Function flattenDestructuringAssignment

test/fixtures/snapshot/typescript.js:91002–91076

* Flattens a DestructuringAssignment or a VariableDeclaration to an expression. * * @param node The node to flatten. * @param visitor An optional visitor used to visit initializers. * @param context The transformation context. * @param level Indicates the extent to which fla

(node, visitor, context, level, needsValue, createAssignmentCallback)

     * @param createAssignmentCallback An optional callback used to create the assignment expression.
     */
    function flattenDestructuringAssignment(node, visitor, context, level, needsValue, createAssignmentCallback) {
        var location = node;
        var value;
        if (ts.isDestructuringAssignment(node)) {
            value = node.right;
            while (ts.isEmptyArrayLiteral(node.left) || ts.isEmptyObjectLiteral(node.left)) {
                if (ts.isDestructuringAssignment(value)) {
                    location = node = value;
                    value = node.right;
                }
                else {
                    return ts.visitNode(value, visitor, ts.isExpression);
                }
            }
        }
        var expressions;
        var flattenContext = {
            context: context,
            level: level,
            downlevelIteration: !!context.getCompilerOptions().downlevelIteration,
            hoistTempVariables: true,
            emitExpression: emitExpression,
            emitBindingOrAssignment: emitBindingOrAssignment,
            createArrayBindingOrAssignmentPattern: function (elements) { return makeArrayAssignmentPattern(context.factory, elements); },
            createObjectBindingOrAssignmentPattern: function (elements) { return makeObjectAssignmentPattern(context.factory, elements); },
            createArrayBindingOrAssignmentElement: makeAssignmentElement,
            visitor: visitor
        };
        if (value) {
            value = ts.visitNode(value, visitor, ts.isExpression);
            if (ts.isIdentifier(value) && bindingOrAssignmentElementAssignsToName(node, value.escapedText) ||
                bindingOrAssignmentElementContainsNonLiteralComputedName(node)) {
                // If the right-hand value of the assignment is also an assignment target then
                // we need to cache the right-hand value.
                value = ensureIdentifier(flattenContext, value, /*reuseIdentifierExpressions*/ false, location);
            }
            else if (needsValue) {
                // If the right-hand value of the destructuring assignment needs to be preserved (as
                // is the case when the destructuring assignment is part of a larger expression),
                // then we need to cache the right-hand value.
                //
                // The source map location for the assignment should point to the entire binary
                // expression.
                value = ensureIdentifier(flattenContext, value, /*reuseIdentifierExpressions*/ true, location);
            }
            else if (ts.nodeIsSynthesized(node)) {
                // Generally, the source map location for a destructuring assignment is the root
                // expression.
                //
                // However, if the root expression is synthesized (as in the case
                // of the initializer when transforming a ForOfStatement), then the source map
                // location should point to the right-hand value of the expression.
                location = value;
            }
        }
        flattenBindingOrAssignmentElement(flattenContext, node, value, location, /*skipInitializer*/ ts.isDestructuringAssignment(node));
        if (value && needsValue) {
            if (!ts.some(expressions)) {