Class: Diff::LCS::SDiffCallbacks

Class | Diff::LCS::SDiffCallbacks
In: | lib/diff/lcs/callbacks.rb
Parent: | Object

This will produce a simple array of diff change objects. Each element in the diffs array is a single ContextChange. In the set of diffs provided by SDiffCallbacks, both old and new objects will be presented for both changed <strong>and unchanged</strong> objects. `nil` will be substituted for a discarded object.

The diffset produced by this callback, when provided to Diff::LCS#sdiff, will compute and display the necessary components to show two sequences and their minimized differences side by side, just like the Unix utility `sdiff`.

        same             same
        before     |     after
        old        <     -
        -          >     new

        seq1 = %w(a b c e h j l m n p)
        seq2 = %w(b c d e f j k l m r s t)

        diffs = Diff::LCS.sdiff(seq1, seq2)
          # This example shows a simplified array format.
          # [ [ "-", [  0, "a"], [  0, nil ] ],
          #   [ "=", [  1, "b"], [  0, "b" ] ],
          #   [ "=", [  2, "c"], [  1, "c" ] ],
          #   [ "+", [  3, nil], [  2, "d" ] ],
          #   [ "=", [  3, "e"], [  3, "e" ] ],
          #   [ "!", [  4, "h"], [  4, "f" ] ],
          #   [ "=", [  5, "j"], [  5, "j" ] ],
          #   [ "+", [  6, nil], [  6, "k" ] ],
          #   [ "=", [  6, "l"], [  7, "l" ] ],
          #   [ "=", [  7, "m"], [  8, "m" ] ],
          #   [ "!", [  8, "n"], [  9, "r" ] ],
          #   [ "!", [  9, "p"], [ 10, "s" ] ],
          #   [ "+", [ 10, nil], [ 11, "t" ] ] ]

The result of this operation is similar to that of Diff::LCS::ContextDiffCallbacks. They may be compared as:

        s = Diff::LCS.sdiff(seq1, seq2).reject { |e| e.action == "=" }
        c = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks).flatten

        s == c # -> true

### Use

This callback object must be initialised and is used by the Diff::LCS#sdiff method.

        cbo = Diff::LCS::SDiffCallbacks.new
        Diff::LCS.LCS(seq1, seq2, cbo)

As with the other initialisable callback objects, Diff::LCS::SDiffCallbacks can be initialised with a block. As there is no "fininishing" to be done, this has no effect on the state of the object.

        cbo = Diff::LCS::SDiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }

### Simplified Array Format

The simplified array format used in the example above can be obtained with:

        require 'pp'
        pp diffs.map { |e| e.to_a }

### Methods

change discard_a discard_b match new

### Attributes

diffs | [R] | Returns the difference set collected during the diff process.

### Public Class methods

new( {|self if block_given?| ...}

### Public Instance methods

change(event)
discard_a(event)
discard_b(event)
match(event)

[Validate]