expression

package
v0.0.0-...-52100cb Latest Latest
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 Go to latest Published: Mar 20, 2017 License: Apache-2.0 Imports: 34 Imported by: 0

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Index

Constants

This section is empty.

Variables

View Source 
var (
	// CurrentTimestamp is the keyword getting default value for datetime and timestamp type.
	CurrentTimestamp = "CURRENT_TIMESTAMP"

	// ZeroTimestamp shows the zero datetime and timestamp.
	ZeroTimestamp = "0000-00-00 00:00:00"
)
View Source 
var EvalAstExpr func(expr ast.ExprNode, ctx context.Context) (types.Datum, error)

EvalAstExpr evaluates ast expression directly.

View Source 
var MaxPropagateColsCnt = 100

MaxPropagateColsCnt means the max number of columns that can participate propagation.

View Source 
var Null = &Constant{
	Value:   types.NewDatum(nil),
	RetType: types.NewFieldType(mysql.TypeTiny),
}

Null stands for null constant.

View Source 
var One = &Constant{
	Value:   types.NewDatum(1),
	RetType: types.NewFieldType(mysql.TypeTiny),
}

One stands for a number 1.

View Source 
var Zero = &Constant{
	Value:   types.NewDatum(0),
	RetType: types.NewFieldType(mysql.TypeTiny),
}

Zero stands for a number 0.

Functions

func EvalBool 

func EvalBool(expr Expression, row []types.Datum, ctx context.Context) (bool, error)

EvalBool evaluates expression to a boolean value.

func GetTimeValue 

func GetTimeValue(ctx context.Context, v interface{}, tp byte, fsp int) (types.Datum, error)

GetTimeValue gets the time value with type tp.

func IsCurrentTimeExpr 

func IsCurrentTimeExpr(e ast.ExprNode) bool

IsCurrentTimeExpr returns whether e is CurrentTimeExpr.

Types

type AggFunctionMode 

type AggFunctionMode int

AggFunctionMode stands for the aggregation function's mode. 

const (
	// CompleteMode function accepts origin data.
	CompleteMode AggFunctionMode = iota
	// FinalMode function accepts partial data.
	FinalMode
)

type AggregationFunction 

type AggregationFunction interface {
	fmt.Stringer
	json.Marshaler
	// Update during executing.
	Update(row []types.Datum, groupKey []byte, ctx context.Context) error

	// StreamUpdate updates data using streaming algo.
	StreamUpdate(row []types.Datum, ctx context.Context) error

	// SetMode sets aggFunctionMode for aggregate function.
	SetMode(mode AggFunctionMode)

	// GetMode gets aggFunctionMode from aggregate function.
	GetMode() AggFunctionMode

	// GetGroupResult will be called when all data have been processed.
	GetGroupResult(groupKey []byte) types.Datum

	// GetStreamResult gets a result using streaming agg.
	GetStreamResult() types.Datum

	// GetArgs stands for getting all arguments.
	GetArgs() []Expression

	// GetName gets the aggregation function name.
	GetName() string

	// SetArgs sets argument by index.
	SetArgs(args []Expression)

	// Clear collects the mapper's memory.
	Clear()

	// IsDistinct indicates if the aggregate function contains distinct attribute.
	IsDistinct() bool

	// SetContext sets the aggregate evaluation context.
	SetContext(ctx map[string](*aggEvaluateContext))

	// Equal checks whether two aggregation functions are equal.
	Equal(agg AggregationFunction, ctx context.Context) bool

	// Clone copies an aggregate function totally.
	Clone() AggregationFunction

	// GetType gets field type of aggregate function.
	GetType() *types.FieldType

	// CalculateDefaultValue gets the default value when the aggregate function's input is null.
	// The input stands for the schema of Aggregation's child. If the function can't produce a default value, the second
	// return value will be false.
	CalculateDefaultValue(schema *Schema, ctx context.Context) (types.Datum, bool)
}

AggregationFunction stands for aggregate functions.

func NewAggFunction 

func NewAggFunction(funcType string, funcArgs []Expression, distinct bool) AggregationFunction

