/
refTransform.ts
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/
refTransform.ts
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import {
Node,
Identifier,
BlockStatement,
CallExpression,
ObjectPattern,
VariableDeclaration,
ArrayPattern,
Program,
VariableDeclarator
} from '@babel/types'
import MagicString, { SourceMap } from 'magic-string'
import { walk } from 'estree-walker'
import {
extractIdentifiers,
isFunctionType,
isInDestructureAssignment,
isReferencedIdentifier,
isStaticProperty,
walkFunctionParams
} from '@vue/compiler-core'
import { parse, ParserPlugin } from '@babel/parser'
import { babelParserDefaultPlugins } from '@vue/shared'
const TO_VAR_SYMBOL = '$'
const TO_REF_SYMBOL = '$$'
const shorthands = ['ref', 'computed', 'shallowRef']
const transformCheckRE = /[^\w]\$(?:\$|ref|computed|shallowRef)?\s*(\(|\<)/
export function shouldTransform(src: string): boolean {
return transformCheckRE.test(src)
}
type Scope = Record<string, boolean>
export interface RefTransformOptions {
filename?: string
sourceMap?: boolean
parserPlugins?: ParserPlugin[]
importHelpersFrom?: string
}
export interface RefTransformResults {
code: string
map: SourceMap | null
rootVars: string[]
importedHelpers: string[]
}
export function transform(
src: string,
{
filename,
sourceMap,
parserPlugins,
importHelpersFrom = 'vue'
}: RefTransformOptions = {}
): RefTransformResults {
const plugins: ParserPlugin[] = parserPlugins || []
if (filename) {
if (/\.tsx?$/.test(filename)) {
plugins.push('typescript')
}
if (filename.endsWith('x')) {
plugins.push('jsx')
}
}
const ast = parse(src, {
sourceType: 'module',
plugins: [...new Set([...babelParserDefaultPlugins, ...plugins])]
})
const s = new MagicString(src)
const res = transformAST(ast.program, s)
// inject helper imports
if (res.importedHelpers.length) {
s.prepend(
`import { ${res.importedHelpers
.map(h => `${h} as _${h}`)
.join(', ')} } from '${importHelpersFrom}'\n`
)
}
return {
...res,
code: s.toString(),
map: sourceMap
? s.generateMap({
source: filename,
hires: true,
includeContent: true
})
: null
}
}
export function transformAST(
ast: Program,
s: MagicString,
offset = 0,
knownRootVars?: string[]
): {
rootVars: string[]
importedHelpers: string[]
} {
// TODO remove when out of experimental
warnExperimental()
const importedHelpers = new Set<string>()
const rootScope: Scope = {}
const scopeStack: Scope[] = [rootScope]
let currentScope: Scope = rootScope
const excludedIds = new WeakSet<Identifier>()
const parentStack: Node[] = []
if (knownRootVars) {
for (const key of knownRootVars) {
rootScope[key] = true
}
}
function error(msg: string, node: Node) {
const e = new Error(msg)
;(e as any).node = node
throw e
}
function helper(msg: string) {
importedHelpers.add(msg)
return `_${msg}`
}
function registerBinding(id: Identifier, isRef = false) {
excludedIds.add(id)
if (currentScope) {
currentScope[id.name] = isRef
} else {
error(
'registerBinding called without active scope, something is wrong.',
id
)
}
}
const registerRefBinding = (id: Identifier) => registerBinding(id, true)
function walkScope(node: Program | BlockStatement) {
for (const stmt of node.body) {
if (stmt.type === 'VariableDeclaration') {
if (stmt.declare) continue
for (const decl of stmt.declarations) {
let toVarCall
if (
decl.init &&
decl.init.type === 'CallExpression' &&
decl.init.callee.type === 'Identifier' &&
(toVarCall = isToVarCall(decl.init.callee.name))
) {
processRefDeclaration(
toVarCall,
decl.init as CallExpression,
decl.id,
stmt
)
} else {
for (const id of extractIdentifiers(decl.id)) {
