overlookmotel / livepack / 6956398548

/* --------------------

 * livepack module

 * Code instrumentation block functions

 * ------------------*/

'use strict';

// Export

module.exports = {

        createBlock,

        createBlockWithId,

        createAndEnterBlock,

        createBlockId,

        createBinding,

        createBindingWithoutNameCheck,

        createThisBinding,

        createArgumentsBinding,

        createNewTargetBinding,

        getOrCreateExternalVar,

        activateBlock,

        activateBinding,

        createBlockTempVar

};

// Modules

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

// Imports

const {

                createScopeIdVarNode, createTempVarNode, checkInternalVarNameClash

        } = require('./internalVars.js'),

        {createArrayOrPush} = require('../shared/functions.js');

// Exports

/**

 * Create block.

 * @param {string} [name] - Block name

 * @param {boolean} isVarsBlock - `true` if is a vars block

 * @param {Object} state - State object

 * @returns {Object} - Block object

 */

function createBlock(name, isVarsBlock, state) {

        return createBlockWithId(createBlockId(state), name, isVarsBlock, state);

}

/**

 * Create block with specified ID.

 * @param {number} id - Block ID

 * @param {string} [name] - Block name

 * @param {boolean} isVarsBlock - `true` if is a vars block

 * @param {Object} state - State object

 * @returns {Object} - Block object

 */

function createBlockWithId(id, name, isVarsBlock, state) {

        const parent = state.currentBlock;

                name,

                parent,

                bindings: Object.create(null),

                varsBlock: undefined,

                scopeIdVarNode: undefined,

                tempVarNodes: undefined

        };

        block.varsBlock = isVarsBlock ? block : parent.varsBlock;

        return block;

}

/**

 * Create block and enter it.

 * @param {string} [name] - Block name

 * @param {boolean} isVarsBlock - `true` if is a vars block

 * @param {Object} state - State object

 * @returns {Object} - Block object

 */

function createAndEnterBlock(name, isVarsBlock, state) {

        // eslint-disable-next-line no-return-assign

        return state.currentBlock = createBlock(name, isVarsBlock, state);

}

/**

 * Create unique block ID.

 * @param {Object} state - State object

 * @returns {number} - Block ID

 */

function createBlockId(state) {

        return state.nextBlockId++;

}

/**

 * Create binding for variable in block.

 * Also check if `varName` potentially clashes with Livepack's internal vars.

 *

 * @param {Object} block - Block object

 * @param {string} varName - Variable name

 * @param {Object} props - Properties object

 * @param {boolean} [props.isConst=false] - `true` if is const

 * @param {boolean} [props.isSilentConst=false] - `true` if is function expression name,

 *   assignment to which fails silently in sloppy mode

 * @param {boolean} [props.isVar=false] - `true` if defined with `var` statement or function declaration

 * @param {boolean} [props.isFrozenName=false] - `true` if is var which is not renamed when used

 *   inside function in which it's bound

 * @param {Array<string>} [props.argNames] - Linked argument names (only relevant for `arguments`)

 * @param {Object} state - State object

 * @returns {Object} - Binding object

 */

function createBinding(block, varName, props, state) {

        checkInternalVarNameClash(varName, state);

        return createBindingWithoutNameCheck(block, varName, props);

}

/**

 * Create binding for variable in block.

 * Do not check if `varName` potentially clashes with Livepack's internal vars.

 * Intended to be called for vars which it's known are non-clashing e.g. `arguments`.

 *

 * @param {Object} block - Block object

 * @param {string} varName - Variable name

 * @param {Object} props - Properties object

 * @param {Object} [props.varNode] - Identifier AST node for var which will go in tracker function call

 * @param {boolean} [props.isConst=false] - `true` if is const

 * @param {boolean} [props.isSilentConst=false] - `true` if is function expression name,

 *   assignment to which fails silently in sloppy mode

 * @param {boolean} [props.isVar=false] - `true` if defined with `var` statement or function declaration

 * @param {boolean} [props.isFrozenName=false] - `true` if is var which is not renamed when used

