feat: add OffsetDateTime, nesting limits and uniform Marshaler dispatch

Assisted-by: DeepSeek V4.1 Flash

parser.go

@@ -30,6 +30,12 @@ type parser struct {
 	line int
 	ctx  context.Context
 
+	// maxDepth and depth bound the nesting the recursive descent may follow:
+	// arrays and inline tables nest through parseValue, and without a limit a
+	// hostile document would exhaust the stack.
+	maxDepth int
+	depth    int
+
 	root    map[string]any
 	current map[string]any
 	headers map[string]bool
@@ -40,6 +46,23 @@ type parser struct {
 	currentPath []string
 }
 
+// maxNestingDepth bounds how deeply arrays and inline tables may nest when no
+// limit is set. It matches the default encoding/json uses for the same reason,
+// and sits far above any document a person writes.
+const maxNestingDepth = 10000
+
+// enterNesting counts one level of array or inline-table nesting and reports a
+// document that nests deeper than the limit allows.
+func (p *parser) enterNesting() error {
+	p.depth++
+	if p.depth > p.maxDepth {
+		return p.errf("nesting exceeds the limit of %d", p.maxDepth)
+	}
+	return nil
+}
+
+func (p *parser) leaveNesting() { p.depth-- }
+
 func (p *parser) parse() (map[string]any, error) {
 	p.root = map[string]any{}
 	p.current = p.root
@@ -676,6 +699,10 @@ func (p *parser) readUnicode(n int) (rune, error) {
 // --- arrays and inline tables ---------------------------------------------
 
 func (p *parser) parseArray() (any, error) {
+	if err := p.enterNesting(); err != nil {
+		return nil, err
+	}
+	defer p.leaveNesting()
 	p.pos++ // '['
 	arr := []any{}
 	for {
@@ -713,6 +740,10 @@ func (p *parser) parseArray() (any, error) {
 }
 
 func (p *parser) parseInlineTable() (any, error) {
+	if err := p.enterNesting(); err != nil {
+		return nil, err
+	}
+	defer p.leaveNesting()
 	p.pos++ // '{'
 	tbl := map[string]any{}
 	assigned := map[string]bool{}