PureYAML/Sources/Parsing/Scanner.swift
Mihaela Mihaljevic cd05976fac feat(parsing): handle directives and document-end boundaries
Three root causes: (1) a '%' begins a directive only in directive position (before document content, outside flow); everywhere else it is plain content, fixing misfires inside plain scalars, flow mappings, and block scalars. (2) %YAML accepts any 1.x (a higher minor is treated as 1.2 without error), rejects major != 1 and duplicate %YAML, and requires a following '---'; reserved and %TAG directives are accepted and ignored. A directive not followed by a document start is rejected with the new directiveWithoutDocument error. (3) An explicit '...' end marker closes the current document so following content begins a fresh document in parseStream; single-document parse still rejects multi-document input at compose time.

Tests/UnsupportedYAMLGapsFixtures.swift, StreamParsingTests, ScannerTests, and ParsingErrorTests were updated in lockstep to assert the now-correct behavior (percent-after-content is plain text; '...' then content is two documents; %YAML 1.3 is valid while 2.0 and duplicate %YAML are rejected); no test was weakened and multi-document rejection for single-document parse is still covered.

Flips 15 official YAML test suite cases (295/402); SF5V, 9MMA, B63P, H7TQ now correctly rejected. 6LVF and W4TN are reclassified to json-mismatch (blocked by other scalar gaps). Updates the manifest, fixtures, counts, and roadmap.
2026-06-23 21:31:58 +02:00

366 lines
12 KiB
Swift

extension PureYAML.Parsing {
struct Scanner {
init() {}
func scan(_ yaml: String) throws -> [Token] {
var state = State(reader: Reader(yaml))
state.append(.streamStart)
while !state.reader.isAtEnd {
if isLineBreak(state.reader.peek()) {
state.reader.advance()
state.isAtLineStart = true
continue
}
if state.isAtLineStart {
try scanIndentation(&state)
if state.reader.isAtEnd {
break
}
if isLineBreak(state.reader.peek()) {
continue
}
if try scanDirectiveOrDocumentMarker(&state) {
continue
}
state.isAtLineStart = false
}
try scanToken(&state)
}
if state.hasPendingDirective {
throw PureYAML.Parsing.ParseError.directiveWithoutDocument(line: state.reader.mark.line)
}
closeIndentation(&state)
state.append(.streamEnd)
return state.tokens
}
}
}
extension PureYAML.Parsing.Scanner {
struct State {
var reader: PureYAML.Parsing.Reader
var tokens: [PureYAML.Parsing.Token] = []
var indentation: [Int] = [0]
var isAtLineStart = true
var hasDocumentContent = false
var hasDocumentStartMarker = false
var isDocumentClosed = false
/// True once a `%YAML` directive has been scanned for the document that
/// the next `---` will start. A second `%YAML` before that `---` is a
/// duplicate and is rejected; the flag resets at every document boundary.
var sawYAMLDirective = false
/// True once any directive has been scanned in the current directive
/// section. A directive section must be terminated by a `---` document
/// start; reaching a `...` end marker or the end of the stream with a
/// directive still pending is an error.
