react/packages/react-refresh/src/ReactFreshBabelPlugin.js
2019-07-02 17:54:10 +01:00

741 lines
24 KiB
JavaScript

/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
'use strict';
export default function(babel) {
if (typeof babel.getEnv === 'function') {
// Only available in Babel 7.
const env = babel.getEnv();
if (env !== 'development') {
throw new Error(
'React Refresh Babel transform should only be enabled in development environment. ' +
'Instead, the environment is: "' +
env +
'".',
);
}
}
const {types: t} = babel;
const registrationsByProgramPath = new Map();
function createRegistration(programPath, persistentID) {
const handle = programPath.scope.generateUidIdentifier('c');
if (!registrationsByProgramPath.has(programPath)) {
registrationsByProgramPath.set(programPath, []);
}
const registrations = registrationsByProgramPath.get(programPath);
registrations.push({
handle,
persistentID,
});
return handle;
}
function isComponentishName(name) {
return typeof name === 'string' && name[0] >= 'A' && name[0] <= 'Z';
}
function findInnerComponents(inferredName, path, callback) {
const node = path.node;
switch (node.type) {
case 'Identifier': {
if (!isComponentishName(node.name)) {
return false;
}
// export default hoc(Foo)
// const X = hoc(Foo)
callback(inferredName, node, null);
return true;
}
case 'FunctionDeclaration': {
// function Foo() {}
// export function Foo() {}
// export default function Foo() {}
callback(inferredName, node.id, null);
return true;
}
case 'ArrowFunctionExpression': {
if (node.body.type === 'ArrowFunctionExpression') {
return false;
}
// let Foo = () => {}
// export default hoc1(hoc2(() => {}))
callback(inferredName, node, path);
return true;
}
case 'FunctionExpression': {
// let Foo = function() {}
// const Foo = hoc1(forwardRef(function renderFoo() {}))
// export default memo(function() {})
callback(inferredName, node, path);
return true;
}
case 'CallExpression': {
const argsPath = path.get('arguments');
if (argsPath === undefined || argsPath.length === 0) {
return false;
}
const calleePath = path.get('callee');
switch (calleePath.node.type) {
case 'MemberExpression':
case 'Identifier': {
const calleeSource = calleePath.getSource();
const firstArgPath = argsPath[0];
const innerName = inferredName + '$' + calleeSource;
const foundInside = findInnerComponents(
innerName,
firstArgPath,
callback,
);
if (!foundInside) {
return false;
}
// const Foo = hoc1(hoc2(() => {}))
// export default memo(React.forwardRef(function() {}))
callback(inferredName, node, path);
return true;
}
default: {
return false;
}
}
}
case 'VariableDeclarator': {
const init = node.init;
if (init === null) {
return false;
}
const name = node.id.name;
if (!isComponentishName(name)) {
return false;
}
switch (init.type) {
case 'ArrowFunctionExpression':
case 'FunctionExpression':
// Likely component definitions.
break;
case 'CallExpression': {
// Maybe a HOC.
// Try to determine if this is some form of import.
const callee = init.callee;
const calleeType = callee.type;
if (calleeType === 'Import') {
return false;
} else if (calleeType === 'Identifier') {
if (callee.name.indexOf('require') === 0) {
return false;
} else if (callee.name.indexOf('import') === 0) {
return false;
}
// Neither require nor import. Might be a HOC.
// Pass through.
} else if (calleeType === 'MemberExpression') {
// Could be something like React.forwardRef(...)
// Pass through.
} else {
// More complicated call.
return false;
}
break;
}
case 'TaggedTemplateExpression':
// Maybe something like styled.div`...`
break;
default:
return false;
}
const initPath = path.get('init');
const foundInside = findInnerComponents(
inferredName,
initPath,
callback,
);
if (foundInside) {
return true;
}
// See if this identifier is used in JSX. Then it's a component.