NewAggFunction creates a new AggregationFunction.

type Assignment 

type Assignment struct {
	Col  *Column
	Expr Expression
}

Assignment represents a set assignment in Update, such as Update t set c1 = hex(12), c2 = c3 where c2 = 1

type BuiltinFunc 

type BuiltinFunc func([]types.Datum, context.Context) (types.Datum, error)

BuiltinFunc is the function signature for builtin functions

type Column 

type Column struct {
	FromID  string
	ColName model.CIStr
	DBName  model.CIStr
	TblName model.CIStr
	RetType *types.FieldType
	ID      int64
	// Position means the position of this column that appears in the select fields.
	// e.g. SELECT name as id , 1 - id as id , 1 + name as id, name as id from src having id = 1;
	// There are four ids in the same schema, so you can't identify the column through the FromID and ColName.
	Position int
	// IsAggOrSubq means if this column is referenced to a Aggregation column or a Subquery column.
	// If so, this column's name will be the plain sql text.
	IsAggOrSubq bool

	// Only used for execution.
	Index int
	// contains filtered or unexported fields
}

Column represents a column.

func ExtractColumns 

func ExtractColumns(expr Expression) (cols []*Column)

ExtractColumns extracts all columns from an expression.

func (*Column) Clone 

func (col *Column) Clone() Expression

Clone implements Expression interface.

func (*Column) Decorrelate 

func (col *Column) Decorrelate(_ *Schema) Expression

Decorrelate implements Expression interface.

func (*Column) Equal 

func (col *Column) Equal(expr Expression, _ context.Context) bool

Equal implements Expression interface.

func (*Column) Eval 

func (col *Column) Eval(row []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*Column) GetType 

func (col *Column) GetType() *types.FieldType

GetType implements Expression interface.

func (*Column) HashCode 

func (col *Column) HashCode() []byte

HashCode implements Expression interface.

func (*Column) IsCorrelated 

func (col *Column) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*Column) MarshalJSON 

func (col *Column) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*Column) ResolveIndices 

func (col *Column) ResolveIndices(schema *Schema)

ResolveIndices implements Expression interface.

func (*Column) String 

func (col *Column) String() string

String implements Stringer interface.

type Constant 

type Constant struct {
	Value   types.Datum
	RetType *types.FieldType
}

Constant stands for a constant value.

func (*Constant) Clone 

func (c *Constant) Clone() Expression

Clone implements Expression interface.

func (*Constant) Decorrelate 

func (c *Constant) Decorrelate(_ *Schema) Expression

Decorrelate implements Expression interface.

func (*Constant) Equal 

func (c *Constant) Equal(b Expression, ctx context.Context) bool

Equal implements Expression interface.

func (*Constant) Eval 

func (c *Constant) Eval(_ []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*Constant) GetType 

func (c *Constant) GetType() *types.FieldType

GetType implements Expression interface.

func (*Constant) HashCode 

func (c *Constant) HashCode() []byte

HashCode implements Expression interface.

func (*Constant) IsCorrelated 

func (c *Constant) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*Constant) MarshalJSON 

func (c *Constant) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*Constant) ResolveIndices 

func (c *Constant) ResolveIndices(_ *Schema)

ResolveIndices implements Expression interface.

func (*Constant) String 

func (c *Constant) String() string

String implements fmt.Stringer interface.

type CorrelatedColumn 

type CorrelatedColumn struct {
	Column

	Data *types.Datum
}

CorrelatedColumn stands for a column in a correlated sub query.

func (*CorrelatedColumn) Clone 

func (col *CorrelatedColumn) Clone() Expression

Clone implements Expression interface.

func (*CorrelatedColumn) Decorrelate 

func (col *CorrelatedColumn) Decorrelate(schema *Schema) Expression

Decorrelate implements Expression interface.

func (*CorrelatedColumn) Equal 

func (col *CorrelatedColumn) Equal(expr Expression, ctx context.Context) bool

Equal implements Expression interface.