registerBinding(id)
}
}
}
} else if (
stmt.type === 'FunctionDeclaration' ||
stmt.type === 'ClassDeclaration'
) {
if (stmt.declare || !stmt.id) continue
registerBinding(stmt.id)
}
}
}
function processRefDeclaration(
method: string,
call: CallExpression,
id: VariableDeclarator['id'],
statement: VariableDeclaration
) {
excludedIds.add(call.callee as Identifier)
if (statement.kind !== 'let') {
error(`${method}() bindings can only be declared with let`, call)
}
if (method === TO_VAR_SYMBOL) {
// $
// remove macro
s.remove(call.callee.start! + offset, call.callee.end! + offset)
if (id.type === 'Identifier') {
// single variable
registerRefBinding(id)
} else if (id.type === 'ObjectPattern') {
processRefObjectPattern(id, statement)
} else if (id.type === 'ArrayPattern') {
processRefArrayPattern(id, statement)
}
} else {
// shorthands
if (id.type === 'Identifier') {
registerRefBinding(id)
// replace call
s.overwrite(
call.start! + offset,
call.start! + method.length + offset,
helper(method.slice(1))
)
} else {
error(`${method}() cannot be used with destructure patterns.`, call)
}
}
}
function processRefObjectPattern(
pattern: ObjectPattern,
statement: VariableDeclaration
) {
for (const p of pattern.properties) {
let nameId: Identifier | undefined
if (p.type === 'ObjectProperty') {
if (p.key.start! === p.value.start!) {
// shorthand { foo } --> { foo: __foo }
nameId = p.key as Identifier
s.appendLeft(nameId.end! + offset, `: __${nameId.name}`)
if (p.value.type === 'Identifier') {
// avoid shorthand value identifier from being processed
excludedIds.add(p.value)
} else if (
p.value.type === 'AssignmentPattern' &&
p.value.left.type === 'Identifier'
) {
// { foo = 1 }
excludedIds.add(p.value.left)
}
} else {
if (p.value.type === 'Identifier') {
// { foo: bar } --> { foo: __bar }
nameId = p.value
s.prependRight(nameId.start! + offset, `__`)
} else if (p.value.type === 'ObjectPattern') {
processRefObjectPattern(p.value, statement)
} else if (p.value.type === 'ArrayPattern') {
processRefArrayPattern(p.value, statement)
} else if (p.value.type === 'AssignmentPattern') {
// { foo: bar = 1 } --> { foo: __bar = 1 }
nameId = p.value.left as Identifier
s.prependRight(nameId.start! + offset, `__`)
}
}
} else {
// rest element { ...foo } --> { ...__foo }
nameId = p.argument as Identifier
s.prependRight(nameId.start! + offset, `__`)
}
if (nameId) {
registerRefBinding(nameId)
// append binding declarations after the parent statement
s.appendLeft(
statement.end! + offset,
`\nconst ${nameId.name} = ${helper('shallowRef')}(__${nameId.name});`
)
}
}
}
function processRefArrayPattern(
pattern: ArrayPattern,
statement: VariableDeclaration
) {
for (const e of pattern.elements) {
if (!e) continue
let nameId: Identifier | undefined
if (e.type === 'Identifier') {
// [a] --> [__a]
nameId = e
} else if (e.type === 'AssignmentPattern') {
// [a = 1] --> [__a = 1]
nameId = e.left as Identifier
} else if (e.type === 'RestElement') {
// [...a] --> [...__a]
nameId = e.argument as Identifier
} else if (e.type === 'ObjectPattern') {
processRefObjectPattern(e, statement)
} else if (e.type === 'ArrayPattern') {
processRefArrayPattern(e, statement)
}
if (nameId) {
registerRefBinding(nameId)
// prefix original
s.prependRight(nameId.start! + offset, `__`)
// append binding declarations after the parent statement
s.appendLeft(
statement.end! + offset,
`\nconst ${nameId.name} = ${helper('shallowRef')}(__${nameId.name});`
)
}
}
}
function checkRefId(
scope: Scope,
id: Identifier,
parent: Node,
parentStack: Node[]
