You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
211 lines
6.5 KiB
211 lines
6.5 KiB
// Copyright 2020 PingCAP, 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,
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package expression
|
|
|
|
import (
|
|
"strings"
|
|
|
|
"github.com/pingcap/parser/ast"
|
|
"github.com/pingcap/parser/charset"
|
|
"github.com/pingcap/tidb/sessionctx"
|
|
"github.com/pingcap/tidb/types"
|
|
)
|
|
|
|
type collationInfo struct {
|
|
coer Coercibility
|
|
coerInit bool
|
|
|
|
charset string
|
|
collation string
|
|
flen int
|
|
}
|
|
|
|
func (c *collationInfo) HasCoercibility() bool {
|
|
return c.coerInit
|
|
}
|
|
|
|
func (c *collationInfo) Coercibility() Coercibility {
|
|
return c.coer
|
|
}
|
|
|
|
// SetCoercibility implements CollationInfo SetCoercibility interface.
|
|
func (c *collationInfo) SetCoercibility(val Coercibility) {
|
|
c.coer = val
|
|
c.coerInit = true
|
|
}
|
|
|
|
func (c *collationInfo) SetCharsetAndCollation(chs, coll string) {
|
|
c.charset, c.collation = chs, coll
|
|
}
|
|
|
|
func (c *collationInfo) CharsetAndCollation(ctx sessionctx.Context) (string, string) {
|
|
if c.charset != "" || c.collation != "" {
|
|
return c.charset, c.collation
|
|
}
|
|
|
|
if ctx != nil && ctx.GetSessionVars() != nil {
|
|
c.charset, c.collation = ctx.GetSessionVars().GetCharsetInfo()
|
|
}
|
|
if c.charset == "" || c.collation == "" {
|
|
c.charset, c.collation = charset.GetDefaultCharsetAndCollate()
|
|
}
|
|
c.flen = types.UnspecifiedLength
|
|
return c.charset, c.collation
|
|
}
|
|
|
|
// CollationInfo contains all interfaces about dealing with collation.
|
|
type CollationInfo interface {
|
|
// HasCoercibility returns if the Coercibility value is initialized.
|
|
HasCoercibility() bool
|
|
|
|
// Coercibility returns the coercibility value which is used to check collations.
|
|
Coercibility() Coercibility
|
|
|
|
// SetCoercibility sets a specified coercibility for this expression.
|
|
SetCoercibility(val Coercibility)
|
|
|
|
// CharsetAndCollation ...
|
|
CharsetAndCollation(ctx sessionctx.Context) (string, string)
|
|
|
|
// SetCharsetAndCollation ...
|
|
SetCharsetAndCollation(chs, coll string)
|
|
}
|
|
|
|
// Coercibility values are used to check whether the collation of one item can be coerced to
|
|
// the collation of other. See https://dev.mysql.com/doc/refman/8.0/en/charset-collation-coercibility.html
|
|
type Coercibility int
|
|
|
|
const (
|
|
// CoercibilityExplicit is derived from an explicit COLLATE clause.
|
|
CoercibilityExplicit Coercibility = 0
|
|
// CoercibilityNone is derived from the concatenation of two strings with different collations.
|
|
CoercibilityNone Coercibility = 1
|
|
// CoercibilityImplicit is derived from a column or a stored routine parameter or local variable.
|
|
CoercibilityImplicit Coercibility = 2
|
|
// CoercibilitySysconst is derived from a “system constant” (the string returned by functions such as USER() or VERSION()).
|
|
CoercibilitySysconst Coercibility = 3
|
|
// CoercibilityCoercible is derived from a literal.
|
|
CoercibilityCoercible Coercibility = 4
|
|
// CoercibilityNumeric is derived from a numeric or temporal value.
|
|
CoercibilityNumeric Coercibility = 5
|
|
// CoercibilityIgnorable is derived from NULL or an expression that is derived from NULL.
