luhn-generator
Version:
A generator of numbers that passes the validation of Luhn algorithm or Luhn formula, also known as the 'modulus 10' or 'mod 10' algorithm
589 lines (485 loc) • 18.9 kB
JavaScript
"use strict";
const Charset = require("./charset");
const ScopeTracker = require("./scope-tracker");
const isLabelIdentifier = require("./is-label-identifier");
const bfsTraverseCreator = require("./bfs-traverse");
const fixupVarScoping = require("./fixup-var-scoping");
const _require = require("babel-helper-mark-eval-scopes"),
markEvalScopes = _require.markEvalScopes,
isEvalScopesMarked = _require.isMarked,
hasEval = _require.hasEval;
const newIssueUrl = "https://github.com/babel/minify/issues/new";
module.exports = babel => {
const t = babel.types,
traverse = babel.traverse;
const bfsTraverse = bfsTraverseCreator(babel);
const hop = Object.prototype.hasOwnProperty;
class Mangler {
constructor(charset, program, {
exclude = {},
keepFnName = false,
keepClassName = false,
eval: _eval = false,
topLevel = false
} = {}) {
this.charset = charset;
this.program = program; // user passed options
this.exclude = toObject(exclude);
this.keepFnName = keepFnName;
this.keepClassName = keepClassName;
this.topLevel = topLevel;
this.eval = _eval; // tracking
this.visitedScopes = new Set();
this.scopeTracker = new ScopeTracker();
this.renamedNodes = new Set();
}
/**
* Run the mangler
*/
run() {
this.crawlScope();
this.collect();
this.fixup();
this.charset.sort();
this.mangle();
}
/**
* Tells if a variable name is excluded
* @param {String} name
*/
isExcluded(name) {
return hop.call(this.exclude, name) && this.exclude[name];
}
/**
* Clears traverse cache and recrawls the AST
*
* to recompute the bindings, references, other scope information
* and paths because the other transformations in the same pipeline
* (other plugins and presets) changes the AST and does NOT update
* the scope objects
*/
crawlScope() {
(traverse.clearCache || traverse.cache.clear)();
this.program.scope.crawl();
}
/**
* Re-crawling comes with a side-effect that let->var conversion
* reverts the update of the binding information (block to fn scope).
* This function takes care of it by updating it again.
*
* TODO: This is unnecessary work and needs to be fixed in babel.
* https://github.com/babel/babel/issues/4818
*
* When this is removed, remember to remove fixup's dependency in
* ScopeTracker
*/
fixup() {
fixupVarScoping(this);
}
/**
* A single pass through the AST to collect info for
*
* 1. Scope Tracker
* 2. Unsafe Scopes (direct eval scopes)
* 3. Charset considerations for better gzip compression
*
* Traversed in the same fashion(BFS) the mangling is done
*/
collect() {
const mangler = this;
const scopeTracker = mangler.scopeTracker;
scopeTracker.addScope(this.program.scope);
/**
* Same usage as in DCE, whichever runs first
*/
if (!isEvalScopesMarked(mangler.program)) {
markEvalScopes(mangler.program);
}
/**
* The visitors to be used in traversal.
*
* Note: BFS traversal supports only the `enter` handlers, `exit`
* handlers are simply dropped without Errors
*
* Collects items defined in the ScopeTracker
*/
const collectVisitor = {
Scopable({
scope
}) {
scopeTracker.addScope(scope); // Collect bindings defined in the scope
Object.keys(scope.bindings).forEach(name => {
scopeTracker.addBinding(scope.bindings[name]); // add all constant violations as references
scope.bindings[name].constantViolations.forEach(() => {
scopeTracker.addReference(scope, scope.bindings[name], name);
});
});
},
/**
* This is required because after function name transformation
* plugin (part of es2015), the function name is NOT added to the
* scope's bindings. So to fix this issue, we simply add a hack to
* handle that case - fix it to the scope tree.
