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Added sequential parser

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This commit is contained in:
Felix Krause 2015-12-05 12:10:17 +01:00
parent 26c1c07567
commit 0544a8bba0
1 changed files with 215 additions and 0 deletions
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src/yaml/sequential.nim Normal file
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import streams, tables, strutils
import private.lexer
type
YamlParserEventKind* = enum
yamlStartDocument, yamlEndDocument, yamlStartMap, yamlEndMap,
yamlStartSequence, yamlEndSequence, yamlScalar, yamlAlias,
yamlError, yamlWarning
YamlParserEvent* = ref object
case kind*: YamlParserEventKind
of yamlStartMap, yamlStartSequence:
objAnchor* : string # may be nil, may not be empty
objTag* : string # may not be nil or empty, is a complete URI.
of yamlScalar:
scalarAnchor* : string # may be nil
scalarTag* : string # may not be nil, is a complete URI.
scalarContent*: string # may not be nil (but empty)
of yamlEndMap, yamlEndSequence, yamlStartDocument, yamlEndDocument:
discard
of yamlAlias:
aliasName* : string # may not be nil nor empty
of yamlError, yamlWarning:
description* : string
line* : int
column* : int
YamlParserState = enum
ylInitial, ylSkipDirective, ylBlock, ylFlow
OutcomeEnum = enum
oOkay, oWarn, oContinue
LevelKind = enum
lUnknown, lSequence, lMap
DocumentLevel = object
kind: LevelKind
indicatorColumn: int
readKey: bool
anchor: string
tag: string
template yieldWarning(d: string) {.dirty.} =
yield YamlParserEvent(kind: yamlWarning, description: d,
line: lex.line, column: lex.column)
template yieldError(d: string) {.dirty.} =
yield YamlParserEvent(kind: yamlError, description: d,
line: lex.line, column: lex.column)
template tag(): string {.dirty.} =
if isNil(level.tag):
case level.kind
of lUnknown:
result = "!!str"
of lSequence:
result = "!!seq"
of lMap:
result = "!!map"
else:
return level.tag
template closeLevel() {.dirty.} =
case level.kind
of lUnknown:
yield YamlParserEvent(kind: yamlScalar, scalarAnchor: level.anchor,
scalarTag: tag(), scalarContent: "")
of lSequence:
yield YamlParserEvent(kind: yamlEndSequence)
of lMap:
yield YamlParserEvent(kind: yamlEndMap)
template closeLevelsByIndicator() {.dirty.} =
while levels.len > 0:
let level = levels[levels.high]
if level.indicatorColumn > lex.column:
closeLevel()
else:
break
levels.pop()
iterator events*(input: Stream): YamlParserEvent =
var
state = ylInitial
lex : YamlLexer
foundYamlDirective = false
tagShorthands = initTable[string, string]()
levels = initSeq[DocumentLevel]()
curIndentation: int
lex.open(input)
var nextToken = lexer.tokens
var token = nextToken(lex)
while not finished(nextToken):
case state
of ylInitial:
case token.kind
of yamlYamlDirective:
if foundYamlDirective:
yield YamlParserEvent(kind: yamlError,
description: "Duplicate %YAML tag",
line: lex.line,
column: lex.column)
state = ylSkipDirective
else:
var
outcome = oOkay
actualVersion = ""
for version in [1, 2]:
token = nextToken(lex)
if finished(nextToken):
yieldError("Missing or badly formatted YAML version")
outcome = oContinue
break
if token.kind != yamlVersionPart:
yieldError("Missing or badly formatted YAML version")
outcome = oContinue
break
if parseInt(lex.content) != version:
outcome = oWarn
if actualVersion.len > 0: actualVersion &= "."
actualVersion &= $version
case outcome
of oContinue:
continue
of oWarn:
yieldWarning("Unsupported version: " & actualVersion &
", trying to parse anyway")
else:
discard
foundYamlDirective = true
of yamlTagDirective:
token = nextToken(lex)
if finished(nextToken):
yieldError("Incomplete %TAG directive")
continue
if token.kind != yamlTagHandle:
yieldError("Invalid token (expected tag handle)")
state = ylSkipDirective
continue
let tagHandle = lex.content
token = nextToken(lex)
if finished(nextToken):
yieldError("Incomplete %TAG directive")
continue
if token.kind != yamlTagURI:
yieldError("Invalid token (expected tag URI)")
state = ylSkipDirective
continue
tagShorthands[tagHandle] = lex.content
of yamlUnknownDirective:
yieldWarning("Unknown directive: " & lex.content)
state = ylSkipDirective
of yamlComment:
discard
of yamlDirectivesEnd:
yield YamlParserEvent(kind: yamlStartDocument)
state = ylLineStart
of yamlDocumentEnd:
yield YamlParserEvent(kind: yamlStartDocument)
yield YamlParserEvent(kind: yamlEndDocument)
else:
yield YamlParserEvent(kind: yamlStartDocument)
state = ylLineStart
continue
of ylSkipDirective:
if token.kind not in [yamlUnknownDirectiveParam, yamlTagHandle,
yamlTagURI, yamlVersionPart, yamlComment]:
state = ylInitial
continue
of ylBlock:
case token.kind
of yamlLineStart:
discard
of yamlDash:
closeLevelsByIndicator()
if levels.count > 0:
let level = levels[levels.high]
if level.kind == lUnknown:
level.kind = lSequence
level.indicatorColumn = lex.column
levels.add(DocumentLevel(kind: lUnknown,
indicatorColumn = -1,
readKey: false,
anchor: nil, tag: nil))
elif level.indicatorColumn < lex.column:
yieldError("Invalid indentation for '-'")
elif level.kind == lSequence:
levels.add(DocumentLevel(kind: lUnknown,
indicatorColumn: -1,
readKey: false,
anchor: nil, tag: nil))
else:
yieldError("Unexpected token: '-'")
else:
levels.add(DocumentLevel(kind: lSequence,
indicatorColumn: lex.column,
readKey: false,
anchor: nil, tag: nil))
levels.add(DocumentLevel(kind: lUnknown,
indicatorColmun: -1,
readKey: false,
anchor: nil, tag: nil))
of yamlQuestionmark:
of yamlColon:
else:
discard
token = nextToken(lex)