7094432425

Committed 05 Dec 2023 12:27AM UTC coverage: 90.476% (+0.2%) from 90.307%

Build # 7094432425

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github

Committed by

overlookmotel

Commit Message

Instrument: Prevent side-effects serializing classes with properties [fix]

Fixes #549.

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88.89

/lib/instrument/tracking.js

/* --------------------
 * livepack module
 * Code instrumentation functions to add vars and tracker to functions/blocks
 * ------------------*/

'use strict';

// Export
module.exports = {
        insertBlockVarsIntoBlockStatement,
        insertTrackerCodeIntoFunction
};

// Modules
const t = require('@babel/types');

// Imports
const {createTempVarNode} = require('./internalVars.js'),
        {copyLocAndComments} = require('./utils.js');

// Exports

/**
 * Insert block var declarations at start of block statement.
 * @param {Object} block - Block object
 * @param {Object} blockNode - Statement block / program AST node
 * @param {Object} state - State object
 * @returns {undefined}
 */
function insertBlockVarsIntoBlockStatement(block, blockNode, state) {
        const {scopeIdVarNode} = block;
        if (!scopeIdVarNode) return;

        // `const livepack_scopeId_1 = livepack_getScopeId()`
        const statementNodes = [
                t.variableDeclaration(
                        'const', [t.variableDeclarator(scopeIdVarNode, t.callExpression(state.getScopeIdVarNode, []))]
                )
        ];

        // `let livepack_temp_2, livepack_temp_3`
        const {tempVarNodes} = block;
        if (tempVarNodes) {
                statementNodes[1] = t.variableDeclaration(
                        'let', tempVarNodes.map(tempVarNode => t.variableDeclarator(tempVarNode, null))
                );
        }

        blockNode.body.unshift(...statementNodes);
}

/**
 * Insert tracker code, scope ID var and temp vars into function.
 * If function has complex params, insert into params. Otherwise, into function body.
 * @param {Object} fn - Function object
 * @param {Object} fnNode - Function AST node
 * @param {Object} paramsBlock - Function params block object
 * @param {Object} [bodyBlock] - Function body block object
 *   (`undefined` if arrow function with no body block)
 * @param {Object} [trackerNode] - AST node for tracker call (or undefined if no tracker to insert)
 * @param {Object} state - State object
 * @returns {undefined}
 */
function insertTrackerCodeIntoFunction(fn, fnNode, paramsBlock, bodyBlock, trackerNode, state) {
        const {firstComplexParamIndex} = fn;
        if (firstComplexParamIndex === undefined) {
                insertTrackerCodeIntoFunctionBody(fnNode, paramsBlock, bodyBlock, trackerNode, state);
        } else {
                insertTrackerCodeIntoFunctionParams(
                        fnNode, paramsBlock, bodyBlock, trackerNode, firstComplexParamIndex, state
                );
        }
}

/**
 * Insert tracker code, scope ID var and temp vars into function body.
 * @param {Object} fnNode - Function AST node
 * @param {Object} paramsBlock - Function params block object
 * @param {Object} [bodyBlock] - Function body block object
 *   (`undefined` if arrow function with no body block)
 * @param {Object} [trackerNode] - AST node for tracker call (or undefined if no tracker to insert)
 * @param {Object} state - State object
 * @returns {undefined}
 */
function insertTrackerCodeIntoFunctionBody(fnNode, paramsBlock, bodyBlock, trackerNode, state) {
        // Exit if no tracker, scope ID var, or temp vars to insert
        const block = bodyBlock || paramsBlock;
        if (!trackerNode && !block.scopeIdVarNode) return;

        // If body is not a block statement, convert it to one
        let bodyNode = fnNode.body;
        if (!bodyBlock) bodyNode = fnNode.body = t.blockStatement([t.returnStatement(bodyNode)]);

        // Insert scope ID and temp var nodes
        insertBlockVarsIntoBlockStatement(block, bodyNode, state);

