AST normalization experiment
Branch: master
Clone or download
Quasilyte better string literals normalization
Signed-off-by: Iskander Sharipov <quasilyte@gmail.com>
Latest commit 544300f Jan 31, 2019
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
cmd cmd/grepfunc: add verbose mode Jan 25, 2019
example
testdata better string literals normalization Jan 31, 2019
.travis.yml use "go vet" instead of "go tool vet" Jan 24, 2019
LICENSE Create LICENSE Jan 24, 2019
README.md readme: add demo script link Jan 25, 2019
astnorm.go add package doc comment Jan 24, 2019
logo.jpg make logo even better Jan 25, 2019
normalizer.go handle labeled stmt Jan 25, 2019
normalizer_test.go add simple 1-stmt level normalization Jan 24, 2019
utils.go better string literals normalization Jan 31, 2019

README.md

Go Report Card GoDoc Build Status

logo

astnorm

Go AST normalization experiment.

THIS IS NOT A PROPER LIBRARY (yet?).
DO NOT USE.
It will probably be completely re-written before it becomes usable.

Normalized code examples

  1. Swap values.
Before After
tmp := xs[i]
xs[i] = ys[i]
ys[i] = tmp
xs[i], ys[i] = ys[i], xs[i]
  1. Remove elements that are equal to toRemove+1.
Before After
const toRemove = 10
var filtered []int
filtered = xs[0:0]
for i := int(0); i < len(xs); i++ {
        x := xs[i]
        if toRemove+1 != x {
                filtered = append(filtered, x)
        }
}
return (filtered)
filtered := []int(nil)
filtered = xs[:0]
for _, x := range xs {
       if x != 11 {
               filtered = append(filtered, x)
       }
}
return filtered

Usage examples

Potential workflow for code searching:

1. Code search

  • Normalize the entire Go stdlib
  • Then normalize your function
  • Run grepfunc against normalized stdlib
  • If function you implemented has implementation under the stdlib, you'll probably find it

Basically, instead of stdlib you can use any kind of Go corpus.

Another code search related tasks that can be simplified by astnorm are code similarity evaluation and code duplication detection of any kind.

2. Static analysis

Suppose we have badcode.go file:

package badpkg

func NotEqual(x1, x2 int) bool {
	return (x1) != x1
}

There is an obvious mistake there, x1 used twice, but because of extra parenthesis, linters may not detect this issue:

$ staticcheck badcode.go
# No output

Let's normalize the input first and then run staticcheck:

go-normalize badcode.go > normalized_badcode.go
staticcheck normalized_badcode.go
normalized_badcode.go:4:9: identical expressions on the left and right side of the '!=' operator (SA4000)

And we get the warning we deserve! No changes into staticcheck or any other linter are required.

See also: demo script.