README
¶
FuzzyPatch
FuzzyPatch is a Go library that enables fuzzy matching and patching of text files. It's particularly useful for applying patches when the exact line positions may have changed. It's meant for use with AI coding agents which often make small mistakes when generating diffs.
Installation
go get github.com/icholy/fuzzypatch
Usage
FuzzyPatch accepts diff in the following format:
<<<<<<< SEARCH line:<n>
[search text...]
=======
[replace text...]
>>>>>>> REPLACE
Where:
<n>is the line number hint where the search should start[search text...]is the text to find (can span multiple lines)[replace text...]is the text to replace it with (can span multiple lines)
Example
package main
import (
"fmt"
"github.com/icholy/fuzzypatch"
)
var difftext = `
<<<<<<< SEARCH line:2
console.log("Hello, world!");
=======
console.log("Hello, Universe!");
>>>>>>> REPLACE
`
var source = `
function sayHello() {
console.log("Hello, world!");
// Some comment
doSomethingElse();
}
`
func main() {
// Parse a diff block
diffs, _ := fuzzypatch.Parse(difftext)
// Map diffs to edits
var edits []fuzzypatch.Edit
for _, diff := range diffs {
// Search with 0.9 similarity threshold (90% similar)
if edit, ok := fuzzypatch.Search(source, diff, 0.9); ok {
edits = append(edits, edit)
}
}
// Apply all edits in one pass
result, _ := fuzzypatch.Apply(source, edits)
fmt.Println(result)
}
Documentation
¶
Index ¶
Constants ¶
const (
EOF tokenType
)
Variables ¶
This section is empty.
Functions ¶
Types ¶
type Diff ¶
type Diff struct {
Line int // 1-based line number where the search should start
Search string // Text to find in the document
Replace string // Text to replace the found section with
}
Diff represents a text replacement operation with search and replace strings that should be applied at a specific line position in a document.
type Edit ¶
type Edit struct {
Start int // Byte offset where the edit starts (inclusive)
End int // Byte offset where the edit ends (exclusive)
Text string // New text to replace the section between Start and End
}
Edit represents a specific text edit operation with byte offsets that can be applied to a document.
func Search ¶
Search tries to locate `diff.Search` inside `source`. It begins at the requested line and expands alternately upward/downward until a slice whose similarity ≥ threshold is found.
Similarity = 1 - (levenshtein distance / maxLen). On success it returns the byte‑offset edit [Start, End) to replace and true. If nothing satisfies the threshold it returns (zero Edit, false).
Source Files