Started re-implementing parser

* Made TagLibrary a ref object
 * Started writing fastparse.nim, a parser aimed to deliver
   much faster speeds than the current implementation. It
   currently is only able to parse block content

private/events.nim

@@ -70,3 +70,6 @@ proc scalarEvent*(content: string = "", tag: TagId = yTagQuestionMark,
                   anchor: AnchorId = yAnchorNone): YamlStreamEvent =
     result = YamlStreamEvent(kind: yamlScalar, scalarTag: tag,
                              scalarAnchor: anchor, scalarContent: content)
+
+proc aliasEvent*(anchor: AnchorId): YamlStreamEvent =
+  result = YamlStreamEvent(kind: yamlAlias, aliasTarget: anchor)

private/fastparse.nim

@@ -0,0 +1,901 @@
+type
+  FastParseState = enum
+    fpInitial, fpBlockLineStart, fpBlockAfterScalar, fpBlockAfterPlainScalar,
+    fpBlockObjectStart, fpBlockContinueScalar, fpExpectDocEnd
+  
+  FastParseLevelKind = enum
+    fplUnknown, fplSequence, fplMapKey, fplMapValue, fplScalar
+  
+  FastParseLevel = object
+    kind: FastParseLevelKind
+    indentation: int
+  
+  LexedDirective = enum
+    ldYaml, ldTag, ldUnknown
+  
+  LexedPossibleDirectivesEnd = enum
+    lpdeDirectivesEnd, lpdeSequenceItem, lpdeScalarContent
+  
+  YamlContext = enum
+    cFlowIn, cFlowOut, cFlowKey, cBlockKey, cBlockIn, cBlockOut
+  
+  FastLexer = object of BaseLexer
+    tokenstart: int
+
+const
+  space          = [' ', '\t']
+  lineEnd        = ['\x0A', '\c', EndOfFile]
+  spaceOrLineEnd = [' ', '\t', '\x0A', '\c', EndOfFile]
+  digits         = '0'..'9'
+  flowIndicators = ['[', ']', '{', '}', ',']
+
+template debug(message: string) {.dirty.} =
+  when defined(yamlDebug):
+    try: styledWriteLine(stdout, fgBlue, message)
+    except IOError: discard
+
+template raiseError(message: string) {.dirty.} =
+  var e = newException(YamlParserError, message)
+  e.line = lexer.lineNumber
+  e.column = lexer.tokenstart
+  e.lineContent = lexer.getCurrentLine(false) &
+      repeat(' ', lexer.getColNumber(lexer.bufpos)) & "^\n"
+  raise e
+
+template raiseError(message: string, col: int) {.dirty.} =
+  var e = newException(YamlParserError, message)
+  e.line = lexer.lineNumber
+  e.column = col
+  e.lineContent = lexer.getCurrentLine(false) &
+      repeat(' ', lexer.getColNumber(lexer.bufpos)) & "^\n"
+  raise e
+
+template closeLevel() {.dirty.} =
+  case level.kind
+  of fplSequence:
+    yield endSeqEvent()
+  of fplMapKey:
+    yield endMapEvent()
+  of fplMapValue:
+    yield scalarEvent("", tag, anchor)
+    tag = yTagQuestionMark
+    anchor = yAnchorNone
+    yield endMapEvent()
+  of fplScalar:
+    applyObjectProperties()
+    yield cachedScalar
+  of fplUnknown:
+    yield scalarEvent("")
+  if ancestry.len > 0:
+    level = ancestry.pop()
+
+template handleLineEnd(insideDocument: bool) {.dirty.} =
+  case lexer.buf[lexer.bufpos]
+  of '\x0A':
+    lexer.bufpos = lexer.handleLF(lexer.bufpos)
+  of '\c':
+    lexer.bufpos = lexer.handleCR(lexer.bufpos)
+  of EndOfFile:
+    when insideDocument:
+      closeEverything()
+    return
+  else:
+    discard
+
+template handleObjectEnd() {.dirty.} =
+  tag = yTagQuestionMark
+  anchor = yAnchorNone
+  case level.kind
+  of fplMapKey:
+    level.kind = fplMapValue
+  of fplMapValue:
+    level.kind = fplMapKey
+  of fplSequence:
+    discard
+  of fplUnknown, fplScalar:
+    raiseError("Internal error!")
+
+template handleStartObject(k: YamlStreamEventKind) {.dirty.} =
+  when k == yamlStartMap:
+    yield startMapEvent(objectTag, objectAnchor)
+    debug("started map at " & $lexer.tokenstart)
+  else:
+    yield startSeqEvent(objectTag, objectAnchor)
+    debug("started sequence at " & $lexer.tokenstart)
+  objectTag = yTagQuestionMark
+  objectAnchor = yAnchorNone
+  
+template closeMoreIndentedLevels() {.dirty.} =
+  while ancestry.len > 0:
+    let parent = ancestry[ancestry.high]
+    if parent.indentation >= indentation:
+      debug("Closing because level.indentation =" & $level.indentation &
+            ", but indentation = " & $indentation)
+      closeLevel()
+      handleObjectEnd()
+    else:
+      break
+
+template closeEverything() {.dirty.} =
+  indentation = 0
+  closeMoreIndentedLevels()
+  closeLevel()
+  yield endDocEvent()
+
+template handleStartBlockSequence() {.dirty.} =
+  case level.kind
+  of fplUnknown:
+    level.kind = fplSequence
+    handleStartObject(yamlStartSequence)
+  of fplSequence:
+    if level.indentation != indentation:
+      raiseError("Invalid indentation of block sequence indicator",
+                 lexer.bufpos)
+  else:
+      raiseError("Illegal sequence item in map")
+  ancestry.add(level)
+  lexer.skipWhitespace()
+  indentation = lexer.getColNumber(lexer.bufpos)
+  level = FastParseLevel(kind: fplUnknown, indentation: indentation)
+
+template handleStartBlockScalar() {.dirty.} =
+  case level.kind
+  of fplUnknown, fplMapKey:
+    discard
+  of fplSequence:
+    raiseError("Illegal token (expected '- ')")
+  of fplMapValue, fplScalar:
+    raiseError("Internal error!")
+
+template propsToObjectProps() {.dirty.} =