const binding = path.scope.getBinding(name);
if (binding === undefined) {
return;
}
let isLikelyUsedAsType = false;
const referencePaths = binding.referencePaths;
for (let i = 0; i < referencePaths.length; i++) {
const ref = referencePaths[i];
if (
ref.node.type !== 'JSXIdentifier' &&
ref.node.type !== 'Identifier'
) {
continue;
}
const refParent = ref.parent;
if (refParent.type === 'JSXOpeningElement') {
isLikelyUsedAsType = true;
} else if (refParent.type === 'CallExpression') {
const callee = refParent.callee;
let fnName;
switch (callee.type) {
case 'Identifier':
fnName = callee.name;
break;
case 'MemberExpression':
fnName = callee.property.name;
break;
}
switch (fnName) {
case 'createElement':
case 'jsx':
case 'jsxDEV':
case 'jsxs':
isLikelyUsedAsType = true;
break;
}
}
if (isLikelyUsedAsType) {
// const X = ... + later <X />
callback(inferredName, init, initPath);
return true;
}
}
}
}
return false;
}
function isBuiltinHook(hookName) {
switch (hookName) {
case 'useState':
case 'React.useState':
case 'useReducer':
case 'React.useReducer':
case 'useEffect':
case 'React.useEffect':
case 'useLayoutEffect':
case 'React.useLayoutEffect':
case 'useMemo':
case 'React.useMemo':
case 'useCallback':
case 'React.useCallback':
case 'useRef':
case 'React.useRef':
case 'useContext':
case 'React.useContext':
case 'useImperativeMethods':
case 'React.useImperativeMethods':
case 'useDebugValue':
case 'React.useDebugValue':
return true;
default:
return false;
}
}
function getHookCallsSignature(functionNode) {
const fnHookCalls = hookCalls.get(functionNode);
if (fnHookCalls === undefined) {
return null;
}
return {
key: fnHookCalls.map(call => call.name + '{' + call.key + '}').join('\n'),
customHooks: fnHookCalls
.filter(call => !isBuiltinHook(call.name))
.map(call => t.cloneDeep(call.callee)),
};
}
let hasForceResetCommentByFile = new WeakMap();
// We let user do /* @refresh reset */ to reset state in the whole file.
function hasForceResetComment(path) {
const file = path.hub.file;
let hasForceReset = hasForceResetCommentByFile.get(file);
if (hasForceReset !== undefined) {
return hasForceReset;
}
hasForceReset = false;
const comments = file.ast.comments;
for (let i = 0; i < comments.length; i++) {
const cmt = comments[i];
if (cmt.value.indexOf('@refresh reset') !== -1) {
hasForceReset = true;
break;
}
}
hasForceResetCommentByFile.set(file, hasForceReset);
return hasForceReset;
}
function createArgumentsForSignature(node, signature, scope) {
const {key, customHooks} = signature;
let forceReset = hasForceResetComment(scope.path);
let customHooksInScope = [];
customHooks.forEach(callee => {
// Check if a correponding binding exists where we emit the signature.
let bindingName;
switch (callee.type) {
case 'MemberExpression':
if (callee.object.type === 'Identifier') {
bindingName = callee.object.name;
}
break;
case 'Identifier':
bindingName = callee.name;
break;
}
if (scope.hasBinding(bindingName)) {
customHooksInScope.push(callee);
} else {
// We don't have anything to put in the array because Hook is out of scope.
// Since it could potentially have been edited, remount the component.
forceReset = true;
}
});
const args = [node, t.stringLiteral(key)];
if (forceReset || customHooksInScope.length > 0) {
args.push(t.booleanLiteral(forceReset));
}
if (customHooksInScope.length > 0) {
args.push(
// TODO: We could use an arrow here to be more compact.
// However, don't do it until AMA can run them natively.
t.functionExpression(
null,
[],
t.blockStatement([
t.returnStatement(t.arrayExpression(customHooksInScope)),
]),
),
);
}
return args;
}
let seenForRegistration = new WeakSet();
let seenForSignature = new WeakSet();
let seenForOutro = new WeakSet();
let hookCalls = new WeakMap();
const HookCallsVisitor = {
CallExpression(path) {
const node = path.node;
const callee = node.callee;
// Note: this visitor MUST NOT mutate the tree in any way.
// It runs early in a separate traversal and should be very fast.
let name = null;
switch (callee.type) {
case 'Identifier':
name = callee.name;
break;
case 'MemberExpression':
name = callee.property.name;
break;
}
if (name === null || !/^use[A-Z]/.test(name)) {
return;
}
const fnScope = path.scope.getFunctionParent();
if (fnScope === null) {
return;
}
// This is a Hook call. Record it.
const fnNode = fnScope.block;
if (!hookCalls.has(fnNode)) {
hookCalls.set(fnNode, []);
}
let hookCallsForFn = hookCalls.get(fnNode);
let key = '';
if (path.parent.type === 'VariableDeclarator') {
// TODO: if there is no LHS, consider some other heuristic.
key = path.parentPath.get('id').getSource();
}
// Some built-in Hooks reset on edits to arguments.
const args = path.get('arguments');
if (name === 'useState' && args.length > 0) {
// useState second argument is initial state.
key += '(' + args[0].getSource() + ')';
} else if (name === 'useReducer' && args.length > 1) {
// useReducer second argument is initial state.
key += '(' + args[1].getSource() + ')';
}
hookCallsForFn.push({
callee: path.node.callee,
name,
key,
});
},
};
return {
visitor: {
ExportDefaultDeclaration(path) {
const node = path.node;
const decl = node.declaration;
const declPath = path.get('declaration');
if (decl.type !== 'CallExpression') {
// For now, we only support possible HOC calls here.
