panic(d.Type() + ".Prev() not supported")
}
// HasNext implements the Datum interface.
func (d DBytes) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DBytes) Next() Datum {
return DBytes(roachpb.Key(d).Next())
}
// IsMax implements the Datum interface.
func (d DBytes) IsMax() bool {
return false
}
// IsMin implements the Datum interface.
func (d DBytes) IsMin() bool {
return len(d) == 0
}
func (d DBytes) String() string {
return encodeSQLBytes(string(d))
}
// DDate is the date Datum represented as the number of days after
// the Unix epoch.
type DDate int64
// Type implements the Datum interface.
func (d DDate) Type() string {
return "date"
}
// TypeEqual implements the Datum interface.
func (d DDate) TypeEqual(other Datum) bool {
_, ok := other.(DDate)
return ok
}
// Compare implements the Datum interface.
func (d DDate) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DDate)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
if d < v {
return -1
}
if v < d {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DDate) HasPrev() bool {
return true
}
// Prev implements the Datum interface.
func (d DDate) Prev() Datum {
return d - 1
}
// HasNext implements the Datum interface.
func (d DDate) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DDate) Next() Datum {
return d + 1
}
// IsMax implements the Datum interface.
func (d DDate) IsMax() bool {
return d == math.MaxInt64
}
// IsMin implements the Datum interface.
func (d DDate) IsMin() bool {
return d == math.MinInt64
}
func (d DDate) String() string {
return time.Unix(int64(d)*secondsInDay, 0).UTC().Format(dateFormat)
}
// DTimestamp is the timestamp Datum.
type DTimestamp struct {
time.Time
}
// Type implements the Datum interface.
func (d DTimestamp) Type() string {
return "timestamp"
}
// TypeEqual implements the Datum interface.
func (d DTimestamp) TypeEqual(other Datum) bool {
_, ok := other.(DTimestamp)
return ok
}
// Compare implements the Datum interface.
func (d DTimestamp) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DTimestamp)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
if d.Before(v.Time) {
return -1
}
if v.Before(d.Time) {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DTimestamp) HasPrev() bool {
return true
}
// Prev implements the Datum interface.
func (d DTimestamp) Prev() Datum {
return DTimestamp{Time: d.Add(-1)}
}
// HasNext implements the Datum interface.
func (d DTimestamp) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DTimestamp) Next() Datum {
return DTimestamp{Time: d.Add(1)}
}
// IsMax implements the Datum interface.
func (d DTimestamp) IsMax() bool {
// Adding 1 overflows to a smaller value
return d.After(d.Next().(DTimestamp).Time)
}
// IsMin implements the Datum interface.
func (d DTimestamp) IsMin() bool {
// Subtracting 1 underflows to a larger value.
return d.Before(d.Add(-1))
}
func (d DTimestamp) String() string {
return d.UTC().Format(TimestampWithOffsetZoneFormat)
}
// DInterval is the interval Datum.
type DInterval struct {
time.Duration
}
// Type implements the Datum interface.
func (d DInterval) Type() string {
return "interval"
}
// TypeEqual implements the Datum interface.
func (d DInterval) TypeEqual(other Datum) bool {
_, ok := other.(DInterval)
return ok
}
// Compare implements the Datum interface.
func (d DInterval) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DInterval)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
if d.Duration < v.Duration {
return -1
}
if v.Duration < d.Duration {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DInterval) HasPrev() bool {
return true
}
// Prev implements the Datum interface.
func (d DInterval) Prev() Datum {
return DInterval{Duration: d.Duration - 1}
}
// HasNext implements the Datum interface.
func (d DInterval) HasNext() bool {
return true
}
// Next implements the Datum interface.
func (d DInterval) Next() Datum {
return DInterval{Duration: d.Duration + 1}
}
// IsMax implements the Datum interface.
func (d DInterval) IsMax() bool {
return d.Duration == math.MaxInt64
}
// IsMin implements the Datum interface.
func (d DInterval) IsMin() bool {
return d.Duration == math.MinInt64
}
// DTuple is the tuple Datum.
type DTuple []Datum
// Type implements the Datum interface.
func (d DTuple) Type() string {
return "tuple"
}
// TypeEqual implements the Datum interface.
func (d DTuple) TypeEqual(other Datum) bool {
t, ok := other.(DTuple)
if !ok {
return false
}
if len(d) != len(t) {
return false
}
for i := 0; i < len(d); i++ {
if !d[i].TypeEqual(t[i]) {
return false
}
}
return true
}
// Compare implements the Datum interface.
func (d DTuple) Compare(other Datum) int {
if other == DNull {
// NULL is less than any non-NULL value.