+  if objectTag == yTagQuestionmark:
+    objectTag = tag
+    tag = yTagQuestionmark
+  elif tag != yTagQuestionMark:
+    raiseError("Only one tag is allowed per node")
+  if objectAnchor == yAnchorNone:
+    objectAnchor = anchor
+    anchor = yAnchorNone
+  elif anchor != yAnchorNone:
+    raiseError("Only one anchor is allowed per node")
+
+template initDocValues() {.dirty.} =
+  shorthands = initTable[string, string]()
+  anchors = initTable[string, AnchorId]()
+  shorthands["!"] = "!"
+  shorthands["!!"] = "tag:yaml.org,2002:"
+  nextAnchorId = 0.AnchorId
+  level = FastParseLevel(kind: fplUnknown, indentation: -1)
+
+template applyObjectProperties() {.dirty.} =
+  if objectTag != yTagQuestionmark:
+    if cachedScalar.scalarTag != yTagQuestionmark:
+      raiseError("Only one tag is allowed per node")
+    else:
+      cachedScalar.scalarTag = objectTag
+      objectTag = yTagQuestionmark
+  if objectAnchor != yAnchorNone:
+    if cachedScalar.scalarAnchor != yAnchorNone:
+      raiseError("Only one anchor is allowed per node")
+    else:
+      cachedScalar.scalarAnchor = objectAnchor
+      objectAnchor = yAnchorNone
+
+template finishLine(lexer: FastLexer) =
+  debug("lex: finishLine")
+  while lexer.buf[lexer.bufpos] notin lineEnd:
+    lexer.bufpos.inc()
+
+template skipWhitespace(lexer: FastLexer) =
+  debug("lex: skipWhitespace")
+  while lexer.buf[lexer.bufpos] in space: lexer.bufpos.inc()
+
+template skipIndentation(lexer: FastLexer) =
+  debug("lex: skipIndentation")
+  while lexer.buf[lexer.bufpos] == ' ': lexer.bufpos.inc()
+
+template directiveName(lexer: FastLexer, directive: var LexedDirective) =
+  debug("lex: directiveName")
+  directive = ldUnknown
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  lexer.bufpos.inc()
+  if lexer.buf[lexer.bufpos] == 'Y':
+    lexer.bufpos.inc()
+    if lexer.buf[lexer.bufpos] == 'A':
+      lexer.bufpos.inc()
+      if lexer.buf[lexer.bufpos] == 'M':
+        lexer.bufpos.inc()
+        if lexer.buf[lexer.bufpos] == 'L':
+          lexer.bufpos.inc()
+          if lexer.buf[lexer.bufpos] in spaceOrLineEnd:
+            directive = ldYaml
+  elif lexer.buf[lexer.bufpos] == 'T':
+    lexer.bufpos.inc()
+    if lexer.buf[lexer.bufpos] == 'A':
+      lexer.bufpos.inc()
+      if lexer.buf[lexer.bufpos] == 'G':
+        lexer.bufpos.inc()
+        if lexer.buf[lexer.bufpos] in [' ', '\t', '\x0A', '\c', EndOfFile]:
+          directive = ldTag
+  while lexer.buf[lexer.bufpos] notin spaceOrLineEnd:
+    lexer.bufpos.inc()
+
+template yamlVersion(lexer: FastLexer, o: var string) =
+  debug("lex: yamlVersion")
+  while lexer.buf[lexer.bufpos] in space:
+    lexer.bufpos.inc()
+  var c = lexer.buf[lexer.bufpos]
+  if c notin digits:
+    raiseError("Invalid YAML version number")
+  o.add(c)
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  lexer.bufpos.inc()
+  c = lexer.buf[lexer.bufpos]
+  while c in digits:
+    lexer.bufpos.inc()
+    o.add(c)
+    c = lexer.buf[lexer.bufpos]
+  if lexer.buf[lexer.bufpos] != '.':
+    raiseError("Invalid YAML version number")
+  lexer.bufpos.inc()
+  if lexer.buf[lexer.bufpos] notin digits:
+    raiseError("Invalid YAML version number")
+  lexer.bufpos.inc()
+  while lexer.buf[lexer.bufpos] in digits:
+    lexer.bufpos.inc()
+  if lexer.buf[lexer.bufpos] notin spaceOrLineEnd:
+    raiseError("Invalid YAML version number")
+
+template lineEnding(lexer: FastLexer) =
+  debug("lex: lineEnding")
+  if lexer.buf[lexer.bufpos] notin lineEnd:
+    while lexer.buf[lexer.bufpos] in space:
+      lexer.bufpos.inc()
+    if lexer.buf[lexer.bufpos] in lineEnd:
+      discard
+    elif lexer.buf[lexer.bufpos] == '#':
+      while lexer.buf[lexer.bufpos] notin lineEnd:
+        lexer.bufpos.inc()
+    else:
+      raiseError("Unexpected token (expected comment or line end)",
+                 lexer.bufpos)
+
+template tagShorthand(lexer: FastLexer, shorthand: var string) =
+  debug("lex: tagShorthand")
+  while lexer.buf[lexer.bufpos] in space:
+    lexer.bufpos.inc()
+  if lexer.buf[lexer.bufpos] != '!':
+    raiseError("Invalid tag shorthand")
+  shorthand.add('!')
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  lexer.bufpos.inc()
+  var c = lexer.buf[lexer.bufpos]
+  if c in spaceOrLineEnd:
+    discard
+  else:
+    while c != '!':
+      case c
+      of 'a' .. 'z', 'A' .. 'Z', '0' .. '9', '-':
+        shorthand.add(c)
+        lexer.bufpos.inc()
+        c = lexer.buf[lexer.bufpos]
+      else:
+        raiseError("Illegal character in tag shorthand", lexer.bufpos)
+    shorthand.add(c)
+  lexer.bufpos.inc()
+  if lexer.buf[lexer.bufpos] notin spaceOrLineEnd:
+    raiseError("Missing space after tag shorthand", lexer.bufpos)
+
+template tagUri(lexer: FastLexer, uri: var string) =
+  debug("lex: tagUri")
+  while lexer.buf[lexer.bufpos] in space:
+    lexer.bufpos.inc()
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  var c = lexer.buf[lexer.bufpos]
+  while c notin spaceOrLineEnd:
+    case c
+    of 'a' .. 'z', 'A' .. 'Z', '0' .. '9', '#', ';', '/', '?', ':', '@', '&',