*
* Related:
* - https://github.com/babel/minify/issues/829
*/
BindingIdentifier(path) {
if ( // the parent has this id as the name
(path.parentPath.isFunctionExpression({
id: path.node
}) || path.parentPath.isClassExpression({
id: path.node
})) && // and the id isn't yet added to the scope
!hop.call(path.parentPath.scope.bindings, path.node.name)) {
path.parentPath.scope.registerBinding("local", path.parentPath);
}
},
/**
* This is necessary because, in Babel, the scope.references
* does NOT contain the references in that scope. Only the program
* scope (top most level) contains all the references.
*
* We collect the references in a fashion where all the scopes between
* and including the referenced scope and scope where it is declared
* is considered as scope referencing that identifier
*/
ReferencedIdentifier(path) {
if (isLabelIdentifier(path)) {
return;
}
const scope = path.scope,
name = path.node.name;
const binding = scope.getBinding(name);
if (!binding) {
// Do not collect globals as they are already available via
// babel's API
if (scope.hasGlobal(name)) {
return;
} // This should NOT happen ultimately. Panic if this code block is
// reached
throw new Error(`Binding not found for ReferencedIdentifier "${name}" ` + `present in "${path.parentPath.type}". ` + `Please report this at ${newIssueUrl}`);
} else {
// Add it to our scope tracker if everything is fine
scopeTracker.addReference(scope, binding, name);
}
}
};
/**
* These visitors are for collecting the Characters used in the program
* to measure the frequency and generate variable names for mangling so
* as to improve the gzip compression - as gzip likes repetition
*/
if (this.charset.shouldConsider) {
collectVisitor.Identifier = function Identifer(path) {
const node = path.node; // We don't mangle properties, so we collect them as they contribute
// to the frequency of characters
if (path.parentPath.isMemberExpression({
property: node
}) || path.parentPath.isObjectProperty({
key: node
})) {
mangler.charset.consider(node.name);
}
};
collectVisitor.Literal = function Literal({
node
}) {
mangler.charset.consider(String(node.value));
};
} // Traverse the AST
bfsTraverse(mangler.program, collectVisitor);
}
/**
* Tells if a binding is exported as a NamedExport - so as to NOT mangle
*
* Babel treats NamedExports as a binding referenced by this NamedExport decl
* @param {Binding} binding
*/
isExportedWithName(binding) {
// short circuit
if (!this.topLevel) {
return false;
}
const refs = binding.referencePaths;
var _iteratorNormalCompletion = true;
var _didIteratorError = false;
var _iteratorError = undefined;
try {
for (var _iterator = refs[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
const ref = _step.value;
if (ref.isExportNamedDeclaration()) {
return true;
}
} // default
} catch (err) {
_didIteratorError = true;
_iteratorError = err;
} finally {
try {
if (!_iteratorNormalCompletion && _iterator.return != null) {
_iterator.return();
}
} finally {
if (_didIteratorError) {
throw _iteratorError;
}
}
}
return false;
}
/**
* Tells if the name can be mangled in the current observed scope with
* the input binding
*
* @param {string} oldName the old name that needs to be mangled
* @param {Binding} binding Binding of the name
* @param {Scope} scope The current scope the mangler is run
*/
canMangle(oldName, binding, scope) {
const cannotMangle = // arguments - for non-strict mode
oldName === "arguments" || // labels
binding.path.isLabeledStatement() || // ClassDeclaration has binding in two scopes
// 1. The scope in which it is declared
// 2. The class's own scope
binding.path.isClassDeclaration() && binding.path === scope.path || // excluded
this.isExcluded(oldName) || ( // function names
this.keepFnName ? isFunction(binding.path) : false) || ( // class names
this.keepClassName ? isClass(binding.path) : false) || // named export
