nastra commented on code in PR #2: URL: https://github.com/apache/iceberg-go/pull/2#discussion_r1324538828
########## transforms.go: ########## @@ -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. + +package iceberg + +import ( + "encoding" + "fmt" + "strconv" + "strings" +) + +// 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 + } + + n, _ := strconv.Atoi(matches[1]) + return BucketTransform{N: n}, nil + case strings.HasPrefix(s, "truncate"): + matches := regexFromBrackets.FindStringSubmatch(s) + if len(matches) != 2 { + break + } + + 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 + } + } + + return nil, fmt.Errorf("%w: %s", ErrInvalidTransform, s) +} + +// 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 +} + +// IdentityTransform uses the identity function, performing no transformation +// but instead partitioning on the value itself. +type IdentityTransform struct{} + +func (t IdentityTransform) MarshalText() ([]byte, error) { + return []byte(t.String()), nil +} + +func (IdentityTransform) String() string { return "identity" } + +func (IdentityTransform) ResultType(t Type) Type { return t } + +// VoidTransform is a transformation that always returns nil. +type VoidTransform struct{} + +func (t VoidTransform) MarshalText() ([]byte, error) { + return []byte(t.String()), nil +} + +func (VoidTransform) String() string { return "void" } + +func (VoidTransform) ResultType(t Type) Type { return t } + +// 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 +} + +func (t BucketTransform) MarshalText() ([]byte, error) { + return []byte(t.String()), nil +} + +func (t BucketTransform) String() string { return fmt.Sprintf("bucket[%d]", t.N) } + +func (BucketTransform) ResultType(Type) Type { return PrimitiveTypes.Int32 } + +// TruncateTransform is a transformation for truncating a value to a specified width. +type TruncateTransform struct { + W int Review Comment: maybe rename to `width`? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
