babel/lib/6to5/transformation/transformers/es6/parameters.default.js

83 lines
2.0 KiB
JavaScript

"use strict";
var traverse = require("../../../traverse");
var util = require("../../../util");
var t = require("../../../types");
var hasDefaults = function (node) {
for (var i = 0; i < node.params.length; i++) {
if (t.isAssignmentPattern(node.params[i])) return true;
}
return false;
};
var iifeVisitor = {
enter: function (node, parent, scope, context, state) {
if (t.isReferencedIdentifier(node, parent) && scope.hasOwn(node.name)) {
state.iife = true;
context.stop();
}
}
};
exports.Function = function (node, parent, scope) {
if (!hasDefaults(node)) return;
t.ensureBlock(node);
var iife = false;
var body = [];
var argsIdentifier = t.identifier("arguments");
argsIdentifier._ignoreAliasFunctions = true;
var lastNonDefaultParam = 0;
var state = { iife: false, scope: scope };
for (var i = 0; i < node.params.length; i++) {
var param = node.params[i];
if (!t.isAssignmentPattern(param)) {
lastNonDefaultParam = +i + 1;
continue;
}
var left = param.left;
var right = param.right;
node.params[i] = scope.generateUidIdentifier("x");
if (!state.iife) {
if (t.isIdentifier(right) && scope.hasOwn(right.name)) {
state.iife = true;
} else {
traverse(right, iifeVisitor, scope, state);
}
}
var defNode = util.template("default-parameter", {
VARIABLE_NAME: left,
DEFAULT_VALUE: right,
ARGUMENT_KEY: t.literal(+i),
ARGUMENTS: argsIdentifier
}, true);
defNode._blockHoist = node.params.length - i;
body.push(defNode);
}
// we need to cut off all trailing default parameters
node.params = node.params.slice(0, lastNonDefaultParam);
if (state.iife) {
var container = t.functionExpression(null, [], node.body, node.generator);
container._aliasFunction = true;
body.push(t.returnStatement(t.callExpression(container, [])));
node.body = t.blockStatement(body);
} else {
node.body.body = body.concat(node.body.body);
}
};