/**
 * Patch flags are optimization hints generated by the compiler.
 * when a block with dynamicChildren is encountered during diff, the algorithm
 * enters "optimized mode". In this mode, we know that the vdom is produced by
 * a render function generated by the compiler, so the algorithm only needs to
 * handle updates explicitly marked by these patch flags.
 *
 * Patch flags can be combined using the | bitwise operator and can be checked
 * using the & operator, e.g.
 *
 * ```js
 * const flag = TEXT | CLASS
 * if (flag & TEXT) { ... }
 * ```
 *
 * Check the `patchElement` function in '../../runtime-core/src/renderer.ts' to see how the
 * flags are handled during diff.
 */ export const enum PatchFlags { /**
     * Indicates an element with dynamic textContent (children fast path)
     */ TEXT = 1 , /**
     * Indicates an element with dynamic class binding.
     */ CLASS = 1 << 1 , /**
     * Indicates an element with dynamic style
     * The compiler pre-compiles static string styles into static objects
     * + detects and hoists inline static objects
     * e.g. style="color: red" and :style="{ color: 'red' }" both get hoisted as
     *   const style = { color: 'red' }
     *   render() { return e('div', { style }) }
     */ STYLE = 1 << 2 , /**
     * Indicates an element that has non-class/style dynamic props.
     * Can also be on a component that has any dynamic props (includes
     * class/style). when this flag is present, the vnode also has a dynamicProps
     * array that contains the keys of the props that may change so the runtime
     * can diff them faster (without having to worry about removed props)
     */ PROPS = 1 << 3 , /**
     * Indicates an element with props with dynamic keys. When keys change, a full
     * diff is always needed to remove the old key. This flag is mutually
     * exclusive with CLASS, STYLE and PROPS.
     */ FULL_PROPS = 1 << 4 , /**
     * Indicates an element with event listeners (which need to be attached
     * during hydration)
     */ HYDRATE_EVENTS = 1 << 5 , /**
     * Indicates a fragment whose children order doesn't change.
     */ STABLE_FRAGMENT = 1 << 6 , /**
     * Indicates a fragment with keyed or partially keyed children
     */ KEYED_FRAGMENT = 1 << 7 , /**
     * Indicates a fragment with unkeyed children.
     */ UNKEYED_FRAGMENT = 1 << 8 , /**
     * Indicates an element that only needs non-props patching, e.g. ref or
     * directives (onVnodeXXX hooks). since every patched vnode checks for refs
     * and onVnodeXXX hooks, it simply marks the vnode so that a parent block
     * will track it.
     */ NEED_PATCH = 1 << 9 , /**
     * Indicates a component with dynamic slots (e.g. slot that references a v-for
     * iterated value, or dynamic slot names).
     * Components with this flag are always force updated.
     */ DYNAMIC_SLOTS = 1 << 10 , /**
     * Indicates a fragment that was created only because the user has placed
     * comments at the root level of a template. This is a dev-only flag since
     * comments are stripped in production.
     */ DEV_ROOT_FRAGMENT = 1 << 11 , /**
     * SPECIAL FLAGS -------------------------------------------------------------
     * Special flags are negative integers. They are never matched against using
     * bitwise operators (bitwise matching should only happen in branches where
     * patchFlag > 0), and are mutually exclusive. When checking for a special
     * flag, simply check patchFlag === FLAG.
     */ /**
     * Indicates a hoisted static vnode. This is a hint for hydration to skip
     * the entire sub tree since static content never needs to be updated.
     */ HOISTED = - 1 , /**
     * A special flag that indicates that the diffing algorithm should bail out
     * of optimized mode. For example, on block fragments created by renderSlot()
     * when encountering non-compiler generated slots (i.e. manually written
     * render functions, which should always be fully diffed)
     * OR manually cloneVNodes
     */ BAIL = - 2 } /**
 * dev only flag -> name mapping
 */ export const PatchFlagNames = { [ PatchFlags . TEXT ] : `TEXT` , [ PatchFlags . CLASS ] : `CLASS` , [ PatchFlags . STYLE ] : `STYLE` , [ PatchFlags . PROPS ] : `PROPS` , [ PatchFlags . FULL_PROPS ] : `FULL_PROPS` , [ PatchFlags . HYDRATE_EVENTS ] : `HYDRATE_EVENTS` , [ PatchFlags . STABLE_FRAGMENT ] : `STABLE_FRAGMENT` , [ PatchFlags . KEYED_FRAGMENT ] : `KEYED_FRAGMENT` , [ PatchFlags . UNKEYED_FRAGMENT ] : `UNKEYED_FRAGMENT` , [ PatchFlags . NEED_PATCH ] : `NEED_PATCH` , [ PatchFlags . DYNAMIC_SLOTS ] : `DYNAMIC_SLOTS` , [ PatchFlags . DEV_ROOT_FRAGMENT ] : `DEV_ROOT_FRAGMENT` , [ PatchFlags . HOISTED ] : `HOISTED` , [ PatchFlags . BAIL ] : `BAIL` } ;