| // AST walker module for Mozilla Parser API compatible trees |
| |
| // A simple walk is one where you simply specify callbacks to be |
| // called on specific nodes. The last two arguments are optional. A |
| // simple use would be |
| // |
| // walk.simple(myTree, { |
| // Expression: function(node) { ... } |
| // }); |
| // |
| // to do something with all expressions. All Parser API node types |
| // can be used to identify node types, as well as Expression, |
| // Statement, and ScopeBody, which denote categories of nodes. |
| // |
| // The base argument can be used to pass a custom (recursive) |
| // walker, and state can be used to give this walked an initial |
| // state. |
| |
| export function simple(node, visitors, base, state, override) { |
| if (!base) base = exports.base |
| ;(function c(node, st, override) { |
| let type = override || node.type, found = visitors[type] |
| base[type](node, st, c) |
| if (found) found(node, st) |
| })(node, state, override) |
| } |
| |
| // An ancestor walk keeps an array of ancestor nodes (including the |
| // current node) and passes them to the callback as third parameter |
| // (and also as state parameter when no other state is present). |
| export function ancestor(node, visitors, base, state) { |
| if (!base) base = exports.base |
| let ancestors = [] |
| ;(function c(node, st, override) { |
| let type = override || node.type, found = visitors[type] |
| let isNew = node != ancestors[ancestors.length - 1] |
| if (isNew) ancestors.push(node) |
| base[type](node, st, c) |
| if (found) found(node, st || ancestors, ancestors) |
| if (isNew) ancestors.pop() |
| })(node, state) |
| } |
| |
| // A recursive walk is one where your functions override the default |
| // walkers. They can modify and replace the state parameter that's |
| // threaded through the walk, and can opt how and whether to walk |
| // their child nodes (by calling their third argument on these |
| // nodes). |
| export function recursive(node, state, funcs, base, override) { |
| let visitor = funcs ? exports.make(funcs, base) : base |
| ;(function c(node, st, override) { |
| visitor[override || node.type](node, st, c) |
| })(node, state, override) |
| } |
| |
| function makeTest(test) { |
| if (typeof test == "string") |
| return type => type == test |
| else if (!test) |
| return () => true |
| else |
| return test |
| } |
| |
| class Found { |
| constructor(node, state) { this.node = node; this.state = state } |
| } |
| |
| // Find a node with a given start, end, and type (all are optional, |
| // null can be used as wildcard). Returns a {node, state} object, or |
| // undefined when it doesn't find a matching node. |
| export function findNodeAt(node, start, end, test, base, state) { |
| test = makeTest(test) |
| if (!base) base = exports.base |
| try { |
| ;(function c(node, st, override) { |
| let type = override || node.type |
| if ((start == null || node.start <= start) && |
| (end == null || node.end >= end)) |
| base[type](node, st, c) |
| if ((start == null || node.start == start) && |
| (end == null || node.end == end) && |
| test(type, node)) |
| throw new Found(node, st) |
| })(node, state) |
| } catch (e) { |
| if (e instanceof Found) return e |
| throw e |
| } |
| } |
| |
| // Find the innermost node of a given type that contains the given |
| // position. Interface similar to findNodeAt. |
| export function findNodeAround(node, pos, test, base, state) { |
| test = makeTest(test) |
| if (!base) base = exports.base |
| try { |
| ;(function c(node, st, override) { |
| let type = override || node.type |
| if (node.start > pos || node.end < pos) return |
| base[type](node, st, c) |
| if (test(type, node)) throw new Found(node, st) |
| })(node, state) |
| } catch (e) { |
| if (e instanceof Found) return e |
| throw e |
| } |
| } |
| |
| // Find the outermost matching node after a given position. |
| export function findNodeAfter(node, pos, test, base, state) { |
| test = makeTest(test) |
| if (!base) base = exports.base |
| try { |
| ;(function c(node, st, override) { |
| if (node.end < pos) return |
