feat: add slice and file helpers (#62)

file/file.go

@@ -1,7 +1,9 @@
 package file
 
 import (
+	"fmt"
 	"os"
+	"path/filepath"
 )
 
 // The MSDN docs appear to say that a normal path that is 248 bytes long will work;
@@ -42,3 +44,24 @@ func DeleteDir(path string) error {
 
 	return os.Remove(path)
 }
+
+// ExpandFileList takes a list of file globs and expands them into a list
+// of matching file paths. It returns the expanded file list and any errors
+// from glob matching. This allows safely passing user input globs through to
+// glob matching.
+func ExpandFileList(fileList []string) ([]string, error) {
+	var result []string
+
+	for _, glob := range fileList {
+		globbed, err := filepath.Glob(glob)
+		if err != nil {
+			return result, fmt.Errorf("failed to match %s: %w", glob, err)
+		}
+
+		if globbed != nil {
+			result = append(result, globbed...)
+		}
+	}
+
+	return result, nil
+}

slice/slice.go

@@ -0,0 +1,44 @@
+package slice
+
+// SetDifference returns a slice containing the elements in slice a that are not in slice b.
+func SetDifference[T comparable](a, b []T, unique bool) []T {
+	result := make([]T, 0)
+
+	if unique {
+		a = Unique(a)
+	}
+
+	for _, aItem := range a {
+		found := false
+
+		for _, bItem := range b {
+			if aItem == bItem {
+				found = true
+
+				break
+			}
+		}
+
+		if !found {
+			result = append(result, aItem)
+		}
+	}
+
+	return result
+}
+
+// Unique returns a slice containing only the unique elements of the given slice.
+func Unique[T comparable](s []T) []T {
+	seen := make(map[T]struct{})
+	result := make([]T, 0)
+
+	for _, v := range s {
+		if _, ok := seen[v]; !ok {
+			seen[v] = struct{}{}
+
+			result = append(result, v)
+		}
+	}
+
+	return result
+}

slice/slice_test.go

@@ -0,0 +1,91 @@
+package slice
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSetDifference(t *testing.T) {
+	tests := []struct {
+		name     string
+		a        []string
+		b        []string
+		expected []string
+		unique   bool
+	}{
+		{
+			name:     "both empty",
+			a:        []string{},
+			b:        []string{},
+			expected: []string{},
+			unique:   false,
+		},
+		{
+			name:     "remove common element",
+			a:        []string{"a", "b", "c"},
+			b:        []string{"b"},
+			expected: []string{"a", "c"},
+			unique:   false,
+		},
+		{
+			name:     "remove a and c",
+			a:        []string{"a", "b", "c"},
+			b:        []string{"a", "c"},
+			expected: []string{"b"},
+			unique:   false,
+		},
+		{
+			name:     "no common elements",
+			a:        []string{"a", "b", "c"},
+			b:        []string{"d", "e"},
+			expected: []string{"a", "b", "c"},
+			unique:   false,
+		},
+		{
+			name:     "remove duplicates",
+			a:        []string{"a", "a", "b"},
+			b:        []string{"b"},
+			expected: []string{"a"},
+			unique:   true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := SetDifference(tt.a, tt.b, tt.unique)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestUnique(t *testing.T) {
+	tests := []struct {
+		name  string
+		input []int
+		want  []int
+	}{
+		{
+			name:  "empty slice",
+			input: []int{},
+			want:  []int{},
+		},
+		{
+			name:  "single value",
+			input: []int{1},
+			want:  []int{1},
+		},
+		{
+			name:  "duplicates",
+			input: []int{1, 2, 3, 2},
+			want:  []int{1, 2, 3},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := Unique(tt.input)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}