Filter

The Filter type is the primary API for detecting auto-generated Go code files. Create one with NewFilter and functional options, then call Filter, FilterDetailed, or FilterDetailedAndContent depending on how much detail you need.

For the complete API reference with all methods, types, and examples, see pkg.go.dev.

Creating a Filter

NewFilter(configs ...FilterConfig) (*Filter, error)

Creates an immutable filter from functional options. The filter is enabled when any filter options, include patterns, or exclude patterns are provided.

opts, err := gogenfilter.WithFilterOptions(gogenfilter.FilterAll)
if err != nil {
    log.Fatal(err)
}
f, err := gogenfilter.NewFilter(opts)
if err != nil {
    log.Fatal(err)
}

Checking Files

Filter(filePath string) (bool, error)

Returns whether a file is generated. Reads the file lazily during phase-2 detection.

filtered, err := f.Filter("db/models.go")
if err != nil {
    log.Fatal(err)
}
if filtered {
    fmt.Println("skipping generated file")
}

FilterDetailed(filePath string) (FilterResult, error)

Like Filter but returns a FilterResult with the detection reason and trace.

result, err := f.FilterDetailed("db/models.go")
if err != nil {
    log.Fatal(err)
}
if result.Filtered {
    fmt.Printf("filtered: reason=%s\n", result.Reason)
}

FilterDetailedAndContent(filePath string) (FilterResult, []byte, error)

Like FilterDetailed but also returns the file content if it was read during phase-2 detection. Content is nil when no read occurred (filename match, disabled filter, pattern match, or no content-check detectors enabled).

When non-nil, the content was read exactly once and can be reused without a double-read — ideal for tools that need the content for post-detection logic.

result, content, err := f.FilterDetailedAndContent("repository.go")
if err != nil {
    log.Fatal(err)
}
if result.Filtered {
    fmt.Printf("filtered: reason=%s\n", result.Reason)
}
// content is non-nil when phase-2 read the file

Pre-read Content Variants

FilterWithContent(filePath string, content []byte) (bool, error)

Like Filter but accepts pre-read file content. Avoids redundant I/O for analyzers that already have the content (e.g., from AST parsing).

FilterDetailedWithContent(filePath string, content []byte) (FilterResult, error)

Like FilterDetailed but accepts pre-read file content.

Batch Operations

FilterPaths(paths []string) ([]bool, error)

Filters multiple files at once. Returns partial results on error.

FilterPathsDetailed(paths []string) ([]FilterResult, error)

Batch variant of FilterDetailed.

Choosing a Method

Method	Returns	Reads File?	Use When
Filter	(bool, error)	Lazily	Simple skip/no-skip decision
FilterDetailed	(FilterResult, error)	Lazily	Need the detection reason
FilterDetailedAndContent	(FilterResult, []byte, error)	Lazily + returns content	Need content for further analysis
FilterWithContent	(bool, error)	No (you provide)	Already have content from AST
FilterDetailedWithContent	(FilterResult, error)	No (you provide)	Already have content + need reason