| let type = override || node.type |
| if (node.start >= pos && test(type, node)) throw new Found(node, st) |
| base[type](node, st, c) |
| })(node, state) |
| } catch (e) { |
| if (e instanceof Found) return e |
| throw e |
| } |
| } |
| |
| // Find the outermost matching node before a given position. |
| export function findNodeBefore(node, pos, test, base, state) { |
| test = makeTest(test) |
| if (!base) base = exports.base |
| let max |
| ;(function c(node, st, override) { |
| if (node.start > pos) return |
| let type = override || node.type |
| if (node.end <= pos && (!max || max.node.end < node.end) && test(type, node)) |
| max = new Found(node, st) |
| base[type](node, st, c) |
| })(node, state) |
| return max |
| } |
| |
| // Fallback to an Object.create polyfill for older environments. |
| const create = Object.create || function(proto) { |
| function Ctor() {} |
| Ctor.prototype = proto |
| return new Ctor |
| } |
| |
| // Used to create a custom walker. Will fill in all missing node |
| // type properties with the defaults. |
| export function make(funcs, base) { |
| if (!base) base = exports.base |
| let visitor = create(base) |
| for (var type in funcs) visitor[type] = funcs[type] |
| return visitor |
| } |
| |
| function skipThrough(node, st, c) { c(node, st) } |
| function ignore(_node, _st, _c) {} |
| |
| // Node walkers. |
| |
| export const base = {} |
| |
| base.Program = base.BlockStatement = (node, st, c) => { |
| for (let i = 0; i < node.body.length; ++i) |
| c(node.body[i], st, "Statement") |
| } |
| base.Statement = skipThrough |
| base.EmptyStatement = ignore |
| base.ExpressionStatement = base.ParenthesizedExpression = |
| (node, st, c) => c(node.expression, st, "Expression") |
| base.IfStatement = (node, st, c) => { |
| c(node.test, st, "Expression") |
| c(node.consequent, st, "Statement") |
| if (node.alternate) c(node.alternate, st, "Statement") |
| } |
| base.LabeledStatement = (node, st, c) => c(node.body, st, "Statement") |
| base.BreakStatement = base.ContinueStatement = ignore |
| base.WithStatement = (node, st, c) => { |
| c(node.object, st, "Expression") |
| c(node.body, st, "Statement") |
| } |
| base.SwitchStatement = (node, st, c) => { |
| c(node.discriminant, st, "Expression") |
| for (let i = 0; i < node.cases.length; ++i) { |
| let cs = node.cases[i] |
| if (cs.test) c(cs.test, st, "Expression") |
| for (let j = 0; j < cs.consequent.length; ++j) |
| c(cs.consequent[j], st, "Statement") |
| } |
| } |
| base.ReturnStatement = base.YieldExpression = (node, st, c) => { |
| if (node.argument) c(node.argument, st, "Expression") |
| } |
| base.ThrowStatement = base.SpreadElement = |
| (node, st, c) => c(node.argument, st, "Expression") |
| base.TryStatement = (node, st, c) => { |
| c(node.block, st, "Statement") |
| if (node.handler) c(node.handler, st) |
| if (node.finalizer) c(node.finalizer, st, "Statement") |
| } |
| base.CatchClause = (node, st, c) => { |
| c(node.param, st, "Pattern") |
| c(node.body, st, "ScopeBody") |
| } |
| base.WhileStatement = base.DoWhileStatement = (node, st, c) => { |
| c(node.test, st, "Expression") |
| c(node.body, st, "Statement") |
| } |
| base.ForStatement = (node, st, c) => { |
| if (node.init) c(node.init, st, "ForInit") |
| if (node.test) c(node.test, st, "Expression") |
| if (node.update) c(node.update, st, "Expression") |
| c(node.body, st, "Statement") |
| } |
| base.ForInStatement = base.ForOfStatement = (node, st, c) => { |
| c(node.left, st, "ForInit") |
| c(node.right, st, "Expression") |
| c(node.body, st, "Statement") |
| } |
| base.ForInit = (node, st, c) => { |
| if (node.type == "VariableDeclaration") c(node, st) |
| else c(node, st, "Expression") |
| } |
| base.DebuggerStatement = ignore |
| |
| base.FunctionDeclaration = (node, st, c) => c(node, st, "Function") |
| base.VariableDeclaration = (node, st, c) => { |
| for (let i = 0; i < node.declarations.length; ++i) |
| c(node.declarations[i], st) |
| } |
| base.VariableDeclarator = (node, st, c) => { |
| c(node.id, st, "Pattern") |
| if (node.init) c(node.init, st, "Expression") |
| } |
| |