func (*CorrelatedColumn) Eval 

func (col *CorrelatedColumn) Eval(row []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*CorrelatedColumn) IsCorrelated 

func (col *CorrelatedColumn) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*CorrelatedColumn) ResolveIndices 

func (col *CorrelatedColumn) ResolveIndices(_ *Schema)

ResolveIndices implements Expression interface.

type Expression 

type Expression interface {
	fmt.Stringer
	json.Marshaler
	// Eval evaluates an expression through a row.
	Eval(row []types.Datum) (types.Datum, error)

	// Get the expression return type.
	GetType() *types.FieldType

	// Clone copies an expression totally.
	Clone() Expression

	// HashCode create the hashcode for expression
	HashCode() []byte

	// Equal checks whether two expressions are equal.
	Equal(e Expression, ctx context.Context) bool

	// IsCorrelated checks if this expression has correlated key.
	IsCorrelated() bool

	// Decorrelate try to decorrelate the expression by schema.
	Decorrelate(schema *Schema) Expression

	// ResolveIndices resolves indices by the given schema.
	ResolveIndices(schema *Schema)
}

Expression represents all scalar expression in SQL.

func Column2Exprs 

func Column2Exprs(cols []*Column) []Expression

Column2Exprs will transfer column slice to expression slice.

func ColumnSubstitute 

func ColumnSubstitute(expr Expression, schema *Schema, newExprs []Expression) Expression

ColumnSubstitute substitutes the columns in filter to expressions in select fields. e.g. select * from (select b as a from t) k where a < 10 => select * from (select b as a from t where b < 10) k.

func ComposeCNFCondition 

func ComposeCNFCondition(ctx context.Context, conditions ...Expression) Expression

ComposeCNFCondition composes CNF items into a balance deep CNF tree, which benefits a lot for pb decoder/encoder.

func ComposeDNFCondition 

func ComposeDNFCondition(ctx context.Context, conditions ...Expression) Expression

ComposeDNFCondition composes DNF items into a balance deep DNF tree.

func EvaluateExprWithNull 

func EvaluateExprWithNull(ctx context.Context, schema *Schema, expr Expression) (Expression, error)

EvaluateExprWithNull sets columns in schema as null and calculate the final result of the scalar function. If the Expression is a non-constant value, it means the result is unknown.

func FoldConstant 

func FoldConstant(expr Expression) Expression

FoldConstant does constant folding optimization on an expression.

func NewFunction 

func NewFunction(ctx context.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error)

NewFunction creates a new scalar function or constant.

func PropagateConstant 

func PropagateConstant(ctx context.Context, conditions []Expression) []Expression

PropagateConstant propagate constant values of equality predicates and inequality predicates in a condition.

func ScalarFuncs2Exprs 

func ScalarFuncs2Exprs(funcs []*ScalarFunction) []Expression

ScalarFuncs2Exprs converts []*ScalarFunction to []Expression.

func SplitCNFItems 

func SplitCNFItems(onExpr Expression) []Expression

SplitCNFItems splits CNF items. CNF means conjunctive normal form, e.g. "a and b and c".

func SplitDNFItems 

func SplitDNFItems(onExpr Expression) []Expression

SplitDNFItems splits DNF items. DNF means disjunctive normal form, e.g. "a or b or c".

type KeyInfo 

type KeyInfo []*Column

KeyInfo stores the columns of one unique key or primary key.

func (KeyInfo) Clone 

func (ki KeyInfo) Clone() KeyInfo

Clone copies the entire UniqueKey.

type ScalarFunction 

type ScalarFunction struct {
	FuncName model.CIStr
	// TODO: Implement type inference here, now we use ast's return type temporarily.
	RetType  *types.FieldType
	Function builtinFunc
}

ScalarFunction is the function that returns a value.

func NewCastFunc 

func NewCastFunc(tp *types.FieldType, arg Expression, ctx context.Context) *ScalarFunction

NewCastFunc creates a new cast function.

func NewValuesFunc 

func NewValuesFunc(offset int, retTp *types.FieldType, ctx context.Context) *ScalarFunction

NewValuesFunc creates a new values function.

