render-static.js
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/* @flow */
/**
* Runtime helper for rendering static trees.
*/
export function renderStatic (
index: number,
isInFor: boolean
): VNode | Array<VNode> {
const cached = this._staticTrees || (this._staticTrees = [])
let tree = cached[index]
// if has already-rendered static tree and not inside v-for,
// we can reuse the same tree.
if (tree && !isInFor) {
return tree
}
// otherwise, render a fresh tree.
tree = cached[index] = this.$options.staticRenderFns[index].call(
this._renderProxy,
null,
this // for render fns generated for functional component templates
)
markStatic(tree, `__static__${index}`, false)
return tree
}
/**
* Runtime helper for v-once.
* Effectively it means marking the node as static with a unique key.
*/
export function markOnce (
tree: VNode | Array<VNode>,
index: number,
key: string
) {
markStatic(tree, `__once__${index}${key ? `_${key}` : ``}`, true)
return tree
}
function markStatic (
tree: VNode | Array<VNode>,
key: string,
isOnce: boolean
) {
if (Array.isArray(tree)) {
for (let i = 0; i < tree.length; i++) {
if (tree[i] && typeof tree[i] !== 'string') {
markStaticNode(tree[i], `${key}_${i}`, isOnce)
}
}
} else {
markStaticNode(tree, key, isOnce)
}
}
function markStaticNode (node, key, isOnce) {
node.isStatic = true
node.key = key
node.isOnce = isOnce
}