| base.Function = (node, st, c) => { |
| if (node.id) c(node.id, st, "Pattern") |
| for (let i = 0; i < node.params.length; i++) |
| c(node.params[i], st, "Pattern") |
| c(node.body, st, node.expression ? "ScopeExpression" : "ScopeBody") |
| } |
| // FIXME drop these node types in next major version |
| // (They are awkward, and in ES6 every block can be a scope.) |
| base.ScopeBody = (node, st, c) => c(node, st, "Statement") |
| base.ScopeExpression = (node, st, c) => c(node, st, "Expression") |
| |
| base.Pattern = (node, st, c) => { |
| if (node.type == "Identifier") |
| c(node, st, "VariablePattern") |
| else if (node.type == "MemberExpression") |
| c(node, st, "MemberPattern") |
| else |
| c(node, st) |
| } |
| base.VariablePattern = ignore |
| base.MemberPattern = skipThrough |
| base.RestElement = (node, st, c) => c(node.argument, st, "Pattern") |
| base.ArrayPattern = (node, st, c) => { |
| for (let i = 0; i < node.elements.length; ++i) { |
| let elt = node.elements[i] |
| if (elt) c(elt, st, "Pattern") |
| } |
| } |
| base.ObjectPattern = (node, st, c) => { |
| for (let i = 0; i < node.properties.length; ++i) |
| c(node.properties[i].value, st, "Pattern") |
| } |
| |
| base.Expression = skipThrough |
| base.ThisExpression = base.Super = base.MetaProperty = ignore |
| base.ArrayExpression = (node, st, c) => { |
| for (let i = 0; i < node.elements.length; ++i) { |
| let elt = node.elements[i] |
| if (elt) c(elt, st, "Expression") |
| } |
| } |
| base.ObjectExpression = (node, st, c) => { |
| for (let i = 0; i < node.properties.length; ++i) |
| c(node.properties[i], st) |
| } |
| base.FunctionExpression = base.ArrowFunctionExpression = base.FunctionDeclaration |
| base.SequenceExpression = base.TemplateLiteral = (node, st, c) => { |
| for (let i = 0; i < node.expressions.length; ++i) |
| c(node.expressions[i], st, "Expression") |
| } |
| base.UnaryExpression = base.UpdateExpression = (node, st, c) => { |
| c(node.argument, st, "Expression") |
| } |
| base.BinaryExpression = base.LogicalExpression = (node, st, c) => { |
| c(node.left, st, "Expression") |
| c(node.right, st, "Expression") |
| } |
| base.AssignmentExpression = base.AssignmentPattern = (node, st, c) => { |
| c(node.left, st, "Pattern") |
| c(node.right, st, "Expression") |
| } |
| base.ConditionalExpression = (node, st, c) => { |
| c(node.test, st, "Expression") |
| c(node.consequent, st, "Expression") |
| c(node.alternate, st, "Expression") |
| } |
| base.NewExpression = base.CallExpression = (node, st, c) => { |
| c(node.callee, st, "Expression") |
| if (node.arguments) for (let i = 0; i < node.arguments.length; ++i) |
| c(node.arguments[i], st, "Expression") |
| } |
| base.MemberExpression = (node, st, c) => { |
| c(node.object, st, "Expression") |
| if (node.computed) c(node.property, st, "Expression") |
| } |
| base.ExportNamedDeclaration = base.ExportDefaultDeclaration = (node, st, c) => { |
| if (node.declaration) |
| c(node.declaration, st, node.type == "ExportNamedDeclaration" || node.declaration.id ? "Statement" : "Expression") |
| if (node.source) c(node.source, st, "Expression") |
| } |
| base.ExportAllDeclaration = (node, st, c) => { |
| c(node.source, st, "Expression") |
| } |
| base.ImportDeclaration = (node, st, c) => { |
| for (let i = 0; i < node.specifiers.length; i++) |
| c(node.specifiers[i], st) |
| c(node.source, st, "Expression") |
| } |
| base.ImportSpecifier = base.ImportDefaultSpecifier = base.ImportNamespaceSpecifier = base.Identifier = base.Literal = ignore |
| |
| base.TaggedTemplateExpression = (node, st, c) => { |
| c(node.tag, st, "Expression") |
| c(node.quasi, st) |
| } |
| base.ClassDeclaration = base.ClassExpression = (node, st, c) => c(node, st, "Class") |
| base.Class = (node, st, c) => { |
| if (node.id) c(node.id, st, "Pattern") |
| if (node.superClass) c(node.superClass, st, "Expression") |
| for (let i = 0; i < node.body.body.length; i++) |
| c(node.body.body[i], st) |
| } |
| base.MethodDefinition = base.Property = (node, st, c) => { |
| if (node.computed) c(node.key, st, "Expression") |
| c(node.value, st, "Expression") |
| } |