$parent

bkl.go

@@ -9,15 +9,18 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 )
 
 var (
-	Err                 = fmt.Errorf("bkl error")
+	Err = fmt.Errorf("bkl error")
+
 	ErrEncode           = fmt.Errorf("encoding error (%w)", Err)
 	ErrDecode           = fmt.Errorf("decoding error (%w)", Err)
 	ErrInvalidIndex     = fmt.Errorf("invalid index (%w)", Err)
 	ErrInvalidDirective = fmt.Errorf("invalid directive (%w)", Err)
+	ErrInvalidFilename  = fmt.Errorf("invalid filename (%w)", Err)
 	ErrInvalidType      = fmt.Errorf("invalid type (%w)", Err)
 	ErrMissingFile      = fmt.Errorf("missing file (%w)", Err)
 	ErrNoMatchFound     = fmt.Errorf("no document matched $match (%w)", Err)
@@ -25,6 +28,7 @@ var (
 	ErrUnknownFormat    = fmt.Errorf("unknown format (%w)", Err)
 
 	ErrInvalidMergeType   = fmt.Errorf("invalid $merge type (%w)", ErrInvalidDirective)
+	ErrInvalidParentType  = fmt.Errorf("invalid $parent type (%w)", ErrInvalidDirective)
 	ErrInvalidPatchType   = fmt.Errorf("invalid $patch type (%w)", ErrInvalidDirective)
 	ErrInvalidPatchValue  = fmt.Errorf("invalid $patch value (%w)", ErrInvalidDirective)
 	ErrInvalidReplaceType = fmt.Errorf("invalid $replace type (%w)", ErrInvalidDirective)
@@ -195,30 +199,28 @@ func (p *Parser) MergeFile(path string) error {
 // MergeFileLayers determines relevant layers from the supplied path and merges
 // them in order.
 func (p *Parser) MergeFileLayers(path string) error {
-	dir := filepath.Dir(path)
-	base := filepath.Base(path)
+	paths := []string{
+		path,
+	}
 
-	parts := strings.Split(base, ".")
-
-	for i := 1; i < len(parts); i++ {
-		layerPath := filepath.Join(dir, strings.Join(parts[:i], "."))
-
-		extPath := FindFile(layerPath)
-		if extPath == "" {
-			return fmt.Errorf("%s: %w", layerPath, ErrMissingFile)
+	for {
+		parent, err := GetParent(path)
+		if err != nil {
+			return err
 		}
 
-		dest, _ := os.Readlink(extPath)
-		if dest != "" {
-			err := p.MergeFileLayers(dest)
-			if err != nil {
-				return err
-			}
-
-			continue
+		if parent == "" {
+			break
 		}
 
-		err := p.MergeFile(extPath)
+		path = parent
+		paths = append(paths, path)
+	}
+
+	slices.Reverse(paths)
+
+	for _, path := range paths {
+		err := p.MergeFile(path)
 		if err != nil {
 			return err
 		}
@@ -248,7 +250,7 @@ func (p *Parser) GetOutputIndex(index int, ext string) ([][]byte, error) {
 		return nil, err
 	}
 
-	obj, err = PostMerge(obj, obj)
+	obj, err = PostMerge(obj)
 	if err != nil {
 		return nil, err
 	}
@@ -316,6 +318,114 @@ func (p *Parser) log(format string, v ...any) {
 	log.Printf(format, v...)
 }
 