+       '-', '=', '+', '$', ',', '_', '.', '~', '*', '\'', '(', ')':
+      uri.add(c)
+      lexer.bufpos.inc()
+      c = lexer.buf[lexer.bufpos]
+    else:
+      raiseError("Invalid tag uri")
+
+template directivesEnd(lexer: FastLexer, content: var string,
+                       token: var LexedPossibleDirectivesEnd) =
+  debug("lex: directivesEnd")
+  content.add('-')
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  lexer.bufpos.inc()
+  case lexer.buf[lexer.bufpos]
+  of '-':
+    content.add('-')
+    lexer.bufpos.inc()
+    if lexer.buf[lexer.bufpos] == '-':
+      content.add('-')
+      lexer.bufpos.inc()
+      if lexer.buf[lexer.bufpos] in spaceOrLineEnd:
+        token = lpdeDirectivesEnd
+      else:
+        token = lpdeScalarContent
+    else:
+      token = lpdeScalarContent
+  of spaceOrLineEnd:
+    token = lpdeSequenceItem
+  else:
+    token = lpdeScalarContent
+
+template documentEnd(lexer: var FastLexer, content: var string,
+                     isDocumentEnd: var bool) =
+  content.add('.')
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  lexer.bufpos.inc()
+  if lexer.buf[lexer.bufpos] == '.':
+    content.add('.')
+    lexer.bufpos.inc()
+    if lexer.buf[lexer.bufpos] == '.':
+      content.add('.')
+      lexer.bufpos.inc()
+      if lexer.buf[lexer.bufpos] in spaceOrLineEnd:
+        isDocumentEnd = true
+      else:
+        isDocumentEnd = false
+    else:
+      isDocumentEnd = false
+  else:
+    isDocumentEnd = false
+
+template singleQuotedScalar(lexer: FastLexer, content: var string) =
+  debug("lex: singleQuotedScalar")
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  lexer.bufpos.inc()
+  while true:
+    case lexer.buf[lexer.bufpos]
+    of '\'':
+      lexer.bufpos.inc()
+      if lexer.buf[lexer.bufpos] == '\'':
+        content.add('\'')
+      else:
+        break
+    of EndOfFile:
+      raiseError("Unfinished single quoted string")
+    else:
+      content.add(lexer.buf[lexer.bufpos])
+    lexer.bufpos.inc()
+
+proc unicodeSequence(lexer: var FastLexer, length: int):
+      string {.raises: [YamlParserError].} =
+  debug("lex: unicodeSequence")
+  var unicodeChar = 0.Rune
+  let start = lexer.bufpos - 1
+  for i in countup(0, length - 1):
+    lexer.bufpos.inc()
+    let
+      digitPosition = length - i - 1
+      c = lexer.buf[lexer.bufpos]
+    case c
+    of EndOFFile:
+        raiseError("Unfinished unicode escape sequence", start)
+    of '0' .. '9':
+        unicodeChar = unicodechar or
+                (cast[int](c) - 0x30) shl (digitPosition * 4)
+    of 'A' .. 'F':
+        unicodeChar = unicodechar or
+                (cast[int](c) - 0x37) shl (digitPosition * 4)
+    of 'a' .. 'f':
+        unicodeChar = unicodechar or
+                (cast[int](c) - 0x57) shl (digitPosition * 4)
+    else:
+      raiseError("Invalid character in unicode escape sequence", lexer.bufpos)
+  return toUTF8(unicodeChar)
+
+template doublyQuotedScalar(lexer: FastLexer, content: var string) =
+  debug("lex: doublyQuotedScalar")
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  while true:
+    lexer.bufpos.inc()
+    let c = lexer.buf[lexer.bufpos]
+    case c
+    of EndOfFile:
+      raiseError("Unfinished doubly quoted string")
+    of '\\':
+      lexer.bufpos.inc()
+      case lexer.buf[lexer.bufpos]
+      of EndOfFile:
+        raiseError("Unfinished escape sequence")
+      of '0':       content.add('\0')
+      of 'a':       content.add('\x07')
+      of 'b':       content.add('\x08')
+      of '\t', 't': content.add('\t')
+      of 'n':       content.add('\x0A')
+      of 'v':       content.add('\v')
+      of 'f':       content.add('\f')
+      of 'r':       content.add('\r')
+      of 'e':       content.add('\e')
+      of ' ':       content.add(' ')
+      of '"':       content.add('"')
+      of '/':       content.add('/')
+      of '\\':      content.add('\\')
+      of 'N':       content.add(UTF8NextLine)
+      of '_':       content.add(UTF8NonBreakingSpace)
+      of 'L':       content.add(UTF8LineSeparator)
+      of 'P':       content.add(UTF8ParagraphSeparator)
+      of 'x':       content.add(lexer.unicodeSequence(2))
+      of 'u':       content.add(lexer.unicodeSequence(4))
+      of 'U':       content.add(lexer.unicodeSequence(8))
+      else:
+        raiseError("Illegal character in escape sequence")
+    of '"':
+      lexer.bufpos.inc()
+      break
+    else:
+      content.add(c)
+
+proc isPlainSafe(lexer: FastLexer, index: int, context: YamlContext): bool =
+  case lexer.buf[lexer.bufpos + 1]
+  of spaceOrLineEnd:
+    result = false
+  of flowIndicators:
+    result = context in [cFlowOut, cBlockKey]
+  else:
+    result = true
+
+template plainScalar(lexer: FastLexer, content: var string,
+                     context: YamlContext) =
+  debug("lex: plainScalar")
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  content.add(lexer.buf[lexer.bufpos])
+  block outer:
+    while true:
+      lexer.bufpos.inc()
+      let c = lexer.buf[lexer.bufpos]
+      case c
