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Scanners.scala
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package dotty.tools
package dotc
package parsing
import scala.language.unsafeNulls
import core.Names.*, core.Contexts.*, core.Decorators.*, util.Spans.*
import core.StdNames.*, core.Comments.*
import util.SourceFile
import util.Chars.*
import util.{SourcePosition, CharBuffer}
import util.Spans.Span
import config.Config
import Tokens.*
import scala.annotation.{switch, tailrec}
import scala.collection.mutable
import scala.collection.immutable.SortedMap
import rewrites.Rewrites.patch
import config.Feature
import config.Feature.migrateTo3
import config.SourceVersion.{`3.0`, `3.0-migration`}
import config.MigrationVersion
import reporting.{NoProfile, Profile, Message}
import java.util.Objects
import dotty.tools.dotc.reporting.Message.rewriteNotice
import dotty.tools.dotc.config.Feature.sourceVersion
object Scanners {
/** Offset into source character array */
type Offset = Int
/** An undefined offset */
val NoOffset: Offset = -1
type Token = Int
private val identity: IndentWidth => IndentWidth = Predef.identity
trait TokenData {
/** the next token */
var token: Token = EMPTY
/** the offset of the first character of the current token */
var offset: Offset = 0
/** the offset of the character following the token preceding this one */
var lastOffset: Offset = 0
/** the offset of the newline immediately preceding the token, or -1 if
* token is not preceded by a newline.
*/
var lineOffset: Offset = -1
/** the name of an identifier */
var name: SimpleName = null
/** the string value of a literal */
var strVal: String = null
/** the base of a number */
var base: Int = 0
def copyFrom(td: TokenData): Unit = {
this.token = td.token
this.offset = td.offset
this.lastOffset = td.lastOffset
this.lineOffset = td.lineOffset
this.name = td.name
this.strVal = td.strVal
this.base = td.base
}
def isNewLine = token == NEWLINE || token == NEWLINES
def isStatSep = isNewLine || token == SEMI
def isIdent = token == IDENTIFIER || token == BACKQUOTED_IDENT
def isIdent(name: Name) = token == IDENTIFIER && this.name == name
def isNestedStart = token == LBRACE || token == INDENT
def isNestedEnd = token == RBRACE || token == OUTDENT
def isColon =
token == COLONop || token == COLONfollow || token == COLONeol
/** Is current token first one after a newline? */
def isAfterLineEnd: Boolean = lineOffset >= 0
def isOperator =
token == BACKQUOTED_IDENT
|| token == IDENTIFIER && isOperatorPart(name(name.length - 1))
def isArrow =
token == ARROW || token == CTXARROW
}
abstract class ScannerCommon(source: SourceFile)(using Context) extends CharArrayReader with TokenData {
val buf: Array[Char] = source.content
def nextToken(): Unit
// Errors -----------------------------------------------------------------
/** the last error offset
*/
var errOffset: Offset = NoOffset
/** Implements CharArrayReader's error method */
protected def error(msg: String, off: Offset): Unit =
error(msg.toMessage, off)
/** Generate an error at the given offset */
def error(msg: Message, off: Offset = offset): Unit = {
errorButContinue(msg, off)
token = ERROR
errOffset = off
}
def errorButContinue(msg: Message, off: Offset = offset): Unit =
report.error(msg, sourcePos(off))
/** signal an error where the input ended in the middle of a token */
def incompleteInputError(msg: Message): Unit = {
report.incompleteInputError(msg, sourcePos())
token = EOF
errOffset = offset
}
def sourcePos(off: Offset = offset): SourcePosition =
source.atSpan(Span(off))
// Setting token data ----------------------------------------------------
protected def initialCharBufferSize = 1024
/** A character buffer for literals
*/
protected val litBuf = CharBuffer(initialCharBufferSize)
/** append Unicode character to "litBuf" buffer
*/
protected def putChar(c: Char): Unit = litBuf.append(c)
/** Finish an IDENTIFIER with `this.name`. */
inline def finishNamed(): Unit = finishNamedToken(IDENTIFIER, this)
/** Clear buffer and set name and token.
* If `target` is different from `this`, don't treat identifiers as end tokens.