return 1
}
v, ok := other.(DTuple)
if !ok {
panic(fmt.Sprintf("unsupported comparison: %s to %s", d.Type(), other.Type()))
}
n := len(d)
if n > len(v) {
n = len(v)
}
for i := 0; i < n; i++ {
c := d[i].Compare(v[i])
if c != 0 {
return c
}
}
if len(d) < len(v) {
return -1
}
if len(d) > len(v) {
return 1
}
return 0
}
// HasPrev implements the Datum interface.
func (d DTuple) HasPrev() bool {
for i := len(d) - 1; i >= 0; i-- {
if d[i].HasPrev() {
return true
}
}
return false
}
// Prev implements the Datum interface.
func (d DTuple) Prev() Datum {
n := make(DTuple, len(d))
copy(n, d)
for i := len(n) - 1; i >= 0; i-- {
if n[i].HasPrev() {
n[i] = n[i].Prev()
return n
}
}
panic(fmt.Errorf("Prev() cannot be computed on a tuple whose datum does not support it"))
}
// HasNext implements the Datum interface.
func (d DTuple) HasNext() bool {
for i := len(d) - 1; i >= 0; i-- {
if d[i].HasNext() {
return true
}
}
return false
}
// Next implements the Datum interface.
func (d DTuple) Next() Datum {
n := make(DTuple, len(d))
copy(n, d)
for i := len(n) - 1; i >= 0; i-- {
if n[i].HasNext() {
n[i] = n[i].Next()
return n
}
}
panic(fmt.Errorf("Next() cannot be computed on a tuple whose datum does not support it"))
}
// IsMax implements the Datum interface.
func (d DTuple) IsMax() bool {
// Unimplemented for DTuple. Seems possible to provide an implementation
// which called IsMax for each of the elements, but currently this isn't
// needed.
return false
}
// IsMin implements the Datum interface.
func (d DTuple) IsMin() bool {
// Unimplemented for DTuple. Seems possible to provide an implementation
// which called IsMin for each of the elements, but currently this isn't
// needed.
return false
}
func (d DTuple) String() string {
var buf bytes.Buffer
_ = buf.WriteByte('(')
for i, v := range d {
if i > 0 {
buf.WriteString(", ")
}
buf.WriteString(v.String())
}
_ = buf.WriteByte(')')
return buf.String()
}
func (d DTuple) Len() int {
return len(d)
}
func (d DTuple) Less(i, j int) bool {
return d[i].Compare(d[j]) < 0
}
func (d DTuple) Swap(i, j int) {
d[i], d[j] = d[j], d[i]
}
// Normalize sorts and uniques the datum tuple.
func (d *DTuple) Normalize() {
sort.Sort(d)
d.makeUnique()
}
func (d *DTuple) makeUnique() {
n := 0
for i := 0; i < len(*d); i++ {
if (*d)[i] == DNull {
continue
}
if n == 0 || (*d)[n-1].Compare((*d)[i]) < 0 {
(*d)[n] = (*d)[i]
n++
}
}
*d = (*d)[:n]
}
type dNull struct{}
// Type implements the Datum interface.
func (d dNull) Type() string {
return "NULL"
}
// TypeEqual implements the Datum interface.
func (d dNull) TypeEqual(other Datum) bool {
_, ok := other.(dNull)
return ok
}
// Compare implements the Datum interface.
func (d dNull) Compare(other Datum) int {
if other == DNull {
return 0
}
return -1
}
// HasPrev implements the Datum interface.
func (d dNull) HasPrev() bool {
return false
}
// Prev implements the Datum interface.
func (d dNull) Prev() Datum {
panic(d.Type() + ".Prev not supported")
}
// HasNext implements the Datum interface.
func (d dNull) HasNext() bool {
return false
}
// Next implements the Datum interface.
func (d dNull) Next() Datum {
panic(d.Type() + ".Next not supported")
}
// IsMax implements the Datum interface.
func (d dNull) IsMax() bool {
return true
}
// IsMin implements the Datum interface.
func (d dNull) IsMin() bool {
return true
}
func (d dNull) String() string {
return "NULL"
}
var _ VariableExpr = DValArg{}
// DValArg is the named bind var argument Datum.
type DValArg struct {
name string
}
// Variable implements the VariableExpr interface.
func (DValArg) Variable() {}
// Type implements the Datum interface.
func (DValArg) Type() string {
return "parameter"
}
// TypeEqual implements the Datum interface.
func (d DValArg) TypeEqual(other Datum) bool {
_, ok := other.(DValArg)
return ok
}
// Compare implements the Datum interface.
func (d DValArg) Compare(other Datum) int {
panic(d.Type() + ".Compare not supported")
}
// HasPrev implements the Datum interface.
func (d DValArg) HasPrev() bool {