Function pathShapeMatchesRoot

path_fuzz_test.go:411–466

pathShapeMatchesRoot reports whether the path is semantically applicable to the JSON data's container structure. Used to gate the json.Valid post-condition for Set/Delete. Returns false (soft-skip the post-condition) when ANY of these documented-open-bug conditions hold: - First component is array

(data []byte, path []string)

// For all other shapes — including out-of-range valid-syntax indices and
// unknown object keys — the post-condition is asserted.
func pathShapeMatchesRoot(data []byte, path []string) bool {
	if len(path) == 0 {
		return true
	}
	// Empty-string components anywhere in the path → documented bug class.
	for _, c := range path {
		if c == "" {
			return false
		}
		// Keys containing bytes that require JSON escaping → D10.
		for i := 0; i < len(c); i++ {
			b := c[i]
			if b == '"' || b == '\\' || b < 0x20 {
				return false
			}
		}
		// Malformed array-index syntax → KI-3 variant. A component that
		// starts with '[' but is not exactly '[' + digits + ']' (e.g. "[]",
		// "[abc]", "[1") is treated as isIndex by createInsertComponent
		// but produces malformed JSON output when spliced into an object
		// body. Same hazard class as a well-formed [N] under an object
		// parent (KI-3 proper); skip the json.Valid post-condition until
		// the type-mismatch guard lands.
		if len(c) > 0 && c[0] == '[' {
			if len(c) < 3 || c[len(c)-1] != ']' {
				return false
			}
			for i := 1; i < len(c)-1; i++ {
				if c[i] < '0' || c[i] > '9' {
					return false
				}
			}
		}
	}
	// Find first non-whitespace byte.
	rootByte := byte(0)
	for _, b := range data {
		switch b {
		case ' ', '\t', '\n', '\r':
			continue
		default:
			rootByte = b
			goto found
		}
	}
	return false
found:
	isArrayIdx := len(path[0]) > 0 && path[0][0] == '['
	if isArrayIdx && rootByte != '[' {
		return false // array-index path on non-array root — D6
	}
	if !isArrayIdx && rootByte == '[' {
		return false // object-key path on array root — also undefined
	}
	return true
}

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