github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/diff/docs_diffs.go (about)

     1  // Copyright 2020 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 diff
    16  
    17  import (
    18  	"context"
    19  	"strconv"
    20  
    21  	"github.com/dolthub/dolt/go/libraries/doltcore/doltdocs"
    22  
    23  	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
    24  )
    25  
    26  type docComparison struct {
    27  	DocName     string
    28  	CurrentText []byte
    29  	OldText     []byte
    30  }
    31  
    32  // DocsDiff returns the added, modified and removed docs when comparing a root value with an other (newer) value. If the other value,
    33  // is not provided, then we compare the docs on the root value to the docs provided.
    34  func DocsDiff(ctx context.Context, root *doltdb.RootValue, other *doltdb.RootValue, docs doltdocs.Docs) (added, modified, removed []string, err error) {
    35  	docComparisons, err := DocsDiffToComparisons(ctx, root, other, docs)
    36  
    37  	if err != nil {
    38  		return nil, nil, nil, err
    39  	}
    40  
    41  	a, m, r := computeDiffsFromDocComparisons(docComparisons)
    42  	return a, m, r, nil
    43  }
    44  
    45  // DocsDiffToComparisons returns the docComparisons between an old root, a new root, and a set of docs. It is exported
    46  // due to the cli usage of doc diffs.
    47  func DocsDiffToComparisons(ctx context.Context, root *doltdb.RootValue, other *doltdb.RootValue, docs doltdocs.Docs) ([]docComparison, error) {
    48  	if other == nil {
    49  		return compareRootWithDocs(ctx, root, docs)
    50  	} else {
    51  		return compareDocsBtwnRoots(ctx, root, other)
    52  	}
    53  }
    54  
    55  // compareRootWithDocs compares a root and set of new docs.
    56  func compareRootWithDocs(ctx context.Context, root *doltdb.RootValue, docs doltdocs.Docs) ([]docComparison, error) {
    57  	oldDocs, found, err := doltdocs.GetAllDocs(ctx, root)
    58  	if err != nil {
    59  		return nil, err
    60  	}
    61  	if !found {
    62  		oldDocs = make(doltdocs.Docs, 0)
    63  	}
    64  
    65  	return getDocComparisons(oldDocs, docs), nil
    66  }
    67  
    68  // compareDocsBtwnRoots takes an oldRoot and a newRoot and compares the docs tables between the two.
    69  func compareDocsBtwnRoots(ctx context.Context, oldRoot *doltdb.RootValue, newRoot *doltdb.RootValue) ([]docComparison, error) {
    70  	oldDocs, found, err := doltdocs.GetAllDocs(ctx, oldRoot)
    71  	if err != nil {
    72  		return nil, err
    73  	}
    74  	if !found {
    75  		oldDocs = make(doltdocs.Docs, 0)
    76  	}
    77  
    78  	newDocs, found, err := doltdocs.GetAllDocs(ctx, newRoot)
    79  	if err != nil {
    80  		return nil, err
    81  	}
    82  	if !found {
    83  		newDocs = make(doltdocs.Docs, 0)
    84  	}
    85  
    86  	return getDocComparisons(oldDocs, newDocs), nil
    87  }
    88  
    89  // getDocComparisons compares two sets of docs looking for modifications, removals, and additions as docComparisons
    90  func getDocComparisons(oldDocs doltdocs.Docs, newDocs doltdocs.Docs) []docComparison {
    91  	docComparisons := make([]docComparison, 0)
    92  
    93  	// First case is looking at the old docs and seeing what was modified or removed
    94  	for _, oldDoc := range oldDocs {
    95  		dc := docComparison{DocName: oldDoc.DocPk, OldText: oldDoc.Text, CurrentText: getMatchingText(oldDoc, newDocs)}
    96  		docComparisons = append(docComparisons, dc)
    97  	}
    98  
    99  	// Second case is looking back at the old docs and seeing what was added
   100  	for _, newDoc := range newDocs {
   101  		oldText := getMatchingText(newDoc, oldDocs)
   102  		if oldText == nil {
   103  			dc := docComparison{DocName: newDoc.DocPk, OldText: nil, CurrentText: newDoc.Text}
   104  			docComparisons = append(docComparisons, dc)
   105  		}
   106  	}
   107  
   108  	return docComparisons
   109  }
   110  
   111  // getMatchingText matches a doc in a set of other docs and returns the relevant text.
   112  func getMatchingText(doc doltdocs.Doc, docs doltdocs.Docs) []byte {
   113  	for _, toCompare := range docs {
   114  		if doc.DocPk == toCompare.DocPk {
   115  			return toCompare.Text
   116  		}
   117  	}
   118  
   119  	return nil
   120  }
   121  
   122  // computeDiffsFromDocComparisons takes the docComparisons and returns the final add, modified, removed count.
   123  func computeDiffsFromDocComparisons(docComparisons []docComparison) (added, modified, removed []string) {
   124  	added = []string{}
   125  	modified = []string{}
   126  	removed = []string{}
   127  	for _, doc := range docComparisons {
   128  		added, modified, removed = appendDocDiffs(added, modified, removed, doc.OldText, doc.CurrentText, doc.DocName)
   129  	}
   130  	return added, modified, removed
   131  }
   132  
   133  func appendDocDiffs(added, modified, removed []string, olderVal []byte, newerVal []byte, docPk string) (add, mod, rem []string) {
   134  	if olderVal == nil && newerVal != nil {
   135  		added = append(added, docPk)
   136  	} else if olderVal != nil {
   137  		if newerVal == nil {
   138  			removed = append(removed, docPk)
   139  		} else if strconv.Quote(string(olderVal)) != strconv.Quote(string(newerVal)) {
   140  			modified = append(modified, docPk)
   141  		}
   142  	}
   143  	return added, modified, removed
   144  }