        // Insert tracker call
        if (trackerNode) bodyNode.body.unshift(t.expressionStatement(trackerNode));
}

/**
 * Insert tracker code, scope ID var and temp vars into function params.
 *
 * Objectives:
 *   - Insert tracker call before any code in function params which could produce side effects.
 *   - Initialize scope ID and temp vars before they may be used
 *     (including coping with scenario where error thrown in params)
 *   - Allow functions defined in params to access other params.
 *   - Allow functions defined in params to access vars outside function which are shadowed in
 *     function body.
 *   - Do not move initialization of params into function body, to:
 *     1. Preserve behavior of generator functions which execute params upon calling function
 *        but only execute function body when `.next()` called on generator.
 *     2. Avoid complications with hoisted `var` statements and sloppy function declarations.
 *
 * See https://github.com/overlookmotel/livepack/issues/108
 *
 * Solution is to add an object pattern rest element to end of params.
 * Tracker call is added as key for object property and is first to be evaluated.
 * `livepack_tracker()` returns a dummy Symbol, so this property will never exist
 * on the rest object being destructured.
 * Any complex params are moved into an array deconstruction expression and will be evaluated
 * in original order.
 * If function already has a rest element, it's merged with the substitute.
 *
 * `(x = 1, {y}, ...z) => () => [x, y, z]` ->
 * `(
 *   livepack_temp1 = void 0, // `= void 0` preserves `fn.length = 0`
 *   livepack_temp2,
 *   ...{
 *     [ livepack_tracker(...) ]: [
 *       livepack_scopeId_1,
 *       livepack_temp3,
 *       x = 1,
 *       {y}
 *     ] = [
 *       livepack_getScopeId(),
 *       () => z = livepack_getScopeId.toRest(z) // Convert `z` from object to array,
 *       livepack_temp1,
 *       livepack_temp2
 *     ],
 *     ...z
 *   }
 * ) => ( livepack_temp3(), () => [x, y, z] )`
 *
 * @param {Object} fnNode - Function AST node
 * @param {Object} paramsBlock - Function params block object
 * @param {Object} [bodyBlock] - Function body block object
 *   (`undefined` if arrow function with no body block)
 * @param {Object} [trackerNode] - AST node for tracker call (or undefined if no tracker to insert)
 * @param {number} firstComplexParamIndex - Index of first param which is a complex param
 * @param {Object} state - State object
 * @returns {undefined}
 */
function insertTrackerCodeIntoFunctionParams(
        fnNode, paramsBlock, bodyBlock, trackerNode, firstComplexParamIndex, state
) {
        // Exit if no tracker, scope ID var, or temp vars to insert
        const {scopeIdVarNode} = paramsBlock;
        if (!trackerNode && !scopeIdVarNode) return;

        // Create object pattern to use as rest element.
        // `{ [ livepack_tracker(...) ]: [] = [] }`
        // Assignments will be added to each side of `[] = []` to init vars and assign to them.
        // If no tracker to insert (class constructor where class has prototype properties),
        // create `livepack_tracker()` call with no arguments.
        const leftNodes = [],
                rightNodes = [],
                propNodes = [
                        t.objectProperty(
                                trackerNode || t.callExpression(state.trackerVarNode, []),
                                t.assignmentPattern(t.arrayPattern(leftNodes), t.arrayExpression(rightNodes)),
                                true
                        )
                ],
                objNode = t.objectPattern(propNodes);

        function addAssignment(leftNode, rightNode) {
                leftNodes.push(leftNode);
                rightNodes.push(rightNode);
        }

        // Insert assignments for scope ID var node and temp var nodes
        if (scopeIdVarNode) {
                addAssignment(scopeIdVarNode, t.callExpression(state.getScopeIdVarNode, []));

                const {tempVarNodes} = paramsBlock;
                if (tempVarNodes) tempVarNodes.forEach(tempVarNode => addAssignment(tempVarNode, null));
        }