+      of lineEnd:
+        break
+      of ' ', '\t':
+        var after = "" & c
+        while true:
+          lexer.bufpos.inc()
+          let c2 = lexer.buf[lexer.bufpos]
+          case c2
+          of ' ', '\t':
+            after.add(c2)
+          of lineEnd:
+            break outer
+          of ':':
+            if lexer.isPlainSafe(lexer.bufpos + 1, context):
+              content.add(after & ':')
+            else:
+              break outer
+          of '#':
+            break outer
+          else:
+            content.add(after)
+            content.add(c2)
+            break
+      of flowIndicators:
+        if context in [cFlowOut, cBlockKey]:
+          content.add(c)
+        else:
+          break
+      of ':':
+        if lexer.isPlainSafe(lexer.bufpos + 1, context):
+          content.add(':')
+        else:
+          break outer
+      of '#':
+        break outer
+      else:
+        content.add(c)
+
+template continueMultilineScalar() {.dirty.} =
+  cachedScalar.scalarContent.add(if newlines == 1: " " else:
+                                 repeat('\x0A', newlines - 1))
+  lexer.plainScalar(cachedScalar.scalarContent, cBlockOut)
+  state = fpBlockAfterPlainScalar
+
+template tagHandle(lexer: var FastLexer, content: var string,
+                   shorthandEnd: var int) =
+  debug("lex: tagHandle")
+  shorthandEnd = 0
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  content.add(lexer.buf[lexer.bufpos])
+  var i = 0
+  while true:
+    lexer.bufpos.inc()
+    i.inc()
+    let c = lexer.buf[lexer.bufpos]
+    case c
+    of spaceOrLineEnd:
+      if shorthandEnd == -1:
+        raiseError("Unclosed verbatim tag")
+      break
+    of '!':
+      if shorthandEnd == -1 and i == 2:
+        content.add(c)
+      elif shorthandEnd != 0:
+        raiseError("Illegal character in tag suffix", lexer.bufpos)
+      shorthandEnd = i
+      content.add(c)
+    of 'a' .. 'z', 'A' .. 'Z', '0' .. '9', '#', ';', '/', '?', ':', '@', '&',
+       '-', '=', '+', '$', ',', '_', '.', '~', '*', '\'', '(', ')':
+      content.add(c)
+    of '<':
+      if i == 1:
+        shorthandEnd = -1
+        content = ""
+      else:
+        raiseError("Illegal character in tag handle", lexer.bufpos)
+    of '>':
+      if shorthandEnd == -1:
+        lexer.bufpos.inc()
+        if lexer.buf[lexer.bufpos] notin spaceOrLineEnd:
+          raiseError("Missing space after verbatim tag handle", lexer.bufpos)
+        break
+      else:
+        raiseError("Illegal character in tag handle", lexer.bufpos)
+    else:
+      raiseError("Illegal character in tag handle", lexer.bufpos)
+
+template anchorName(lexer: FastLexer, content: var string) =
+  debug("lex: anchorName")
+  lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+  while true:
+    lexer.bufpos.inc()
+    let c = lexer.buf[lexer.bufpos]
+    case c
+    of spaceOrLineEnd:
+      break
+    of '[', ']', '{', '}', ',':
+      raiseError("Illegal character in anchor", lexer.bufpos)
+    else:
+      content.add(c)
+
+proc fastparse*(tagLib: TagLibrary, s: Stream): YamlStream =
+  result = iterator(): YamlStreamEvent =
+    var
+      lexer: FastLexer
+      state = fpInitial
+      shorthands: Table[string, string]
+      anchors: Table[string, AnchorId]
+      nextAnchorId: AnchorId
+      content: string
+      tag, objectTag: TagId = yTagQuestionMark
+      anchor, objectAnchor: AnchorId = yAnchorNone
+      ancestry = newSeq[FastParseLevel]()
+      level: FastParseLevel
+      cachedScalar: YamlStreamEvent
+      indentation: int
+      newlines: int
+    
+    lexer.open(s)
+    initDocValues()
+    
+    while true:
+      case state
+      of fpInitial:
+        debug("state: initial")
+        case lexer.buf[lexer.bufpos]
+        of '%':
+          var ld: LexedDirective
+          lexer.directiveName(ld)
+          case ld
+          of ldYaml:
+            var version = ""
+            lexer.yamlVersion(version)
+            if version != "1.2":
+              echo "version is not 1.2!"
+              # TODO: warning (unknown version)
+              discard
+            lexer.lineEnding()
+            handleLineEnd(false)
+          of ldTag:
+            var shorthand, uri = ""
+            lexer.tagShorthand(shorthand)
+            lexer.tagUri(uri)
+            shorthands.add(shorthand, uri)
+            lexer.lineEnding()
+            handleLineEnd(false)
+          of ldUnknown:
+            # TODO: warning (unknown directive)
+            lexer.finishLine()
+            handleLineEnd(false)
+        of ' ', '\t':
+          lexer.bufpos.inc()
+        of '\x0A':
+          lexer.bufpos = lexer.handleLF(lexer.bufpos)
+        of '\c':
+          lexer.bufpos = lexer.handleCR(lexer.bufpos)
+          lexer.bufpos.inc()
+        of EndOfFile:
+          return
+        of '#':
+          lexer.lineEnding()
+          handleLineEnd(false)
+        of '-':
+          var token: LexedPossibleDirectivesEnd
+          content = ""
+          lexer.directivesEnd(content, token)
+          yield startDocEvent()
