add -ol and -or flags

Author: gabotechs

README.md

@@ -145,7 +145,8 @@ clustering and no clear separation between them:
 
 ### Explain
 
-Given two pieces of code, displays what are the dependencies between them, for example:
+Given two pieces of code, displays what are the dependencies between them. These pieces
+of code are specified using a glob patterns, for example:
 
 ```shell
 dep-tree explain 'src/products/**/*.go' 'src/orders/**/*.go'
@@ -168,6 +169,23 @@ src/products/price.go  -> src/orders/order_manager.go
 src/products/storage.go -> src/orders/order_manager.go
 ```
 
+Additionally, the `--overlap-left` (`-ol`) or `--overlap-right` (`-or`) arguments can be passed:
+- `--overlap-left`: when the left and right glob patterns have some files in common, keep only the
+  common files at the left, and discard them from the right. This flag is useful for retrieving any
+  external dependencies of a specific folder: 
+```shell
+# Retrieves dependencies from files in src/products to any other file that is not inside src/products
+dep-tree explain 'src/products/**/*.go' '**/*.go' --overlap-left
+```
+
+- `--overlap-right`: when the left and right glob patterns have some files in common, keep only the
+  common files at the right, and discard them from the left. This flag is useful for retrieving
+  any file outside a specific folder that depends on that folder.
+```shell
+# Retrieves dependencies from any folder but src/products that point to files inside src/products
+dep-tree explain '**/*.go' 'src/products/**/*.go' --overlap-right
+```
+
 ### Tree
 
 Choose the file that will act as the root of the dependency graph (for example `my-file.py`), and run:

cmd/explain.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"errors"
 	"os"
 	"slices"
 	"strings"
@@ -9,16 +10,24 @@ import (
 	"github.com/gabotechs/dep-tree/internal/explain"
 	"github.com/gabotechs/dep-tree/internal/graph"
 	"github.com/gabotechs/dep-tree/internal/language"
+	"github.com/gabotechs/dep-tree/internal/utils"
 	"github.com/spf13/cobra"
 )
 
 func ExplainCmd(cfgF func() (*config.Config, error)) *cobra.Command {
+	var overlapLeft bool
+	var overlapRight bool
+
 	cmd := &cobra.Command{
 		Use:     "explain",
 		Short:   "Shows all the dependencies between two parts of the code",
 		GroupID: explainGroupId,
 		Args:    cobra.ExactArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
+			if overlapLeft && overlapRight {
+				return errors.New("only one of --overlap-left (-ol) or --overlap-right (-or) can be used at a time")
+			}
+
 			fromFiles, err := filesFromArgs([]string{args[0]})
 			if err != nil {
 				return err
@@ -29,6 +38,14 @@ func ExplainCmd(cfgF func() (*config.Config, error)) *cobra.Command {
 				return err
 			}
 
+			if overlapLeft {
+				fromFiles = utils.RemoveOverlap(fromFiles, toFiles)
+			}
+
+			if overlapRight {
+				toFiles = utils.RemoveOverlap(toFiles, fromFiles)
+			}
+
 			cfg, err := cfgF()
 			if err != nil {
 				return err
@@ -85,6 +102,9 @@ func ExplainCmd(cfgF func() (*config.Config, error)) *cobra.Command {
 		},
 	}
 
+	cmd.Flags().BoolVarP(&overlapLeft, "overlap-left", "ol", false, "When there's an overlap between the files at the left and the right, keep the ones at the left")
+	cmd.Flags().BoolVarP(&overlapRight, "overlap-right", "or", false, "When there's an overlap between the files at the left and the right, keep the ones at the right")
+
 	return cmd
 }
 

internal/utils/remove_overlap.go

@@ -0,0 +1,14 @@
+package utils
+
+// RemoveOverlap removes elements from a that are also on b.
+func RemoveOverlap[T comparable](a, b []T) []T {
+	res := make([]T, 0, len(a))
+	bSet := SetFromSlice(b)
+	for _, el := range a {
+		if _, ok := bSet[el]; !ok {
+			res = append(res, el)
+		}
+	}
+
+	return res
+}

internal/utils/remove_overlap_test.go

@@ -0,0 +1,42 @@
+package utils
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRemoveOverlap(t *testing.T) {
+	tests := []struct {
+		Name     string
+		A        []string
+		B        []string
+		Expected []string
+	}{
+		{
+			Name:     "No overlap",
+			A:        []string{"a", "b", "c"},
+			B:        []string{"d", "e", "f"},
+			Expected: []string{"a", "b", "c"},
+		},
+		{
+			Name:     "Partial overlap",
+			A:        []string{"a", "b", "c"},
+			B:        []string{"b", "c", "d"},
+			Expected: []string{"a"},
+		},
+		{
+			Name:     "Full overlap",
+			A:        []string{"a", "b", "c"},
+			B:        []string{"a", "b", "c"},
+			Expected: []string{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			assert.Equal(t, tt.Expected, RemoveOverlap(tt.A, tt.B))
+
+		})
+	}
+}