Got rid of yamlWarning, use YamlPresenterError

* Added YamlWarningCallback that may be used to capture
   parser warnings
 * Removed yamlWarning as event kind
 * Replaced checks for well-formedness in presenter with asserts
 * Added checks for JSON compatibility of YamlStream in presenter
 * Added proper type hints for special float values in
   serializer to be able to check for them in the presenter

private/events.nim

@@ -23,9 +23,6 @@ proc `==`*(left: YamlStreamEvent, right: YamlStreamEvent): bool =
                  left.scalarType == right.scalarType
     of yamlAlias:
         result = left.aliasTarget == right.aliasTarget
-    of yamlWarning:
-        result = left.description == right.description and
-                 left.line == right.line and left.column == right.column
 
 proc `$`*(event: YamlStreamEvent): string =
     result = $event.kind & '('
@@ -48,9 +45,6 @@ proc `$`*(event: YamlStreamEvent): string =
         result &= ", content=\"" & event.scalarContent & '\"'
     of yamlAlias:
         result &= "aliasTarget=" & $event.aliasTarget
-    of yamlWarning:
-        result &= "line=" & $event.line & ", column=" & $event.column
-        result &= ", description=\"" & event.description & '\"'
     result &= ")"
 
 proc startDocEvent*(): YamlStreamEvent =

private/json.nim

@@ -138,9 +138,6 @@ proc constructJson*(s: YamlStream): seq[JsonNode] =
                     discard # will never happen
             else:
                 discard # wait for yamlEndDocument
-        of yamlWarning:
-            echo "YAML warning at line ", event.line, ", column ", event.column,
-                 ": ", event.description
         of yamlAlias:
             # we can savely assume that the alias exists in anchors
             # (else the parser would have already thrown an exception)

private/parser.nim

@@ -57,6 +57,10 @@ proc newParser*(tagLib: YamlTagLibrary): YamlSequentialParser =
     result.tagLib = tagLib
     result.anchors = initOrderedTable[string, AnchorId]()
 
+proc setWarningCallback*(parser: YamlSequentialParser,
+                         callback: YamlWarningCallback) =
+    parser.callback = callback
+
 proc anchor*(parser: YamlSequentialParser, id: AnchorId): string =
     for pair in parser.anchors.pairs:
         if pair[1] == id:
@@ -64,8 +68,8 @@ proc anchor*(parser: YamlSequentialParser, id: AnchorId): string =
     return nil
         
 template yieldWarning(d: string) {.dirty.} =
-    yield YamlStreamEvent(kind: yamlWarning, description: d,
+    if parser.callback != nil:
-                          line: lex.line, column: lex.column)
+        parser.callback(lex.line, lex.column, lex.getCurrentLine(), d)
 
 template raiseError(message: string) {.dirty.} =
     var e = newException(YamlParserError, message)

private/presenter.nim

@@ -155,13 +155,22 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
                 writeTagAndAnchor(target,
                                   item.scalarTag, tagLib, item.scalarAnchor)
             
