New pragmas for customizing presentation

* added yaml/style that defines representation pragmas `scalar` and `collection` * implemented those pragmas * updated docs. also fixes some invalid links in docs
2023-11-11 15:36:10 +01:00 · 2023-11-11 15:36:10 +01:00 · a698289223
parent 03c95da97c
commit a698289223
10 changed files with 190 additions and 50 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -2,6 +2,9 @@

 Features:

+ * New pragmas ``scalar`` and ``collection`` allow you to modify the
+   presentation style used for certain types and object fields.
+   Defined in new module ``yaml/style``.
 * The presenter now honors the node style set in the events it presents,
   if possible. So if a scalar is set to be a literal block scalar, it is
   presented as such unless impossible or presenter options specifically
--- a/doc/api.txt
+++ b/doc/api.txt
@ -26,7 +26,7 @@ Intermediate Representation

 The base of all YAML processing with NimYAML is the
 `YamlStream <api/stream.html#YamlStream>`_. This is basically an iterator over
-`YamlStreamEvent <api/stream.html#YamlStreamEvent>`_ objects. Every proc that
+`Event <api/data.html#Event>`_ objects. Every proc that
 represents a single stage of the loading or dumping process will either take a
 ``YamlStream`` as input or return a ``YamlStream``. Procs that implement the
 whole process in one step hide the ``YamlStream`` from the user. Every proc that
@ -45,7 +45,7 @@ Loading YAML
 ============

 If you want to load YAML character data directly into a native Nim variable, you
-can use `load <api/serialization.html#load,,K>`_. This is the easiest and
+can use `load <api/loading.html#load%2C%2CK>`_. This is the easiest and
 recommended way to load YAML data. This section gives an overview about how
 ``load`` is implemented. It is absolutely possible to reimplement the loading
 step using the low-level API.
@ -68,21 +68,21 @@ Dumping YAML
 ============

 Dumping is preferredly done with
-`dump <api/serialization.html#dump,K,Stream,TagStyle,AnchorStyle,PresentationOptions>`_,
-which serializes a native Nim variable to a character stream. As with ``load``,
+`dump <api/dumping.html#dump%2CDumper%2CK>`_,
+which serializes a native Nim value to a character stream. As with ``load``,
 the following paragraph describes how ``dump`` is implemented using the
 low-level API.

 A Nim value is transformed into a ``YamlStream`` with
-`represent <api/serialization.html#represent,T,TagStyle,AnchorStyle>`_.
-Depending on the ``AnchorStyle`` you specify, this will transform ``ref``
+`represent <api/native.html#represent%2CT%2CSerializationOptions>`_.
+Depending on the ``AnchorStyle`` you specify in the given ``SerializationOptions``, this will transform ``ref``
 variables with multiple instances into anchored elements and aliases (for
 ``asTidy`` and ``asAlways``) or write the same element into all places it
 occurs (for ``asNone``). Be aware that if you use ``asNone``, the value you
 serialize might not round-trip.

 Transforming a ``YamlStream`` into YAML character data is done with
-`present <api/presenter.html#present,YamlStream,Stream,TagLibrary,PresentationOptions>`_.
+`present <api/presenter.html#present%2CYamlStream%2CStream%2CPresentationOptions>`_.
 You can choose from multiple presentation styles. ``psJson`` is not able to
 process some features of ``YamlStream`` s, the other styles support all features
 and are guaranteed to round-trip to the same ``YamlStream`` if you parse the
--- a/doc/serialization.txt
+++ b/doc/serialization.txt
@ -247,7 +247,7 @@ These tags are generated on the fly based on the types you instantiate
 ``Table`` or ``seq`` with.

 You may customize the tags used for your types by using the template
-`setTagUri <yaml.taglib.html#setTagUri.t,typedesc,string>`_. It may not
+`setTagUri <api/taglib.html#setTagUri.t%2Ctypedesc%2Cstring>`_. It may not
 be applied to scalar and collection types implemented by NimYAML, but you can
 for example use it on a certain ``seq`` type:

@ -386,7 +386,7 @@ serialization context via ``ctx.put``. Follow the following guidelines when
 implementing a custom ``representObject`` proc:

