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Monorepo for Tangled
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Go
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import ( "errors" "fmt" "reflect" "strconv" "strings"
"gopkg.in/yaml.v3" "tangled.org/core/workflow")
// how many lines of context to show on above / below of an offending line.const frameContext = 3
type manifestError struct { line int msg string}
func (e *manifestError) Error() string { return e.msg }
// codeFrame renders the lines around `line` with a gutter and a `>` marker on// the offending line, eg.//// 4 | image: alpine// > 5 | registre:// 6 | nixpkgs: github:nixos/nixpkgs/nixos-unstablefunc codeFrame(raw string, line int) string { lines := strings.Split(raw, "\n") if line < 1 || line > len(lines) { return "" } start := max(line-frameContext, 1) end := min(line+frameContext, len(lines)) width := len(strconv.Itoa(end))
var b strings.Builder for n := start; n <= end; n++ { marker := " " if n == line { marker = "> " } fmt.Fprintf(&b, "%s%*d | %s\n", marker, width, n, lines[n-1]) } return strings.TrimRight(b.String(), "\n")}
var genericWorkflowKeys = ignoredKeys(reflect.TypeFor[workflow.Workflow]())
// ignoredKeys is the set of yaml keys we ignore on field checks for a struct.// real, parseable keys come straight from the tags (via fieldsByYAMLName); on// top of those we tolerate `yaml:"-"` fields by their conventional spelling.// those have no yaml key of their own (the program fills them in itself, eg.// `name` from the filename, `raw` from the file bytes), but users sometimes// write one in the body anyway, and that's harmless rather than a typo.func ignoredKeys(t reflect.Type) map[string]bool { if t.Kind() == reflect.Pointer { t = t.Elem() } keys := make(map[string]bool) for k := range fieldsByYAMLName(t) { keys[k] = true } for i := 0; i < t.NumField(); i++ { f := t.Field(i) if tag, _, _ := strings.Cut(f.Tag.Get("yaml"), ","); tag == "-" { keys[strings.ToLower(f.Name)] = true } } return keys}
// this exists because yaml.v3 reports mismatches as "cannot unmarshal !!seq into// map[string]interface {}", which is kind of confusing, even if it outputs a line.// so we use reflection, walk the node tree alongside the schema type, and point// at the field that's actually mis-shaped.//// returns nil when nothing is structurally wrong.func DescribeManifestError(raw string, schema any, renamed ...map[string]string) error { var doc yaml.Node if err := yaml.Unmarshal([]byte(raw), &doc); err != nil { return nil } if len(doc.Content) == 0 { return nil } var renames map[string]string if len(renamed) > 0 { renames = renamed[0] } err := checkNode(doc.Content[0], reflect.TypeOf(schema), "", genericWorkflowKeys, renames) var me *manifestError if !errors.As(err, &me) { return err // nil } if frame := codeFrame(raw, me.line); frame != "" { return fmt.Errorf("%s\n\n%s", me.msg, frame) } return errors.New(me.msg)}
// checkNode walks a yaml node against the type it's expected to decode into,// recursing through structs, maps and slices. allowExtra names keys that are// valid at this level despite not being in the struct (only the root uses it).// renamed maps removed root-level keys to their new names, for better errors.func checkNode(node *yaml.Node, t reflect.Type, path string, allowExtra map[string]bool, renamed map[string]string) error { if node.Kind == yaml.AliasNode && node.Alias != nil { node = node.Alias } if t == nil { return nil } if t.Kind() == reflect.Pointer { t = t.Elem() } // `any` accepts anything (eg. registry values) so we can't check more if t.Kind() == reflect.Interface { return nil } // an empty value (eg. `registry:` with nothing under it) is harmless if node.Kind == yaml.ScalarNode && (node.Tag == "!!null" || node.Value == "") { return nil }
want, ok := yamlKindForType(t) if !ok { return nil } if node.Kind != want { return &manifestError{line: node.Line, msg: fmt.Sprintf( "%s must be %s, but got %s (line %d)", describePath(path), yamlKindName(want), yamlKindName(node.Kind), node.Line)} }
switch t.Kind() { case reflect.Struct: fields := fieldsByYAMLName(t) for i := 0; i+1 < len(node.Content); i += 2 { key, val := node.Content[i], node.Content[i+1] ft, ok := fields[key.Value] if !ok { // a struct has a fixed set of fields, so anything else is a typo. // (maps, take arbitrary user-defined keys and don't count) if allowExtra[key.Value] { continue } if newName, wasRenamed := renamed[key.Value]; wasRenamed && path == "" { return &manifestError{line: key.Line, msg: fmt.Sprintf( "field %s was renamed to %s (line %d)", describePath(joinKey(path, key.Value)), newName, key.Line)} } return &manifestError{line: key.Line, msg: fmt.Sprintf( "unknown field %s (line %d)", describePath(joinKey(path, key.Value)), key.Line)} } if err := checkNode(val, ft, joinKey(path, key.Value), nil, nil); err != nil { return err } } case reflect.Map: for i := 0; i+1 < len(node.Content); i += 2 { key, val := node.Content[i], node.Content[i+1] if err := checkNode(val, t.Elem(), joinKey(path, key.Value), nil, nil); err != nil { return err } } case reflect.Slice, reflect.Array: for idx, val := range node.Content { if err := checkNode(val, t.Elem(), fmt.Sprintf("%s[%d]", path, idx), nil, nil); err != nil { return err } } } return nil}
// fieldsByYAMLName maps a struct's yaml keys to their field types, mirroring how// yaml.v3 resolves keys: explicit tag name, else the lowercased field name.func fieldsByYAMLName(t reflect.Type) map[string]reflect.Type { fields := make(map[string]reflect.Type) for i := 0; i < t.NumField(); i++ { f := t.Field(i) name, _, _ := strings.Cut(f.Tag.Get("yaml"), ",") if name == "-" { continue } if name == "" { name = strings.ToLower(f.Name) } fields[name] = f.Type } return fields}
func joinKey(path, key string) string { if path == "" { return key } return path + "." + key}
func describePath(path string) string { if path == "" { return "the manifest" } return "`" + path + "`"}
func yamlKindForType(t reflect.Type) (yaml.Kind, bool) { switch t.Kind() { case reflect.Pointer: return yamlKindForType(t.Elem()) case reflect.Map, reflect.Struct: return yaml.MappingNode, true case reflect.Slice, reflect.Array: return yaml.SequenceNode, true case reflect.String, reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64: return yaml.ScalarNode, true default: return 0, false }}
func yamlKindName(k yaml.Kind) string { switch k { case yaml.MappingNode: return "a mapping" case yaml.SequenceNode: return "a list" case yaml.ScalarNode: return "a scalar value" case yaml.AliasNode: return "an alias" default: return "an unknown value" }}