-            if (style == ypsJson and item.scalarTag in [yTagQuestionMark,
+            if style == ypsJson:
-                                                          yTagBoolean] and
+                if item.scalarTag in [yTagQuestionMark, yTagBoolean] and
-                    item.scalarType in [yTypeBoolTrue, yTypeBoolFalse]):
+                        item.scalarType in [yTypeBoolTrue, yTypeBoolFalse]:
                     if item.scalarType == yTypeBoolTrue:
                         target.write("true")
                     else:
                         target.write("false")
+                elif item.scalarTag in [yTagQuestionMark, yTagNull] and
+                        item.scalarType == yTypeNull:
+                    target.write("null")
+                elif item.scalarTag in [yTagQuestionMark, yTagFloat] and
+                        item.scalarType in [yTypeFloatInf, yTypeFloatNaN]:
+                    raise newException(YamlPresenterError,
+                            "Infinity and not-a-number values cannot be presented as JSON!")
+                else:
+                    target.write(item.scalarContent)
             elif style == ypsCanonical or item.scalarContent.needsEscaping or
                (style == ypsJson and
                 (item.scalarTag notin [yTagQuestionMark, yTagInteger, yTagFloat,
@@ -173,9 +182,7 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
             else:
                 target.write(item.scalarContent)
         of yamlAlias:
-            if levels.len == 0:
+            assert levels.len > 0
-                raise newException(ValueError, "Malformed YamlStream")
-            else:
             startItem(target, style, indentation, levels[levels.high])
             target.write('*')
             target.write(cast[byte]('a') + cast[byte](item.aliasTarget))
@@ -186,8 +193,7 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
                 var length = 0
                 while true:
                     let next = s()
-                    if finished(s):
+                    assert (not finished(s))
-                        raise newException(ValueError, "Malformed YamlStream")
                     cached.enqueue(next)
                     case next.kind
                     of yamlScalar:
@@ -201,7 +207,13 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
                         break
                 nextState = if length <= 60: dFlowSequenceStart else:
                             dBlockSequenceItem
-            of ypsMinimal, ypsJson, ypsCanonical:
+            of ypsJson:
+                if levels[levels.high] in
+                        [dFlowImplicitMapStart, dFlowImplicitMapValue]:
+                    raise newException(YamlPresenterError,
+                            "Cannot have sequence as map key in JSON output!")
+                nextState = dFlowSequenceStart
+            of ypsMinimal, ypsCanonical:
                 nextState = dFlowSequenceStart
             of ypsBlockOnly:
                 nextState = dBlockSequenceItem 
@@ -240,8 +252,7 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
                 var length = 0
                 while true:
                     let next = s()
-                    if finished(s):
+                    assert (not finished(s))
-                        raise newException(ValueError, "Malformed YamlStream")
                     cached.enqueue(next)
                     case next.kind
                     of yamlScalar:
@@ -262,6 +273,10 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
             of ypsCanonical:
                 nextState = dFlowExplicitMapStart
             of ypsJson:
+                if levels[levels.high] in
+                        [dFlowImplicitMapStart, dFlowImplicitMapValue]:
+                    raise newException(YamlPresenterError,
+                            "Cannot have map as map key in JSON output!")
                 nextState = dFlowImplicitMapStart
             of ypsBlockOnly:
                 nextState = if item.mapMayHaveKeyObjects:
@@ -305,8 +320,7 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
             levels.add(nextState)
             
         of yamlEndSequence:
-            if levels.len == 0:
+            assert levels.len > 0
-                raise newException(ValueError, "Malformed YamlStream")
             case levels.pop()
             of dFlowSequenceItem:
                 case style
@@ -333,11 +347,10 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
             of dBlockSequenceItem:
                 discard
             else:
-                raise newException(ValueError, "Malformed YamlStream")
+                assert false
             indentation -= indentationStep
         of yamlEndMap:
-            if levels.len == 0:
+            assert levels.len > 0
-                raise newException(ValueError, "Malformed YamlStream")
             case levels.pop()
             of dFlowImplicitMapValue, dFlowExplicitMapValue:
                 case style
@@ -364,7 +377,7 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
             of dBlockImplicitMapValue, dBlockExplicitMapValue:
                 discard
             else:
-                raise newException(ValueError, "Malformed YamlStream")
+                assert false
             indentation -= indentationStep
         of yamlEndDocument:
             let next = s()
@@ -372,8 +385,6 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
                 break
             target.write("...\x0A")
             cached.enqueue(next)
-        of yamlWarning:
-            discard
 
 proc transform*(input: Stream, output: Stream, style: YamlPresentationStyle,
                 indentationStep: int = 2) =

