1 files changed, 71 insertions, 0 deletions
diff --git a/predicate.go b/predicate.go
new file mode 100644
index 0000000..5ba544b
--- /dev/null
+++ b/predicate.go
@@ -0,0 +1,71 @@
+package complete
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// Predicate determines what terms can follow a command or a flag
+type Predicate struct {
+	// Expects determine if the predicate expects something after.
+	// flags/commands that do not expect any specific argument should
+	// leave it on false
+	Expects bool
+	// Predictor is function that returns list of arguments that can
+	// come after the flag/command
+	Predictor func() []Option
+}
+
+func (f *Predicate) predict() []Option {
+	if f.Predictor == nil {
+		return nil
+	}
+	return f.Predictor()
+}
+
+var (
+	PredictNothing  = Predicate{Expects: false}
+	PredictAnything = Predicate{Expects: true}
+)
+
+func PredictFiles(pattern string) Predicate {
+	return Predicate{
+		Expects:   true,
+		Predictor: glob(pattern),
+	}
+}
+
+func glob(pattern string) func() []Option {
+	return func() []Option {
+		files, err := filepath.Glob(pattern)
+		if err != nil {
+			logger("failed glob operation with pattern '%s': %s", pattern, err)
+		}
+		if !filepath.IsAbs(pattern) {
+			filesToRel(files)
+		}
+		options := make([]Option, len(files))
+		for i, f := range files {
+			options[i] = ArgFileName(f)
+		}
+		return options
+	}
+}
+func filesToRel(files []string) {
+	wd, err := os.Getwd()
+	if err != nil {
+		return
+	}
+	for i := range files {
+		abs, err := filepath.Abs(files[i])
+		if err != nil {
+			continue
+		}
+		rel, err := filepath.Rel(wd, abs)
+		if err != nil {
+			continue
+		}
+		files[i] = "./" + rel
+	}
+	return
+}