go library parse gitignore file, source code most from docker

package main

import (
    "bytes"
    "io/ioutil"
    "log"

    ignore "github.com/codeskyblue/dockerignore"
)

func main() {
    // patterns, err := ignore.ReadIgnoreFile(".gitignore")
    rd := ioutil.NopCloser(bytes.NewBufferString("*.exe"))
    patterns, err := ignore.ReadIgnore(rd)
    if err != nil {
        log.Fatal(err)
    }   
    isSkip, err := ignore.Matches("hello.exe", patterns)
    if err != nil {
        log.Fatal(err)
    }   
    log.Printf("Should skipped true, got %v", isSkip)
}

The Go lib interprets a .dockerignore like file as a newline-separated list of patterns similar to the file globs of Unix shells. For the purposes of matching, the root of the context is considered to be both the working and the root directory. For example, the patterns /foo/bar and foo/bar both exclude a file or directory named bar in the foo subdirectory of PATH or in the root of the git repository located at URL. Neither excludes anything else.

Here is an example .dockerignore file:

*/temp*
*/*/temp*
temp?

This file causes the following build behavior:

Matching is done using Go’s filepath.Match rules. A preprocessing step removes leading and trailing whitespace and eliminates . and .. elements using Go’s filepath.Clean. Lines that are blank after preprocessing are ignored.

Lines starting with ! (exclamation mark) can be used to make exceptions to exclusions. The following is an example .dockerignore file that uses this mechanism:

*.md
!README.md

All markdown files except README.md are excluded from the context.

The placement of ! exception rules influences the behavior: the last line of the .dockerignore that matches a particular file determines whether it is included or excluded. Consider the following example:

*.md
!README*.md
README-secret.md

No markdown files are included in the context except README files other than README-secret.md

Now consider this example:

*.md
README-secret.md
!README*.md

All of the README files are included. The middle line has no effect because !README*.md matches README-secret.md and comes last.

You can even use the .dockerignore file to exclude the Dockerfile and .dockerignore files. These files are still sent to the daemon because it needs them to do its job. But the ADD and COPY commands do not copy them to the the image.

Finally, you may want to specify which files to include in the context, rather than which to exclude. To achieve this, specify * as the first pattern, followed by one or more ! exception patterns.

Note: For historical reasons, the pattern . is ignored.

Folow the docker license, this lib use APACHE V2 LICENSE