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https://github.com/flynx/diff.js.git
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moved walk(..) to its own module...
Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>
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61b57bca2a
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210
diff.js
210
diff.js
@ -8,6 +8,7 @@
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/*********************************************************************/
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var object = require('ig-object')
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var walk = require('generic-walk').walk
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@ -263,215 +264,6 @@ var proxy = function(path, func){
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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//
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// Construct a reusable walker function...
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// walk(get(..))
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// -> func(state, ...nodes)
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//
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// Construct a reusable walker function with set initial state...
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// walk(get(..), state)
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// -> func(...nodes)
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//
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// Walk the nodes...
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// walk(get(..), state, ...nodes)
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// -> res
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//
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// The get(..) that walk(..) expects has the following signature:
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// get(res, node, next(..), down(..), stop(..))
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// -> res
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//
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// Queue next nodes to walk...
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// next(...nodes)
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// -> undefined
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// NOTE: this will just queue the nodes and return immediately.
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// NOTE: the state is passed to the nodes implicitly, the get(..)
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// handling first node from this list will get the last result
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// returned by the last get(..) call on this level as it's
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// state.
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//
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// Walk the next set of nodes...
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// down(state, ...nodes)
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// -> res
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// NOTE: this will process all the nodes and then return the
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// result.
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//
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// Stop the walk...
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// stop()
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// stop(result)
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// -> undefined
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// NOTE: this will break current function execution in a similar
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// effect to 'return', i.e. no code in function will be
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// executed after stop(..) call...
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// NOTE: this is done by throwing a special error, this error
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// should either not be caught or must be re-thrown, as
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// shadowing this exception may have unexpected results...
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//
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//
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// Example:
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// // sum all the values of a nested array...
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// var sum = walk(function(res, node, next){
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// return node instanceof Array ?
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// // compensate for that next(..) returns undefined...
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// next(...node)
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// || res
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// : res + node }, 0)
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//
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// // depth first walker...
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// var sumd = walk(function(res, node, next, down, stop){
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// return node instanceof Array ?
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// down(res, ...node)
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// : res + node }, 0)
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//
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// sum([1, [2], 3, [[4, 5]]]) // -> 15 ...walks the nodes: 1, 3, 2, 4, 5
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// sumd([1, [2], 3, [[4, 5]]]) // -> 15 ...walks the nodes: 1, 2, 3, 4, 5
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//
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//
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// Example:
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// // XXX res/path threading seem unnatural here...
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// var __firstZero = walk(function(res, node, next, down, stop){
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// var k = node[0]
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// var v = node[1]
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// var path = res[0]
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// return v === 0 ?
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// // NOTE: we .slice(1) here to remove the initial null
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// // we added in firstZero(..)...
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// stop([ path.slice(1).concat([k]) ])
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// : v instanceof Object?
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// down(
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// [path.concat([k]), null],
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// ...Object.entries(v))
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// : res }, [[], null])
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// var firstZero = function(value){
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// // NOTE: we are wrapping the input here to make it the same
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// // format as that of Object.entries(..) items...
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// return __firstZero([null, value]).pop() }
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//
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//
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// // same as the above but illustrates a different strategy, a bit
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// // cleaner but creates a walker every time it's called...
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// var firstZero = function(value){
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// return walk(
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// function(res, node, next, down, stop){
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// var k = node[0]
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// var v = node[1]
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// var path = res[0]
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// return v === 0 ?
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// // NOTE: we .slice(1) here to remove the initial null
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// // we added in firstZero(..)...
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// stop([ path.slice(1).concat([k]) ])
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// : v instanceof Object?
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// down(
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// [path.concat([k]), null],
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// ...Object.entries(v))
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// : res },
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// [[], null],
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// // wrap the input to make it compatible with Object.entries(..)
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// // items...
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// [null, value])
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// // separate the result from path...
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// .pop() }
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//
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//
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// firstZero([10, 5, [{x: 1, y: 0}, 4]]) // -> ['2', '0', 'y']
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//
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//
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//
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// NOTE: a walker is returned iff walk(..) is passed a single argument.
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// NOTE: the following two are equivalent:
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// walk(get, start, ...nodes)
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// walk(get)(start, ...nodes)
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// NOTE: walk goes breadth first...
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//
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// XXX might be a good idea to move this into it's own module...
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// generic-walk might be a good name...
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var walk = function(get, state, ...nodes){
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// this is used to break out of the recursion...
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// NOTE: this can leak out but we only care about it's identity thus
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// no damage can be done...
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var WalkStopException
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var err_res
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var _step = function(nodes, res){
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// construct a comfortable env for the user and handle the
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// results...
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var _get = function(node){
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var next = []
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res = get(
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res,
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node,
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// breadth first step...
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// next(...nodes) -> undefined
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function(...nodes){ next = nodes },
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// depth first step...
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// down(state, ..nodes) -> res
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function(res, ...nodes){
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return _step(nodes, res) },
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// stop...
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// stop()
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// stop(value)
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//
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// NOTE: 'throw' is used to stop all handling, including
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// the rest of the current level...
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function(r){
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err_res = r
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WalkStopException = new Error('WALK_STOP_EVENT')
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throw WalkStopException
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})
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return next
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}
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return nodes.length == 0 ?
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// no new nodes to walk...
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res
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// do the next level...
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// NOTE: see note below... ( ;) )
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: _step(nodes
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.map(_get)
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.reduce(function(next, e){
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return e instanceof Array ?
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next.concat(e)
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: next.push(e) }, []), res)
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}
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// call _step(..) and handle WalkStopException...
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var _walk = function(nodes, res){
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try{
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return _step(nodes, res)
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} catch(e){
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// handle the abort condition...
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if(e === WalkStopException){
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return err_res
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}
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// something broke...
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throw e
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}
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}
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return (
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// return a reusable walker...
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arguments.length == 1 ?
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// NOTE: this wrapper is here so as to isolate and re-order res
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// construction and passing it to the next level...
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// this is needed as when we do:
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// step(res, ...nodes.map(_get).reduce(...))
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// res (if immutable) will first get passed by value and
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// then will get re-assigned in _get(..), thus step(..) will
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// not see the updated version...
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// This approach simply pushes the pass-by-value of res till
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// after it gets updated by _get(..).
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function(res, ...nodes){
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return _walk(nodes, res) }
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// reusable walker with a curried initial state...
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// NOTE: better keep this immutable or clone this in get(..)
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: arguments.length == 2 ?
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function(...nodes){
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return _walk(nodes, state) }
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// walk...
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: _walk(nodes, state))
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}
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//---------------------------------------------------------------------
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@ -24,6 +24,7 @@
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},
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"homepage": "https://github.com/flynx/object-diff.js#readme",
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"dependencies": {
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"generic-walk": "0.0.5",
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"ig-object": "^1.0.7"
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}
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}
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