|
|
CoercibilityIgnorable Coercibility = 6
|
|
)
|
|
|
|
var (
|
|
sysConstFuncs = map[string]struct{}{
|
|
ast.User: {},
|
|
ast.Version: {},
|
|
ast.Database: {},
|
|
ast.CurrentRole: {},
|
|
ast.CurrentUser: {},
|
|
}
|
|
|
|
// collationPriority is the priority when infer the result collation, the priority of collation a > b iff collationPriority[a] > collationPriority[b]
|
|
collationPriority = map[string]int{
|
|
charset.CollationASCII: 0,
|
|
charset.CollationLatin1: 1,
|
|
"utf8_general_ci": 2,
|
|
charset.CollationUTF8: 3,
|
|
"utf8mb4_general_ci": 4,
|
|
charset.CollationUTF8MB4: 5,
|
|
charset.CollationBin: 6,
|
|
}
|
|
|
|
// CollationStrictness indicates the strictness of comparison of the collation. The unequal order in a weak collation also holds in a strict collation.
|
|
// For example, if a < b in a weak collation(e.g. general_ci), then there must be a < b in a strict collation(e.g. _bin).
|
|
CollationStrictness = map[string]int{
|
|
"utf8_general_ci": 0,
|
|
"utf8mb4_general_ci": 0,
|
|
charset.CollationASCII: 1,
|
|
charset.CollationLatin1: 1,
|
|
charset.CollationUTF8: 1,
|
|
charset.CollationUTF8MB4: 1,
|
|
charset.CollationBin: 2,
|
|
}
|
|
)
|
|
|
|
func deriveCoercibilityForScarlarFunc(sf *ScalarFunction) Coercibility {
|
|
if _, ok := sysConstFuncs[sf.FuncName.L]; ok {
|
|
return CoercibilitySysconst
|
|
}
|
|
if sf.RetType.EvalType() != types.ETString {
|
|
return CoercibilityNumeric
|
|
}
|
|
coer := CoercibilityIgnorable
|
|
for _, arg := range sf.GetArgs() {
|
|
if arg.Coercibility() < coer {
|
|
coer = arg.Coercibility()
|
|
}
|
|
}
|
|
return coer
|
|
}
|
|
|
|
func deriveCoercibilityForConstant(c *Constant) Coercibility {
|
|
if c.Value.IsNull() {
|
|
return CoercibilityIgnorable
|
|
} else if c.RetType.EvalType() != types.ETString {
|
|
return CoercibilityNumeric
|
|
}
|
|
return CoercibilityCoercible
|
|
}
|
|
|
|
func deriveCoercibilityForColumn(c *Column) Coercibility {
|
|
if c.RetType.EvalType() != types.ETString {
|
|
return CoercibilityNumeric
|
|
}
|
|
return CoercibilityImplicit
|
|
}
|
|
|
|
// DeriveCollationFromExprs derives collation information from these expressions.
|
|
func DeriveCollationFromExprs(ctx sessionctx.Context, exprs ...Expression) (dstCharset, dstCollation string) {
|
|
curCoer := CoercibilityCoercible
|
|
curCollationPriority := -1
|
|
dstCharset, dstCollation = charset.GetDefaultCharsetAndCollate()
|
|
if ctx != nil && ctx.GetSessionVars() != nil {
|
|
dstCharset, dstCollation = ctx.GetSessionVars().GetCharsetInfo()
|
|
if dstCharset == "" || dstCollation == "" {
|
|
dstCharset, dstCollation = charset.GetDefaultCharsetAndCollate()
|
|
}
|
|
}
|
|
hasStrArg := false
|
|
// see https://dev.mysql.com/doc/refman/8.0/en/charset-collation-coercibility.html
|
|
for _, e := range exprs {
|
|
if e.GetType().EvalType() != types.ETString {
|
|
continue
|
|
}
|
|
hasStrArg = true
|
|
|
|
coer := e.Coercibility()
|
|
ft := e.GetType()
|
|
collationPriority, ok := collationPriority[strings.ToLower(ft.Collate)]
|
|
if !ok {
|
|
collationPriority = -1
|
|
}
|
|
if coer != curCoer {
|
|
if coer < curCoer {
|
|
curCoer, curCollationPriority, dstCharset, dstCollation = coer, collationPriority, ft.Charset, ft.Collate
|
|
}
|
|
continue
|
|
}
|
|
if !ok || collationPriority <= curCollationPriority {
|
|
continue
|
|
}
|
|
curCollationPriority, dstCharset, dstCollation = collationPriority, ft.Charset, ft.Collate
|
|
}
|
|
if !hasStrArg {
|
|
dstCharset, dstCollation = charset.CharsetBin, charset.CollationBin
|
|
}
|
|
return
|
|
}
|
|
|