+func GetParent(path string) (string, error) {
+	// TODO: Needs a different API so it can specify no parent
+	parent, err := GetParentFromOverride(path)
+	if err != nil {
+		return "", err
+	}
+
+	if parent != "" {
+		return parent, nil
+	}
+
+	parent, err = GetParentFromSymlink(path)
+	if err != nil {
+		return "", err
+	}
+
+	if parent != "" {
+		return parent, nil
+	}
+
+	return GetParentFromFilename(path)
+}
+
+func GetParentFromOverride(path string) (string, error) {
+	fh, err := os.Open(path)
+	if err != nil {
+		return "", fmt.Errorf("%s: %w", path, err)
+	}
+
+	defer fh.Close()
+
+	b, err := io.ReadAll(fh)
+	if err != nil {
+		return "", err
+	}
+
+	ext := Ext(path)
+
+	f, found := formatByExtension[ext]
+	if !found {
+		return "", fmt.Errorf("%s: %w", ext, ErrUnknownFormat)
+	}
+
+	patch, err := f.decode(b)
+	if err != nil {
+		return "", fmt.Errorf("%w / %w", err, ErrDecode)
+	}
+
+	patchMap, ok := patch.(map[string]any)
+	if !ok {
+		return "", nil
+	}
+
+	if parent, found := patchMap["$parent"]; found {
+		parentStr, ok := parent.(string)
+		if !ok {
+			return "", fmt.Errorf("%T: %w", parent, ErrInvalidParentType)
+		}
+
+		parentPath := FindFile(parentStr)
+		if parentPath == "" {
+			return "", fmt.Errorf("%s: %w", parentStr, ErrMissingFile)
+		}
+
+		return parentPath, nil
+	}
+
+	return "", nil
+}
+
+func GetParentFromSymlink(path string) (string, error) {
+	dest, _ := os.Readlink(path)
+
+	if dest == "" {
+		// Not a link
+		return "", nil
+	}
+
+	return GetParentFromFilename(dest)
+}
+
+func GetParentFromFilename(path string) (string, error) {
+	dir := filepath.Dir(path)
+	base := filepath.Base(path)
+
+	parts := strings.Split(base, ".")
+	// Last part is file extension
+
+	switch {
+	case len(parts) < 2:
+		return "", fmt.Errorf("%s: %w", path, ErrInvalidFilename)
+
+	case len(parts) == 2:
+		// Base template
+		return "", nil
+
+	default:
+		layerPath := filepath.Join(dir, strings.Join(parts[:len(parts)-2], "."))
+
+		extPath := FindFile(layerPath)
+		if extPath == "" {
+			return "", fmt.Errorf("%s: %w", layerPath, ErrMissingFile)
+		}
+
+		return extPath, nil
+	}
+}
+
 // Ext returns the file extension for path, or "".
 func Ext(path string) string {
 	return strings.TrimPrefix(filepath.Ext(path), ".")

docs/index.html

@@ -220,10 +220,6 @@ op {
 	font-size: 30px;
 }
 
-ref {
-	color: var(--green2);
-}
-
 code.labeled {
 	border-radius: 0 5px 5px 5px;
 }
@@ -255,6 +251,8 @@ focus, focus > * {
 inlineFocus {
 	background: var(--neutral8);
 	color: var(--red6);
+	display: inline-block;
+	padding: 0 3px 0 3px;
 	white-space: nowrap;
 }
 </style>
@@ -299,7 +297,7 @@ inlineFocus {
 
 <vSpace></vSpace>
 
-<p>bkl knows that <ref>service.test.toml</ref> inherits from <ref>service.yaml</ref> by the filename pattern, and uses filename extensions to determine formats.</p>
+<p>bkl knows that <inlineFocus>service.test.toml</inlineFocus> inherits from <inlineFocus>service.yaml</inlineFocus> by the filename pattern (<a href="#inheritance">override with <inlineFocus>$parent</inlineFocus></a>), and uses filename extensions to determine formats.</p>
 
 
 
@@ -357,19 +355,19 @@ inlineFocus {
 
 
 
-<h2><a name="advanced-input">Advanced Input</a></h2>
+<h2><a name="multiple-input-files">Multiple Input Files</a></h2>
 
-<label>Multiple Files</label>
-<code class="labeled">$ <cmd>bkl</cmd> <focus><string>a.b.yaml</string> <string>c.d.yaml</string></focus>   # (a.yaml + a.b.yaml) + (c.yaml + c.d.yaml)</code>
+<code>$ <cmd>bkl</cmd> <focus><string>a.b.yaml</string> <string>c.d.yaml</string></focus>   # (a.yaml + a.b.yaml) + (c.yaml + c.d.yaml)</code>
 
 <vSpace></vSpace>
 
 <p>Specifying multiple input files evaluates them as normal, then merges them onto each other in order.</p>
 
-<vSpace></vSpace>
 
-<label>Symlinks</label>
-<code class="labeled">$ <cmd>ln</cmd> <string>-s</string> <focus><string>a.b.yaml</string> <string>c.yaml</string></focus>
+
+<h2><a name="symlinks">Symlinks</a></h2>
+
+<code>$ <cmd>ln</cmd> <string>-s</string> <focus><string>a.b.yaml</string> <string>c.yaml</string></focus>
 $ <cmd>bkl</cmd> <focus><string>c.d.yaml</string></focus>   # a.yaml + a.b.yaml (c.yaml) + c.d.yaml</code>
 
