Add snapshotted mapping configuration sources

internal/engine/source.go

@@ -9,6 +9,8 @@ import (
 	"path/filepath"
 	"reflect"
 	"sync/atomic"
+
+	"gitea.maximumdirect.net/eric/ConfigKit/internal/document"
 )
 
 const (
@@ -25,6 +27,10 @@ type Source struct {
 	namespace *nativeNamespace
 	data      []byte
 	reader    *readerSource
+	mapping   *document.Node
+	mapIssue  *valueIssue
+	mapBytes  int64
+	mapNodes  int
 	createErr sourceCreationError
 }
 
@@ -36,6 +42,7 @@ const (
 	sourceFilesystem
 	sourceBytes
 	sourceReader
+	sourceMapping
 	sourceNone
 )
 
@@ -50,6 +57,7 @@ const (
 	creationInvalidFilesystem
 	creationInvalidFilesystemLabel
 	creationInvalidFilesystemPath
+	creationInvalidMappingRoot
 )
 
 // Filesystem is a reusable opaque namespace for caller-owned fs.FS inputs.
@@ -148,6 +156,24 @@ func Reader(label string, input io.Reader) Source {
 	return source
 }
 
+// Mapping snapshots supported built-in values into an owned document at
+// construction. Invalid values are retained as safe deferred diagnostics.
+func Mapping(label string, values map[string]any) Source {
+	source := Source{kind: sourceMapping, label: label}
+	if !validOverrideLabel(label) {
+		source.createErr = creationInvalidLabel
+		return source
+	}
+	if values == nil {
+		source.createErr = creationInvalidMappingRoot
+		return source
+	}
+	builder := valueBuilder{active: make(map[valueVisit]bool)}
+	source.mapping, source.mapIssue = builder.build(values, Path{}, 0)
+	source.mapBytes, source.mapNodes = builder.bytes, builder.nodes
+	return source
+}
+
 // NoSource explicitly selects a defaults-only input. It creates no source record.
 func NoSource() Source {
 	return Source{kind: sourceNone}
@@ -163,14 +189,24 @@ func defaultSourceLimits() sourceLimits {
 }
 
 type sourceRead struct {
-	data []byte
-	info *SourceInfo
+	data     []byte
+	document *document.Node
+	bytes    int64
+	info     *SourceInfo
 }
 
 func readSource(source Source, sourceID string, limits sourceLimits) (sourceRead, []Diagnostic) {
 	if diagnostic := sourceConstructorDiagnostic(source); diagnostic != nil {
+		if source.kind == sourceMapping {
+			diagnostic.Primary = &Location{SourceID: sourceID}
+			return sourceRead{info: mappingSourceInfo(source, sourceID)}, []Diagnostic{*diagnostic}
+		}
 		return sourceRead{}, []Diagnostic{*diagnostic}
 	}
+	if source.kind == sourceMapping && source.mapIssue != nil {
+		diagnostic := source.mapIssue.sourceDiagnostic(sourceID)
+		return sourceRead{info: mappingSourceInfo(source, sourceID)}, []Diagnostic{diagnostic}
+	}
 	if source.kind == sourceNone {
 		return sourceRead{}, nil
 	}
@@ -219,6 +255,13 @@ func readSource(source Source, sourceID string, limits sourceLimits) (sourceRead
 			return sourceRead{info: info}, []Diagnostic{sourceDiagnostic(CodeSourceReaderUsed, sourceID, "reader source has already been consumed")}
 		}
 		input = source.reader.input
+	case sourceMapping:
+		if source.mapBytes > limit || source.mapNodes > maxDocumentNodes {
+			return sourceRead{info: info}, []Diagnostic{sourceDiagnostic(CodeSourceLimitExceeded, sourceID, "mapping source exceeds the configured input limit")}
+		}
+		owned := document.Clone(source.mapping)
+		setDocumentSourceID(owned, sourceID)
+		return sourceRead{document: owned, bytes: source.mapBytes, info: info}, nil
 	default:
 		return sourceRead{info: info}, []Diagnostic{sourceDiagnostic(CodeSourceInvalid, sourceID, "source is invalid")}
 	}
@@ -229,6 +272,14 @@ func readSource(source Source, sourceID string, limits sourceLimits) (sourceRead
 	return sourceRead{data: bytes.Clone(data), info: info}, nil
 }
 
+func mappingSourceInfo(source Source, sourceID string) *SourceInfo {
+	label := source.label
+	if !validOverrideLabel(label) {
+		label = "mapping"
+	}
+	return &SourceInfo{ID: sourceID, Label: label, Layer: LayerBase, Kind: SourceKindMapping}
+}
+
 func sourceConstructorDiagnostic(source Source) *Diagnostic {
 	var message string
 	code := CodeSourceInvalid
@@ -242,6 +293,9 @@ func sourceConstructorDiagnostic(source Source) *Diagnostic {
 		message = "source path must not be empty"
 	case creationInvalidLabel:
 		message = "source label must not be empty"
+		if source.kind == sourceMapping {
+			message = "mapping source label must be nonempty and safe to display"
+		}
 	case creationInvalidReader:
 		message = "source reader must not be nil"
 	case creationTooLarge:
@@ -253,6 +307,8 @@ func sourceConstructorDiagnostic(source Source) *Diagnostic {
 		message = "filesystem label must be nonempty and safe to display"
 	case creationInvalidFilesystemPath:
 		message = "filesystem source path must be a non-root slash-relative valid path"
+	case creationInvalidMappingRoot:
+		message = "mapping source root must be a non-nil mapping"
 	}
 	diagnostic := sourceDiagnostic(code, "", message)
 	return &diagnostic
@@ -268,11 +324,29 @@ func sourceSourceKind(kind sourceKind) SourceKind {
 		return SourceKindBytes
 	case sourceReader:
 		return SourceKindReader
+	case sourceMapping:
+		return SourceKindMapping
 	default:
 		return ""
 	}
 }
 
+func setDocumentSourceID(node *document.Node, sourceID string) {
+	if node == nil {
+		return
+	}
+	node.Location.SourceID = sourceID
+	for index := range node.Mapping {
+		entry := &node.Mapping[index]
+		entry.KeyLocation.SourceID = sourceID
+		entry.ValueLocation.SourceID = sourceID
+		setDocumentSourceID(entry.Value, sourceID)
+	}
+	for _, child := range node.Sequence {
+		setDocumentSourceID(child, sourceID)
+	}
+}
+
 func classifySourceError(err error, sourceID string) Diagnostic {
 	switch {
 	case errors.Is(err, fs.ErrNotExist):