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Diffstat (limited to 'node_modules/regenerator-transform/lib/hoist.js')
| -rw-r--r-- | node_modules/regenerator-transform/lib/hoist.js | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/node_modules/regenerator-transform/lib/hoist.js b/node_modules/regenerator-transform/lib/hoist.js new file mode 100644 index 00000000..93491b06 --- /dev/null +++ b/node_modules/regenerator-transform/lib/hoist.js @@ -0,0 +1,144 @@ +"use strict"; + +var _util = require("./util"); + +var util = _interopRequireWildcard(_util); + +function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (obj != null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj.default = obj; return newObj; } } + +var hasOwn = Object.prototype.hasOwnProperty; + +// The hoist function takes a FunctionExpression or FunctionDeclaration +// and replaces any Declaration nodes in its body with assignments, then +// returns a VariableDeclaration containing just the names of the removed +// declarations. +/** + * Copyright (c) 2014-present, Facebook, Inc. + * + * This source code is licensed under the MIT license found in the + * LICENSE file in the root directory of this source tree. + */ + +exports.hoist = function (funPath) { + var t = util.getTypes(); + t.assertFunction(funPath.node); + + var vars = {}; + + function varDeclToExpr(vdec, includeIdentifiers) { + t.assertVariableDeclaration(vdec); + // TODO assert.equal(vdec.kind, "var"); + var exprs = []; + + vdec.declarations.forEach(function (dec) { + // Note: We duplicate 'dec.id' here to ensure that the variable declaration IDs don't + // have the same 'loc' value, since that can make sourcemaps and retainLines behave poorly. + vars[dec.id.name] = t.identifier(dec.id.name); + + if (dec.init) { + exprs.push(t.assignmentExpression("=", dec.id, dec.init)); + } else if (includeIdentifiers) { + exprs.push(dec.id); + } + }); + + if (exprs.length === 0) return null; + + if (exprs.length === 1) return exprs[0]; + + return t.sequenceExpression(exprs); + } + + funPath.get("body").traverse({ + VariableDeclaration: { + exit: function exit(path) { + var expr = varDeclToExpr(path.node, false); + if (expr === null) { + path.remove(); + } else { + // We don't need to traverse this expression any further because + // there can't be any new declarations inside an expression. + util.replaceWithOrRemove(path, t.expressionStatement(expr)); + } + + // Since the original node has been either removed or replaced, + // avoid traversing it any further. + path.skip(); + } + }, + + ForStatement: function ForStatement(path) { + var init = path.node.init; + if (t.isVariableDeclaration(init)) { + util.replaceWithOrRemove(path.get("init"), varDeclToExpr(init, false)); + } + }, + + ForXStatement: function ForXStatement(path) { + var left = path.get("left"); + if (left.isVariableDeclaration()) { + util.replaceWithOrRemove(left, varDeclToExpr(left.node, true)); + } + }, + + FunctionDeclaration: function FunctionDeclaration(path) { + var node = path.node; + vars[node.id.name] = node.id; + + var assignment = t.expressionStatement(t.assignmentExpression("=", node.id, t.functionExpression(path.scope.generateUidIdentifierBasedOnNode(node), node.params, node.body, node.generator, node.expression))); + + if (path.parentPath.isBlockStatement()) { + // Insert the assignment form before the first statement in the + // enclosing block. + path.parentPath.unshiftContainer("body", assignment); + + // Remove the function declaration now that we've inserted the + // equivalent assignment form at the beginning of the block. + path.remove(); + } else { + // If the parent node is not a block statement, then we can just + // replace the declaration with the equivalent assignment form + // without worrying about hoisting it. + util.replaceWithOrRemove(path, assignment); + } + + // Don't hoist variables out of inner functions. + path.skip(); + }, + + FunctionExpression: function FunctionExpression(path) { + // Don't descend into nested function expressions. + path.skip(); + }, + + ArrowFunctionExpression: function ArrowFunctionExpression(path) { + // Don't descend into nested function expressions. + path.skip(); + } + }); + + var paramNames = {}; + funPath.get("params").forEach(function (paramPath) { + var param = paramPath.node; + if (t.isIdentifier(param)) { + paramNames[param.name] = param; + } else { + // Variables declared by destructuring parameter patterns will be + // harmlessly re-declared. + } + }); + + var declarations = []; + + Object.keys(vars).forEach(function (name) { + if (!hasOwn.call(paramNames, name)) { + declarations.push(t.variableDeclarator(vars[name], null)); + } + }); + + if (declarations.length === 0) { + return null; // Be sure to handle this case! + } + + return t.variableDeclaration("var", declarations); +};
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