 <vSpace></vSpace>
@@ -378,6 +376,19 @@ $ <cmd>bkl</cmd> <focus><string>c.d.yaml</string></focus>   # a.yaml + a.b.yaml
 
 
 
+<h2><a name="inheritance">Inheritance</a></h2>
+
+<p>Inheritance is determined using filenames by default. After stripping the extension, the remaining filename is split on <inlineFocus>.</inlineFocus> and treated as an inheritance hierarchy (e.g. <inlineFocus>a.b.c.yaml</inlineFocus> inherits from <inlineFocus>a.b.&lt;ext&gt;</inlineFocus> inherits from <inlineFocus>a.&lt;ext&gt;</inlineFocus>). Parent templates may have any supported file extension.</p>
+
+<label>Override Inheritance</label>
+<code class="labeled"><focus><key>$parent</key>: <string>a.b</string></focus>   # inherits from a.b.&lt;ext&gt;, from a.&lt;ext&gt;</code>
+
+<vSpace></vSpace>
+
+<p>bkl will still check for all supported endings of a manually-specified parent file, and will still evaluate template layers of the parent in the normal order.</p>
+
+
+
 <h2><a name="streams">Streams</a></h2>
 
 <p>bkl understands input streams (multi-document YAML files delimited with <inlineFocus>---</inlineFocus>). To layer them, it has to match documents between layers. It does this using document ordering within layer files by default, but can be overridden with <inlineFocus>$match</inlineFocus>.</p>

merge.go

@@ -114,7 +114,16 @@ func MergeList(dst []any, src any) (any, error) {
 	}
 }
 
-func PostMerge(root any, obj any) (any, error) {
+func PostMerge(root any) (any, error) {
+	switch rootType := root.(type) {
+	case map[string]any:
+		delete(rootType, "$parent")
+	}
+
+	return PostMergeInt(root, root)
+}
+
+func PostMergeInt(root any, obj any) (any, error) {
 	switch objType := obj.(type) {
 	case map[string]any:
 		if path, found := objType["$merge"]; found {
@@ -135,7 +144,7 @@ func PostMerge(root any, obj any) (any, error) {
 				return nil, err
 			}
 
-			return PostMerge(root, next)
+			return PostMergeInt(root, next)
 		}
 
 		if path, found := objType["$replace"]; found {
@@ -151,11 +160,11 @@ func PostMerge(root any, obj any) (any, error) {
 				return nil, fmt.Errorf("%s: (%w)", pathVal, ErrReplaceRefNotFound)
 			}
 
-			return PostMerge(root, next)
+			return PostMergeInt(root, next)
 		}
 
 		for k, v := range objType {
-			v2, err := PostMerge(root, v)
+			v2, err := PostMergeInt(root, v)
 			if err != nil {
 				return nil, err
 			}
@@ -167,7 +176,7 @@ func PostMerge(root any, obj any) (any, error) {
 
 	case []any:
 		for i, v := range objType {
-			v2, err := PostMerge(root, v)
+			v2, err := PostMergeInt(root, v)
 			if err != nil {
 				return nil, err
 			}
@@ -192,6 +201,7 @@ func FindOutputs(obj any) []any {
 			ret = append(ret, obj)
 		}
 
+		// TODO: Sort by key so output order is stable
 		for _, v := range objType {
 			ret = append(ret, FindOutputs(v)...)
 		}

test

@@ -11,7 +11,7 @@ function cleanup {
 trap cleanup EXIT
 
 go build ./cmd/bkl
-export PATH=$PATH:/opt/homebrew/share/git-core/contrib/diff-highlight:$ROOT
+export PATH=$ROOT:/opt/homebrew/share/git-core/contrib/diff-highlight:$PATH
 
 for TEST in tests/*; do
 	echo TEST $TEST

tests/parent/a.b.yaml

@@ -0,0 +1,2 @@
+$parent: c
+a: 1

tests/parent/c.yaml

@@ -0,0 +1 @@
+b: 2

tests/parent/cmd

@@ -0,0 +1 @@
+bkl -v -f yaml a.b.yaml

tests/parent/expected

@@ -0,0 +1,2 @@
+a: 1
+b: 2