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var assert = require('assert')
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module.exports = dashAst
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/**
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* Call `cb` on each node in `ast`. If `cb` is an object, `cb.enter` is called before processing a Node's children,
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* and `cb.leave` is called after processing a Node's children.
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*/
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function dashAst (ast, cb) {
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assert(ast && typeof ast === 'object' && typeof ast.type === 'string',
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'dash-ast: ast must be an AST node')
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if (typeof cb === 'object') {
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assert(typeof cb.enter === 'function' || typeof cb.leave === 'function',
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'dash-ast: visitor must be an object with enter/leave functions')
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walk(ast, null, cb.enter || undefined, cb.leave || undefined)
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} else {
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assert(cb && typeof cb === 'function',
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'dash-ast: callback must be a function')
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walk(ast, null, cb, undefined)
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}
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}
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/**
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* Call `cb` on each node in `ast`. Each node will have a `.parent` property.
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*/
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dashAst.withParent = function dashAstParent (ast, cb) {
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assert(ast && typeof ast === 'object' && typeof ast.type === 'string',
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'dash-ast.withParent: ast must be an AST node')
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if (typeof cb === 'object') {
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assert(typeof cb.enter === 'function' || typeof cb.leave === 'function',
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'dash-ast.withParent: visitor must be an object with enter/leave functions')
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var enter = cb.enter
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var leave = cb.leave
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walk(ast, null, function (node, parent) {
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node.parent = parent
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if (enter !== undefined) return enter(node)
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}, leave ? function (node) { leave(node) } : undefined)
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} else {
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assert(cb && typeof cb === 'function',
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'dash-ast.withParent: callback must be a function')
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walk(ast, null, function (node, parent) {
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node.parent = parent
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return cb(node)
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}, undefined)
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}
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}
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function walk (node, parent, enter, leave) {
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var cont = enter !== undefined ? enter(node, parent) : undefined
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if (cont === false) return
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for (var k in node) {
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if (has(node, k)) {
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if (k === 'parent') continue
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if (isNode(node[k])) {
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walk(node[k], node, enter, leave)
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} else if (Array.isArray(node[k])) {
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walkArray(node[k], node, enter, leave)
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}
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}
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}
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if (leave !== undefined) leave(node, parent)
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}
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function walkArray (nodes, parent, enter, leave) {
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for (var i = 0; i < nodes.length; i++) {
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if (isNode(nodes[i])) walk(nodes[i], parent, enter, leave)
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}
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}
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function isNode (node) {
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return typeof node === 'object' && node && typeof node.type === 'string'
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}
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function has (obj, prop) {
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return Object.prototype.hasOwnProperty.call(obj, prop)
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}
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