var hasPendingDirective = false
var flowDepth = 0
var flowContexts: [PureYAML.Parsing.ScannerFlowContext] = []
var validImplicitIndentation: Set<Int> = []
var tagHandles = [
"!": "!",
"!!": "tag:yaml.org,2002:",
]
mutating func append(_ kind: PureYAML.Parsing.TokenKind) {
let mark = reader.mark
tokens.append(PureYAML.Parsing.Token(kind: kind, mark: mark, endMark: mark))
markDocumentContentIfNeeded(kind)
}
mutating func append(
_ kind: PureYAML.Parsing.TokenKind,
mark: PureYAML.Parsing.Mark,
endMark: PureYAML.Parsing.Mark,
) {
tokens.append(PureYAML.Parsing.Token(kind: kind, mark: mark, endMark: endMark))
markDocumentContentIfNeeded(kind)
}
mutating func markDocumentContentIfNeeded(_ kind: PureYAML.Parsing.TokenKind) {
switch kind {
case .comment, .dedent, .documentEnd, .documentStart, .indent, .streamEnd, .streamStart:
return
default:
hasDocumentContent = true
}
}
var isExpectingFlowMappingKey: Bool {
flowContexts.last?.kind == .mapping
&& flowContexts.last?.isExpectingKey == true
}
}
}
extension PureYAML.Parsing.Scanner {
func scanToken(_ state: inout State) throws {
skipSeparation(&state)
guard let character = state.reader.peek(), !isLineBreak(character) else {
return
}
if try scanLineIndicatorToken(character, state: &state) {
return
}
if scanFlowToken(character, state: &state) {
return
}
if try scanQuotedOrBlockScalarToken(character, state: &state) {
return
}
if try scanNodePropertyToken(character, state: &state) {
return
}
scanPlainScalar(&state)
}
func scanLineIndicatorToken(
_ character: Character,
state: inout State,
) throws -> Bool {
switch character {
case "#":
scanComment(&state)
return true
case "-" where isBlockEntry(state.reader):
scanFixedToken(.blockEntry, state: &state)
return true
case "?" where isIndicatorBoundary(state.reader.peek(offset: 1)):
scanFixedToken(.mappingKey, state: &state)
return true
case ":" where isAtMappingValueIndicator(state: state):
scanFixedToken(.mappingValue, state: &state)
return true
default:
return false
}
}
func scanFlowToken(
_ character: Character,
state: inout State,
) -> Bool {
switch character {
case "[":
state.flowDepth += 1
state.flowContexts.append(.init(kind: .sequence, isExpectingKey: false))
scanFixedToken(.flowSequenceStart, state: &state)
return true
case "]":
state.flowDepth = max(0, state.flowDepth - 1)
scanFixedToken(.flowSequenceEnd, state: &state)
_ = state.flowContexts.popLast()
return true
case "{":
state.flowDepth += 1
state.flowContexts.append(.init(kind: .mapping, isExpectingKey: true))
scanFixedToken(.flowMappingStart, state: &state)
return true
case "}":
state.flowDepth = max(0, state.flowDepth - 1)
scanFixedToken(.flowMappingEnd, state: &state)
_ = state.flowContexts.popLast()
return true
case ",":
scanFixedToken(.flowEntry, state: &state)
if state.flowContexts.last?.kind == .mapping {
state.flowContexts[state.flowContexts.count - 1].isExpectingKey = true
}
return true
default:
return false
}
}
func scanNodePropertyToken(
_ character: Character,
state: inout State,
) throws -> Bool {
switch character {
case "&":
try scanNamedToken(
kind: PureYAML.Parsing.TokenKind.anchor,
missingNameError: PureYAML.Parsing.ParseError.expectedAnchorName,
state: &state,
)
return true
case "*":
try scanNamedToken(
kind: PureYAML.Parsing.TokenKind.alias,
missingNameError: PureYAML.Parsing.ParseError.expectedAliasName,
state: &state,
)
return true
case "!":
try scanTag(&state)
return true
default:
return false
}
}
func scanQuotedOrBlockScalarToken(
_ character: Character,
state: inout State,
) throws -> Bool {
switch character {
case "\"":
try scanQuotedScalar(.doubleQuoted, state: &state)
return true
case "'":
try scanQuotedScalar(.singleQuoted, state: &state)
return true
case "|":
scanBlockScalarHeader(.literal, state: &state)
return true
case ">":
scanBlockScalarHeader(.folded, state: &state)
return true
default:
return false
}
}