        // Flatten rest array param if present.
        // `(w, ...[x, {y}, ...z])` => `(w, x, {y}, ...z)`
        // `(x, ...[, , y, , z, , ])` => `(x, , , y, , z)`
        // `(...[x, ...[y, ...z]]])` => `(x, y, ...z)`
        // `(...[...[...x]]])` => `(...x)`
        // `(...[])` => `()`
        // If first param replacing rest array would cause function's `.length` to increase,
        // record that it needs to have a default added to prevent this
        const paramNodes = fnNode.params;
        let lastParamIndex = paramNodes.length - 1,
                firstLengthTrucatingIndex = Infinity;
        if (flattenRestArray(paramNodes, lastParamIndex, objNode)) {
                const paramNode = paramNodes[firstComplexParamIndex];
                if (
                        paramNode === null || (paramNode.type !== 'AssignmentPattern' && paramNode.type !== 'RestElement')
                ) {
                        firstLengthTrucatingIndex = lastParamIndex;
                }
                lastParamIndex = paramNodes.length - 1;
        }

        // Handle rest element
        if (lastParamIndex !== -1) {
                const paramNode = paramNodes[lastParamIndex];
                if (paramNode.type === 'RestElement') {
                        const argumentNode = paramNode.argument;
                        if (argumentNode.type === 'Identifier') {
                                // Capture rest arguments as an object.
                                // Create a function which uses `livepack_getScopeId.toRest()` to convert it to an array.
                                // Insert call to this function into function body.
                                // `(...x) => x` -> `(...{
                                //   [livepack_tracker(...)]: [livepack_temp_1] = [() => x = livepack_getScopeId.toRest(x)],
                                //   ...x
                                // }) => (livepack_temp_1(), x)`
                                // NB: Function to convert to array is placed inside params rather than in function body
                                // in case the var is shadowed inside function body by a function declaration.
                                // e.g. `(getX = () => x, ...x) => { function x() {}; return getX; }`
                                const convertToArrayNode = createTempVarNode(state);
                                addAssignment(
                                        convertToArrayNode,
                                        // `() => x = livepack_getScopeId.toRest(x)`
                                        t.arrowFunctionExpression(
                                                [],
                                                t.assignmentExpression('=', argumentNode, t.callExpression(
                                                        t.memberExpression(state.getScopeIdVarNode, t.identifier('toRest')),
                                                        [argumentNode]
                                                ))
                                        )
                                );

                                // Add call in function body
                                const callNode = t.callExpression(convertToArrayNode, []);
                                if (bodyBlock) {
                                        fnNode.body.body.unshift(t.expressionStatement(callNode));
                                } else {
                                        fnNode.body = t.sequenceExpression([callNode, fnNode.body]);
                                }

                                // Add rest element to object pattern
                                propNodes.push(paramNode);
                        } else {
                                // ObjectPattern - add properties to replacement object pattern
                                copyLocAndComments(objNode, paramNode);
                                propNodes.push(...argumentNode.properties);
                        }

                        // Remove rest element
                        paramNodes.pop();
                        lastParamIndex--;
                }
        }

        // Convert all other params to assignments in object pattern
        for (let index = firstComplexParamIndex; index <= lastParamIndex; index++) {
                // Replace param with a temp var
                const paramNode = paramNodes[index],
                        tempVarNode = createTempVarNode(state);
                paramNodes[index] = tempVarNode;

                // Add assignment to object pattern.
                // NB: Function params cannot be `null` usually, but `flattenRestArray()` can produce them.
                if (paramNode) {
                        addAssignment(paramNode, tempVarNode);
                        if (paramNode.type === 'AssignmentPattern' && firstLengthTrucatingIndex > index) {
                                firstLengthTrucatingIndex = index;
                        }
                }
        }

        // If above operations would change function's `.length` property by replacing what were
        // complex params with simple ones, add a default `= void 0` to param
        // to reduce `.length` to as it was originally
        if (firstLengthTrucatingIndex !== Infinity) {
                paramNodes[firstLengthTrucatingIndex] = t.assignmentPattern(
                        paramNodes[firstLengthTrucatingIndex], t.unaryExpression('void', t.numericLiteral(0))
                );
        }

