Update API to support filters

context.go

@@ -26,23 +26,21 @@ import (
 	"os"
 	"runtime"
 	"sync"
-
-	"github.com/bmatcuk/doublestar"
 )
 
 type context struct {
 	gs            *goldsmith
 	plug          Plugin
-	filters       []string
+	filters       []Filter
 	input, output chan *file
 }
 
 func (ctx *context) chain() {
 	defer close(ctx.output)
 
-	var filters []string
-	if initializer, ok := ctx.plug.(Initializer); ok {
 	var err error
+	var filters []Filter
+	if initializer, ok := ctx.plug.(Initializer); ok {
 		filters, err = initializer.Initialize(ctx)
 		if err != nil {
 			ctx.gs.fault(ctx.plug.Name(), nil, err)
@@ -60,20 +58,16 @@ func (ctx *context) chain() {
 				defer wg.Done()
 				for f := range ctx.input {
 					accept := processor != nil
-					matcher := func(patterns []string) {
-						if accept && len(patterns) > 0 {
-							accept = false
-							for _, pattern := range patterns {
-								if match, _ := doublestar.PathMatch(pattern, f.Path()); match {
-									accept = true
+					for _, filter := range append(ctx.filters, filters...) {
+						if accept, err = filter.Accept(ctx, f); err != nil {
+							ctx.gs.fault(filter.Name(), f, err)
+							return
+						}
+
+						if !accept {
 							break
 						}
 					}
-						}
-					}
-
-					matcher(filters)
-					matcher(ctx.filters)
 
 					if accept {
 						if _, err := f.Seek(0, os.SEEK_SET); err != nil {

core.go

@@ -33,18 +33,15 @@ type goldsmith struct {
 	contexts       []*context
 	refs           map[string]bool
 	complete       bool
+	filters        []Filter
 
 	errors   []error
 	errorMtx sync.Mutex
 }
 
-func (gs *goldsmith) pushContext(plug Plugin, filters []string) *context {
-	ctx := &context{
-		gs:      gs,
-		plug:    plug,
-		filters: filters,
-		output:  make(chan *file),
-	}
+func (gs *goldsmith) pushContext(plug Plugin) *context {
+	ctx := &context{gs: gs, plug: plug, output: make(chan *file)}
+	ctx.filters = append(ctx.filters, gs.filters...)
 
 	if len(gs.contexts) > 0 {
 		ctx.input = gs.contexts[len(gs.contexts)-1].output
@@ -102,12 +99,35 @@ func (gs *goldsmith) fault(name string, f *file, err error) {
 //	Goldsmith Implementation
 //
 
-func (gs *goldsmith) Chain(p Plugin, filters ...string) Goldsmith {
+func (gs *goldsmith) Chain(p Plugin) Goldsmith {
 	if gs.complete {
 		panic("attempted reuse of goldsmith instance")
 	}
 
-	gs.pushContext(p, filters)
+	gs.pushContext(p)
+	return gs
+}
+
+func (gs *goldsmith) FilterPush(f Filter) Goldsmith {
+	if gs.complete {
+		panic("attempted reuse of goldsmith instance")
+	}
+
+	gs.filters = append(gs.filters, f)
+	return gs
+}
+
+func (gs *goldsmith) FilterPop() Goldsmith {
+	if gs.complete {
+		panic("attempted reuse of goldsmith instance")
+	}
+
+	count := len(gs.filters)
+	if count == 0 {
+		panic("attempted to pop empty filter stack")
+	}
+
+	gs.filters = gs.filters[:count-1]
 	return gs
 }
 

goldsmith.go

@@ -32,13 +32,15 @@ import (
 )
 
 type Goldsmith interface {
-	Chain(p Plugin, filters ...string) Goldsmith
+	Chain(p Plugin) Goldsmith
+	FilterPush(f Filter) Goldsmith
+	FilterPop() Goldsmith
 	End(dstDir string) []error
 }
 
-func Begin(srcDir string, filters ...string) Goldsmith {
+func Begin(srcDir string) Goldsmith {
 	gs := &goldsmith{srcDir: srcDir, refs: make(map[string]bool)}
-	gs.Chain(new(loader), filters...)
+	gs.Chain(new(loader))
 	return gs
 }
 
@@ -113,7 +115,7 @@ func (e Error) Error() string {
 }
 
 type Initializer interface {
-	Initialize(ctx Context) ([]string, error)
+	Initialize(ctx Context) ([]Filter, error)
 }
 
 type Processor interface {
@@ -124,6 +126,15 @@ type Finalizer interface {
 	Finalize(ctx Context) error
 }
 
-type Plugin interface {
+type Component interface {
 	Name() string
 }
+
+type Filter interface {
+	Component
+	Accept(ctx Context, f File) (bool, error)
+}
+
+type Plugin interface {
+	Component
+}

loader.go

@@ -30,7 +30,7 @@ func (*loader) Name() string {
 	return "loader"
 }
 
-func (*loader) Initialize(ctx Context) ([]string, error) {
+func (*loader) Initialize(ctx Context) ([]Filter, error) {
 	infos := make(chan fileInfo)
 	go scanDir(ctx.SrcDir(), infos)