mirror of https://github.com/status-im/NimYAML.git
375 lines
13 KiB
Nim
375 lines
13 KiB
Nim
# NimYAML - YAML implementation in Nim
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# (c) Copyright 2016 Felix Krause
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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## ===============
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## Module yaml.dom
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## ===============
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##
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## This is the DOM API, which enables you to load YAML into a tree-like
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## structure. It can also dump the structure back to YAML. Formally, it
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## represents the *Representation Graph* as defined in the YAML specification.
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##
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## The main interface of this API are ``loadDom`` and ``dumpDom``. The other
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## exposed procs are low-level and useful if you want to load or generate parts
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## of a ``YamlStream``.
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##
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## The ``YamlNode`` objects in the DOM can be used similarly to the ``JsonNode``
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## objects of Nim's `json module <http://nim-lang.org/docs/json.html>`_.
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import tables, streams, hashes, sets, strutils
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import stream, taglib, serialization, private/internal, parser,
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presenter
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type
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YamlNodeKind* = enum
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yScalar, yMapping, ySequence
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YamlNode* = ref YamlNodeObj not nil
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## Represents a node in a ``YamlDocument``.
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YamlNodeObj* = object
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tag*: string
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case kind*: YamlNodeKind
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of yScalar: content*: string
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of ySequence: elems*: seq[YamlNode]
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of yMapping: fields*: TableRef[YamlNode, YamlNode]
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# compiler does not like Table[YamlNode, YamlNode]
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YamlDocument* = object
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## Represents a YAML document.
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root*: YamlNode
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proc hash*(o: YamlNode): Hash =
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result = o.tag.hash
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case o.kind
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of yScalar: result = result !& o.content.hash
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of yMapping:
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for key, value in o.fields.pairs:
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result = result !& key.hash !& value.hash
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of ySequence:
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for item in o.elems:
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result = result !& item.hash
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result = !$result
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proc eqImpl(x, y: YamlNode, alreadyVisited: var HashSet[pointer]): bool =
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template compare(a, b: YamlNode) {.dirty.} =
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if cast[pointer](a) != cast[pointer](b):
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if cast[pointer](a) in alreadyVisited and
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cast[pointer](b) in alreadyVisited:
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# prevent infinite loop!
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return false
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elif a != b: return false
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if x.kind != y.kind or x.tag != y.tag: return false
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alreadyVisited.incl(cast[pointer](x))
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alreadyVisited.incl(cast[pointer](y))
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case x.kind
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of yScalar: result = x.content == y.content
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of ySequence:
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if x.elems.len != y.elems.len: return false
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for i in 0..<x.elems.len:
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compare(x.elems[i], y.elems[i])
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of yMapping:
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if x.fields.len != y.fields.len: return false
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for xKey, xValue in x.fields.pairs:
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let xKeyVisited = cast[pointer](xKey) in alreadyVisited
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var matchingValue: ref YamlNodeObj = nil
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for yKey, yValue in y.fields.pairs:
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if cast[pointer](yKey) != cast[pointer](xKey):
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if cast[pointer](yKey) in alreadyVisited and xKeyVisited:
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# prevent infinite loop!
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continue
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if xKey == yKey:
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matchingValue = yValue
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break
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else:
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matchingValue = yValue
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break
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if isNil(matchingValue): return false
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compare(xValue, matchingValue)
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proc `==`*(x, y: YamlNode): bool =
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var alreadyVisited = initSet[pointer]()
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result = eqImpl(x, y, alreadyVisited)
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proc `$`*(n: YamlNode): string =
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result = "!<" & n.tag & "> "
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case n.kind
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of yScalar: result.add(escape(n.content))
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of ySequence:
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result.add('[')
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for item in n.elems:
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result.add($item)
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result.add(", ")
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result.setLen(result.len - 1)
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result[^1] = ']'
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of yMapping:
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result.add('{')
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for key, value in n.fields.pairs:
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result.add($key)
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result.add(": ")
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result.add($value)
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result.add(", ")
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result.setLen(result.len - 1)
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result[^1] = '}'
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proc newYamlNode*(content: string, tag: string = "?"): YamlNode =
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YamlNode(kind: yScalar, content: content, tag: tag)
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proc newYamlNode*(elems: openarray[YamlNode], tag: string = "?"):
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YamlNode =
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YamlNode(kind: ySequence, elems: @elems, tag: tag)
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proc newYamlNode*(fields: openarray[(YamlNode, YamlNode)],
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tag: string = "?"): YamlNode =
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YamlNode(kind: yMapping, fields: newTable(fields), tag: tag)
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proc initYamlDoc*(root: YamlNode): YamlDocument = result.root = root
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proc composeNode(s: var YamlStream, tagLib: TagLibrary,
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c: ConstructionContext):