        // Add rest object pattern to function params
        paramNodes.push(t.restElement(objNode));
}

/**
 * Flatten rest array.
 * If last element of rest array is itself a rest array, recursively flatten.
 * Mutates `paramNodes` passed in.
 * e.g. `...[x, y]` -> `x, y`, `...[...[x]]` -> `x`
 * @param {Array<Object>} paramNodes - Function params or rest argument elements AST nodes
 * @param {number} index - `paramNodes.length - 1`
 * @param {Object} objNode - Object pattern AST node
 * @returns {boolean} - `true` if flattened a rest array
 */
function flattenRestArray(paramNodes, index, objNode) {
        // Exit if not a rest array
        const paramNode = paramNodes[index];
        if (paramNode.type !== 'RestElement') return false;
        const argumentNode = paramNode.argument;
        if (argumentNode.type !== 'ArrayPattern') return false;

        // Copy comments from array pattern as it's going to be deleted
        copyLocAndComments(objNode, argumentNode);

        // Remove empty elements from end of array pattern. Exit if none remaining.
        const elementNodes = argumentNode.elements;
        let lastElementIndex = elementNodes.length - 1;
        while (true) { // eslint-disable-line no-constant-condition
                if (lastElementIndex === -1) {
                        paramNodes.pop();
                        return true;
                }
                if (elementNodes[lastElementIndex]) break;
                elementNodes.pop();
                lastElementIndex--;
        }

        // Recusively flatten
        flattenRestArray(elementNodes, lastElementIndex, objNode);
        paramNodes.splice(index, 1, ...elementNodes);

