Re: NimYAML 0.7.0 released
Thanks a ton!
Re: NimYAML 0.7.0 released
`loadToJson` ignores tags because the JSON structures do not know anything
about tags. You have several options:
**Using the serialization API with an implicit variant object**
First, you need to define the type for the tag `!remote`. You need to tell
NimYAML how to load that type. Then, you define a variant object type that can
hold either normal strings or `!remote` values. You then tell NimYAML to treat
this variant object type implicitly for loading the chapters. Example code:
import yaml.serialization, yaml.taglib
type
Remote = distinct string
ChapterKind = enum
ckLocal, ckRemote
Chapter = object
case kind: ChapterKind
of ckLocal:
lValue: string
of ckRemote:
rValue: Remote
Root = object
chapters: seq[Chapter]
proc constructObject*(s: var YamlStream, c: ConstructionContext,
result: var Remote) =
# construct a Remote like a string
constructObject(s, c, string(result))
setTagUri(Remote, "!remote")
markAsImplicit(Chapter)
var root: Root
load("""
chapters:
- foo
- bar
- !remote http://example.com/somefile
""", root)
echo "Parsed chapters:"
for c in root.chapters:
case c.kind
of ckLocal: echo "[Local] ", c.lValue
of ckRemote: echo "[Remote] ", string(c.rValue)
Sadly, you cannot simply transform the chapter values into some `tuple[value:
String, remote: bool]` because NimYAML's serialization API uses tags to denote
types, not annotations.
**Using the DOM API**
Perhaps simpler for simple use cases:
import yaml.dom
var document = loadDOM("""
chapters:
- foo
- bar
- !remote http://example.com/somefile
""")
echo "Parsed chapters:"
for c in document.root.pairs[0].value.children:
echo if c.tag == "!remote": "[Remote] " else: "[Local] ", c.content
The DOM API needs some love; currently mappings are parsed into a
`seq[tuple[key, value: YamlNode]]` which is not ideal for accessing specific
subtrees. A Table would make more sense. Pull requests are welcome :).
**Using the sequential API**
This may be useful for use cases where you need to process the input
sequentially since it doesn't load everything in an object and therefore is
faster:
import yaml.parser, yaml.taglib, yaml.stream
var
myTagLib = initCoreTagLibrary()
yTagRemote = myTagLib.registerUri("!remote")
p = newYamlParser(myTagLib)
events = p.parse("""
chapters:
- foo
- bar
- !remote http://example.com/somefile
""")
doAssert events.next().kind == yamlStartDoc
doAssert events.next().kind == yamlStartMap
let key = events.next()
doAssert key.kind == yamlScalar
doAssert key.scalarContent == "chapters"
doAssert events.next().kind == yamlStartSeq
var cur = events.next()
echo "Parsed chapters:"
while cur.kind != yamlEndSeq:
doAssert cur.kind == yamlScalar
echo if cur.scalarTag == yTagRemote: "[Remote] " else: "[Local] ",
cur.scalarContent
cur = events.next()
doAssert events.next().kind == yamlEndMap
doAssert events.next().kind == yamlEndDoc
doAssert events.finished()
Re: NimYAML 0.7.0 released
Hi @flyx! I'm using NimYAML to parse a config file. I want to use custom tags but can't figure out form the docs how to do it. Here's a glimpse of what I want to be able to handle: chapters: - foo - bar - !remote http://example.com/somefile When I load this content with `loadToJson` and iterate over `[0]["chapters"]` the tag is ignored. I tried registering the tag URI but I don't know what to with with the TagId I get from it. Could you please help me with that?
Re: NimYAML 0.7.0 released
NimYAML 0.8.0 is now available. Its focus was on making it more capable of being used for configuration files: * You can now set default values of object fields with `setDefaultValue`. * You can now mark object fields as transient with `markAsTransient` so that they are not serialized or expected in YAML input. * You can now ignore input keys with `ignoreInputKey`. This makes it easier to parse YAML input that contains data which is not of interest. Moreover, timestamps can now be parsed into `Time` values. However, this is only usable with most recent Nim devel version, since timezones are broken in 0.15.2.
NimYAML 0.7.0 released
Since we have Nim 0.15.0 now, NimYAML 0.7.0 follows. This list is relevant for upgrading from a previous version: * The API has been split over several modules. Importing the [base package](http://forum.nim-lang.org///flyx.github.io/NimYAML/yaml.html) imports all subpackages, so this change is backwards-compatible. However, you are encouraged to import only those parts of the API you need. * It is possible to call all loading procs with a `string` instead of a `Stream` input. Loading YAML directly from a string will enable NimYAML to include correct line content in its parsing exceptions. This is not always possible with using Streams, where it will return an empty string instead if the line content is not available. * The API for writing custom represent/construct procs has changed. [representObject](http://forum.nim-lang.org///flyx.github.io/NimYAML/serialization.html#representobject) does not return a `YamlStreamEvent` iterator anymore. Instead, the implementation shall put its generated event(s) into the `SerializationContext`. You have to update existing code if you use that functionality. Major new features are: * The serialization API features better checks and error messages in case of invalid input. This makes NimYAML feasible for user-written configuration files. * Usage of first-class iterators has been removed to make compiling to JS possible. However, finishing this is still blocked by a Nim compiler bug, see [here](https://github.com/flyx/NimYAML/issues/24). * YAML compliance has been improved. A complete list of changes is available [here](https://github.com/flyx/NimYAML/blob/devel/CHANGELOG.md). NimYAML 0.7.0 requires Nim 0.15.0.
