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create transforms.go, case insensitive parse
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,173 @@ | ||
| // Licensed to the Apache Software Foundation (ASF) under one | ||
| // or more contributor license agreements. See the NOTICE file | ||
| // distributed with this work for additional information | ||
| // regarding copyright ownership. The ASF licenses this file | ||
| // to you 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, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
| // KIND, either express or implied. See the License for the | ||
| // specific language governing permissions and limitations | ||
| // under the License. | ||
|
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| package iceberg | ||
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| import ( | ||
| "encoding" | ||
| "fmt" | ||
| "strconv" | ||
| "strings" | ||
| ) | ||
|
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| // ParseTransform takes the string representation of a transform as | ||
| // defined in the iceberg spec, and produces the appropriate Transform | ||
| // object or an error if the string is not a valid transform string. | ||
| func ParseTransform(s string) (Transform, error) { | ||
| s = strings.ToLower(s) | ||
| switch { | ||
| case strings.HasPrefix(s, "bucket"): | ||
| matches := regexFromBrackets.FindStringSubmatch(s) | ||
| if len(matches) != 2 { | ||
| break | ||
| } | ||
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| n, _ := strconv.Atoi(matches[1]) | ||
| return BucketTransform{N: n}, nil | ||
| case strings.HasPrefix(s, "truncate"): | ||
| matches := regexFromBrackets.FindStringSubmatch(s) | ||
| if len(matches) != 2 { | ||
| break | ||
| } | ||
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| n, _ := strconv.Atoi(matches[1]) | ||
| return TruncateTransform{W: n}, nil | ||
| default: | ||
| switch s { | ||
| case "identity": | ||
| return IdentityTransform{}, nil | ||
| case "void": | ||
| return VoidTransform{}, nil | ||
| case "year": | ||
| return YearTransform{}, nil | ||
| case "month": | ||
| return MonthTransform{}, nil | ||
| case "day": | ||
| return DayTransform{}, nil | ||
| case "hour": | ||
| return HourTransform{}, nil | ||
| } | ||
| } | ||
|
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| return nil, fmt.Errorf("%w: %s", ErrInvalidTransform, s) | ||
| } | ||
|
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| // Transform is an interface for the various Transformation types | ||
| // in partition specs. Currently they do not yet provide actual | ||
| // transformation functions or implementation. That will come later as | ||
| // data reading gets implemented. | ||
| type Transform interface { | ||
| fmt.Stringer | ||
| encoding.TextMarshaler | ||
| ResultType(t Type) Type | ||
| } | ||
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| // IdentityTransform uses the identity function, performing no transformation | ||
| // but instead partitioning on the value itself. | ||
| type IdentityTransform struct{} | ||
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| func (t IdentityTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
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| func (IdentityTransform) String() string { return "identity" } | ||
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| func (IdentityTransform) ResultType(t Type) Type { return t } | ||
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| // VoidTransform is a transformation that always returns nil. | ||
| type VoidTransform struct{} | ||
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| func (t VoidTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
|
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| func (VoidTransform) String() string { return "void" } | ||
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| func (VoidTransform) ResultType(t Type) Type { return t } | ||
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| // BucketTransform transforms values into a bucket partition value. It is | ||
| // parameterized by a number of buckets. Bucket partition transforms use | ||
| // a 32-bit hash of the source value to produce a positive value by mod | ||
| // the bucket number. | ||
| type BucketTransform struct { | ||
| N int | ||
| } | ||
|
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| func (t BucketTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
|
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| func (t BucketTransform) String() string { return fmt.Sprintf("bucket[%d]", t.N) } | ||
|
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| func (BucketTransform) ResultType(Type) Type { return PrimitiveTypes.Int32 } | ||
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| // TruncateTransform is a transformation for truncating a value to a specified width. | ||
| type TruncateTransform struct { | ||
| W int | ||
| } | ||
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| func (t TruncateTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
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| func (t TruncateTransform) String() string { return fmt.Sprintf("truncate[%d]", t.W) } | ||
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| func (TruncateTransform) ResultType(t Type) Type { return t } | ||
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| // YearTransform transforms a datetime value into a year value. | ||
| type YearTransform struct{} | ||
|
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| func (t YearTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
|
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| func (YearTransform) String() string { return "year" } | ||
|
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| func (YearTransform) ResultType(Type) Type { return PrimitiveTypes.Int32 } | ||
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| // MonthTransform transforms a datetime value into a month value. | ||
| type MonthTransform struct{} | ||
|
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| func (t MonthTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
|
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| func (MonthTransform) String() string { return "month" } | ||
|
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| func (MonthTransform) ResultType(Type) Type { return PrimitiveTypes.Int32 } | ||
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| // DayTransform transforms a datetime value into a date value. | ||
| type DayTransform struct{} | ||
|
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| func (t DayTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
|
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| func (DayTransform) String() string { return "day" } | ||
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| func (DayTransform) ResultType(Type) Type { return PrimitiveTypes.Date } | ||
|
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| // HourTransform transforms a datetime value into an hour value. | ||
| type HourTransform struct{} | ||
|
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| func (t HourTransform) MarshalText() ([]byte, error) { | ||
| return []byte(t.String()), nil | ||
| } | ||
|
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| func (HourTransform) String() string { return "hour" } | ||
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| func (HourTransform) ResultType(Type) Type { return PrimitiveTypes.Int32 } |
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