Mod vcds

vsds: version control data structures (and algorithms)

Types: Diff Keep Change DiffsExtender Picks Patch

Functions

• fn normalize(s)
  normalize a line for comparing (anchoring). This just squashes and trims the end.
• fn apply(base, changes, out--[[{}]]) -> out
  Apply changes to base (TableLines), push to out
• fn toChanges(diffs, full)
• fn toDiffs(base, changes) -> diffs
  Convert Changes to Diffs with full context
• fn createAnchorTop(base, l, aLen)
• fn createAnchorBot(base, l, aLen)
• fn findAnchor(base, baseMap, anchors, above--[[false]]) -> (l, c)
  Find the actual anchor by searching for uniqueness in the anchors
  • above=true: find above (search up)
  • above=false: find below (search down)
• fn pickAnchorsTop(pick) -> isStartOfFile, anchors
• fn pickAnchorsBot(base, pick) -> isEndOfFile, anchors
• fn createPatch(base, baseMap, pick)
  Create a patch item from a pick

  At it's most basic it would just be:

  • find line position via top and/or bottom anchor. We want at least 2 lines
  • convert pick to change. Walk the text applying the change.

  There are some strategies to fix common anchor misses:

  • If an anchor is missing, the nearby change can be used instead. Use either the removed or added lines. For instance, if we are supposed to remove lines then try and find them. Conversely if the patch was already applied then the supposed-to-be added lines will already be there!
  • When adding, existing identical text is okay.
  • When removing, missing text is okay as long as it's followed by an anchor of some kind
  • Keep lines act as an anchor (for above) but are otherwise not required - they are "free" to change or be removed. If they are missing then the algorithm will try to continue the change with or without them (dynamic programming)
  • empty lines are entirely ignored and are not considered an anchor

Record Diff

Single Line Diff This type is good for displaying differences to a user.

Fields:

• b (base) orig file. '+'=added
• c (change) new file. '-'=removed
• text

Methods

• fn:isKeep()

Record Keep

Fields:

• num

Methods

• fn:len()

Record Change

Fields:

• rem removed lines
• add text to add

Methods

• fn:len()

Record DiffsExtender

Fields:

• diffs
• base
• bl base line
• cl change line

Record Picks

Create picks (aka cherry picks) iterator from changes. These can then be applied to a new base using vcds.patch(base, picks)

Each "pick" is a list of Diffs which are anchored by the lines above and below (unless they are start/end of file).

Fields:

• changes list of changes
• ci for iterating
• de
• set settings (need refactor)

Methods

• fn:groupChanges(ci)
  Get which changes to include in a patch group. A group is a series of patches with Keep:len() < anchorLen (default=3) between them.

Record Patch

Fields:

• conflict
• bl