+          case token
+          of lpdeDirectivesEnd:
+            state = fpBlockObjectStart
+          of lpdeSequenceItem:
+            indentation = 0
+            handleStartBlockSequence()
+            state = fpBlockObjectStart
+          of lpdeScalarContent:
+            lexer.plainScalar(content, cBlockOut)
+            cachedScalar = scalarEvent(content, tag, anchor)
+            state = fpBlockAfterPlainScalar
+        else:
+          yield startDocEvent()
+          state = fpBlockLineStart
+      of fpBlockLineStart:
+        debug("state: blockLineStart")
+        case lexer.buf[lexer.bufpos]
+        of '-':
+          var token: LexedPossibleDirectivesEnd
+          content = ""
+          lexer.directivesEnd(content, token)
+          case token
+          of lpdeDirectivesEnd:
+            closeEverything()
+            initDocValues()
+            yield startDocEvent()
+            state = fpBlockObjectStart
+          of lpdeSequenceItem:
+            indentation = 0
+            closeMoreIndentedLevels()
+            handleStartBlockSequence()
+            state = fpBlockObjectStart
+          of lpdeScalarContent:
+            if level.kind == fplScalar:
+              continueMultilineScalar()
+            else:
+              lexer.plainScalar(content, cBlockOut)
+              cachedScalar = scalarEvent(content, tag, anchor)
+              state = fpBlockAfterPlainScalar
+        of '.':
+          var isDocumentEnd: bool
+          content = ""
+          lexer.documentEnd(content, isDocumentEnd)
+          if isDocumentEnd:
+            lexer.lineEnding()
+            closeEverything()
+            initDocValues()
+            state = fpInitial
+          elif level.kind == fplScalar:
+            continueMultilineScalar()
+          else:
+            lexer.plainScalar(content, cBlockOut)
+            cachedScalar = scalarEvent(content, tag, anchor)
+            state = fpBlockAfterPlainScalar
+        of ' ':
+          lexer.skipIndentation()
+          indentation = lexer.getColNumber(lexer.bufpos)
+          closeMoreIndentedLevels()
+          case level.kind
+          of fplScalar:
+            state = fpBlockContinueScalar
+          of fplUnknown:
+            state = fpBlockObjectStart
+            level.indentation = indentation
+          else:
+            state = fpBlockObjectStart
+        else:
+          indentation = 0
+          closeMoreIndentedLevels()
+          case level.kind
+          of fplScalar:
+            state = fpBlockContinueScalar
+          of fplUnknown:
+            state = fpBlockObjectStart
+            level.indentation = indentation
+          else:
+            state = fpBlockObjectStart
+      of fpBlockContinueScalar:
+        debug("state: blockAfterPlainScalar")
+        lexer.skipWhitespace()
+        case lexer.buf[lexer.bufpos]
+        of '\x0A':
+          newlines.inc()
+          lexer.bufpos = lexer.handleLF(lexer.bufpos)
+          state = fpBlockLineStart
+        of '\c':
+          newlines.inc()
+          lexer.bufpos = lexer.handleCR(lexer.bufpos)
+        of ':':
+          if lexer.isPlainSafe(lexer.bufpos + 1, cBlockOut):
+            continueMultilineScalar()
+          else:
+            raiseError("Unexpected token", lexer.bufpos)
+        of '#':
+          yield cachedScalar
+          lexer.lineEnding()
+          handleLineEnd(true)
+          if ancestry.len == 0:
+            state = fpExpectDocEnd
+          else:
+            level = ancestry.pop()
+            handleObjectEnd()
+            state = fpBlockLineStart
+        else:
+          continueMultilineScalar()
+        
+      of fpBlockAfterPlainScalar:
+        debug("state: blockAfterPlainScalar")
+        lexer.skipWhitespace()
+        case lexer.buf[lexer.bufpos]
+        of '\x0A':
+          if level.kind notin [fplUnknown, fplScalar]:
+            raiseError("Unexpected scalar")
+          newlines = 1
+          level.kind = fplScalar
+          lexer.bufpos = lexer.handleLF(lexer.bufpos)
+          state = fpBlockLineStart
+        of '\c':
+          if level.kind notin [fplUnknown, fplScalar]:
+            raiseError("Unexpected scalar")
+          newlines = 1
+          level.kind = fplScalar
+          lexer.bufpos = lexer.handleCR(lexer.bufpos)
+          state = fpBlockLineStart
+        else:
+          state = fpBlockAfterScalar
+      of fpBlockAfterScalar:
+        debug("state: blockAfterScalar")
+        lexer.skipWhitespace()
+        case lexer.buf[lexer.bufpos]
+        of EndOfFile:
+          level.kind = fplScalar
+          closeEverything()
+          break
+        of '\x0A':
+          if level.kind != fplUnknown:
+            raiseError("Unexpected scalar")
+          applyObjectProperties()
+          yield cachedScalar
+          if ancestry.len == 0:
+            state = fpExpectDocEnd
+          else:
+            level = ancestry.pop()
+            handleObjectEnd()
+            state = fpBlockLineStart
+          lexer.bufpos = lexer.handleLF(lexer.bufpos)