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YamlNode {.raises: [YamlStreamError, YamlConstructionError].} =
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template addAnchor(c: ConstructionContext, target: AnchorId): typed =
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if target != yAnchorNone:
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when defined(JS):
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{.emit: [c, """.refs.set(""", target, ", ", result, ");"].}
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else:
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yAssert(not c.refs.hasKey(target))
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c.refs[target] = cast[pointer](result)
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var start: YamlStreamEvent
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shallowCopy(start, s.next())
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new(result)
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try:
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case start.kind
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of yamlStartMap:
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result.tag = tagLib.uri(start.mapTag)
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result.kind = yMapping
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result.fields = newTable[YamlNode, YamlNode]()
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while s.peek().kind != yamlEndMap:
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let
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key = composeNode(s, tagLib, c)
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value = composeNode(s, tagLib, c)
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if result.fields.hasKeyOrPut(key, value):
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raise newException(YamlConstructionError,
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"Duplicate key: " & $key)
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discard s.next()
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addAnchor(c, start.mapAnchor)
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of yamlStartSeq:
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result.tag = tagLib.uri(start.seqTag)
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result.kind = ySequence
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result.elems = newSeq[YamlNode]()
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while s.peek().kind != yamlEndSeq:
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result.elems.add(composeNode(s, tagLib, c))
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addAnchor(c, start.seqAnchor)
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discard s.next()
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of yamlScalar:
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result.tag = tagLib.uri(start.scalarTag)
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result.kind = yScalar
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shallowCopy(result.content, start.scalarContent)
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addAnchor(c, start.scalarAnchor)
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of yamlAlias:
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when defined(JS):
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{.emit: [result, " = ", c, ".refs.get(", start.aliasTarget, ");"].}
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else:
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result = cast[YamlNode](c.refs[start.aliasTarget])
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else: internalError("Malformed YamlStream")
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except KeyError:
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raise newException(YamlConstructionError,
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"Wrong tag library: TagId missing")
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proc compose*(s: var YamlStream, tagLib: TagLibrary): YamlDocument
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{.raises: [YamlStreamError, YamlConstructionError].} =
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var context = newConstructionContext()
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var n: YamlStreamEvent
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shallowCopy(n, s.next())
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yAssert n.kind == yamlStartDoc
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result.root = composeNode(s, tagLib, context)
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n = s.next()
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yAssert n.kind == yamlEndDoc
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proc loadDom*(s: Stream | string): YamlDocument
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{.raises: [IOError, YamlParserError, YamlConstructionError].} =
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var
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tagLib = initExtendedTagLibrary()
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parser = newYamlParser(tagLib)
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events = parser.parse(s)
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try: result = compose(events, tagLib)
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except YamlStreamError:
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let e = getCurrentException()
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if e.parent of YamlParserError:
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raise (ref YamlParserError)(e.parent)
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elif e.parent of IOError:
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raise (ref IOError)(e.parent)
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else: internalError("Unexpected exception: " & e.parent.repr)
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proc serializeNode(n: YamlNode, c: SerializationContext, a: AnchorStyle,
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tagLib: TagLibrary) {.raises: [].}=
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var val = yAnchorNone
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when defined(JS):
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{.emit: ["""
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if (""", a, " != ", asNone, " && ", c, ".refs.has(", n, """) {
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""", val, " = ", c, ".refs.get(", n, """);
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if (""", c, ".refs.get(", n, ") == ", yAnchorNone, ") {"].}
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val = c.nextAnchorId
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{.emit: [c, """.refs.set(""", n, """, """, val, """);"""].}
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c.nextAnchorId = AnchorId(int(c.nextAnchorId) + 1)
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{.emit: "}".}
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c.put(aliasEvent(val))
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return
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{.emit: "}".}
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else:
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let p = cast[pointer](n)
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if a != asNone and c.refs.hasKey(p):
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val = c.refs.getOrDefault(p)
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if val == yAnchorNone:
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val = c.nextAnchorId
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c.refs[p] = val
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c.nextAnchorId = AnchorId(int(c.nextAnchorId) + 1)
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c.put(aliasEvent(val))
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return
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var
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tagId: TagId
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anchor: AnchorId
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if a == asAlways:
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val = c.nextAnchorId
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when defined(JS):
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{.emit: [c, ".refs.set(", n, ", ", val, ");"].}
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else:
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c.refs[p] = c.nextAnchorId
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c.nextAnchorId = AnchorId(int(val) + 1)
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else:
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when defined(JS):
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{.emit: [c, ".refs.set(", n, ", ", yAnchorNone, ");"].}
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else:
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c.refs[p] = yAnchorNone
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tagId = if tagLib.tags.hasKey(n.tag): tagLib.tags.getOrDefault(n.tag) else:
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tagLib.registerUri(n.tag)
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case a
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of asNone: anchor = yAnchorNone
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of asTidy: anchor = cast[AnchorId](n)
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of asAlways: anchor = val
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case n.kind