// Named function declarations are handled in FunctionDeclaration.
// Anonymous direct exports like export default function() {}
// are currently ignored.
return;
}
// Make sure we're not mutating the same tree twice.
// This can happen if another Babel plugin replaces parents.
if (seenForRegistration.has(node)) {
return;
}
seenForRegistration.add(node);
// Don't mutate the tree above this point.
// This code path handles nested cases like:
// export default memo(() => {})
// In those cases it is more plausible people will omit names
// so they're worth handling despite possible false positives.
// More importantly, it handles the named case:
// export default memo(function Named() {})
const inferredName = '%default%';
const programPath = path.parentPath;
findInnerComponents(
inferredName,
declPath,
(persistentID, targetExpr, targetPath) => {
if (targetPath === null) {
// For case like:
// export default hoc(Foo)
// we don't want to wrap Foo inside the call.
// Instead we assume it's registered at definition.
return;
}
const handle = createRegistration(programPath, persistentID);
targetPath.replaceWith(
t.assignmentExpression('=', handle, targetExpr),
);
},
);
},
FunctionDeclaration: {
enter(path) {
const node = path.node;
let programPath;
let insertAfterPath;
switch (path.parent.type) {
case 'Program':
insertAfterPath = path;
programPath = path.parentPath;
break;
case 'ExportNamedDeclaration':
insertAfterPath = path.parentPath;
programPath = insertAfterPath.parentPath;
break;
case 'ExportDefaultDeclaration':
insertAfterPath = path.parentPath;
programPath = insertAfterPath.parentPath;
break;
default:
return;
}
const id = node.id;
if (id === null) {
// We don't currently handle anonymous default exports.
return;
}
const inferredName = id.name;
if (!isComponentishName(inferredName)) {
return;
}
// Make sure we're not mutating the same tree twice.
// This can happen if another Babel plugin replaces parents.
if (seenForRegistration.has(node)) {
return;
}
seenForRegistration.add(node);
// Don't mutate the tree above this point.
// export function Named() {}
// function Named() {}
findInnerComponents(
inferredName,
path,
(persistentID, targetExpr) => {
const handle = createRegistration(programPath, persistentID);
insertAfterPath.insertAfter(
t.expressionStatement(
t.assignmentExpression('=', handle, targetExpr),
),
);
},
);
},
exit(path) {
const node = path.node;
const id = node.id;
if (id === null) {
return;
}
const signature = getHookCallsSignature(node);
if (signature === null) {
return;
}
// Make sure we're not mutating the same tree twice.
// This can happen if another Babel plugin replaces parents.
if (seenForSignature.has(node)) {
return;
}
seenForSignature.add(node);
// Don't mutate the tree above this point.
const sigCallID = path.scope.generateUidIdentifier('_s');
path.scope.parent.push({
id: sigCallID,
init: t.callExpression(t.identifier('$RefreshSig$'), []),
});
// The signature call is split in two parts. One part is called inside the function.
// This is used to signal when first render happens.
path
.get('body')
.unshiftContainer(
'body',
t.expressionStatement(t.callExpression(sigCallID, [])),
);
// The second call is around the function itself.
// This is used to associate a type with a signature.
// Unlike with $RefreshReg$, this needs to work for nested
// declarations too. So we need to search for a path where
// we can insert a statement rather than hardcoding it.
let insertAfterPath = null;
path.find(p => {
if (p.parentPath.isBlock()) {
insertAfterPath = p;
return true;
}
});
if (insertAfterPath === null) {
return;
}
insertAfterPath.insertAfter(
t.expressionStatement(
t.callExpression(
sigCallID,
createArgumentsForSignature(
id,
signature,
insertAfterPath.scope,
),
),
),
);
},
},
'ArrowFunctionExpression|FunctionExpression': {
exit(path) {
const node = path.node;
const signature = getHookCallsSignature(node);
if (signature === null) {
return;
}
// Make sure we're not mutating the same tree twice.