        return true;
}

1	/* --------------------	62✔
2	* livepack module	62✔
3	* Code instrumentation functions to add vars and tracker to functions/blocks	62✔
4	* ------------------*/	62✔
5		62✔
6	'use strict';	62✔
7		62✔
8	// Export	62✔
9	module.exports = {	62✔
10	insertBlockVarsIntoBlockStatement,	62✔
11	insertTrackerCodeIntoFunction	62✔
12	};	62✔
13		62✔
14	// Modules	62✔
15	const t = require('@babel/types');	62✔
16		62✔
17	// Imports	62✔
18	const {createTempVarNode} = require('./internalVars.js'),	62✔
19	{copyLocAndComments} = require('./utils.js');	62✔
20		62✔
21	// Exports	62✔
22		62✔
23	/**	62✔
24	* Insert block var declarations at start of block statement.	62✔
25	* @param {Object} block - Block object	62✔
26	* @param {Object} blockNode - Statement block / program AST node	62✔
27	* @param {Object} state - State object	62✔
28	* @returns {undefined}	62✔
29	*/	62✔
30	function insertBlockVarsIntoBlockStatement(block, blockNode, state) {	33,286✔
31	const {scopeIdVarNode} = block;	33,286✔
32	if (!scopeIdVarNode) return;	33,286✔
33		8,010✔
34	// `const livepack_scopeId_1 = livepack_getScopeId()`	8,010✔
35	const statementNodes = [	8,010✔
36	t.variableDeclaration(	8,010✔
37	'const', [t.variableDeclarator(scopeIdVarNode, t.callExpression(state.getScopeIdVarNode, []))]	8,010✔
38	)	34✔
39	];	34✔
40		34✔
41	// `let livepack_temp_2, livepack_temp_3`	34✔
42	const {tempVarNodes} = block;	34✔
43	if (tempVarNodes) {	34✔
44	statementNodes[1] = t.variableDeclaration(	34✔
45	'let', tempVarNodes.map(tempVarNode => t.variableDeclarator(tempVarNode, null))	34✔
46	);	2✔
47	}	2✔
48		2✔
49	blockNode.body.unshift(...statementNodes);	2✔
50	}	2✔
51		2✔
52	/**	2✔
53	* Insert tracker code, scope ID var and temp vars into function.	2✔
54	* If function has complex params, insert into params. Otherwise, into function body.	2✔
55	* @param {Object} fn - Function object	2✔
56	* @param {Object} fnNode - Function AST node	2✔
UNCOV 57	* @param {Object} paramsBlock - Function params block object	×
58	* @param {Object} [bodyBlock] - Function body block object	×
59	* (`undefined` if arrow function with no body block)	×
NEW 60	* @param {Object} [trackerNode] - AST node for tracker call (or undefined if no tracker to insert)	×
61	* @param {Object} state - State object	34✔
62	* @returns {undefined}	2✔
63	*/	2✔
64	function insertTrackerCodeIntoFunction(fn, fnNode, paramsBlock, bodyBlock, trackerNode, state) {	29,808✔
65	const {firstComplexParamIndex} = fn;	29,808✔
66	if (firstComplexParamIndex === undefined) {	29,808✔
67	insertTrackerCodeIntoFunctionBody(fnNode, paramsBlock, bodyBlock, trackerNode, state);	27,412✔
68	} else {	29,808✔
69	insertTrackerCodeIntoFunctionParams(	2,396✔
70	fnNode, paramsBlock, bodyBlock, trackerNode, firstComplexParamIndex, state	2,396✔
71	);	2,396✔
72	}	2,396✔
73	}	29,808✔
74		62✔
75	/**	62✔
76	* Insert tracker code, scope ID var and temp vars into function body.	62✔
77	* @param {Object} fnNode - Function AST node	62✔
78	* @param {Object} paramsBlock - Function params block object	62✔
79	* @param {Object} [bodyBlock] - Function body block object	62✔
80	* (`undefined` if arrow function with no body block)	34✔
81	* @param {Object} [trackerNode] - AST node for tracker call (or undefined if no tracker to insert)	34✔
82	* @param {Object} state - State object	34✔
UNCOV 83	* @returns {undefined}	×
UNCOV 84	*/	×
85	function insertTrackerCodeIntoFunctionBody(fnNode, paramsBlock, bodyBlock, trackerNode, state) {	27,412✔
86	// Exit if no tracker, scope ID var, or temp vars to insert	27,412✔
87	const block = bodyBlock \|\| paramsBlock;	27,412✔
88	if (!trackerNode && !block.scopeIdVarNode) return;	27,412!