 - You can use the helper template
-  `presentTag <yaml.native.html#presentTag,SerializationContext,TagStyle>`_
+  `presentTag <api/native.html#presentTag%2CSerializationContext%2Ctypedesc>`_
  for outputting the tag.
 - Always output the first token with a ``yAnchorNone``. Anchors will be set
  automatically by ``ref`` type handling.
--- a/nimdoc.cfg
+++ b/nimdoc.cfg
@ -130,6 +130,7 @@ doc.file = """
      <li><a href="/api/parser.html">yaml/parser</a></li>
      <li><a href="/api/presenter.html">yaml/presenter</a></li>
      <li><a href="/api/stream.html">yaml/stream</a></li>
+      <li><a href="/api/style.html">yaml/style</a></li>
      <li><a href="/api/taglib.html">yaml/taglib</a></li>
      <li><a href="/api/tojson.html">yaml/tojson</a></li>
    </ul>
--- a/test/tnative.nim
+++ b/test/tnative.nim
@ -67,6 +67,15 @@ type
  Child = object of Parent
    s*: string
    
+  AsFlow {.collection: csFlow.} = object
+    a* {.scalar: ssSingleQuoted.}: string
+    b* {.scalar: ssDoubleQuoted.}: string
+    c* {.scalar: ssPlain.}: string
+  
+  OverrideColStyle = object
+    flowChild: AsFlow
+    blockChild {.collection: csBlock.}: AsFlow
+
 proc `$`(v: BetterInt): string {.borrow.}
 proc `==`(left, right: BetterInt): bool {.borrow.}

@ -661,3 +670,20 @@ suite "Serialization":
        "- !test:BetterInt 1\n" &
        "- !test:BetterInt 9_998_887\n" &
        "- !test:BetterInt 98_312\n", output
+
+  test "Representation pragmas":
+    let input = OverrideColStyle(
+      flowChild: AsFlow(a: "abc", b: "abc", c: "abc"),
+      blockChild: AsFlow(a: "a\nc", b: "abc", c: "ab:")
+    )
+    var output = blockOnlyDumper().dump(input)
+    assertStringEqual "flowChild: {\n" &
+      "    a: 'abc',\n" &
+      "    b: \"abc\",\n" &
+      "    c: abc\n" &
+      "  }\n" &
+      "blockChild:\n" &
+      "  a: \"a\\\nc\"\n" &
+      "  b: \"abc\"\n" &
+      "  c: \"ab:\"\n", output
+  
--- a/yaml/annotations.nim
+++ b/yaml/annotations.nim
@ -11,6 +11,9 @@
 ## This module provides annotations for object fields that customize
 ## (de)serialization behavior of those fields.

+import style
+export style
+
 template defaultVal*(value : typed) {.pragma.}
  ## This annotation can be put on an object field. During deserialization,
  ## if no value for this field is given, the ``value`` parameter of this
--- a/yaml/data.nim
+++ b/yaml/data.nim
@ -4,8 +4,17 @@
 #    See the file "copying.txt", included in this
 #    distribution, for details about the copyright.

+## ================
+## Module yaml/data
+## ================
+##
+## This module defines the event data structure which serves as internal
+## representation of YAML structures. Every YAML document can be described
+## as stream of events.
+
 import hashes
-import private/escaping
+import style, private/escaping
+export style

 type
  Anchor* = distinct string ## \
@ -19,14 +28,6 @@ type
  Tag* = distinct string ## \
    ## A ``Tag`` contains an URI, like for example ``"tag:yaml.org,2002:str"``.

-  ScalarStyle* = enum
-    ## Original style of the scalar (for input),
-    ## or desired style of the scalar (for output).
-    ssAny, ssPlain, ssSingleQuoted, ssDoubleQuoted, ssLiteral, ssFolded
-
-  CollectionStyle* = enum
-    csAny, csBlock, csFlow, csPair
-
  EventKind* = enum
    ## Kinds of YAML events that may occur in an ``YamlStream``. Event kinds
    ## are discussed in `YamlStreamEvent <#YamlStreamEvent>`_.
@ -303,8 +304,12 @@ proc `$`*(event: Event): string {.raises: [].} =
  of yamlEndDoc:
    result = "-DOC"
    if event.explicitDocumentEnd: result &= " ..."
-  of yamlStartMap: result = "+MAP" & renderAttrs(event.mapProperties)
-  of yamlStartSeq: result = "+SEQ" & renderAttrs(event.seqProperties)
+  of yamlStartMap:
+    result = "+MAP" & (if event.mapStyle == csFlow: " {}" else: "") &
+      renderAttrs(event.mapProperties)
+  of yamlStartSeq:
+    result = "+SEQ" & (if event.seqStyle == csFlow: " []" else: "") &
+      renderAttrs(event.seqProperties)
  of yamlScalar:
    result = "=VAL" & renderAttrs(event.scalarProperties,
                                  event.scalarStyle == ssPlain or
--- a/yaml/native.nim
+++ b/yaml/native.nim
@ -62,6 +62,8 @@ type
    nextAnchorId: string
    options*: SerializationOptions
    putImpl*: proc(ctx: var SerializationContext, e: Event) {.raises: [], closure.}
+    overridingScalarStyle*: ScalarStyle = ssAny
+    overridingCollectionStyle*: CollectionStyle = csAny

