mirror of
https://github.com/dolthub/dolt.git
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123 lines
3.1 KiB
Go
Executable File
123 lines
3.1 KiB
Go
Executable File
// Copyright 2019 Dolthub, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// This file incorporates work covered by the following copyright and
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// permission notice:
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//
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// Copyright 2016 Attic Labs, Inc. All rights reserved.
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// Licensed under the Apache License, version 2.0:
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// http://www.apache.org/licenses/LICENSE-2.0
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package spec
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import (
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"context"
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"errors"
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"github.com/dolthub/dolt/go/store/datas"
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"github.com/dolthub/dolt/go/store/hash"
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"github.com/dolthub/dolt/go/store/types"
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)
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// AbsolutePath describes the location of a Value within a Noms database.
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//
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// To locate a value relative to some other value, see Path. To locate a value
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// globally, see Spec.
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//
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// For more on paths, absolute paths, and specs, see:
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// https://github.com/attic-labs/noms/blob/master/doc/spelling.md.
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type AbsolutePath struct {
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// Dataset is the dataset this AbsolutePath is rooted at. Only one of
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// Dataset and Hash should be set.
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Dataset string
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// Hash is the hash this AbsolutePath is rooted at. Only one of Dataset and
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// Hash should be set.
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Hash hash.Hash
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}
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// NewAbsolutePath attempts to parse 'str' and return an AbsolutePath.
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func NewAbsolutePath(str string) (AbsolutePath, error) {
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if len(str) == 0 {
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return AbsolutePath{}, errors.New("empty path")
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}
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var h hash.Hash
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var dataset string
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if str[0] == '#' {
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tail := str[1:]
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if len(tail) < hash.StringLen {
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return AbsolutePath{}, errors.New("invalid hash: " + tail)
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}
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hashStr := tail[:hash.StringLen]
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if h2, ok := hash.MaybeParse(hashStr); ok {
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h = h2
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} else {
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return AbsolutePath{}, errors.New("invalid hash: " + hashStr)
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}
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} else {
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// This form is only used in the noms command. Commands like `noms show` that use a path with '.' separation will
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// no longer work
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dataset = str
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}
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return AbsolutePath{Hash: h, Dataset: dataset}, nil
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}
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// Resolve returns the Value reachable by 'p' in 'db'.
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func (p AbsolutePath) Resolve(ctx context.Context, db datas.Database, vrw types.ValueReadWriter) (val types.Value, err error) {
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if len(p.Dataset) > 0 {
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var ok bool
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ds, err := db.GetDataset(ctx, p.Dataset)
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if err != nil {
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return nil, err
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}
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if val, ok = ds.MaybeHead(); !ok {
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val = nil
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}
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} else if !p.Hash.IsEmpty() {
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var err error
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val, err = vrw.ReadValue(ctx, p.Hash)
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if err != nil {
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return nil, err
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}
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} else {
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panic("Unreachable")
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}
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return
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}
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func (p AbsolutePath) IsEmpty() bool {
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return p.Dataset == "" && p.Hash.IsEmpty()
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}
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func (p AbsolutePath) String() (str string) {
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if p.IsEmpty() {
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return ""
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}
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if len(p.Dataset) > 0 {
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str = p.Dataset
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} else if !p.Hash.IsEmpty() {
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str = "#" + p.Hash.String()
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} else {
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panic("Unreachable")
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}
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return str
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}
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