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gitea/vendor/github.com/pingcap/tidb/evaluator/builtin.go

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// Copyright 2013 The ql Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSES/QL-LICENSE file.
// Copyright 2015 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 evaluator
import (
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/util/types"
)
// OldFunc is for a old builtin function.
type OldFunc struct {
// F is the specific calling function.
F func([]interface{}, context.Context) (interface{}, error)
// MinArgs is the minimal arguments needed,
MinArgs int
// MaxArgs is the maximal arguments needed, -1 for infinity.
MaxArgs int
// IsStatic shows whether this function can be called statically.
IsStatic bool
// IsAggregate represents whether this function is an aggregate function or not.
IsAggregate bool
}
// Func is for a builtin function.
type Func struct {
// F is the specific calling function.
F func([]types.Datum, context.Context) (types.Datum, error)
// MinArgs is the minimal arguments needed,
MinArgs int
// MaxArgs is the maximal arguments needed, -1 for infinity.
MaxArgs int
}
// OldFuncs holds all has old registered builtin functions.
var OldFuncs = map[string]OldFunc{
// control functions
"if": {builtinIf, 3, 3, true, false},
"ifnull": {builtinIfNull, 2, 2, true, false},
"nullif": {builtinNullIf, 2, 2, true, false},
// string functions
"replace": {builtinReplace, 3, 3, true, false},
"strcmp": {builtinStrcmp, 2, 2, true, false},
"convert": {builtinConvert, 2, 2, true, false},
"substring": {builtinSubstring, 2, 3, true, false},
"substring_index": {builtinSubstringIndex, 3, 3, true, false},
"locate": {builtinLocate, 2, 3, true, false},
"trim": {builtinTrim, 1, 3, true, false},
// information functions
"current_user": {builtinCurrentUser, 0, 0, false, false},
"database": {builtinDatabase, 0, 0, false, false},
"found_rows": {builtinFoundRows, 0, 0, false, false},
"user": {builtinUser, 0, 0, false, false},
"connection_id": {builtinConnectionID, 0, 0, true, false},
"version": {builtinVersion, 0, 0, true, false},
}
// Funcs holds all registered builtin functions.
var Funcs = map[string]Func{
// common functions
"coalesce": {builtinCoalesce, 1, -1},
// math functions
"abs": {builtinAbs, 1, 1},
"pow": {builtinPow, 2, 2},
"power": {builtinPow, 2, 2},
"rand": {builtinRand, 0, 1},
// time functions
"curdate": {builtinCurrentDate, 0, 0},
"current_date": {builtinCurrentDate, 0, 0},
"current_time": {builtinCurrentTime, 0, 1},
"current_timestamp": {builtinNow, 0, 1},
"curtime": {builtinCurrentTime, 0, 1},
"date": {builtinDate, 1, 1},
"day": {builtinDay, 1, 1},
"dayname": {builtinDayName, 1, 1},
"dayofmonth": {builtinDayOfMonth, 1, 1},
"dayofweek": {builtinDayOfWeek, 1, 1},
"dayofyear": {builtinDayOfYear, 1, 1},
"hour": {builtinHour, 1, 1},
"microsecond": {builtinMicroSecond, 1, 1},
"minute": {builtinMinute, 1, 1},
"month": {builtinMonth, 1, 1},
"now": {builtinNow, 0, 1},
"second": {builtinSecond, 1, 1},
"sysdate": {builtinSysDate, 0, 1},
"week": {builtinWeek, 1, 2},
"weekday": {builtinWeekDay, 1, 1},
"weekofyear": {builtinWeekOfYear, 1, 1},
"year": {builtinYear, 1, 1},
"yearweek": {builtinYearWeek, 1, 2},
"extract": {builtinExtract, 2, 2},
"date_arith": {builtinDateArith, 3, 3},
// string functions
"concat": {builtinConcat, 1, -1},
"concat_ws": {builtinConcatWS, 2, -1},
"left": {builtinLeft, 2, 2},
"length": {builtinLength, 1, 1},
"lower": {builtinLower, 1, 1},
"repeat": {builtinRepeat, 2, 2},
"upper": {builtinUpper, 1, 1},
}
// See: http://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html#function_coalesce
func builtinCoalesce(args []types.Datum, ctx context.Context) (d types.Datum, err error) {
for _, d = range args {
if d.Kind() != types.KindNull {
return d, nil
}
}
return d, nil
}