// This can happen if another Babel plugin replaces parents.
if (seenForSignature.has(node)) {
return;
}
seenForSignature.add(node);
// Don't mutate the tree above this point.
const sigCallID = path.scope.generateUidIdentifier('_s');
path.scope.parent.push({
id: sigCallID,
init: t.callExpression(t.identifier('$RefreshSig$'), []),
});
// The signature call is split in two parts. One part is called inside the function.
// This is used to signal when first render happens.
path
.get('body')
.unshiftContainer(
'body',
t.expressionStatement(t.callExpression(sigCallID, [])),
);
// The second call is around the function itself.
// This is used to associate a type with a signature.
if (path.parent.type === 'VariableDeclarator') {
let insertAfterPath = null;
path.find(p => {
if (p.parentPath.isBlock()) {
insertAfterPath = p;
return true;
}
});
if (insertAfterPath === null) {
return;
}
// Special case when a function would get an inferred name:
// let Foo = () => {}
// let Foo = function() {}
// We'll add signature it on next line so that
// we don't mess up the inferred 'Foo' function name.
insertAfterPath.insertAfter(
t.expressionStatement(
t.callExpression(
sigCallID,
createArgumentsForSignature(
path.parent.id,
signature,
insertAfterPath.scope,
),
),
),
);
// Result: let Foo = () => {}; __signature(Foo, ...);
} else {
// let Foo = hoc(() => {})
path.replaceWith(
t.callExpression(
sigCallID,
createArgumentsForSignature(node, signature, path.scope),
),
);
// Result: let Foo = hoc(__signature(() => {}, ...))
}
},
},
VariableDeclaration(path) {
const node = path.node;
let programPath;
let insertAfterPath;
switch (path.parent.type) {
case 'Program':
insertAfterPath = path;
programPath = path.parentPath;
break;
case 'ExportNamedDeclaration':
insertAfterPath = path.parentPath;
programPath = insertAfterPath.parentPath;
break;
case 'ExportDefaultDeclaration':
insertAfterPath = path.parentPath;
programPath = insertAfterPath.parentPath;
break;
default:
return;
}
// Make sure we're not mutating the same tree twice.
// This can happen if another Babel plugin replaces parents.
if (seenForRegistration.has(node)) {
return;
}
seenForRegistration.add(node);
// Don't mutate the tree above this point.
const declPaths = path.get('declarations');
if (declPaths.length !== 1) {
return;
}
const declPath = declPaths[0];
const inferredName = declPath.node.id.name;
findInnerComponents(
inferredName,
declPath,
(persistentID, targetExpr, targetPath) => {
if (targetPath === null) {
// For case like:
// export const Something = hoc(Foo)
// we don't want to wrap Foo inside the call.
// Instead we assume it's registered at definition.
return;
}
const handle = createRegistration(programPath, persistentID);
if (
(targetExpr.type === 'ArrowFunctionExpression' ||
targetExpr.type === 'FunctionExpression') &&
targetPath.parent.type === 'VariableDeclarator'
) {
// Special case when a function would get an inferred name:
// let Foo = () => {}
// let Foo = function() {}
// We'll register it on next line so that
// we don't mess up the inferred 'Foo' function name.
insertAfterPath.insertAfter(
t.expressionStatement(
t.assignmentExpression('=', handle, declPath.node.id),
),
);
// Result: let Foo = () => {}; _c1 = Foo;
} else {
// let Foo = hoc(() => {})
targetPath.replaceWith(
t.assignmentExpression('=', handle, targetExpr),
);
// Result: let Foo = _c1 = hoc(() => {})
}
},
);
},
Program: {
enter(path) {
// This is a separate early visitor because we need to collect Hook calls
// and "const [foo, setFoo] = ..." signatures before the destructuring
// transform mangles them. This extra traversal is not ideal for perf,
// but it's the best we can do until we stop transpiling destructuring.
path.traverse(HookCallsVisitor);
},
exit(path) {
const registrations = registrationsByProgramPath.get(path);
if (registrations === undefined) {
return;
}
// Make sure we're not mutating the same tree twice.
// This can happen if another Babel plugin replaces parents.
const node = path.node;
if (seenForOutro.has(node)) {
return;
}
seenForOutro.add(node);
// Don't mutate the tree above this point.
registrationsByProgramPath.delete(path);
const declarators = [];
path.pushContainer('body', t.variableDeclaration('var', declarators));
registrations.forEach(({handle, persistentID}) => {
path.pushContainer(
'body',
t.expressionStatement(
t.callExpression(t.identifier('$RefreshReg$'), [
handle,
t.stringLiteral(persistentID),
]),
),
);
declarators.push(t.variableDeclarator(handle));
});
},
},
},
};
}