*/
def finishNamedToken(idtoken: Token, target: TokenData): Unit =
target.name = termName(litBuf.chars, 0, litBuf.length)
litBuf.clear()
target.token = idtoken
if idtoken == IDENTIFIER then
val converted = toToken(target.name)
if converted != END || (target eq this) then target.token = converted
/** The token for given `name`. Either IDENTIFIER or a keyword. */
def toToken(name: SimpleName): Token
/** Clear buffer and set string */
def setStrVal(): Unit =
strVal = litBuf.toString
litBuf.clear()
inline def isNumberSeparator(c: Char): Boolean = c == '_'
// disallow trailing numeric separator char, but continue lexing
def checkNoTrailingSeparator(): Unit =
if (!litBuf.isEmpty && isNumberSeparator(litBuf.last))
errorButContinue(em"trailing separator is not allowed", offset + litBuf.length - 1)
}
class Scanner(source: SourceFile, override val startFrom: Offset = 0, profile: Profile = NoProfile, allowIndent: Boolean = true)(using Context) extends ScannerCommon(source) {
val keepComments = !ctx.settings.XdropComments.value
/** A switch whether operators at the start of lines can be infix operators */
private[Scanners] var allowLeadingInfixOperators = true
var debugTokenStream = false
val showLookAheadOnDebug = false
val rewrite = ctx.settings.rewrite.value.isDefined
val oldSyntax = ctx.settings.oldSyntax.value
val newSyntax = ctx.settings.newSyntax.value
val rewriteToIndent = ctx.settings.indent.value && rewrite
val rewriteNoIndent = ctx.settings.noindent.value && rewrite
val noindentSyntax =
ctx.settings.noindent.value
|| ctx.settings.oldSyntax.value
|| (migrateTo3 && !ctx.settings.indent.value)
val indentSyntax =
((if (Config.defaultIndent) !noindentSyntax else ctx.settings.indent.value)
|| rewriteNoIndent)
&& allowIndent
if (rewrite) {
val s = ctx.settings
val rewriteTargets = List(s.newSyntax, s.oldSyntax, s.indent, s.noindent)
val enabled = rewriteTargets.filter(_.value)
if (enabled.length > 1)
error(em"illegal combination of -rewrite targets: ${enabled(0).name} and ${enabled(1).name}")
}
private var myLanguageImportContext: Context = ctx
def languageImportContext = myLanguageImportContext
final def languageImportContext_=(c: Context) = myLanguageImportContext = c
def featureEnabled(name: TermName) = Feature.enabled(name)(using languageImportContext)
def erasedEnabled = featureEnabled(Feature.erasedDefinitions)
def trackedEnabled = featureEnabled(Feature.modularity)
private var postfixOpsEnabledCache = false
private var postfixOpsEnabledCtx: Context = NoContext
def postfixOpsEnabled =
if postfixOpsEnabledCtx ne myLanguageImportContext then
postfixOpsEnabledCache = featureEnabled(nme.postfixOps)
postfixOpsEnabledCtx = myLanguageImportContext
postfixOpsEnabledCache
/** All doc comments kept by their end position in a `Map`.
*
* Note: the map is necessary since the comments are looked up after an
* entire definition is parsed, and a definition can contain nested
* definitions with their own docstrings.
*/
private var docstringMap: SortedMap[Int, Comment] = SortedMap.empty
/* A Buffer for comments */
private val commentBuf = new mutable.ListBuffer[Comment]
/** Return a list of all the comments */
def comments: List[Comment] = commentBuf.toList
private def addComment(comment: Comment): Unit = {
val lookahead = lookaheadReader()
def nextPos: Int = (lookahead.getc(): @switch) match {
case ' ' | '\t' | CR | LF | FF => nextPos
case _ => lookahead.charOffset - 1
}
docstringMap = docstringMap + (nextPos -> comment)
}
/** Returns the closest docstring preceding the position supplied */
def getDocComment(pos: Int): Option[Comment] = docstringMap.get(pos)
/** A buffer for comments */
private val currentCommentBuf = CharBuffer(initialCharBufferSize)
def toToken(identifier: SimpleName): Token =
def handleMigration(keyword: Token): Token =
if scala3keywords.contains(keyword) && migrateTo3 then
val what = tokenString(keyword)
report.errorOrMigrationWarning(
em"$what is now a keyword, write `$what` instead of $what to keep it as an identifier${rewriteNotice("This", `3.0-migration`)}",
sourcePos(),
MigrationVersion.Scala2to3)
if MigrationVersion.Scala2to3.needsPatch then
patch(source, Span(offset), "`")
patch(source, Span(offset + identifier.length), "`")
IDENTIFIER
else keyword
val idx = identifier.start
if (idx >= 0 && idx <= lastKeywordStart) handleMigration(kwArray(idx))
else IDENTIFIER
def newTokenData: TokenData = new TokenData {}
/** We need one token lookahead and one token history
*/
val next = newTokenData
private val prev = newTokenData
/** The current region. This is initially an Indented region with zero indentation width. */
var currentRegion: Region = Indented(IndentWidth.Zero, EMPTY, null)
// Error recovery ------------------------------------------------------------
private def lastKnownIndentWidth: IndentWidth =
def recur(r: Region): IndentWidth =
if r.knownWidth == null then recur(r.enclosing) else r.knownWidth
recur(currentRegion)
private var skipping = false
/** Skip on error to next safe point.
