diff

Documentation

Index

• Constants
• func FormatRangeUnified(start, stop int) string
• type OpCode
• type SequenceMatcher
  • func NewMatcher(a, b []string) *SequenceMatcher
  • func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode

Constants

const (
	OpEqual int8 = iota
	OpInsert
	OpDelete
	OpReplace
)

Tag Codes

Functions

func FormatRangeUnified

func FormatRangeUnified(start, stop int) string

FormatRangeUnified converts range to the "ed" format.

Types

type OpCode

type OpCode struct {
	Tag int8
	I1  int
	I2  int
	J1  int
	J2  int
}

type SequenceMatcher

type SequenceMatcher struct {
	IsJunk func(string) bool
	// contains filtered or unexported fields
}

SequenceMatcher compares sequence of strings. The basic algorithm predates, and is a little fancier than, an algorithm published in the late 1980's by Ratcliff and Obershelp under the hyperbolic name "gestalt pattern matching". The basic idea is to find the longest contiguous matching subsequence that contains no "junk" elements (R-O doesn't address junk). The same idea is then applied recursively to the pieces of the sequences to the left and to the right of the matching subsequence. This does not yield minimal edit sequences, but does tend to yield matches that "look right" to people.

SequenceMatcher tries to compute a "human-friendly diff" between two sequences. Unlike e.g. UNIX(tm) diff, the fundamental notion is the longest *contiguous* & junk-free matching subsequence. That's what catches peoples' eyes. The Windows(tm) windiff has another interesting notion, pairing up elements that appear uniquely in each sequence. That, and the method here, appear to yield more intuitive difference reports than does diff. This method appears to be the least vulnerable to synching up on blocks of "junk lines", though (like blank lines in ordinary text files, or maybe "<P>" lines in HTML files). That may be because this is the only method of the 3 that has a *concept* of "junk" <wink>.

Timing: Basic R-O is cubic time worst case and quadratic time expected case. SequenceMatcher is quadratic time for the worst case and has expected-case behavior dependent in a complicated way on how many elements the sequences have in common; best case time is linear.

func NewMatcher

func NewMatcher(a, b []string) *SequenceMatcher

func (*SequenceMatcher) GetGroupedOpCodes

func (m *SequenceMatcher) GetGroupedOpCodes(n int) [][]OpCode

GetGroupedOpCodes Isolate change clusters by eliminating ranges with no changes.

Return a generator of groups with up to n lines of context. Each group is in the same format as returned by getOpCodes().