Class: Diff::LCS::DiffCallbacks

### Home Classes Methods

### In Files

- lib/diff/lcs/callbacks.rb

### Parent

Object

### Methods

- ::new
- #discard_a
- #discard_b
- #finish
- #match

### Files

- Manifest.txt
- README.rdoc
- COPYING.txt
- artistic.txt

### Class/Module Index

Quicksearch

- Diff
- Diff::LCS
- Diff::LCS::BalancedCallbacks
- Diff::LCS::Block
- Diff::LCS::Change
- Diff::LCS::ContextChange
- Diff::LCS::ContextDiffCallbacks
- Diff::LCS::DefaultCallbacks
- Diff::LCS::DiffCallbacks
- Diff::LCS::HTMLDiff
- Diff::LCS::HTMLDiff::Callbacks
- Diff::LCS::Hunk
- Diff::LCS::Ldiff
- Diff::LCS::SDiffCallbacks
- Diff::LCS::SequenceCallbacks
- Array
- String

No matching classes.

# Diff::LCS::DiffCallbacks

This will produce a compound array of simple diff change objects. Each element in the diffs array is a `hunk` or `hunk` array, where each element in each `hunk` array is a single Change object representing the addition or removal of a single element from one of the two tested sequences. The `hunk` provides the full context for the changes.

    diffs = Diff::LCS.diff(seq1, seq2)
      # This example shows a simplified array format.
      # [ [ [ '-',  0, 'a' ] ],   # 1
      #   [ [ '+',  2, 'd' ] ],   # 2
      #   [ [ '-',  4, 'h' ],     # 3
      #     [ '+',  4, 'f' ] ],
      #   [ [ '+',  6, 'k' ] ],   # 4
      #   [ [ '-',  8, 'n' ],     # 5
      #     [ '-',  9, 'p' ],
      #     [ '+',  9, 'r' ],
      #     [ '+', 10, 's' ],
      #     [ '+', 11, 't' ] ] ]

There are five hunks here. The first hunk says that the `a` at position 0 of the first sequence should be deleted (`'-'`). The second hunk says that the `d` at position 2 of the second sequence should be inserted (`'+'`). The third hunk says that the `h` at position 4 of the first sequence should be removed and replaced with the `f` from position 4 of the second sequence. The other two hunks are described similarly.

### Use

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

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

Note that the call to finish is absolutely necessary, or the last set of changes will not be visible. Alternatively, can be used as:

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

The necessary finish call will be made.

### Simplified Array Format

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

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

### Attributes

diffs[R]

Returns the difference set collected during the diff process.

### Public Class Methods

new() click to toggle source

    # File lib/diff/lcs/callbacks.rb, line 106
    def initialize # :yields self:
      @hunk = []
      @diffs = []

      if block_given?
        begin
          yield self
        ensure
          self.finish
        end
      end
    end

### Public Instance Methods

discard_a(event) click to toggle source

    # File lib/diff/lcs/callbacks.rb, line 129
    def discard_a(event)
      @hunk << Diff::LCS::Change.new('-', event.old_position, event.old_element)
    end

discard_b(event) click to toggle source

    # File lib/diff/lcs/callbacks.rb, line 133
    def discard_b(event)
      @hunk << Diff::LCS::Change.new('+', event.new_position, event.new_element)
    end

finish() click to toggle source

Finalizes the diff process. If an unprocessed hunk still exists, then it is appended to the diff list.

    # File lib/diff/lcs/callbacks.rb, line 121
    def finish
      finish_hunk
    end

match(event) click to toggle source

    # File lib/diff/lcs/callbacks.rb, line 125
    def match(event)
      finish_hunk
    end

[Validate]

Generated with the Darkfish Rdoc Generator 2.