Support named pattern in key fields

internal/bcl/internal/walker/walk_context.go

@@ -277,7 +277,7 @@ func (sc *walkContext) setAttribute(path ScopePath, val parser.ASTValue, appendV
 func (sc *walkContext) setContainerFromScalar(bs schema.BlockSpec, val parser.ASTValue) error {
 	ss := bs.ScalarSplit
 	if ss == nil {
-		return fmt.Errorf("container %s has no method to set from array", bs.ErrName())
+		return fmt.Errorf("container %s has no method to set from scalar", bs.ErrName())
 	}
 
 	var setVals []parser.ASTValue
@@ -301,7 +301,8 @@ func (sc *walkContext) setContainerFromScalar(bs schema.BlockSpec, val parser.AS
 	} else {
 		vals, isArray := val.AsArray()
 		if !isArray {
-			return fmt.Errorf("container %s requires an array when setting from value, got a scalar", bs.ErrName())
+			sc.Logf("ScalarSplit with no delimiter requires array, got %#v", val)
+			return fmt.Errorf("container %s is ScalarSplit with no delimiter, must be set from an array", bs.ErrName())
 		}
 		setVals = vals
 	}

internal/j5s/j5convert/fields.go

@@ -817,6 +817,37 @@ func buildField(ww *conversionVisitor, node sourcewalk.FieldNode) (*descriptorpb
 					Pattern: ff.Custom.Pattern,
 				}
 
+				if ff.Custom.Description != "" {
+					keyExt.PatternInfo = &ext_j5pb.KeyField_PatternInfo{
+						Description: gl.Ptr(ff.Custom.Description),
+					}
+				}
+
+			case *schema_j5pb.KeyFormat_Named_:
+				ref := ff.Named.Ref
+
+				typeRef, err := ww.resolveType(&sourcewalk.RefNode{
+					Source: node.Source,
+					Ref:    ref,
+				})
+				if err != nil {
+					return nil, fmt.Errorf("string format %s: %w", ref, err)
+				}
+
+				if typeRef.StringFormat == nil {
+					return nil, fmt.Errorf("%s refers to a %s, not a string format", ref, typeRef.debugName())
+				}
+
+				keyExt.Type = &ext_j5pb.KeyField_Pattern{
+					Pattern: typeRef.StringFormat.Regex,
+				}
+				keyExt.PatternInfo = &ext_j5pb.KeyField_PatternInfo{
+					Name: gl.Ptr(fmt.Sprintf("%s.%s", typeRef.Package, typeRef.Name)),
+				}
+				if typeRef.StringFormat.Description != "" {
+					keyExt.PatternInfo.Description = gl.Ptr(typeRef.StringFormat.Description)
+				}
+
 			case *schema_j5pb.KeyFormat_Informal_:
 
 			default:

internal/j5s/j5convert/summary.go

@@ -220,6 +220,16 @@ func (cc *summaryWalker) collectFileRefs(sourceFile *sourcedef_j5pb.SourceFile)
 						Ref:    ref,
 					})
 				}
+
+			case *schema_j5pb.Field_Key:
+				if st.Key.Format != nil {
+					if named := st.Key.Format.GetNamed(); named != nil {
+						cc.addRef(&sourcewalk.RefNode{
+							Source: node.Source,
+							Ref:    named.Ref,
+						})
+					}
+				}
 			}
 
 			return nil

proto/core/j5/ext/v1/annotations.proto

@@ -274,4 +274,15 @@ message KeyField {
     FORMAT_ID62 = 3;
   }
   j5.schema.v1.EntityRef foreign = 3;
+
+  // Set when the pattern is annotated
+  PatternInfo patternInfo = 10;
+
+  message PatternInfo {
+    // The full type name of a namedPattern.
+    optional string name = 1;
+
+    // Description given either in the namedPattern or inline for custom
+    optional string description = 2;
+  }
 }

proto/core/j5/schema/v1/schema.proto

@@ -391,7 +391,7 @@ message KeyFormat {
     Custom custom = 2;
     UUID uuid = 3;
     ID62 id62 = 4;
-    StringFormat format = 5;
+    Named named = 5;
   }
 
   message Informal {}
@@ -401,6 +401,17 @@ message KeyFormat {
   }
   message UUID {}
   message ID62 {}
+  message Named {
+    Ref ref = 1;
+
+    option (j5.bcl.v1.block).qualifier.field_name = "ref";
+
+    option (j5.bcl.v1.block).scalar_split = {
+      right_to_left: true
+      required_fields: [{path: "schema"}]
+      remainder_field: {path: "package"}
+    };
+  }
 
   option (j5.bcl.v1.block).type_select = {
     field_name: "."