  ConstructionContext* = object
    ## Context information for the process of constructing Nim values from YAML.
@ -82,6 +84,30 @@ type
 proc put*(ctx: var SerializationContext, e: Event) {.raises: [].} =
  ctx.putImpl(ctx, e)

+proc scalarStyleFor(ctx: var SerializationContext, t: typedesc): ScalarStyle =
+  if ctx.overridingScalarStyle != ssAny:
+    result = ctx.overridingScalarStyle
+    ctx.overridingScalarStyle = ssAny
+  else:
+    when compiles(t.hasCustomPragma(scalar)):
+      when t.hasCustomPragma(scalar):
+        result = t.getCustomPragmaVal(scalar)
+      else: result = ssAny
+    else: result = ssAny
+  ctx.overridingCollectionStyle = csAny
+
+proc collectionStyleFor(ctx: var SerializationContext, t: typedesc): CollectionStyle =
+  if ctx.overridingCollectionStyle != csAny:
+    result = ctx.overridingCollectionStyle
+    ctx.overridingCollectionStyle = csAny
+  else:
+    when compiles(t.hasCustomPragma(collection)):
+      when t.hasCustomPragma(collection):
+        result = t.getCustomPragmaVal(collection)
+      else: result = csAny
+    else: result = csAny
+  ctx.overridingScalarStyle = ssAny
+
 # forward declares

 proc constructChild*[T](
@ -175,7 +201,11 @@ proc safeTagUri(tag: Tag): string {.raises: [].} =
  except KeyError:
    internalError("Unexpected KeyError for Tag " & $tag)

-proc newYamlConstructionError*(s: YamlStream, mark: Mark, msg: string): ref YamlConstructionError =
+proc newYamlConstructionError*(
+  s: YamlStream,
+  mark: Mark,
+  msg: string,
+): ref YamlConstructionError =
  result = newException(YamlConstructionError, msg)
  result.mark = mark
  if not s.getLastTokenContext(result.lineContent):
@ -226,7 +256,7 @@ proc representObject*(
  tag  : Tag,
 ) {.raises: [].} =
  ## represents a string as YAML scalar
-  ctx.put(scalarEvent(value, tag, yAnchorNone))
+  ctx.put(scalarEvent(value, tag, yAnchorNone, ctx.scalarStyleFor(string)))

 proc parseHex[T: int8|int16|int32|int64|uint8|uint16|uint32|uint64](
  s: YamlStream, mark: Mark, val: string
@ -271,8 +301,10 @@ proc constructObject*[T: int8|int16|int32|int64](
  ## constructs an integer value from a YAML scalar
  ctx.input.constructScalarItem(item, T):
    case item.numberStyle
-    of nsHex: result = parseHex[T](ctx.input, item.startPos, item.scalarContent)
-    of nsOctal: result = parseOctal[T](ctx.input, item.startPos, item.scalarContent)
+    of nsHex:
+      result = parseHex[T](ctx.input, item.startPos, item.scalarContent)
+    of nsOctal:
+      result = parseOctal[T](ctx.input, item.startPos, item.scalarContent)
    of nsDecimal:
      let nInt = parseBiggestInt(item.scalarContent)
      if nInt <= T.high:
@ -301,7 +333,7 @@ proc representObject*[T: int8|int16|int32|int64](
  tag  : Tag,
 ) {.raises: [].} =
  ## represents an integer value as YAML scalar
-  ctx.put(scalarEvent($value, tag, yAnchorNone))
+  ctx.put(scalarEvent($value, tag, yAnchorNone, ctx.scalarStyleFor(T)))

 proc representObject*(
  ctx  : var SerializationContext,
@ -312,7 +344,9 @@ proc representObject*(
  ## on 64-bit systems, this may cause a RangeDefect.

