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This is just a proof of concept for #30.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -61,5 +61,6 @@ func main() { | |
| } | ||
| } | ||
| } | ||
| gci.ClearModCache() | ||
| os.Exit(exitCode) | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,109 @@ | ||
| package gci | ||
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| import ( | ||
| "errors" | ||
| "fmt" | ||
| "io/ioutil" | ||
| "os" | ||
| "path/filepath" | ||
| "strings" | ||
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| "golang.org/x/mod/modfile" | ||
| ) | ||
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| // moduleResolver looksup the module path for a given (Go) file. | ||
| // To improve performance, the file paths and module paths are | ||
| // cached. | ||
| // | ||
| // Given the following directory structure: | ||
| // | ||
| // /path/to/example | ||
| // +-- go.mod (module example) | ||
| // +-- cmd/sample/main.go (package main, imports example/util) | ||
| // +-- util/util.go (package util) | ||
| // | ||
| // After looking up main.go and util.go, the internal cache will contain: | ||
| // | ||
| // "/path/to/foobar/": "example" | ||
| // | ||
| // For more complex module structures (i.e. sub-modules), the cache | ||
| // might look like this: | ||
| // | ||
| // "/path/to/example/": "example" | ||
| // "/path/to/example/cmd/sample/": "go.example.com/historic/path" | ||
| // | ||
| // When matching files against this cache, the resolver will select the | ||
| // entry with the most specific path (so that, in this example, the file | ||
| // cmd/sample/main.go will resolve to go.example.com/historic/path). | ||
| type moduleResolver map[string]string | ||
|
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| var modCache = make(moduleResolver) | ||
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| // ClearModCache will reset the internal module cache used by ProcessFile | ||
| // and WalkDir. When invoking either of those functions with an empty | ||
| // FlagSet.LocalFlag, we will try to resolve a matching Go module path. | ||
| // | ||
| // You should call this method when you're done with processing files. | ||
| func ClearModCache() { | ||
| modCache = make(moduleResolver) | ||
| } | ||
|
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| func (m moduleResolver) Lookup(file string) (string, error) { | ||
| var bestMatch string | ||
| for path := range m { | ||
| if strings.HasPrefix(file, path) && len(path) > len(bestMatch) { | ||
| bestMatch = path | ||
| } | ||
| } | ||
|
|
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| if bestMatch != "" { | ||
| return m[bestMatch], nil | ||
| } | ||
|
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| dir, err := filepath.Abs(filepath.Dir(file)) | ||
| if err != nil { | ||
| return "", fmt.Errorf("could not make path absolute: %w", err) | ||
| } | ||
|
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| return m.findRecursively(dir) | ||
| } | ||
|
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| func (m moduleResolver) findRecursively(dir string) (string, error) { | ||
| // When going up the directory tree, we might never find a go.mod | ||
| // file. In this case remember where we started, so that the next | ||
| // time we can short circuit the recursive ascent. | ||
| stop := dir | ||
|
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| for { | ||
| gomod := filepath.Join(dir, "go.mod") | ||
| _, err := os.Stat(gomod) | ||
| if errors.Is(err, os.ErrNotExist) { | ||
| // go.mod doesn't exists at current location | ||
| next := filepath.Dir(dir) | ||
| if next == dir { | ||
| // we're at the top of the filesystem | ||
| m[stop] = "" | ||
| return "", nil | ||
| } | ||
| // go one level up | ||
| dir = next | ||
| continue | ||
| } else if err != nil { | ||
| // other error (likely EPERM | ||
| return "", fmt.Errorf("module lookup failed: %w", err) | ||
| } | ||
|
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| // we found a go.mod | ||
| mod, err := ioutil.ReadFile(gomod) | ||
| if err != nil { | ||
| return "", fmt.Errorf("reading module failed: %w", err) | ||
| } | ||
|
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| // store module path at m[dir]. add path separator to avoid | ||
| // false-positive (think of /foo and /foobar). | ||
| mpath := modfile.ModulePath(mod) | ||
| m[dir+string(os.PathSeparator)] = mpath | ||
|
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| return mpath, nil | ||
| } | ||
| } |