feat: add max_path_depth() function

Author: jippi

.gitignore

@@ -1,16 +1,16 @@
+.direnv
 .env
 .env.*
-!.env.example
-
-dist/
+.idea/
+.scm-engine.yml
+.task/
+3rd-party/
 bin/
+completions/
 coverage.txt
+dist/
+manpages/
 scm-engine
 scm-engine.exe
-.task/
-.idea/
-.direnv
 
-manpages/
-completions/
-3rd-party/
+!.env.example

.golangci.yaml

@@ -177,6 +177,8 @@ linters-settings:
       - tt
       - err
       - i
+      - id
+      - ok
 
   tagalign:
     # Align and sort can be used together or separately.

README.md

@@ -50,6 +50,7 @@
     - [`duration`](#duration)
     - [`uniq`](#uniq)
     - [`filepath_dir`](#filepath_dir)
+    - [`max_path_depth`](#max_path_depth)
 
 ## Installation
 
@@ -509,5 +510,14 @@ If the path is empty, `filepath_dir` returns ".". If the path consists entirely
 The returned path does not end in a separator unless it is the root directory.
 
 ```expr
-filepath_dir("/example/directory/file.go") == "/example/directory"
+filepath_dir("example/directory/file.go") == "example/directory"
+```
+
+#### `max_path_depth`
+
+`max_path_depth` takes a path structure, and limits it to the configured maximum depth. Particularly useful when using `generated` labels from a directory structure, and want to to have a label naming scheme that only uses path of the path.
+
+```expr
+max_path_depth("path1/path2/path3/path4", 2), == "path1/path2"
+max_path_depth("path1/path2", 3), == "path1/path2"
 ```

pkg/stdlib/functions.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"slices"
+	"strings"
 
 	"github.com/expr-lang/expr"
 	"github.com/xhit/go-str2duration/v2"
@@ -74,3 +75,29 @@ var Duration = expr.Function(
 	},
 	str2duration.ParseDuration,
 )
+
+var MaxPathDepth = expr.Function(
+	"max_path_depth",
+	func(args ...any) (any, error) {
+		if len(args) != 2 {
+			return nil, errors.New("max_path_depth() expect exactly two arguments")
+		}
+
+		input, ok := args[0].(string)
+		if !ok {
+			return nil, errors.New("first input to max_path_depth() must be of type 'string'")
+		}
+
+		length, ok := args[1].(int)
+		if !ok {
+			return nil, errors.New("second input to max_path_depth() must be of type 'int'")
+		}
+
+		chunks := strings.Split(input, "/")
+		if len(chunks) <= length {
+			return input, nil
+		}
+
+		return strings.Join(chunks[0:length-1], "/"), nil
+	},
+)

pkg/stdlib/stdlib.go

@@ -10,6 +10,9 @@ var Functions = []expr.Option{
 	// filepath.Dir
 	FilepathDir,
 
+	// some/deep/path/ok => some/deep
+	MaxPathDepth,
+
 	// slices.Sort + slices.Compact
 	Uniq,
 }