func (*ScalarFunction) Clone 

func (sf *ScalarFunction) Clone() Expression

Clone implements Expression interface.

func (*ScalarFunction) Decorrelate 

func (sf *ScalarFunction) Decorrelate(schema *Schema) Expression

Decorrelate implements Expression interface.

func (*ScalarFunction) Equal 

func (sf *ScalarFunction) Equal(e Expression, ctx context.Context) bool

Equal implements Expression interface.

func (*ScalarFunction) Eval 

func (sf *ScalarFunction) Eval(row []types.Datum) (types.Datum, error)

Eval implements Expression interface.

func (*ScalarFunction) GetArgs 

func (sf *ScalarFunction) GetArgs() []Expression

GetArgs gets arguments of function.

func (*ScalarFunction) GetCtx 

func (sf *ScalarFunction) GetCtx() context.Context

GetCtx gets the context of function.

func (*ScalarFunction) GetType 

func (sf *ScalarFunction) GetType() *types.FieldType

GetType implements Expression interface.

func (*ScalarFunction) HashCode 

func (sf *ScalarFunction) HashCode() []byte

HashCode implements Expression interface.

func (*ScalarFunction) IsCorrelated 

func (sf *ScalarFunction) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*ScalarFunction) MarshalJSON 

func (sf *ScalarFunction) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*ScalarFunction) ResolveIndices 

func (sf *ScalarFunction) ResolveIndices(schema *Schema)

ResolveIndices implements Expression interface.

func (*ScalarFunction) String 

func (sf *ScalarFunction) String() string

String implements fmt.Stringer interface.

type Schema 

type Schema struct {
	Columns   []*Column
	Keys      []KeyInfo
	MaxOneRow bool
}

Schema stands for the row schema and unique key information get from input.

func MergeSchema 

func MergeSchema(lSchema, rSchema *Schema) *Schema

MergeSchema will merge two schema into one schema.

func NewSchema 

func NewSchema(cols ...*Column) *Schema

NewSchema returns a schema made by its parameter.

func TableInfo2Schema 

func TableInfo2Schema(tbl *model.TableInfo) *Schema

TableInfo2Schema converts table info to schema.

func (*Schema) Append 

func (s *Schema) Append(col ...*Column)

Append append new column to the columns stored in schema.

func (*Schema) Clone 

func (s *Schema) Clone() *Schema

Clone copies the total schema.

func (*Schema) ColumnIndex 

func (s *Schema) ColumnIndex(col *Column) int

ColumnIndex finds the index for a column.

func (*Schema) ColumnsIndices 

func (s *Schema) ColumnsIndices(cols []*Column) (ret []int)

ColumnsIndices will return a slice which contains the position of each column in schema. If there is one column that doesn't match, nil will be returned.

func (*Schema) Contains 

func (s *Schema) Contains(col *Column) bool

Contains checks if the schema contains the column.

func (*Schema) FindColumn 

func (s *Schema) FindColumn(astCol *ast.ColumnName) (*Column, error)

FindColumn finds an Column from schema for a ast.ColumnName. It compares the db/table/column names. If there are more than one result, it will raise ambiguous error.

func (*Schema) IsUniqueKey 

func (s *Schema) IsUniqueKey(col *Column) bool

IsUniqueKey checks if this column is a unique key.

func (*Schema) Len 

func (s *Schema) Len() int

Len returns the number of columns in schema.

func (*Schema) RetrieveColumn 

func (s *Schema) RetrieveColumn(col *Column) *Column

RetrieveColumn retrieves column in expression from the columns in schema.

func (*Schema) SetUniqueKeys 

func (s *Schema) SetUniqueKeys(keys []KeyInfo)

SetUniqueKeys will set the value of Schema.Keys.

func (*Schema) String 

func (s *Schema) String() string

String implements fmt.Stringer interface.

type VarAssignment 

type VarAssignment struct {
	Name        string
	Expr        Expression
	IsDefault   bool
	IsGlobal    bool
	IsSystem    bool
	ExtendValue *Constant
}

VarAssignment represents a variable assignment in Set, such as set global a = 1.

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