this.isExportedWithName(binding);
return !cannotMangle;
}
/**
* Tells if the newName can be used as a valid name for the input binding
* in the input scope
*
* @param {string} newName the old name that needs to be mangled
* @param {Binding} binding Binding of the name that this new name will replace
* @param {Scope} scope The current scope the mangler is run
*/
isValidName(newName, binding, scope) {
return t.isValidIdentifier(newName) && !this.scopeTracker.hasBinding(scope, newName) && !scope.hasGlobal(newName) && !this.scopeTracker.hasReference(scope, newName) && this.scopeTracker.canUseInReferencedScopes(binding, newName);
}
/**
* Mangle the scope
* @param {Scope} scope
*/
mangleScope(scope) {
const mangler = this;
const scopeTracker = mangler.scopeTracker; // Unsafe Scope
if (!mangler.eval && hasEval(scope)) {
return;
} // Already visited
// This is because for a function, in Babel, the function and
// the function body's BlockStatement has the same scope, and will
// be visited twice by the Scopable handler, and we want to mangle
// it only once
if (mangler.visitedScopes.has(scope)) {
return;
}
mangler.visitedScopes.add(scope);
const bindings = scopeTracker.bindings.get(scope);
const names = [...bindings.keys()]; // A counter to generate names and reset
// so we can reuse removed names
let counter = 0;
/**
* 1. Iterate through the list of BindingIdentifiers
* 2. Rename each of them in-place
* 3. Update the scope tree.
*
* We cannot use a for..of loop over bindings.keys()
* because (2) we rename in place and update the bindings
* as we traverse through the keys
*/
for (var _i = 0; _i < names.length; _i++) {
const oldName = names[_i];
const binding = bindings.get(oldName);
if (mangler.canMangle(oldName, binding, scope)) {
let next;
do {
next = mangler.charset.getIdentifier(counter++);
} while (!mangler.isValidName(next, binding, scope)); // Reset so variables which are removed can be reused
//
// the following is an assumtion (for perf)
// the length 3 is an assumption that if the oldName isn't
// 1 or 2 characters, then probably we are not going to find
// a name - because for almost all usecases we have 1 or 2
// character new names only. And for the edge cases where
// one scope has lots and lots of variables, it's okay to
// name something with 3 characters instead of 1
if (oldName.length < 3) {
counter = 0;
} // Once we detected a valid `next` Identifier which could be used,
// call the renamer
mangler.rename(scope, binding, oldName, next);
}
}
}
/**
* The mangle function that traverses through all the Scopes in a BFS
* fashion - calls mangleScope
*/
mangle() {
const mangler = this;
bfsTraverse(this.program, {
Scopable(path) {
if (!path.isProgram() || mangler.topLevel) mangler.mangleScope(path.scope);
}
});
}
/**
* Given a NodePath, collects all the Identifiers which are BindingIdentifiers
* and replaces them with the new name
*
* For example,
* var a = 1, { b } = c; // a and b are BindingIdentifiers
*
* @param {NodePath} path
* @param {String} oldName
* @param {String} newName
* @param {Function} predicate
*/
renameBindingIds(path, oldName, newName, predicate = () => true) {
const bindingIds = path.getBindingIdentifierPaths(true, false);
for (const name in bindingIds) {
if (name !== oldName) continue;
var _iteratorNormalCompletion2 = true;
var _didIteratorError2 = false;
var _iteratorError2 = undefined;
try {
for (var _iterator2 = bindingIds[name][Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
const idPath = _step2.value;
if (predicate(idPath)) {
idPath.node.name = newName; // babel-7 don't requeue
// idPath.replaceWith(t.identifier(newName));
this.renamedNodes.add(idPath.node);
}
}
} catch (err) {
_didIteratorError2 = true;
_iteratorError2 = err;
} finally {
try {
if (!_iteratorNormalCompletion2 && _iterator2.return != null) {
_iterator2.return();
}
} finally {
if (_didIteratorError2) {
