oracular (3) Diffing.3o.gz

NAME

       Diffing - Parametric diffing

Module

       Module   Diffing

Documentation

       Module Diffing
        : sig end

       Parametric diffing

       This module implements diffing over lists of arbitrary content.  It is parameterized by

       -The content of the two lists

       -The equality witness when an element is kept

       -The diffing witness when an element is changed

       Diffing  is  extended  to  maintain state depending on the computed changes while walking through the two
       lists.

       The     underlying     algorithm     is      a      modified      Wagner-Fischer      algorithm      (see
       <https://en.wikipedia.org/wiki/Wagner%E2%80%93Fischer_algorithm>).

       We  provide  the  following guarantee: Given two lists l and r , if different patches result in different
       states, we say that the state diverges.

       -We always return the optimal patch on prefixes of l and r on which state does not diverge.

       -Otherwise, we return a correct but non-optimal patch where  subpatches  with  no  divergent  states  are
       optimal for the given initial state.

       More precisely, the optimality of Wagner-Fischer depends on the property that the edit-distance between a
       k-prefix of the left input and a l-prefix of the right input d(k,l) satisfies

       d(k,l) = min ( del_cost + d(k-1,l), insert_cost + d(k,l-1), change_cost + d(k-1,l-1) )

       Under this hypothesis, it is optimal to choose greedily the state of the minimal patch  transforming  the
       left  k-prefix  into  the  right  l-prefix  as  a  representative  of  the states of all possible patches
       transforming the left k-prefix into the right l-prefix.

       If this property is not satisfied, we can still choose greedily  a  representative  state.  However,  the
       computed  patch is no more guaranteed to be globally optimal.  Nevertheless, it is still a correct patch,
       which is even optimal among all explored patches.

       module type Defs = sig end

       The core types of a diffing implementation

       type change_kind =
        | Deletion
        | Insertion
        | Modification
        | Preservation

       The kind of changes which is used to share printing and styling across implementation

       val prefix : Format.formatter -> int * change_kind -> unit

       val style : change_kind -> Misc.Style.style list

       type ('left, 'right, 'eq, 'diff) change =
        | Delete of 'left
        | Insert of 'right
        | Keep of 'left * 'right * 'eq
        | Change of 'left * 'right * 'diff

       val classify : ('a, 'b, 'c, 'd) change -> change_kind

       module Define : functor (D : Defs) -> sig end

       Define(Defs) creates the diffing types from the types defined in Defs and the functors that  need  to  be
       instantatied with the diffing algorithm parameters