Add a strict and lax mode for each list given

.gitignore

@@ -12,3 +12,4 @@
 *.out
 
 .idea
+.null-ls*.go

README.md

@@ -23,6 +23,7 @@ The following is an example configuration file.
       "$all",
       "!$test"
     ],
+    "listMode": "Strict",
     "allow": [
       "$gostd",
       "github.com/OpenPeeDeeP"
@@ -35,6 +36,7 @@ The following is an example configuration file.
     "files": [
       "$test"
     ],
+    "listMode": "Lax",
     "deny": {
       "github.com/stretchr/testify": "Please use standard library for tests"
     }
@@ -47,6 +49,7 @@ the linter's output.
 - `files` - list of file globs that will match this list of settings to compare against
 - `allow` - list of allowed packages
 - `deny` - map of packages that are not allowed where the value is a suggestion
+= `listMode` - the mode to use for package matching
 
 Files are matched using [Globs](https://github.com/gobwas/glob). If the files 
 list is empty, then all files will match that list. Prefixing a file
@@ -66,6 +69,21 @@ A Prefix List just means that a package will match a value, if the value is a
 prefix of the package. Example `github.com/OpenPeeDeeP/depguard` package will match
 a value of `github.com/OpenPeeDeeP` but won't match `github.com/OpenPeeDeeP/depguard/v2`.
 
+ListMode is used to determine the package matching priority. There are three
+different modes; Original, Strict, and Lax.
+
+Original is the original way that the package was written to use. It is not recommended
+to stay with this and is only here for backwards compatibility.
+
+Strict, at its roots, is everything is denied unless in allowed.
+
+Lax, at its roots, is everything is allowed unless it is denied.
+
+There are cases where a package can be matched in both the allow and denied lists.
+You may allow a subpackage but deny the root or vice versa. The `settings_tests.go` file
+has many scenarios listed out under `TestListImportAllowed`. These tests will stay
+up to date as features are added.
+
 ### Variables
 
 There are variable replacements for each type of list (file or package). This is

cmd/depguard/main_test.go

@@ -13,8 +13,9 @@ var testfiles embed.FS
 
 var expectedConfigStruct = &depguard.LinterSettings{
 	"main": &depguard.List{
-		Files: []string{"$all", "!$test"},
-		Allow: []string{"$gostd", "github.com/"},
+		ListMode: "Strict",
+		Files:    []string{"$all", "!$test"},
+		Allow:    []string{"$gostd", "github.com/"},
 		Deny: map[string]string{
 			"reflect":                "Who needs reflection",
 			"github.com/OpenPeeDeeP": "Use Something Else",

cmd/depguard/testfiles/.depguard.json

@@ -4,6 +4,7 @@
       "$all",
       "!$test"
     ],
+    "listMode": "Strict",
     "allow": [
       "$gostd",
       "github.com/"
@@ -24,4 +25,4 @@
       "github.com/OpenPeeDeeP/": "Use Something Else"
     }
   }
-}
+}

cmd/depguard/testfiles/.depguard.toml

@@ -3,6 +3,7 @@ files = [
 	"$all",
     "!$test"
 ]
+listMode = "Strict"
 allow = [
   "$gostd",
   "github.com/"
@@ -19,4 +20,4 @@ allow = [
 	"github.com/test"
 ]
 [tests.deny]
-"github.com/OpenPeeDeeP/" = "Use Something Else"
+"github.com/OpenPeeDeeP/" = "Use Something Else"

cmd/depguard/testfiles/.depguard.yaml

@@ -2,6 +2,7 @@ main:
   files:
   - "$all"
   - "!$test"
+  listMode: Strict
   allow:
   - "$gostd"
   - github.com/
@@ -14,4 +15,4 @@ tests:
   allow:
   - github.com/test
   deny:
-    github.com/OpenPeeDeeP/: Use Something Else
+    github.com/OpenPeeDeeP/: Use Something Else

settings.go

@@ -20,7 +20,9 @@ type List struct {
 type listMode int
 
 const (
-	listModeStrict listMode = iota
+	listModeOriginal listMode = iota
+	listModeStrict
+	listModeLax
 )
 
 type list struct {
@@ -44,9 +46,13 @@ func (l *List) compile() (*list, error) {
 	// Determine List Mode
 	switch strings.ToLower(l.ListMode) {
 	case "":
-		li.listMode = listModeStrict
+		li.listMode = listModeOriginal
+	case "original":
+		li.listMode = listModeOriginal
 	case "strict":
 		li.listMode = listModeStrict
+	case "lax":
+		li.listMode = listModeLax
 	default:
 		errs = append(errs, fmt.Errorf("%s is not a known list mode", l.ListMode))
 	}
@@ -131,16 +137,25 @@ func (l *list) fileMatch(fileName string) bool {
 }
 
 func (l *list) importAllowed(imp string) (bool, string) {
-	inAllowed := len(l.allow) == 0
-	if !inAllowed {
-		inAllowed, _ = strInPrefixList(imp, l.allow)
+	inAllowed, aIdx := strInPrefixList(imp, l.allow)
+	inDenied, dIdx := strInPrefixList(imp, l.deny)
+	var allowed bool
+	switch l.listMode {
+	case listModeOriginal:
+		inAllowed = len(l.allow) == 0 || inAllowed
+		allowed = inAllowed && !inDenied
+	case listModeStrict:
+		allowed = inAllowed && (!inDenied || len(l.allow[aIdx]) > len(l.deny[dIdx]))
+	case listModeLax:
+		allowed = !inDenied || (inAllowed && len(l.allow[aIdx]) > len(l.deny[dIdx]))
+	default:
+		allowed = false
 	}
-	inDenied, suggIdx := strInPrefixList(imp, l.deny)
 	sugg := ""
-	if inDenied && suggIdx != -1 {
-		sugg = l.suggestions[suggIdx]
+	if !allowed && inDenied && dIdx != -1 {
+		sugg = l.suggestions[dIdx]
 	}
-	return inAllowed && !inDenied, sugg
+	return allowed, sugg
 }
 
 type LinterSettings map[string]*List