  # currently, sizeof(int) is at least sizeof(int32).
-  try: ctx.put(scalarEvent($int32(value), tag, yAnchorNone))
+  try:
+    ctx.put(scalarEvent(
+      $int32(value), tag, yAnchorNone, ctx.scalarStyleFor(int)))
  except RangeDefect as rd:
    var e = newException(YamlSerializationError, rd.msg)
    e.parent = rd
@ -330,8 +364,10 @@ proc constructObject*[T: DefiniteUIntTypes](
  ## construct an unsigned integer value from a YAML scalar
  ctx.input.constructScalarItem(item, T):
    case item.numberStyle
-    of nsHex: result = parseHex[T](ctx.input, item.startPos, item.scalarContent)
-    of nsOctal: result = parseOctal[T](ctx.input, item.startPos, item.scalarContent)
+    of nsHex:
+      result = parseHex[T](ctx.input, item.startPos, item.scalarContent)
+    of nsOctal:
+      result = parseOctal[T](ctx.input, item.startPos, item.scalarContent)
    else:
      let nUInt = parseBiggestUInt(item.scalarContent)
      if nUInt <= T.high:
@ -365,7 +401,7 @@ proc representObject*[T: uint8|uint16|uint32|uint64](
  tag  : Tag,
 ) {.raises: [].} =
  ## represents an unsigned integer value as YAML scalar
-  ctx.put(scalarEvent($value, tag, yAnchorNone))
+  ctx.put(scalarEvent($value, tag, yAnchorNone, ctx.scalarStyleFor(T)))

 proc representObject*(
  ctx  : var SerializationContext,
@ -374,7 +410,9 @@ proc representObject*(
 ) {.raises: [YamlSerializationError], inline.} =
  ## represent an unsigned integer of architecture-defined length by casting it
  ## to int32. on 64-bit systems, this may cause a RangeDefect.
-  try: ctx.put(scalarEvent($uint32(value), tag, yAnchorNone))
+  try:
+    ctx.put(scalarEvent(
+      $uint32(value), tag, yAnchorNone, ctx.scalarStyleFor(uint)))
  except RangeDefect as rd:
    var e = newException(YamlSerializationError, rd.msg)
    e.parent = rd
@ -413,10 +451,10 @@ proc representObject*[T: float|float32|float64](
 ) {.raises: [].} =
  ## represents a float value as YAML scalar
  case value
-  of Inf: ctx.put(scalarEvent(".inf", tag))
-  of NegInf: ctx.put(scalarEvent("-.inf", tag))
-  of NaN: ctx.put(scalarEvent(".nan", tag))
-  else: ctx.put(scalarEvent($value, tag))
+  of Inf: ctx.put(scalarEvent(".inf", tag, ctx.scalarStyleFor(T)))
+  of NegInf: ctx.put(scalarEvent("-.inf", tag, ctx.scalarStyleFor(T)))
+  of NaN: ctx.put(scalarEvent(".nan", tag, ctx.scalarStyleFor(T)))
+  else: ctx.put(scalarEvent($value, tag, ctx.scalarStyleFor(T)))

 proc yamlTag*(T: typedesc[bool]): Tag {.inline, raises: [].} = yTagBoolean

@ -441,7 +479,8 @@ proc representObject*(
  tag  : Tag,
 )  {.raises: [].} =
  ## represents a bool value as a YAML scalar
-  ctx.put(scalarEvent(if value: "true" else: "false", tag, yAnchorNone))
+  ctx.put(scalarEvent(if value: "true" else: "false",
+    tag, yAnchorNone, ctx.scalarStyleFor(bool)))

 proc constructObject*(
  ctx   : var ConstructionContext,
@ -462,7 +501,7 @@ proc representObject*(
  tag  : Tag
 ) {.raises: [].} =
  ## represents a char value as YAML scalar
-  ctx.put(scalarEvent("" & value, tag, yAnchorNone))
+  ctx.put(scalarEvent("" & value, tag, yAnchorNone, ctx.scalarStyleFor(char)))

 proc yamlTag*(T: typedesc[Time]): Tag {.inline, raises: [].} = yTagTimestamp

@ -534,7 +573,8 @@ proc representObject*(
  tag  : Tag,
 ) {.raises: [].} =
  let tmp = value.utc()
-  ctx.put(scalarEvent(tmp.format("yyyy-MM-dd'T'HH:mm:ss'Z'")))
+  ctx.put(scalarEvent(tmp.format(
+    "yyyy-MM-dd'T'HH:mm:ss'Z'"), tag, yAnchorNone, ctx.scalarStyleFor(Time)))

 proc yamlTag*[I](T: typedesc[seq[I]]): Tag {.inline, raises: [].} =
  return nimTag("system:seq(" & safeTagUri(yamlTag(I)) & ')')
@ -578,7 +618,8 @@ proc representObject*[T](
  tag  : Tag,
 ) {.raises: [YamlSerializationError].} =
  ## represents a Nim seq as YAML sequence
-  ctx.put(startSeqEvent(tag = tag))
+  ctx.put(
+    startSeqEvent(tag = tag, style = ctx.collectionStyleFor(type(value))))
  for item in value: ctx.representChild(item)
  ctx.put(endSeqEvent())