89		27,412✔
90	// If body is not a block statement, convert it to one	27,412✔
91	let bodyNode = fnNode.body;	27,412✔
92	if (!bodyBlock) bodyNode = fnNode.body = t.blockStatement([t.returnStatement(bodyNode)]);	27,412✔
93		27,412✔
94	// Insert scope ID and temp var nodes	27,412✔
95	insertBlockVarsIntoBlockStatement(block, bodyNode, state);	27,412✔
96		27,412✔
97	// Insert tracker call	27,412✔
98	if (trackerNode) bodyNode.body.unshift(t.expressionStatement(trackerNode));	27,412✔
99	}	27,412✔
100		62✔
101	/**	62✔
102	* Insert tracker code, scope ID var and temp vars into function params.	62✔
103	*	62✔
104	* Objectives:	62✔
105	* - Insert tracker call before any code in function params which could produce side effects.	62✔
106	* - Initialize scope ID and temp vars before they may be used	62✔
107	* (including coping with scenario where error thrown in params)	32✔
108	* - Allow functions defined in params to access other params.	32✔
109	* - Allow functions defined in params to access vars outside function which are shadowed in	32✔
110	* function body.	32✔
111	* - Do not move initialization of params into function body, to:	32✔
112	* 1. Preserve behavior of generator functions which execute params upon calling function	32!
113	* but only execute function body when `.next()` called on generator.	32✔
114	* 2. Avoid complications with hoisted `var` statements and sloppy function declarations.	32✔
115	*	32✔
116	* See https://github.com/overlookmotel/livepack/issues/108	32✔
117	*	32✔
118	* Solution is to add an object pattern rest element to end of params.	32✔
119	* Tracker call is added as key for object property and is first to be evaluated.	62✔
120	* `livepack_tracker()` returns a dummy Symbol, so this property will never exist	62✔
121	* on the rest object being destructured.	62✔
122	* Any complex params are moved into an array deconstruction expression and will be evaluated	62✔
123	* in original order.	62✔
124	* If function already has a rest element, it's merged with the substitute.	62✔
125	*	62✔
126	* `(x = 1, {y}, ...z) => () => [x, y, z]` ->	62✔
127	* `(	62✔
128	* livepack_temp1 = void 0, // `= void 0` preserves `fn.length = 0`	62✔
129	* livepack_temp2,	62✔
130	* ...{	62✔
131	* [ livepack_tracker(...) ]: [	62✔
132	* livepack_scopeId_1,	62✔
133	* livepack_temp3,	62✔
134	* x = 1,	62✔
135	* {y}	62✔
136	* ] = [	62✔
137	* livepack_getScopeId(),	62✔
138	* () => z = livepack_getScopeId.toRest(z) // Convert `z` from object to array,	62✔
139	* livepack_temp1,	62✔
140	* livepack_temp2	62✔
141	* ],	62✔
142	* ...z	62✔
143	* }	62✔
144	* ) => ( livepack_temp3(), () => [x, y, z] )`	62✔
145	*	62✔
146	* @param {Object} fnNode - Function AST node	62✔
147	* @param {Object} paramsBlock - Function params block object	62✔
148	* @param {Object} [bodyBlock] - Function body block object	62✔
149	* (`undefined` if arrow function with no body block)	62✔
150	* @param {Object} [trackerNode] - AST node for tracker call (or undefined if no tracker to insert)	62✔
151	* @param {number} firstComplexParamIndex - Index of first param which is a complex param	62✔
152	* @param {Object} state - State object	62✔
153	* @returns {undefined}	62✔
154	*/	62✔
155	function insertTrackerCodeIntoFunctionParams(	2,396✔
156	fnNode, paramsBlock, bodyBlock, trackerNode, firstComplexParamIndex, state	2,396✔
157	) {	2,396✔
158	// Exit if no tracker, scope ID var, or temp vars to insert	2,396✔
159	const {scopeIdVarNode} = paramsBlock;	2,396✔
160	if (!trackerNode && !scopeIdVarNode) return;	2,396!
161		2,396✔
162	// Create object pattern to use as rest element.	2,396✔
163	// `{ [ livepack_tracker(...) ]: [] = [] }`	2,396✔