test/parsing.nim

@@ -48,8 +48,6 @@ proc alias(target: AnchorId): YamlStreamEvent =
 proc printDifference(expected, actual: YamlStreamEvent) =
     if expected.kind != actual.kind:
         echo "expected " & $expected.kind & ", got " & $actual.kind
-        if actual.kind == yamlWarning:
-            echo "Warning message: " & actual.description
     else:
         case expected.kind
         of yamlScalar:
@@ -117,7 +115,7 @@ template ensure(input: string, expected: varargs[YamlStreamEvent]) {.dirty.} =
                 break
             i.inc()
     except YamlParserError:
-        let e = cast[YamlParserError](getCurrentException())
+        let e = cast[ref YamlParserError](getCurrentException())
         echo "Parser error:", getCurrentExceptionMsg()
         echo e.lineContent
         fail()

yaml.nim

@@ -50,7 +50,7 @@ type
         ## Kinds of YAML events that may occur in an ``YamlStream``. Event kinds
         ## are discussed in ``YamlStreamEvent``.
         yamlStartDocument, yamlEndDocument, yamlStartMap, yamlEndMap,
-        yamlStartSequence, yamlEndSequence, yamlScalar, yamlAlias, yamlWarning
+        yamlStartSequence, yamlEndSequence, yamlScalar, yamlAlias
     
     TagId* = distinct int ## \
         ## A ``TagId`` identifies a tag URI, like for example 
@@ -107,24 +107,13 @@ type
             discard
         of yamlAlias:
             aliasTarget* : AnchorId
-        of yamlWarning:
-            description* : string
-            line*        : int
-            column*      : int
     
     YamlStream* = iterator(): YamlStreamEvent ## \
         ## A ``YamlStream`` is an iterator that yields a well-formed stream of
         ## ``YamlStreamEvents``. Well-formed means that every ``yamlStartMap``
         ## is terminated by a ``yamlEndMap``, every ``yamlStartSequence`` is
         ## terminated by a ``yamlEndSequence`` and every ``yamlStartDocument``
-        ## is terminated by a ``yamlEndDocument``. The only exception to this
+        ## is terminated by a ``yamlEndDocument``.
-        ## rule is a ``yamlError``, which may occur anywhere in the stream and
-        ## must be the last element in the stream, which may leave any number of
-        ## objects open.
-        ##
-        ## A ``yamlWarning`` may also occur anywhere in the stream, but will not
-        ## invalidate the structure of the event stream, and may not abruptly
-        ## end the stream as ``yamlError`` does.
         ##
         ## The creator of a ``YamlStream`` is responsible for it being
         ## well-formed. A user of the stream may assume that it is well-formed
@@ -157,6 +146,15 @@ type
         nextCustomTagId*: TagId
         secondaryPrefix*: string
     
+    YamlWarningCallback* = proc(line, column: int, lineContent: string,
+                                message: string)
+        ## Callback for parser warnings. Currently, this callback may be called
+        ## on two occasions while parsing a YAML document stream:
+        ##
+        ## - If the version number in the ``%YAML`` directive does not match
+        ##   ``1.2``.
+        ## - If there is an unknown directive encountered.
+    
     YamlSequentialParser* = ref object
         ## A parser object. Retains its ``YamlTagLibrary`` across calls to
         ## `parse <#parse,YamlSequentialParser,Stream,YamlStream>`_. Can be used
@@ -165,6 +163,7 @@ type
         ## ``yamlEndDocument`` is yielded).
         tagLib: YamlTagLibrary
         anchors: OrderedTable[string, AnchorId]
+        callback: YamlWarningCallback
     
     YamlPresentationStyle* = enum
         ## Different styles for YAML character stream output.
@@ -186,7 +185,18 @@ type
         ##   flow style at all.
         ypsMinimal, ypsCanonical, ypsDefault, ypsJson, ypsBlockOnly
     