+        of '\c':
+          if level.kind != fplUnknown:
+            raiseError("Unexpected scalar")
+          applyObjectProperties()
+          yield cachedScalar
+          if ancestry.len == 0:
+            state = fpExpectDocEnd
+          else:
+            level = ancestry.pop()
+            handleObjectEnd()
+            state = fpBlockLineStart
+          lexer.bufpos = lexer.handleCR(lexer.bufpos)
+        of ':':
+          case level.kind
+          of fplUnknown:
+            level.kind = fplMapKey
+            handleStartObject(yamlStartMap)
+          of fplMapValue:
+            yield scalarEvent("", yTagQuestionMark, yAnchorNone)
+            level.kind = fplMapKey
+          of fplMapKey:
+            if level.indentation != indentation:
+              raiseError("Invalid indentation for map key")
+          of fplSequence:
+            raiseError("Illegal token (expected sequence item)")
+          of fplScalar:
+            raiseError("Multiline scalars may not be implicit map keys")
+          handleObjectEnd()
+          yield cachedScalar
+          ancestry.add(level)
+          lexer.bufpos.inc()
+          lexer.skipWhitespace()
+          indentation = lexer.getColNumber(lexer.bufpos)
+          level = FastParseLevel(kind: fplUnknown, indentation: indentation)
+          state = fpBlockObjectStart
+        of '#':
+          applyObjectProperties()
+          yield cachedScalar
+          lexer.lineEnding()
+          handleLineEnd(true)
+          state = fpBlockLineStart
+        else:
+          raiseError("Illegal token (expected ':', comment or line end)",
+                     lexer.bufpos)
+      of fpBlockObjectStart:
+        debug("state: blockObjectStart")
+        lexer.skipWhitespace()
+        let objectStart = lexer.getColNumber(lexer.bufpos)
+        case lexer.buf[lexer.bufpos]
+        of '\x0A':
+          propsToObjectProps()
+          lexer.bufpos = lexer.handleLF(lexer.bufpos)
+          state = fpBlockLineStart
+        of '\c':
+          propsToObjectProps()
+          lexer.bufpos = lexer.handleCR(lexer.bufpos)
+          state = fpBlockLineStart
+        of EndOfFile:
+          closeEverything()
+          return
+        of '#':
+          lexer.lineEnding()
+          handleLineEnd(true)
+        of '\'':
+          handleStartBlockScalar()
+          content = ""
+          lexer.singleQuotedScalar(content)
+          if tag == yTagQuestionMark:
+            tag = yTagExclamationMark
+          cachedScalar = scalarEvent(content, tag, anchor)
+          state = fpBlockAfterScalar
+        of '"':
+          handleStartBlockScalar()
+          content = ""
+          lexer.doublyQuotedScalar(content)
+          if tag == yTagQuestionMark:
+            tag = yTagExclamationMark
+          cachedScalar = scalarEvent(content, tag, anchor)
+          state = fpBlockAfterScalar
+        of '-':
+          if lexer.isPlainSafe(lexer.bufpos + 1, cBlockOut):
+            handleStartBlockScalar()
+            lexer.tokenstart = lexer.getColNumber(lexer.bufpos)
+            lexer.plainScalar(content, cBlockOut)
+            cachedScalar = scalarEvent(content, tag, anchor)
+            state = fpBlockAfterPlainScalar
+          else:
+            lexer.bufpos.inc()
+            handleStartBlockSequence()
+        of '!':
+          if tag != yTagQuestionmark:
+            raiseError("Only one tag handle is allowed per node")
+          content = ""
+          var
+            shorthandEnd: int
+            tagUri: string
+          lexer.tagHandle(content, shorthandEnd)
+          if shorthandEnd != -1:
+            try:
+              let prefix = shorthands[content[0..shorthandEnd]]
+              tagUri = prefix & content[shorthandEnd + 1 .. ^1]
+            except KeyError:
+              raiseError("Undefined tag shorthand: " & content[0..shorthandEnd])
+          else:
+            shallowCopy(tagUri, content)
+          try:
+            tag = tagLib.tags[tagUri]
+          except KeyError:
+            tag = tagLib.registerUri(tagUri)
+        of '&':
+          if anchor != yAnchorNone:
+            raiseError("Only one anchor is allowed per node", lexer.bufpos)
+          content = ""
+          lexer.anchorName(content)
+          anchor = nextAnchorId
+          anchors[content] = anchor
+          nextAnchorId = cast[AnchorId](cast[int](nextAnchorId) + 1)
+        of '*':
+          if anchor != yAnchorNone or tag != yTagQuestionmark:
+            raiseError("Alias may not have anchor or tag")
+          content = ""
+          lexer.anchorName(content)
+          try:
+            cachedScalar = aliasEvent(anchors[content])
+          except KeyError:
+            raiseError("Unknown anchor")
+          state = fpBlockAfterScalar
+        else:
+          handleStartBlockScalar()
+          content = ""
+          lexer.plainScalar(content, cBlockOut)
+          cachedScalar = scalarEvent(content, tag, anchor)
+          state = fpBlockAfterPlainScalar
+      of fpExpectDocEnd:
+        discard # TODO

