Xml 以与HXT一致的方式解析外部文档和当前元素

更新：我现在已经解决了我的主要问题，因此我将奖励我的解决方案是否符合风格的优秀评审

最近我一直在尝试解析文件，这些文件是描述地图的XML文件。该格式中一个有趣的地方是可以指定外部瓷砖集

因为它已经处理了大部分工作，所以我一直在尝试扩展该库，以便它处理外部tileset，但迄今为止没有成功

基本上，我在这里要完成的任务是，给定两个文档，

map.tmx

：

<?xml version="1.0" encoding="UTF-8"?>
<map version="1.0" orientation="orthogonal" width="12" height="12" tilewidth="64" tileheight="64">
 <tileset firstgid="1" source="ground.tsx"/>
 ...
</map>

返回结构：

Map {..., tilesets = [Tileset { name = "ground", ...}]}

解析（仅限内部）TileSet的工作方法是：

tilesets ∷ IOSArrow XmlTree [Tileset]
tilesets = listA tileset

tileset ∷ IOSArrow XmlTree Tileset
tileset = isElem >>> hasName "tileset" >>> proc ts → do
  tsName        ← getAttrValue "name"                        ⤙ ts
  tsInitialGid  ← getAttrR "firstgid"                        ⤙ ts
  tsTileWidth   ← getAttrR "tilewidth"                       ⤙ ts
  tsTileHeight  ← getAttrR "tileheight"                      ⤙ ts
  tsMargin      ← arr (fromMaybe 0) . getAttrMaybe "margin"  ⤙ ts
  tsSpacing     ← arr (fromMaybe 0) . getAttrMaybe "spacing" ⤙ ts
  tsImages      ← images                                     ⤙ ts
  tsTileProperties ← listA tileProperties                    ⤙ ts
  returnA ⤙ Tileset {..}
  where tileProperties ∷ IOSArrow XmlTree (Word32, Properties)
        tileProperties = getChildren >>> isElem >>> hasName "tile"
                     >>> getAttrR "id" &&& properties
        images = listA (getChildren >>> image)

我已尝试调整

tilesets

方法，使其根据当前元素的

source

属性使用当前元素或外部文档，但无效：

tilesets ∷ IOSArrow XmlTree [Tileset]
tilesets = listA $ proc ts → do
  source ← isElem >>> hasName "tileset" >>> getAttrValue "source" ⤙ ts
  case source of
    "" → tileset ⤙ ts
    f → tileset ⤙ readDocument [withValidate no, withWarnings yes] f

（这是我多次尝试中的一次）

---

通常情况下，GHC会告诉我没有使用箭头命令，或者我的值在箭头内，而它不应该在箭头内。我知道我不能以类型安全的方式透明地执行IO（也可能是XHT中间操作），但我被困在这里了。我真的不确定如何继续。

我让它与

readFromDocument

和

ifA

tilesets ∷ FilePath → IOSArrow XmlTree [Tileset]
tilesets mapPath =
  listA $ getChildren >>> isElem >>> hasName "tileset"
  >>> getAttrR "firstgid" &&& ifA (hasAttr "source") (externalTileset mapPath) id
  >>> tileset

externalTileset ∷ FilePath → IOSArrow XmlTree XmlTree
externalTileset mapPath =
  arr (const (dropFileName mapPath)) &&& getAttrValue "source"
  >>> arr (uncurry (</>))
  >>> readFromDocument [ withValidate no, withWarnings yes ]
  >>> getChildren >>> isElem >>> hasName "tileset"

tileset ∷ IOSArrow (Word32, XmlTree) Tileset
tileset = proc (tsInitialGid, ts) → do
  tsName           ← getAttrValue "name"                        ⤙ ts
  tsTileWidth      ← getAttrR "tilewidth"                       ⤙ ts
  tsTileHeight     ← getAttrR "tileheight"                      ⤙ ts
  tsMargin         ← arr (fromMaybe 0) . getAttrMaybe "margin"  ⤙ ts
  tsSpacing        ← arr (fromMaybe 0) . getAttrMaybe "spacing" ⤙ ts
  tsImages         ← images                                     ⤙ ts
  tsTileProperties ← listA tileProperties                       ⤙ ts
  returnA ⤙ Tileset {..}
  where tileProperties ∷ IOSArrow XmlTree (Word32, Properties)
        tileProperties = getChildren >>> isElem >>> hasName "tile"
                         >>> getAttrR "id" &&& properties
        images = listA (getChildren >>> image)

tileset∷ 文件路径→ IOSArrow XmlTree[Tileset]
tilesets映射路径=
listA$getChildren>>>isElem>>>具有名称“tileset”
>>>getattr“firstgid”和&ifA（hasAttr“source”）（externalTileset映射路径）id
>>>蒂莱塞特
外部TILESET∷ 文件路径→ IOSROW XmlTree XmlTree
外部TILESET映射路径=
arr（const（dropFileName映射路径））&&&getAttrValue“源”
>>>arr（uncurry（））
>>>readFromDocument[带验证否，带警告是]
>>>getChildren>>>>isElem>>具有名称“tileset”
蒂莱塞特∷ IOSArrow（Word32，XmlTree）Tileset
tileset=proc（初始ID，ts）→ 做
tsName← getAttrValue“名称”⤙ ts
蒂莱维特← getAttrR“tilewidth”⤙ ts
tsTileHeight← getAttrR“tileheight”⤙ ts
tsMargin← arr（从0开始）。“利润”⤙ ts
TSP间距← arr（从0开始）。“间距”⤙ ts
tsImages← 图像⤙ ts
tsTileProperties← listA tileProperties⤙ ts
海归⤙ Tileset{..}
tileProperties在哪里∷ IOSArrow XmlTree（Word32，属性）
tileProperties=getChildren>>>isElem>>>具有名称“tile”
>>>getAttrR“id”&&&properties
images=listA（getChildren>>>image）

tilesets ∷ FilePath → IOSArrow XmlTree [Tileset]
tilesets mapPath =
  listA $ getChildren >>> isElem >>> hasName "tileset"
  >>> getAttrR "firstgid" &&& ifA (hasAttr "source") (externalTileset mapPath) id
  >>> tileset

externalTileset ∷ FilePath → IOSArrow XmlTree XmlTree
externalTileset mapPath =
  arr (const (dropFileName mapPath)) &&& getAttrValue "source"
  >>> arr (uncurry (</>))
  >>> readFromDocument [ withValidate no, withWarnings yes ]
  >>> getChildren >>> isElem >>> hasName "tileset"

tileset ∷ IOSArrow (Word32, XmlTree) Tileset
tileset = proc (tsInitialGid, ts) → do
  tsName           ← getAttrValue "name"                        ⤙ ts
  tsTileWidth      ← getAttrR "tilewidth"                       ⤙ ts
  tsTileHeight     ← getAttrR "tileheight"                      ⤙ ts
  tsMargin         ← arr (fromMaybe 0) . getAttrMaybe "margin"  ⤙ ts
  tsSpacing        ← arr (fromMaybe 0) . getAttrMaybe "spacing" ⤙ ts
  tsImages         ← images                                     ⤙ ts
  tsTileProperties ← listA tileProperties                       ⤙ ts
  returnA ⤙ Tileset {..}
  where tileProperties ∷ IOSArrow XmlTree (Word32, Properties)
        tileProperties = getChildren >>> isElem >>> hasName "tile"
                         >>> getAttrR "id" &&& properties
        images = listA (getChildren >>> image)