 *   inside function in which it's bound

 * @param {Array<string>} [props.argNames] - Linked argument names (only relevant for `arguments`)

 * @returns {Object} - Binding object

 */

function createBindingWithoutNameCheck(block, varName, props) {

        return block.bindings[varName] = { // eslint-disable-line no-return-assign

                name: varName,

                varNode: props.varNode,

                isConst: !!props.isConst,

                isSilentConst: !!props.isSilentConst,

                isVar: !!props.isVar,

                isFrozenName: !!props.isFrozenName,

                argNames: props.argNames,

                trails: [] // Trails of usages within same function as binding, where var not function or frozen

        };

}

/**

 * Create binding for `this`.

 * @param {Object} block - Block object

 * @returns {Object} - Binding object

 */

function createThisBinding(block) {

        // `isFrozenName: true` because it cannot be renamed within function in which it's created.

        // If `this` has to be substituted for a temp var for transpiled `super()`,

        // `isFrozenName` will be set to false.

        return createBindingWithoutNameCheck(

                // eslint-disable-next-line no-use-before-define

                block, 'this', {varNode: thisNode, isConst: true, isFrozenName: true}

        );

}

const thisNode = t.thisExpression();

/**

 * Create binding for function `arguments`.

 * @param {Object} block - Block object

 * @param {boolean} isConst - `true` if is const (strict mode)

 * @param {Array<string>} argNames - Linked argument names

 * @returns {Object} - Binding object

 */

function createArgumentsBinding(block, isConst, argNames) {

        // `isFrozenName: true` because it cannot be renamed within function in which it's created

        return createBindingWithoutNameCheck(block, 'arguments', {isConst, isFrozenName: true, argNames});

}

/**

 * Create binding for `new.target`.

 * @param {Object} block - Block object

 * @returns {Object} - Binding object

 */

function createNewTargetBinding(block) {

        // `isFrozenName: true` because it cannot be renamed within function in which it's created

        /* eslint-disable no-use-before-define */

        newTargetNode ||= t.metaProperty(t.identifier('new'), t.identifier('target'));

        return createBindingWithoutNameCheck(

                block, 'new.target', {varNode: newTargetNode, isConst: true, isFrozenName: true}

        /* eslint-enable no-use-before-define */

}

let newTargetNode;

/**

 * Get or create an external var in a function.

 * @param {Map} externalVars - External vars for function. Map keyed by block object.

 * @param {Object} block - Block object

 * @param {string} varName - Var name

 * @param {Object} binding - Binding object

 * @returns {Object} - External var object

 */

function getOrCreateExternalVar(externalVars, block, varName, binding) {

        let blockVars = externalVars.get(block),

                externalVar;

        if (blockVars) {

                externalVar = blockVars[varName];

        } else {

                blockVars = Object.create(null);

                externalVars.set(block, blockVars);

        }

        if (!externalVar) {

                externalVar = {

                        binding,

                        isReadFrom: false,

                        isAssignedTo: false,

                        isFrozenName: false,

                        trails: []

                };

                blockVars[varName] = externalVar;

        }

        return externalVar;

}

/**

 * Activate block.

 * Called when block contains a binding which is referenced within a function.

 * @param {Object} block - Block object

 * @param {Object} state - State object

 * @returns {undefined}

 */

function activateBlock(block, state) {

        const {varsBlock} = block;

        if (!varsBlock.scopeIdVarNode) varsBlock.scopeIdVarNode = createScopeIdVarNode(varsBlock.id, state);

}

/**

 * Activate binding.

 * Called when a binding is accessed from within a function.

 * @param {Object} binding - Binding object

 * @param {string} varName - Var name

 * @returns {undefined}

 */

function activateBinding(binding, varName) {

        if (!binding.varNode) binding.varNode = t.identifier(varName);

}

/**

 * Create temp var in block.

 * @param {Object} block - Block object

 * @param {Object} state - State object

 * @returns {undefined}

 */

function createBlockTempVar(block, state) {

        const tempVarNode = createTempVarNode(state);

        createArrayOrPush(block.varsBlock, 'tempVarNodes', tempVarNode);

        return tempVarNode;

}