private/lexer.nim

@@ -153,8 +153,7 @@ template yieldToken(kind: YamlLexerToken) {.dirty.} =
 
 template yieldScalarPart() {.dirty.} =
     when defined(yamlDebug):
-        echo "Lexer token: tScalarPart(\"", my.content, "\".", typeHintState,
-             ")"
+        echo "Lexer token: tScalarPart(\"", my.content, "\")"
     yield tScalarPart
     my.content = ""
 

private/tagLibrary.nim

@@ -5,11 +5,12 @@
 #    distribution, for details about the copyright.
 
 proc initTagLibrary*(): TagLibrary =
+    new(result)
     result.tags = initTable[string, TagId]()
     result.nextCustomTagId = yFirstCustomTagId
     result.secondaryPrefix = yamlTagRepositoryPrefix
 
-proc registerUri*(tagLib: var TagLibrary, uri: string): TagId =
+proc registerUri*(tagLib: TagLibrary, uri: string): TagId =
     tagLib.tags[uri] = tagLib.nextCustomTagId
     result = tagLib.nextCustomTagId
     tagLib.nextCustomTagId = cast[TagId](cast[int](tagLib.nextCustomTagId) + 1)

yaml.nim

@@ -20,6 +20,9 @@
 import streams, unicode, lexbase, tables, strutils, json, hashes, queues, macros
 export streams, tables, json
 