): boolean {
if (id.name in scope) {
if (scope[id.name]) {
if (isStaticProperty(parent) && parent.shorthand) {
// let binding used in a property shorthand
// { foo } -> { foo: foo.value }
// skip for destructure patterns
if (
!(parent as any).inPattern ||
isInDestructureAssignment(parent, parentStack)
) {
s.appendLeft(id.end! + offset, `: ${id.name}.value`)
}
} else {
s.appendLeft(id.end! + offset, '.value')
}
}
return true
}
return false
}
// check root scope first
walkScope(ast)
;(walk as any)(ast, {
enter(node: Node, parent?: Node) {
parent && parentStack.push(parent)
// function scopes
if (isFunctionType(node)) {
scopeStack.push((currentScope = {}))
walkFunctionParams(node, registerBinding)
if (node.body.type === 'BlockStatement') {
walkScope(node.body)
}
return
}
// non-function block scopes
if (node.type === 'BlockStatement' && !isFunctionType(parent!)) {
scopeStack.push((currentScope = {}))
walkScope(node)
return
}
if (
parent &&
parent.type.startsWith('TS') &&
parent.type !== 'TSAsExpression' &&
parent.type !== 'TSNonNullExpression' &&
parent.type !== 'TSTypeAssertion'
) {
return this.skip()
}
if (
node.type === 'Identifier' &&
isReferencedIdentifier(node, parent!, parentStack) &&
!excludedIds.has(node)
) {
// walk up the scope chain to check if id should be appended .value
let i = scopeStack.length
while (i--) {
if (checkRefId(scopeStack[i], node, parent!, parentStack)) {
return
}
}
}
if (node.type === 'CallExpression' && node.callee.type === 'Identifier') {
const callee = node.callee.name
const toVarCall = isToVarCall(callee)
if (toVarCall && (!parent || parent.type !== 'VariableDeclarator')) {
return error(
`${toVarCall} can only be used as the initializer of ` +
`a variable declaration.`,
node
)
}
if (callee === TO_REF_SYMBOL) {
s.remove(node.callee.start! + offset, node.callee.end! + offset)
return this.skip()
}
// TODO remove when out of experimental
if (callee === '$raw') {
error(
`$raw() has been replaced by $$(). ` +
`See ${RFC_LINK} for latest updates.`,
node
)
}
if (callee === '$fromRef') {
error(
`$fromRef() has been replaced by $(). ` +
`See ${RFC_LINK} for latest updates.`,
node
)
}
}
},
leave(node: Node, parent?: Node) {
parent && parentStack.pop()
if (
(node.type === 'BlockStatement' && !isFunctionType(parent!)) ||
isFunctionType(node)
) {
scopeStack.pop()
currentScope = scopeStack[scopeStack.length - 1] || null
}
}
})
return {
rootVars: Object.keys(rootScope).filter(key => rootScope[key]),
importedHelpers: [...importedHelpers]
}
}
function isToVarCall(callee: string): string | false {
if (callee === TO_VAR_SYMBOL) {
return TO_VAR_SYMBOL
}
if (callee[0] === TO_VAR_SYMBOL && shorthands.includes(callee.slice(1))) {
return callee
}
return false
}
const RFC_LINK = `https://github.com/vuejs/rfcs/discussions/369`
const hasWarned: Record<string, boolean> = {}
function warnExperimental() {
// eslint-disable-next-line
if (typeof window !== 'undefined') {
return
}
warnOnce(
`@vue/ref-transform is an experimental feature.\n` +
`Experimental features may change behavior between patch versions.\n` +
`It is recommended to pin your vue dependencies to exact versions to avoid breakage.\n` +
`You can follow the proposal's status at ${RFC_LINK}.`
)
}
function warnOnce(msg: string) {
const isNodeProd =
typeof process !== 'undefined' && process.env.NODE_ENV === 'production'
if (!isNodeProd && !__TEST__ && !hasWarned[msg]) {
hasWarned[msg] = true
warn(msg)
}
}
function warn(msg: string) {
console.warn(
`\x1b[1m\x1b[33m[@vue/compiler-sfc]\x1b[0m\x1b[33m ${msg}\x1b[0m\n`
)
}