babel/lib/6to5/transformers/destructuring.js

93 lines
2.1 KiB
JavaScript

var util = require("../util");
var b = require("ast-types").builders;
var _ = require("lodash");
var isPattern = function (id) {
return id.type === "ArrayPattern" || id.type === "ObjectPattern";
};
exports.VariableDeclaration = function (node, parent, opts, generateUid) {
var nodes = [];
var hasPattern = false;
_.each(node.declarations, function (declar) {
if (isPattern(declar.id)) {
hasPattern = true;
return false;
}
});
if (!hasPattern) return;
//
var buildVariableAssign = function (id, init) {
return b.variableDeclaration(node.kind, [
b.variableDeclarator(id, init)
]);
};
var push = function (pattern, parentId) {
if (pattern.type === "ObjectPattern") {
pushObjectPattern(pattern, parentId);
} else if (pattern.type === "ArrayPattern") {
pushArrayPattern(pattern, parentId);
}
};
var pushObjectPattern = function (pattern, parentId) {
_.each(pattern.properties, function (prop) {
var id = prop.value;
var init = b.memberExpression(parentId, prop.key, false);
if (isPattern(id)) {
push(id, init);
} else {
nodes.push(buildVariableAssign(id, init));
}
});
};
var pushArrayPattern = function (pattern, parentId) {
_.each(pattern.elements, function (id, i) {
var init = b.memberExpression(parentId, b.literal(i), true);
if (id.type === "Identifier") {
nodes.push(buildVariableAssign(id, init));
} else {
push(id, init);
}
});
};
var pushPattern = function (id, init) {
if (init.type !== "MemberExpression" && init.type !== "Identifier") {
var key = generateUid("ref");
nodes.push(util.template("variable-assign", {
KEY: key,
VALUE: init
}, true));
init = b.identifier(key);
}
push(id, init);
};
//
_.each(node.declarations, function (declar) {
var init = declar.init;
var id = declar.id;
if (isPattern(id)) {
pushPattern(id, init);
} else {
nodes.push(buildVariableAssign(id, init));
}
});
return nodes;
};