+when defined(yamlDebug):
+  import terminal
+
 type
     TypeHint* = enum
         ## A type hint is a friendly message from the YAML lexer, telling you
@@ -55,9 +58,9 @@ type
     TagId* = distinct int ## \
         ## A ``TagId`` identifies a tag URI, like for example 
         ## ``"tag:yaml.org,2002:str"``. The URI corresponding to a ``TagId`` can
-        ## be queried from the `YamlTagLibrary <#YamlTagLibrary>`_ which was
+        ## be queried from the `TagLibrary <#TagLibrary>`_ which was
         ## used to create this ``TagId`` with
-        ## `uri <#uri,YamlTagLibrary,TagId>`_. URI strings are
+        ## `uri <#uri,TagLibrary,TagId>`_. URI strings are
         ## mapped to ``TagId`` s for efficiency  reasons (you do not need to
         ## compare strings every time) and to be able to discover unknown tag
         ## URIs early in the parsing process.
@@ -68,7 +71,7 @@ type
         ## (for example, because the parser yielded a ``yamlEndDocument``
         ## event). ``AnchorId`` s exists because of efficiency, much like
         ## ``TagId`` s. The actual anchor name can be queried with
-        ## `anchor <#anchor,YamlSequentialParser,AnchorId>`_.
+        ## `anchor <#anchor,YamlParser,AnchorId>`_.
     
     YamlStreamEvent* = object
         ## An element from a `YamlStream <#YamlStream>`_. Events that start an
@@ -80,7 +83,7 @@ type
         ## the non-specific tags ``?`` or ``!`` according to the YAML
         ## specification. These are by convention mapped to the ``TagId`` s
         ## ``yTagQuestionMark`` and ``yTagExclamationMark`` respectively.
-        ## Mapping is done by a `YamlTagLibrary <#YamlTagLibrary>`_.
+        ## Mapping is done by a `TagLibrary <#TagLibrary>`_.
         case kind*: YamlStreamEventKind
         of yamlStartMap:
             mapAnchor* : AnchorId
@@ -110,7 +113,7 @@ type
         ## always yield a well-formed ``YamlStream`` and expect it to be
         ## well-formed if it's an input.
     
-    TagLibrary* = object
+    TagLibrary* = ref object
         ## A ``YamlTagLibrary`` maps tag URIs to ``TagId`` s. YAML tag URIs
         ## that are defined in the YAML specification or in the
         ## `YAML tag repository <http://yaml.org/type/>`_ should be mapped to
@@ -121,8 +124,8 @@ type
         ## `coreTagLibrary <#coreTagLibrary>`_, and 
         ## `extendedTagLibrary <#extendedTagLibrary>`_.
         ##
-        ## If the ``YamlSequentialParser`` encounters a tag which is not part of
-        ## the ``YamlTagLibrary``, it will create a new ``TagId`` equal to
+        ## If the ``YamlParser`` encounters a tag which is not part of
+        ## the ``TagLibrary``, it will create a new ``TagId`` equal to
         ## ``nextCustomTagId`` and increase that variable. It will be
         ## initialized to `yFirstCustomTagId <#yFirstCustomTagId>`_. If you do
         ## not want to allow unknown tag URIs to be processed, just abort
@@ -309,6 +312,7 @@ proc endSeqEvent*(): YamlStreamEvent {.inline, raises: [].}
 proc scalarEvent*(content: string = "", tag: TagId = yTagQuestionMark,
                   anchor: AnchorId = yAnchorNone):
                   YamlStreamEvent {.inline, raises: [].}
+proc aliasEvent*(anchor: AnchorId): YamlStreamEvent {.inline, raises: [].}
 
 proc `==`*(left, right: TagId): bool {.borrow.}
 proc `$`*(id: TagId): string
@@ -322,7 +326,7 @@ proc initTagLibrary*(): TagLibrary
     ## initializes the ``tags`` table and sets ``nextCustomTagId`` to
     ## ``yFirstCustomTagId``.
 
-proc registerUri*(tagLib: var TagLibrary, uri: string): TagId
+proc registerUri*(tagLib: TagLibrary, uri: string): TagId
     ## registers a custom tag URI with a ``YamlTagLibrary``. The URI will get
     ## the ``TagId`` ``nextCustomTagId``, which will be incremented.
     
@@ -375,6 +379,9 @@ proc parse*(parser: YamlParser, s: Stream):
             YamlStream {.raises: [IOError, YamlParserError].}
     ## Parse a YAML character stream. ``s`` must be readable.
 
+proc fastparse*(tagLib: TagLibrary, s: Stream):
+        YamlStream {.raises: [IOError, YamlParserError].}
+
 proc constructJson*(s: YamlStream): seq[JsonNode]
     ## Construct an in-memory JSON tree from a YAML event stream. The stream may
     ## not contain any tags apart from those in ``coreTagLibrary``. Anchors and
@@ -415,3 +422,4 @@ include private.parser
 include private.json
 include private.presenter
 include private.hints
+include private.fastparse