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split.go
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/
split.go
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package function
import (
"fmt"
"regexp"
"github.com/src-d/go-mysql-server/sql"
"github.com/src-d/go-mysql-server/sql/expression"
)
// Split receives a string and returns the parts of it splitted by a
// delimiter.
type Split struct {
expression.BinaryExpression
}
// NewSplit creates a new Split UDF.
func NewSplit(str, delimiter sql.Expression) sql.Expression {
return &Split{expression.BinaryExpression{
Left: str,
Right: delimiter,
}}
}
// Eval implements the Expression interface.
func (f *Split) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
left, err := f.Left.Eval(ctx, row)
if err != nil {
return nil, err
}
if left == nil {
return nil, nil
}
left, err = sql.Text.Convert(left)
if err != nil {
return nil, err
}
right, err := f.Right.Eval(ctx, row)
if err != nil {
return nil, err
}
if right == nil {
return nil, nil
}
right, err = sql.Text.Convert(right)
if err != nil {
return nil, err
}
re, err := regexp.Compile(right.(string))
if err != nil {
return nil, err
}
parts := re.Split(left.(string), -1)
var result = make([]interface{}, len(parts))
for i, part := range parts {
result[i] = part
}
return result, nil
}
// Type implements the Expression interface.
func (*Split) Type() sql.Type { return sql.Array(sql.Text) }
// IsNullable implements the Expression interface.
func (f *Split) IsNullable() bool { return f.Left.IsNullable() || f.Right.IsNullable() }
func (f *Split) String() string {
return fmt.Sprintf("split(%s, %s)", f.Left, f.Right)
}
// WithChildren implements the Expression interface.
func (f *Split) WithChildren(children ...sql.Expression) (sql.Expression, error) {
if len(children) != 2 {
return nil, sql.ErrInvalidChildrenNumber.New(f, len(children), 2)
}
return NewSplit(children[0], children[1]), nil
}