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of yScalar: c.put(scalarEvent(n.content, tagId, anchor))
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of ySequence:
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c.put(startSeqEvent(tagId, anchor))
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for item in n.elems:
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serializeNode(item, c, a, tagLib)
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c.put(endSeqEvent())
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of yMapping:
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c.put(startMapEvent(tagId, anchor))
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for key, value in n.fields.pairs:
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serializeNode(key, c, a, tagLib)
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serializeNode(value, c, a, tagLib)
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c.put(endMapEvent())
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template processAnchoredEvent(target: untyped, c: SerializationContext): typed =
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var anchorId: AnchorId
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when defined(JS):
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{.emit: [anchorId, " = ", c, ".refs.get(", target, ");"].}
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else:
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anchorId = c.refs.getOrDefault(cast[pointer](target))
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if anchorId != yAnchorNone: target = anchorId
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else: target = yAnchorNone
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proc serialize*(doc: YamlDocument, tagLib: TagLibrary, a: AnchorStyle = asTidy):
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YamlStream {.raises: [].} =
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var
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bys = newBufferYamlStream()
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c = newSerializationContext(a, proc(e: YamlStreamEvent) {.raises: [].} =
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bys.put(e)
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)
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c.put(startDocEvent())
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serializeNode(doc.root, c, a, tagLib)
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c.put(endDocEvent())
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if a == asTidy:
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for event in bys.mitems():
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case event.kind
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of yamlScalar: processAnchoredEvent(event.scalarAnchor, c)
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of yamlStartMap: processAnchoredEvent(event.mapAnchor, c)
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of yamlStartSeq: processAnchoredEvent(event.seqAnchor, c)
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else: discard
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result = bys
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proc dumpDom*(doc: YamlDocument, target: Stream,
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anchorStyle: AnchorStyle = asTidy,
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options: PresentationOptions = defaultPresentationOptions)
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{.raises: [YamlPresenterJsonError, YamlPresenterOutputError,
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YamlStreamError].} =
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## Dump a YamlDocument as YAML character stream.
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var
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tagLib = initExtendedTagLibrary()
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events = serialize(doc, tagLib,
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if options.style == psJson: asNone else: anchorStyle)
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present(events, target, tagLib, options)
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proc `[]`*(node: YamlNode, i: int): YamlNode =
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## Get the node at index *i* from a sequence. *node* must be a *ySequence*.
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assert node.kind == ySequence
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node.elems[i]
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proc `[]=`*(node: var YamlNode, i: int, val: YamlNode) =
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## Set the node at index *i* of a sequence. *node* must be a *ySequence*.
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assert node.kind == ySequence
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node.elems[i] = val
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proc `[]`*(node: YamlNode, key: YamlNode): YamlNode =
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## Get the value for a key in a mapping. *node* must be a *yMapping*.
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assert node.kind == yMapping
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node.fields[key]
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proc `[]=`*(node: YamlNode, key: YamlNode, value: YamlNode) =
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## Set the value for a key in a mapping. *node* must be a *yMapping*.
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node.fields[key] = value
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proc `[]`*(node: YamlNode, key: string): YamlNode =
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## Get the value for a string key in a mapping. *node* must be a *yMapping*.
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## This searches for a scalar key with content *key* and either no explicit
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## tag or the explicit tag ``!!str``.
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assert node.kind == yMapping
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var keyNode = YamlNode(kind: yScalar, tag: "!", content: key)
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result = node.fields.getOrDefault(keyNode)
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if isNil(result):
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keyNode.tag = "?"
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result = node.fields.getOrDefault(keyNode)
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if isNil(result):
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keyNode.tag = nimTag(yamlTagRepositoryPrefix & "str")
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result = node.fields.getOrDefault(keyNode)
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if isNil(result):
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raise newException(KeyError, "No key " & escape(key) & " exists!")
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proc len*(node: YamlNode): int =
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## If *node* is a *yMapping*, return the number of key-value pairs. If *node*
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## is a *ySequence*, return the number of elements. Else, return ``0``
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case node.kind
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of yMapping: result = node.fields.len
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of ySequence: result = node.elems.len
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of yScalar: result = 0
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iterator items*(node: YamlNode): YamlNode =
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## Iterates over all items of a sequence. *node* must be a *ySequence*.
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assert node.kind == ySequence
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for item in node.elems: yield item
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iterator mitems*(node: var YamlNode): YamlNode =
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## Iterates over all items of a sequence. *node* must be a *ySequence*.
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## Values can be modified.
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assert node.kind == ySequence
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for item in node.elems.mitems: yield item
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iterator pairs*(node: YamlNode): tuple[key, value: YamlNode] =
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## Iterates over all key-value pairs of a mapping. *node* must be a
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## *yMapping*.
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assert node.kind == yMapping
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for key, value in node.fields: yield (key, value)
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iterator mpairs*(node: var YamlNode):
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tuple[key: YamlNode, value: var YamlNode] =
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## Iterates over all key-value pairs of a mapping. *node* must be a
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## *yMapping*. Values can be modified.
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doAssert node.kind == yMapping
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for key, value in node.fields.mpairs: yield (key, value) |