-    YamlParserError* = object of Exception
+    YamlLoadingError* = object of Exception
+        ## Base class for all exceptions that may be raised during the process
+        ## of loading a YAML character stream. 
+        line*: int ## line number (1-based) where the error was encountered
+        column*: int ## \
+            ## column number (1-based) where the error was encountered
+        lineContent*: string ## \
+            ## content of the line where the error was encountered. Includes a
+            ## second line with a marker ``^`` at the position where the error
+            ## was encountered, as returned by ``lexbase.getCurrentLine``.
+    
+    YamlParserError* = object of YamlLoadingError
         ## A parser error is raised if the character stream that is parsed is
         ## not a valid YAML character stream. This stream cannot and will not be
         ## parsed wholly nor partially and all events that have been emitted by
@@ -216,16 +226,16 @@ type
         ##
         ## Some elements in this list are vague. For a detailed description of a
         ## valid YAML character stream, see the YAML specification.
-        line*: int ## line number (1-based) where the error was encountered
-        column*: int ## \
-            ## column number (1-based) where the error was encountered
-        lineContent*: string ## \
-            ## content of the line where the error was encountered. Includes a
-            ## second line with a marker ``^`` at the position where the error
-            ## was encountered, as returned by ``lexbase.getCurrentLine``.
     
     YamlPresenterError* = object of Exception
-        ## Exception that may be raised by the YAML presenter.
+        ## Exception that may be raised by the YAML presenter. Currently, the
+        ## only ocassion this exception may be raised is when the presenter is
+        ## instructed to output JSON, but is unable to do so. This may occur if:
+        ##
+        ## - The given `YamlStream <#YamlStream>`_ contains a map which has any
+        ##   non-scalar type as key.
+        ## - Any float scalar bears a ``NaN`` or positive/negative infinity
+        ##   value 
 const
     # failsafe schema
 
@@ -350,6 +360,9 @@ proc extendedTagLibrary*(): YamlTagLibrary
 proc newParser*(tagLib: YamlTagLibrary): YamlSequentialParser
     ## Instanciates a parser
 
+proc setWarningCallback*(parser: YamlSequentialParser,
+                         callback: YamlWarningCallback)
+
 proc anchor*(parser: YamlSequentialParser, id: AnchorId): string
     ## Get the anchor name which an ``AnchorId`` maps to
 

yaml/serialization.nim

@@ -233,7 +233,7 @@ proc safeTagUri*(id: TagId): string =
 proc construct*(s: YamlStream, result: var string) =
     let item = s()
     if finished(s) or item.kind != yamlScalar:
-        raise newException(ValueError, "Construction error!" & $item.description)
+        raise newException(ValueError, "Construction error!")
     if item.scalarTag notin [yTagQuestionMark, yTagExclamationMark, yTagString]:
         raise newException(ValueError, "Wrong tag for string.")
     result = item.scalarContent
@@ -306,15 +306,27 @@ proc construct*(s: YamlStream, result: var float) =
 proc serialize*(value: float,
                 tagStyle: YamlTagStyle = ytsNone): YamlStream =
     result = iterator(): YamlStreamEvent =
-        var asString = case value
+        var
-            of Inf: ".inf"
+            asString: string
-            of NegInf: "-.inf"
+            hint: YamlTypeHint
-            of NaN: ".nan"
+        case value
-            else: $value
+        of Inf:
+            asString = ".inf"
+            hint = yTypeFloatInf
+        of NegInf:
+            asString = "-.inf"
+            hint = yTypeFloatInf
+        of NaN:
+            asString = ".nan"
+            hint = yTypeFloatNaN
+        else:
+            asString = $value
+            hint = yTypeFloat
     
         yield YamlStreamEvent(kind: yamlScalar,
                 scalarTag: presentTag(float, tagStyle),
-                scalarAnchor: yAnchorNone, scalarContent: asString)
+                scalarAnchor: yAnchorNone, scalarContent: asString,
+                scalarType: hint)
 
 proc yamlTag*(T: typedesc[bool]): TagId {.inline.} = yTagBoolean