164	// Assignments will be added to each side of `[] = []` to init vars and assign to them.	2,396✔
165	// If no tracker to insert (class constructor where class has prototype properties),	2,396✔
166	// create `livepack_tracker()` call with no arguments.	2,396✔
167	const leftNodes = [],	2,396✔
168	rightNodes = [],	2,396✔
169	propNodes = [	2,396✔
170	t.objectProperty(	2,396✔
171	trackerNode \|\| t.callExpression(state.trackerVarNode, []),	2,396✔
172	t.assignmentPattern(t.arrayPattern(leftNodes), t.arrayExpression(rightNodes)),	2,396✔
173	true	2,396✔
174	)	2,396✔
175	],	2,396✔
176	objNode = t.objectPattern(propNodes);	2,396✔
177		2,396✔
178	function addAssignment(leftNode, rightNode) {	2,396✔
179	leftNodes.push(leftNode);	3,120✔
180	rightNodes.push(rightNode);	3,120✔
181	}	3,120✔
182		2,396✔
183	// Insert assignments for scope ID var node and temp var nodes	2,396✔
184	if (scopeIdVarNode) {	2✔
185	addAssignment(scopeIdVarNode, t.callExpression(state.getScopeIdVarNode, []));	2✔
186		2✔
187	const {tempVarNodes} = paramsBlock;	2✔
188	if (tempVarNodes) tempVarNodes.forEach(tempVarNode => addAssignment(tempVarNode, null));	2✔
189	}	2✔
190		2✔
191	// Flatten rest array param if present.	2✔
UNCOV 192	// `(w, ...[x, {y}, ...z])` => `(w, x, {y}, ...z)`	×
193	// `(x, ...[, , y, , z, , ])` => `(x, , , y, , z)`	2✔
194	// `(...[x, ...[y, ...z]]])` => `(x, y, ...z)`	2✔
195	// `(...[...[...x]]])` => `(...x)`	2✔
196	// `(...[])` => `()`	2✔
197	// If first param replacing rest array would cause function's `.length` to increase,	2!
198	// record that it needs to have a default added to prevent this	2✔
199	const paramNodes = fnNode.params;	2✔
200	let lastParamIndex = paramNodes.length - 1,	2✔
201	firstLengthTrucatingIndex = Infinity;	2✔
202	if (flattenRestArray(paramNodes, lastParamIndex, objNode)) {	2✔
203	const paramNode = paramNodes[firstComplexParamIndex];	2✔
204	if (	2✔
205	paramNode === null \|\| (paramNode.type !== 'AssignmentPattern' && paramNode.type !== 'RestElement')	2!
UNCOV 206	) {	✔
207	firstLengthTrucatingIndex = lastParamIndex;	2✔
208	}	2✔
209	lastParamIndex = paramNodes.length - 1;	2✔
210	}	2✔
211		2✔
212	// Handle rest element	2✔
213	if (lastParamIndex !== -1) {	2✔
214	const paramNode = paramNodes[lastParamIndex];	2✔
215	if (paramNode.type === 'RestElement') {	8✔
216	const argumentNode = paramNode.argument;	8✔
217	if (argumentNode.type === 'Identifier') {	8✔
218	// Capture rest arguments as an object.	8✔
219	// Create a function which uses `livepack_getScopeId.toRest()` to convert it to an array.	2✔
220	// Insert call to this function into function body.	2✔
221	// `(...x) => x` -> `(...{	2✔
222	// [livepack_tracker(...)]: [livepack_temp_1] = [() => x = livepack_getScopeId.toRest(x)],	×
223	// ...x	×
UNCOV 224	// }) => (livepack_temp_1(), x)`	×
UNCOV 225	// NB: Function to convert to array is placed inside params rather than in function body	×
UNCOV 226	// in case the var is shadowed inside function body by a function declaration.	×
UNCOV 227	// e.g. `(getX = () => x, ...x) => { function x() {}; return getX; }`	×
228	const convertToArrayNode = createTempVarNode(state);	2✔
229	addAssignment(	2✔
230	convertToArrayNode,	2✔
231	// `() => x = livepack_getScopeId.toRest(x)`	2✔
232	t.arrowFunctionExpression(	2✔
233	[],	2✔
234	t.assignmentExpression('=', argumentNode, t.callExpression(	2✔
235	t.memberExpression(state.getScopeIdVarNode, t.identifier('toRest')),	2✔
236	[argumentNode]	2✔
237	))	2✔
238	)	2✔
239	);	2✔
240		2✔
241	// Add call in function body	2✔
242	const callNode = t.callExpression(convertToArrayNode, []);	2✔
243	if (bodyBlock) {	2✔
