TTkTextDocument

TTkTextDocument🌶️

class TTkTextDocument(*, text: TTkString = ' ')[source]🌶️

Bases: object

Undo,Redo Logic

Old:

_snapshotId: = last saved/undo/redo state
                       3 = doc4
_snapshots:
    [doc1, doc2, doc3, doc4, doc5, doc6, . . .]

New:

SnapshotId:
                  2
Snapshots:                  _lastSnap     _dataLines (unstaged)
    ╒═══╕ ╒═══╕ ╒═══╕ ╒═══╕ ╒═══╕         ╒═══╕
    │ 0 │ │ 1 │ │ 2 │ │ 3 │ │ 4 │         │ 5 │
    └───┘ └───┘ └───┘ └───┘ └───┘         └───┘
Cursors:
     c0,   c1,   c2,   c3,   c4 = _lastCursor
Diffs:
    [   d01,  d12,  d23,  d34   ] = Forward  Diffs
    [   d10,  d21,  d32,  d43   ] = Backward Diffs
Slices: = common txt slices between snapshots
    [   s01,  s12,  s23,  s34   ]

Data Structure
            ╔═══════════════╗                         ╔═══════════════╗
            ║   Snapshot B  ║          ┌─────────────>║   Snapshot C  ║
            ╟───────────────╢          │              ╟───────────────╢
            ║ _nextDiff     ║──────┐   │              ║ _nextDiff     ║───> Next snapshot
        ┌───║ _prevDiff     ║      │   │          ┌───║ _prevDiff     ║  or Null if at the end
        │   ╚═══════════════╝      │   │          │   ╚═══════════════╝
        V              A           V   │          V
    ╔═══════════════╗  │  ╔═══════════════╗   ╔═══════════════╗
    ║   Diff B->A   ║  │  ║   Diff B->C   ║   ║   Diff C->B   ║
    ╟───────────────╢  │  ╟───────────────╢   ╟───────────────╢
    ║ slice = txtBA ║  │  ║ slice = txtBC ║   ║ slice = txtBA ║
    ║ snap          ║  │  ║ snap          ║   ║ snap          ║
    ╚═══════════════╝  │  ╚═══════════════╝   ╚═══════════════╝
                       │                             │
                       └─────────────────────────────┘