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| 1 | +// Copyright 2023 Dolthub, Inc. |
| 2 | +// |
| 3 | +// Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +// you may not use this file except in compliance with the License. |
| 5 | +// You may obtain a copy of the License at |
| 6 | +// |
| 7 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +// |
| 9 | +// Unless required by applicable law or agreed to in writing, software |
| 10 | +// distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +// See the License for the specific language governing permissions and |
| 13 | +// limitations under the License. |
| 14 | + |
| 15 | +package function |
| 16 | + |
| 17 | +import ( |
| 18 | + "fmt" |
| 19 | + "strings" |
| 20 | + |
| 21 | + "github.com/dolthub/go-mysql-server/sql" |
| 22 | + "github.com/dolthub/go-mysql-server/sql/expression" |
| 23 | + "github.com/dolthub/go-mysql-server/sql/types" |
| 24 | +) |
| 25 | + |
| 26 | +// FindInSet takes out the specified unit(s) from the time expression. |
| 27 | +type FindInSet struct { |
| 28 | + expression.BinaryExpression |
| 29 | +} |
| 30 | + |
| 31 | +var _ sql.FunctionExpression = (*FindInSet)(nil) |
| 32 | +var _ sql.CollationCoercible = (*FindInSet)(nil) |
| 33 | + |
| 34 | +// NewFindInSet creates a new FindInSet expression. |
| 35 | +func NewFindInSet(e1, e2 sql.Expression) sql.Expression { |
| 36 | + return &FindInSet{ |
| 37 | + expression.BinaryExpression{ |
| 38 | + Left: e1, |
| 39 | + Right: e2, |
| 40 | + }, |
| 41 | + } |
| 42 | +} |
| 43 | + |
| 44 | +// FunctionName implements sql.FunctionExpression |
| 45 | +func (f *FindInSet) FunctionName() string { |
| 46 | + return "find_in_set" |
| 47 | +} |
| 48 | + |
| 49 | +// Description implements sql.FunctionExpression |
| 50 | +func (f *FindInSet) Description() string { |
| 51 | + return "returns a value in the range of 1 to N if the string str is in the string list strlist consisting of N substrings" |
| 52 | +} |
| 53 | + |
| 54 | +// Type implements the Expression interface. |
| 55 | +func (f *FindInSet) Type() sql.Type { return types.Int64 } |
| 56 | + |
| 57 | +// CollationCoercibility implements the interface sql.CollationCoercible. |
| 58 | +func (*FindInSet) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) { |
| 59 | + return ctx.GetCollation(), 5 |
| 60 | +} |
| 61 | + |
| 62 | +func (f *FindInSet) String() string { |
| 63 | + return fmt.Sprintf("%s(%s from %s)", f.FunctionName(), f.Left, f.Right) |
| 64 | +} |
| 65 | + |
| 66 | +// WithChildren implements the Expression interface. |
| 67 | +func (f *FindInSet) WithChildren(children ...sql.Expression) (sql.Expression, error) { |
| 68 | + if len(children) != 2 { |
| 69 | + return nil, sql.ErrInvalidChildrenNumber.New(f, len(children), 2) |
| 70 | + } |
| 71 | + return NewFindInSet(children[0], children[1]), nil |
| 72 | +} |
| 73 | + |
| 74 | +// Eval implements the Expression interface. |
| 75 | +func (f *FindInSet) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) { |
| 76 | + if f.Left == nil || f.Right == nil { |
| 77 | + return nil, nil |
| 78 | + } |
| 79 | + |
| 80 | + left, err := f.Left.Eval(ctx, row) |
| 81 | + if err != nil { |
| 82 | + return nil, err |
| 83 | + } |
| 84 | + |
| 85 | + right, err := f.Right.Eval(ctx, row) |
| 86 | + if err != nil { |
| 87 | + return nil, err |
| 88 | + } |
| 89 | + |
| 90 | + if left == nil || right == nil { |
| 91 | + return nil, nil |
| 92 | + } |
| 93 | + |
| 94 | + lVal, _, err := types.LongText.Convert(left) |
| 95 | + if err != nil { |
| 96 | + return nil, err |
| 97 | + } |
| 98 | + l := lVal.(string) |
| 99 | + |
| 100 | + // always returns 0 when left contains a comma |
| 101 | + if strings.Contains(l, ",") { |
| 102 | + return 0, nil |
| 103 | + } |
| 104 | + |
| 105 | + var r string |
| 106 | + rType := f.Right.Type() |
| 107 | + if setType, ok := rType.(types.SetType); ok { |
| 108 | + // TODO: set type should take advantage of bit arithmetic |
| 109 | + r, err = setType.BitsToString(right.(uint64)) |
| 110 | + if err != nil { |
| 111 | + return nil, err |
| 112 | + } |
| 113 | + } else if enumType, ok := rType.(types.EnumType); ok { |
| 114 | + r, ok = enumType.At(int(right.(uint16))) |
| 115 | + if !ok { |
| 116 | + return nil, fmt.Errorf("enum missing index %v", r) |
| 117 | + } |
| 118 | + } else { |
| 119 | + var rVal interface{} |
| 120 | + rVal, _, err = types.LongText.Convert(right) |
| 121 | + if err != nil { |
| 122 | + return nil, err |
| 123 | + } |
| 124 | + r = rVal.(string) |
| 125 | + } |
| 126 | + |
| 127 | + leftColl, leftCoer := sql.GetCoercibility(ctx, f.Left) |
| 128 | + rightColl, rightCoer := sql.GetCoercibility(ctx, f.Right) |
| 129 | + collPref, _ := sql.ResolveCoercibility(leftColl, leftCoer, rightColl, rightCoer) |
| 130 | + |
| 131 | + strType := types.CreateLongText(collPref) |
| 132 | + for i, r := range strings.Split(r, ",") { |
| 133 | + cmp, err := strType.Compare(l, r) |
| 134 | + if err != nil { |
| 135 | + return nil, err |
| 136 | + } |
| 137 | + if cmp == 0 { |
| 138 | + return i + 1, nil |
| 139 | + } |
| 140 | + } |
| 141 | + |
| 142 | + return 0, nil |
| 143 | +} |
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