244	fnNode.body.body.unshift(t.expressionStatement(callNode));	2✔
245	} else {	2✔
246	fnNode.body = t.sequenceExpression([callNode, fnNode.body]);	2!
UNCOV 247	}	×
UNCOV 248		×
UNCOV 249	// Add rest element to object pattern	×
UNCOV 250	propNodes.push(paramNode);	×
UNCOV 251	} else {	✔
UNCOV 252	// ObjectPattern - add properties to replacement object pattern	×
UNCOV 253	copyLocAndComments(objNode, paramNode);	×
254	propNodes.push(...argumentNode.properties);	2✔
255	}	2✔
256		2✔
257	// Remove rest element	2✔
258	paramNodes.pop();	2✔
259	lastParamIndex--;	2✔
260	}	2✔
261	}	2✔
262		2✔
263	// Convert all other params to assignments in object pattern	2✔
264	for (let index = firstComplexParamIndex; index <= lastParamIndex; index++) {	2✔
265	// Replace param with a temp var	2✔
266	const paramNode = paramNodes[index],	2✔
267	tempVarNode = createTempVarNode(state);	2✔
268	paramNodes[index] = tempVarNode;	2✔
269		2✔
270	// Add assignment to object pattern.	2✔
271	// NB: Function params cannot be `null` usually, but `flattenRestArray()` can produce them.	2✔
272	if (paramNode) {	2✔
273	addAssignment(paramNode, tempVarNode);	2✔
274	if (paramNode.type === 'AssignmentPattern' && firstLengthTrucatingIndex > index) {	2✔
275	firstLengthTrucatingIndex = index;	2✔
276	}	2✔
277	}	2✔
278	}	2✔
279		2✔
280	// If above operations would change function's `.length` property by replacing what were	2✔
281	// complex params with simple ones, add a default `= void 0` to param	2✔
282	// to reduce `.length` to as it was originally	2✔
283	if (firstLengthTrucatingIndex !== Infinity) {	2✔
284	paramNodes[firstLengthTrucatingIndex] = t.assignmentPattern(	2✔
285	paramNodes[firstLengthTrucatingIndex], t.unaryExpression('void', t.numericLiteral(0))	2✔
286	);	2✔
287	}	2✔
288		2✔
289	// Add rest object pattern to function params	2✔
290	paramNodes.push(t.restElement(objNode));	2✔
291	}	2✔
292		2✔
293	/**	2✔
294	* Flatten rest array.	2✔
295	* If last element of rest array is itself a rest array, recursively flatten.	2✔
296	* Mutates `paramNodes` passed in.	2✔
297	* e.g. `...[x, y]` -> `x, y`, `...[...[x]]` -> `x`	2✔
298	* @param {Array<Object>} paramNodes - Function params or rest argument elements AST nodes	2✔
299	* @param {number} index - `paramNodes.length - 1`	2✔
300	* @param {Object} objNode - Object pattern AST node	2!
301	* @returns {boolean} - `true` if flattened a rest array	2✔
302	*/	2✔
303	function flattenRestArray(paramNodes, index, objNode) {	2,492✔
304	// Exit if not a rest array	2,492!
305	const paramNode = paramNodes[index];	2,492✔
306	if (paramNode.type !== 'RestElement') return false;	2,492✔
307	const argumentNode = paramNode.argument;	240✔
308	if (argumentNode.type !== 'ArrayPattern') return false;	1,354✔
309		96✔
310	// Copy comments from array pattern as it's going to be deleted	96✔
311	copyLocAndComments(objNode, argumentNode);	96✔
312		96✔
313	// Remove empty elements from end of array pattern. Exit if none remaining.	96✔
314	const elementNodes = argumentNode.elements;	96✔
315	let lastElementIndex = elementNodes.length - 1;	96✔
316	while (true) { // eslint-disable-line no-constant-condition	96✔
317	if (lastElementIndex === -1) {	96!
UNCOV 318	paramNodes.pop();	×
UNCOV 319	return true;	×
UNCOV 320	}	×
321	if (elementNodes[lastElementIndex]) break;	96✔
UNCOV 322	elementNodes.pop();	×
UNCOV 323	lastElementIndex--;	×
UNCOV 324	}	×
325		96✔
326	// Recusively flatten	96✔
327	flattenRestArray(elementNodes, lastElementIndex, objNode);	96✔
328	paramNodes.splice(index, 1, ...elementNodes);	96✔
329		96✔
330	return true;	96✔
331	}	2,492✔

overlookmotel / livepack / 7094432425

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