throw _iteratorError2;
}
}
}
}
}
/**
* The Renamer:
* Renames the following for one Binding in a Scope
*
* 1. Binding in that Scope
* 2. All the Binding's constant violations
* 3. All its References
* 4. Updates mangler.scopeTracker
* 5. Updates Babel's Scope tracking
*
* @param {Scope} scope
* @param {Binding} binding
* @param {String} oldName
* @param {String} newName
*/
rename(scope, binding, oldName, newName) {
const mangler = this;
const scopeTracker = mangler.scopeTracker; // rename at the declaration level
this.renameBindingIds(binding.path, oldName, newName, idPath => idPath.node === binding.identifier); // update mangler's ScopeTracker
scopeTracker.renameBinding(scope, oldName, newName); // update all constant violations
const violations = binding.constantViolations;
for (let i = 0; i < violations.length; i++) {
if (violations[i].isLabeledStatement()) continue;
this.renameBindingIds(violations[i], oldName, newName);
scopeTracker.updateReference(violations[i].scope, binding, oldName, newName);
} // update all referenced places
const refs = binding.referencePaths;
for (let i = 0; i < refs.length; i++) {
const path = refs[i];
const node = path.node;
if (!path.isIdentifier()) {
// Ideally, this should not happen
// it happens in these places now -
// case 1: Export Statements
// This is a bug in babel
// https://github.com/babel/babel/pull/3629
// case 2: Replacements in other plugins
// eg: https://github.com/babel/minify/issues/122
// replacement in dce from `x` to `!x` gives referencePath as `!x`
path.traverse({
ReferencedIdentifier(refPath) {
if (refPath.node.name !== oldName) {
return;
}
const actualBinding = refPath.scope.getBinding(oldName);
if (actualBinding !== binding) {
return;
}
refPath.node.name = newName; // babel-7 don't requeue
// refPath.replaceWith(t.identifier(newName));
mangler.renamedNodes.add(refPath.node);
scopeTracker.updateReference(refPath.scope, binding, oldName, newName);
}
});
} else if (!isLabelIdentifier(path)) {
if (path.node.name === oldName) {
path.node.name = newName; // babel-7 don't requeue
// path.replaceWith(t.identifier(newName));
mangler.renamedNodes.add(path.node);
scopeTracker.updateReference(path.scope, binding, oldName, newName);
} else if (mangler.renamedNodes.has(path.node)) {
// already renamed,
// just update the references
scopeTracker.updateReference(path.scope, binding, oldName, newName);
} else {
throw new Error(`Unexpected Rename Error: ` + `Trying to replace "${node.name}": from "${oldName}" to "${newName}". ` + `Please report it at ${newIssueUrl}`);
}
} // else label identifier - silently ignore
} // update babel's internal tracking
binding.identifier.name = newName; // update babel's internal scope tracking
const bindings = scope.bindings;
bindings[newName] = binding;
delete bindings[oldName];
}
}
return {
name: "minify-mangle-names",
visitor: {
/**
* Mangler is run as a single pass. It's the same pattern as used in DCE
*/
Program: {
exit(path) {
// If the source code is small then we're going to assume that the user
// is running on this on single files before bundling. Therefore we
// need to achieve as much determinisim and we will not do any frequency
// sorting on the character set. Currently the number is pretty arbitrary.
const shouldConsiderSource = path.getSource().length > 70000;
const charset = new Charset(shouldConsiderSource);
const mangler = new Mangler(charset, path, this.opts);
mangler.run();
}
}
}
};
}; // convert value to object
function toObject(value) {
if (!Array.isArray(value)) {
return value;
}
const map = {};
for (let i = 0; i < value.length; i++) {
map[value[i]] = true;
}
return map;
} // for keepFnName
function isFunction(path) {
return path.isFunctionExpression() || path.isFunctionDeclaration();
} // for keepClassName
function isClass(path) {
return path.isClassExpression() || path.isClassDeclaration();
}