func skipSeparation(_ state: inout State) {
while state.reader.peek() == " " {
state.reader.advance()
}
}
func scanFixedToken(
_ kind: PureYAML.Parsing.TokenKind,
state: inout State,
) {
let start = state.reader.mark
state.reader.advance()
state.append(kind, mark: start, endMark: state.reader.mark)
if case .blockEntry = kind, hasNodeOnSameLine(afterCurrentPositionIn: state.reader) {
state.validImplicitIndentation.insert(start.column + 1)
}
if case .mappingValue = kind, state.flowContexts.last?.kind == .mapping {
state.flowContexts[state.flowContexts.count - 1].isExpectingKey = false
}
}
func scanComment(_ state: inout State) {
let start = state.reader.mark
state.reader.advance()
if state.reader.peek() == " " {
state.reader.advance()
}
let value = state.reader.consume { character in
!isLineBreak(character)
}
state.append(.comment(value), mark: start, endMark: state.reader.mark)
}
func scanQuotedScalar(
_ style: PureYAML.Parsing.ScalarStyle,
state: inout State,
) throws {
let start = state.reader.mark
let quote: Character = style == .doubleQuoted ? "\"" : "'"
state.reader.advance()
var value = ""
var previousWasEscape = false
while let character = state.reader.peek() {
if style == .singleQuoted, character == quote, state.reader.peek(offset: 1) == quote {
value.append(character)
state.reader.advance()
value.append(character)
state.reader.advance()
continue
}
if character == quote, !previousWasEscape {
break
}
value.append(character)
previousWasEscape = character == "\\" && style == .doubleQuoted && !previousWasEscape
state.reader.advance()
if character != "\\" {
previousWasEscape = false
}
}
guard state.reader.peek() == quote else {
throw PureYAML.Parsing.ParseError.unterminatedQuotedString(line: start.line)
}
state.reader.advance()
appendMappingKeyIfNeeded(start: start, state: &state)
state.append(.scalar(value: value, style: style), mark: start, endMark: state.reader.mark)
}
func scanNamedToken(
kind: (String) -> PureYAML.Parsing.TokenKind,
missingNameError: (Int) -> PureYAML.Parsing.ParseError,
state: inout State,
) throws {
let start = state.reader.mark
state.reader.advance()
// An anchor or alias name is a run of name characters that ends at the
// first non-name character, mirroring `yaml_parser_scan_anchor`: the
// name must stop at whitespace, `:`, `?`, flow indicators, and the other
// indicator characters so that `*alias:` reads the alias `alias`
// followed by a `:` mapping indicator rather than swallowing the colon.
let name = state.reader.consume { character in
isAnchorNameCharacter(character)
}
guard !name.isEmpty else {
throw missingNameError(start.line)
}
state.append(kind(name), mark: start, endMark: state.reader.mark)
}
func scanTag(_ state: inout State) throws {
let start = state.reader.mark
state.reader.advance()
var value = "!"
if state.reader.peek() == "<" {
value.append(state.reader.advance() ?? "<")
var didClose = false
while let character = state.reader.peek() {
value.append(character)
state.reader.advance()
if character == ">" {
didClose = true
break
}
}
guard didClose else {
throw PureYAML.Parsing.ParseError.unterminatedTag(line: start.line)
}
} else {
value += state.reader.consume { character in
!isTokenTerminator(character)
}
value = expandTag(value, state: state)
}
state.append(.tag(value), mark: start, endMark: state.reader.mark)
}
func scanPlainScalar(_ state: inout State) {
let start = state.reader.mark
var value = ""
while let character = state.reader.peek() {
if shouldEndPlainScalar(character, state: state, accumulated: value) {
break
}
value.append(character)
state.reader.advance()
}
var trimmed = trimTrailingSpaces(value)
let isMappingKey = appendMappingKeyIfNeeded(start: start, state: &state)
if !isMappingKey {
trimmed = scanPlainScalarContinuations(
after: trimmed,
state: &state,
)
}
state.append(.scalar(value: trimmed, style: .plain), mark: start, endMark: state.reader.mark)
}
}