DeltaCode Scoring

Delta Objects

A File-Level Comparison of Two Codebases

A Delta object represents the file-level comparison (i.e., the "delta") of two codebases, typically two versions of the same codebase, using ScanCode-generated JSON output files as input for the comparison process.

Based on how the user constructs the command-line input, DeltaCode's naming convention treats one codebase as the "new" codebase and the other as the "old" codebase:

deltacode -n [path to the 'new' codebase] -o [path to the 'old' codebase] [...]

Basic Scoring

A DeltaCode codebase comparison produces a collection of file-level Delta objects. Depending on the nature of the file-level change between the two codebases, each Delta object is characterized as belonging to one of the categories listed below.

Each category has an associated score intended to convey its potential importance to a user's analysis of the changes between the new and old codebases. In descending order of importance, the categories are:

1. added: A file has been added to the new codebase.
2. modified: The file is contained in both the new and old codebase and has been modified. This modification is demonstrated among other things by a change in the file's sha1 attribute.
3. moved: The file is contained in both the new and old codebase and has not been modified but has been moved.
4. removed: A file has been removed from the old codebase.
5. unmodified: The file is contained in both the new and old codebase and has not been modified or moved.

The score of a Delta object characterized as added or modified may be increased based on the detection of license- and/or copyright-related changes. See License Additions and Changes and Copyright Holder Additions and Changes below.

Delta Object Fields and Values

Each Delta object includes the following fields and values:

• factors: One or more strings representing the factors that characterize the file-level comparison and resulting score, e.g.,

      "factors": [
        "added",
        "license info added",
        "copyright info added"
      ],

• score: A number representing the magnitude/importance of the file-level change -- the higher the score, the greater the change.
• new: The ScanCode-based file attributes (path, licenses, copyrights etc.) for the file (if any)* in the codebase designated by the user as new.
• old: The ScanCode-based file attributes for the file (if any)* in the codebase designated by the user as old.

Each Delta object will always have a new or an old file and often will have both. For example:

• added and removed: If a file has been added to the new codebase, the Delta object will contain the file attributes for the new file. Since the file has been added, there is therefore no corresponding file in the old codebase, and the Delta object's value for the old file will be null. Where a file has been removed from the old codebase, the Delta object will contain the file attributes for the old file and the value for the new file will be null.
• modified, moved and unmodified: [coming . . .]

License Additions and Changes

[coming . . .]

Copyright Holder Additions and Changes

[coming . . .]

Moved, Removed and Unmodified

[coming . . .]