const eslintScope = require("eslint-scope");
const esquery = require("esquery");
const {
first,
get,
isString
} = require("lodash");
/**
* @private
* @ignore
*/
const nullResult = {
"meta": {
"kind": "Object"
},
"name": null,
"superClass": {
}
};
/**
* @private
* @ignore
*/
const queryContext = (context, descriptor) => first(esquery.match(
context.code.ast,
esquery.parse(descriptor)
));
/**
* @private
* @ignore
*/
const visitClass = (context) => {
const descriptor = ":matches(ClassDeclaration, ClassExpression)";
const node = queryContext(context, descriptor);
return {
"meta": {
"kind": "class"
},
"name": get(node, "id.name"),
"superClass": get(node, "superClass")
};
};
/**
* @private
* @ignore
*/
const visitNewExpression = (context) => {
const descriptor =
"ExpressionStatement > [left.property.name=\"prototype\"]" +
"[right.type=\"NewExpression\"]";
const node = queryContext(context, descriptor);
return {
"meta": {
"kind": "function"
},
"name": get(node, "left.object.name"),
"superClass": get(node, "right.callee")
};
};
/**
* @private
* @ignore
*/
const getSuperClass = (context, node) => {
const superClassName = get(
first(get(node, "declarations")),
"id.name"
);
return first(esquery.match(
context.code.ast,
esquery.parse(`Identifier[name="${superClassName}"]`)
));
};
/**
* @private
* @ignore
*/
const visitObjectExpression = (context) => {
const descriptor = ":matches(VariableDeclaration, AssignmentExpression" +
"[left.property.name=\"prototype\"][right.type=\"CallExpression\"]," +
"[right.callee.object.name=\"Object\"]" +
"[callee.property.name=\"create\"][arguments]" +
" [object][property.name=\"prototype\"])";
const node = queryContext(context, descriptor);
const superClass = getSuperClass(context, node);
return {
"meta": {
"kind": "Object"
},
"name": get(context.nodes.get(context.filePath), "name"),
superClass
};
};
/**
* @private
* @ignore
*/
const visitPrototypeConstructor = (context) => {
const descriptor = "AssignmentExpression" +
"[left.property.name=\"constructor\"][right.type=\"Identifier\"]";
const node = queryContext(context, descriptor);
return {
"meta": {
"kind": "function"
},
"name": get(node, "left.object.object.name"),
"superClass": get(node, "right")
};
};
/**
* Detects the prototype of an object whenever possible.
*
* @class
* @throws {TypeError} ⛔️ **Note:** PrototypeInspector does not have a
* working constructor. Invoking new PrototypeInspector will throw a TypeError.
*/
class PrototypeInspector {
constructor () {
const msg = "PrototypeInspector is static and does not " +
"have a working constructor.";
throw new TypeError(msg);
}
/**
* Returns a prototype [`ASTNode`](https://goo.gl/yTwW1m#node-objects).
*
* @param {ASTNode} node - A node to check. This node type is one of
* `Program`, `FunctionDeclaratikon`, `FunctionExpression`, and
* `ArrowFunctionExpression`.
* @memberOf PrototypeInspector
* @returns {ASTNode} The node's prototype.
* @static
*/
static getPrototypeOf (node) {
let index = 0;
const ONE = 1;
let proto = nullResult;
const fns = [
visitClass,
visitNewExpression,
visitPrototypeConstructor,
visitObjectExpression
];
for (; index < fns.length; index += ONE) {
proto = get(fns, index)(node);
if (isString(get(proto, "name"))) {
break;
}
}
return proto;
}
/**
* Returns the [`Scope`](https://goo.gl/AXjJ84#scope-interface) for
* a given Context.
*
* @param {CrcContext} context - A CrcContext instance.
* @memberOf PrototypeInspector
* @returns {Scope} The ESLint [`Scope`](https://goo.gl/AXjJ84#scope-interface).
* @static
*/
static getScopeOf (context) {
const scopeManager = eslintScope.analyze(context.code.ast);
return scopeManager.acquire(context.code.ast);
}
}
module.exports = PrototypeInspector;
