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