@ -610,7 +651,7 @@ proc representObject*[I, T](
  tag  : Tag,
 ) {.raises: [YamlSerializationError].} =
  ## represents a Nim array as YAML sequence
-  ctx.put(startSeqEvent(tag = tag))
+  ctx.put(startSeqEvent(tag = tag, style = ctx.collectionStyleFor(array[I, T])))
  for item in value: ctx.representChild(item)
  ctx.put(endSeqEvent())

@ -646,7 +687,8 @@ proc representObject*[K, V](
  tag  : Tag,
 ) {.raises: [YamlSerializationError].} =
  ## represents a Nim Table as YAML mapping
-  ctx.put(startMapEvent(tag = tag))
+  ctx.put(
+    startMapEvent(tag = tag, style = ctx.collectionStyleFor(Table[K, V])))
  for key, value in value.pairs:
    ctx.representChild(key)
    ctx.representChild(value)
@ -694,7 +736,8 @@ proc representObject*[K, V](
  value: OrderedTable[K, V],
  tag  : Tag,
 ) {.raises: [YamlSerializationError].} =
-  ctx.put(startSeqEvent(tag = tag))
+  ctx.put(startSeqEvent(
+    tag = tag, style = ctx.collectionStyleFor(OrderedTable[K, V])))
  for key, value in value.pairs:
    ctx.put(startMapEvent())
    ctx.representChild(key)
@ -1198,6 +1241,11 @@ proc recGenFieldRepresenters(
          `fieldName`,
          tag = if ctx.emitTag: yTagNimField else: yTagQuestionMark
        ))
+        when `fieldAccessor`.hasCustomPragma(scalar):
+          ctx.overridingScalarStyle = `fieldAccessor`.getCustomPragmaVal(scalar)
+          echo "set scalar style to ", $ctx.overridingScalarStyle
+        when `fieldAccessor`.hasCustomPragma(collection):
+          ctx.overridingCollectionStyle = `fieldAccessor`.getCustomPragmaVal(collection)
        ctx.representChild(`fieldAccessor`)
        ctx.put(endMapEvent())
      )
@ -1231,6 +1279,11 @@ proc recGenFieldRepresenters(
                  `name`,
                  tag = if ctx.emitTag: yTagNimField else: yTagQuestionMark 
                ))
+                when `itemAccessor`.hasCustomPragma(scalar):
+                  ctx.overridingScalarStyle = `itemAccessor`.getCustomPragmaVal(scalar)
+                  echo "set scalar style to ", $ctx.overridingScalarStyle
+                when `itemAccessor`.hasCustomPragma(collection):
+                  ctx.overridingCollectionStyle = `itemAccessor`.getCustomPragmaVal(collection)
                ctx.representChild(`itemAccessor`)
                ctx.put(endMapEvent())
            )
@ -1252,6 +1305,11 @@ proc recGenFieldRepresenters(
            if ctx.emitTag: yTagNimField else: yTagQuestionMark,
            yAnchorNone
          ))
+          when `childAccessor`.hasCustomPragma(scalar):
+            ctx.overridingScalarStyle = `childAccessor`.getCustomPragmaVal(scalar)
+            echo "set scalar style to ", $ctx.overridingScalarStyle
+          when `childAccessor`.hasCustomPragma(collection):
+            ctx.overridingCollectionStyle = `childAccessor`.getCustomPragmaVal(collection)
          ctx.representChild(`childAccessor`)
          when bool(`isVO`): ctx.put(endMapEvent())
        when not `childAccessor`.hasCustomPragma(transient):
@ -1276,8 +1334,10 @@ proc representObject*[O: object](
  tag  : Tag,
 ) {.raises: [YamlSerializationError].} =
  ## represents a Nim object or tuple as YAML mapping
-  when isVariantObject(getType(O)): ctx.put(startSeqEvent(tag = tag))
-  else: ctx.put(startMapEvent(tag = tag))
+  when isVariantObject(getType(O)):
+    ctx.put(startSeqEvent(tag = tag, style = ctx.collectionStyleFor(O)))
+  else:
+    ctx.put(startMapEvent(tag = tag, style = ctx.collectionStyleFor(O)))
  genRepresentObject(O, value)
  when isVariantObject(getType(O)): ctx.put(endSeqEvent())
  else: ctx.put(endMapEvent())
@ -1288,7 +1348,7 @@ proc representObject*[O: tuple](
  tag  : Tag,
 ) {.raises: [YamlSerializationError].} =
  var fieldIndex = 0'i16
-  ctx.put(startMapEvent(tag = tag))
+  ctx.put(startMapEvent(tag = tag, style = ctx.collectionStyleFor(O)))
  for name, fvalue in fieldPairs(value):
    ctx.put(scalarEvent(
      name,
@ -1322,7 +1382,7 @@ proc representObject*[O: enum](
  tag  : Tag,
 ) {.raises: [].} =
  ## represents a Nim enum as YAML scalar
-  ctx.put(scalarEvent($value, tag, yAnchorNone))
+  ctx.put(scalarEvent($value, tag, yAnchorNone, ctx.scalarStyleFor(O)))

 proc yamlTag*[O](T: typedesc[ref O]): Tag {.inline, raises: [].} = yamlTag(O)

@ -1621,7 +1681,7 @@ proc representChild*[O](
  ctx  : var SerializationContext,
  value: ref O,
 ) =
-  if isNil(value): ctx.put(scalarEvent("~", yTagNull))
+  if isNil(value): ctx.put(scalarEvent("~", yTagNull, style = ctx.scalarStyleFor(O)))
  else:
    when nimvm: discard
    else:
@ -1643,6 +1703,8 @@ proc representChild*[O](
          if not val.referenced:
            ctx.refs[p] = (val.a, true)
          ctx.put(aliasEvent(val.a))
+          ctx.overridingScalarStyle = ssAny
+          ctx.overridingCollectionStyle = csAny
          return
      ctx.refs[p] = val
      nextAnchor(ctx.nextAnchorId, len(ctx.nextAnchorId) - 1)
@ -1675,7 +1737,7 @@ proc representChild*[T](
  if value.isSome:
    ctx.representChild(value.get())
  else:
-    ctx.put(scalarEvent("~", yTagNull))
+    ctx.put(scalarEvent("~", yTagNull, style = ctx.scalarStyleFor(Option[T])))

 proc representChild*[O](
  ctx  : var SerializationContext,
--- a/yaml/stream.nim
+++ b/yaml/stream.nim
@ -8,9 +8,9 @@
 ## Module yaml/stream
 ## ==================
 ##
-## The stream API provides the basic data structure on which all low-level APIs
-## operate. It is not named ``streams`` to not confuse it with the modle in the
-## stdlib with that name.
+## The stream API provides the basic data structure ``YamlStream`` on which all
+## low-level APIs operate. It is not named ``streams`` to not confuse it with
+## the module in the stdlib with that name.

 import data

--- a/yaml/style.nim
+++ b/yaml/style.nim
@ -0,0 +1,40 @@
+#            NimYAML - YAML implementation in Nim
+#        (c) Copyright 2015-2023 Felix Krause
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+
+## =================
+## Module yaml/style
+## =================
+##
+## The style API provides enums describing the style of YAML nodes.
+## It also provides custom pragmas with which you can define the style
+## with which values should be serialized.
+
+type
+  ScalarStyle* = enum
+    ## Original style of the scalar (for input),
+    ## or desired style of the scalar (for output).
+    ssAny, ssPlain, ssSingleQuoted, ssDoubleQuoted, ssLiteral, ssFolded
+
+  CollectionStyle* = enum
+    ## Original style of the collection (for input).
+    ## or desired style of the collection (for output).
+    csAny, csBlock, csFlow, csPair
+
+template scalar*(style: ScalarStyle) {.pragma.}
+  ## This annotation can be put on an object field or on a type.
+  ## It causes the value in the field or a value of this type
+  ## to be presented with the given scalar style if possible.
+  ## Ignored if the value does not serialize to a scalar.
+  ##
+  ## A pragma on a field overrides a pragma on the field's type.
+
+template collection*(style: CollectionStyle) {.pragma.}
+  ## This annotation can be put on an object field or on a type.
+  ## It causes the value in the field or a value of this type
+  ## to be presented with the given collection style if possible.
+  ## Ignored if the value does not serialize to a collection.
+  ##
+  ## A pragma on a field overrides a pragma on the field's type.