*/
def skip(): Unit =
val lastRegion = currentRegion
skipping = true
def atStop =
token == EOF
|| (currentRegion eq lastRegion)
&& (isStatSep
|| closingParens.contains(token) && lastRegion.toList.exists(_.closedBy == token)
|| token == COMMA && lastRegion.toList.exists(_.commasExpected)
|| token == OUTDENT && indentWidth(offset) < lastKnownIndentWidth)
// stop at OUTDENT if the new indentwidth is smaller than the indent width of
// currentRegion. This corrects for the problem that sometimes we don't see an INDENT
// when skipping and therefore might erroneously end up syncing on a nested OUTDENT.
if debugTokenStream then
println(s"\nSTART SKIP AT ${sourcePos().line + 1}, $this in $currentRegion")
var noProgress = 0
// Defensive measure to ensure we always get out of the following while loop
// even if source file is weirdly formatted (i.e. we never reach EOF)
var prevOffset = offset
while !atStop && noProgress < 3 do
nextToken()
if offset <= prevOffset then
noProgress += 1
else
prevOffset = offset
noProgress = 0
if debugTokenStream then
println(s"\nSTOP SKIP AT ${sourcePos().line + 1}, $this in $currentRegion")
if token == OUTDENT then dropUntil(_.isInstanceOf[Indented])
skipping = false
// Get next token ------------------------------------------------------------
/** Are we directly in a multiline string interpolation expression?
* @pre inStringInterpolation
*/
private def inMultiLineInterpolation = currentRegion match {
case InString(multiLine, _) => multiLine
case _ => false
}
/** Are we in a `${ }` block? such that RBRACE exits back into multiline string. */
private def inMultiLineInterpolatedExpression =
currentRegion match {
case InBraces(InString(true, _)) => true
case _ => false
}
/** read next token and return last offset
*/
def skipToken(): Offset = {
val off = offset
nextToken()
off
}
def skipToken[T](result: T): T =
nextToken()
result
private inline def dropUntil(inline matches: Region => Boolean): Unit =
while !matches(currentRegion) && !currentRegion.isOutermost do
currentRegion = currentRegion.enclosing
def adjustSepRegions(lastToken: Token): Unit = (lastToken: @switch) match {
case LPAREN | LBRACKET =>
currentRegion = InParens(lastToken, currentRegion)
case LBRACE =>
currentRegion = InBraces(currentRegion)
case RBRACE =>
dropUntil(_.isInstanceOf[InBraces])
if !currentRegion.isOutermost then currentRegion = currentRegion.enclosing
case RPAREN | RBRACKET =>
currentRegion match {
case InParens(prefix, outer) if prefix + 1 == lastToken => currentRegion = outer
case _ =>
}
case OUTDENT =>
currentRegion match
case r: Indented => currentRegion = r.enclosing
case _ =>
case STRINGLIT =>
currentRegion match {
case InString(_, outer) => currentRegion = outer
case _ =>
}
case _ =>
}
/** Read a token or copy it from `next` tokenData */
private def getNextToken(lastToken: Token): Unit =
if next.token == EMPTY then
lastOffset = lastCharOffset
currentRegion match
case InString(multiLine, _) if lastToken != STRINGPART => fetchStringPart(multiLine)
case _ => fetchToken()
if token == ERROR then adjustSepRegions(STRINGLIT) // make sure we exit enclosing string literal
else
this.copyFrom(next)
next.token = EMPTY
/** Produce next token, filling TokenData fields of Scanner.
*/
def nextToken(): Unit =
val lastToken = token
val lastName = name
adjustSepRegions(lastToken)
getNextToken(lastToken)
if isAfterLineEnd then handleNewLine(lastToken)
postProcessToken(lastToken, lastName)
profile.recordNewToken()
printState()
final def printState() =
if debugTokenStream && (showLookAheadOnDebug || !isInstanceOf[LookaheadScanner]) then
print(s"[$show${if isInstanceOf[LookaheadScanner] then "(LA)" else ""}]")
/** Insert `token` at assumed `offset` in front of current one. */
def insert(token: Token, offset: Int) = {
assert(next.token == EMPTY, next)
next.copyFrom(this)
this.offset = offset
this.token = token
}
/** A leading symbolic or backquoted identifier is treated as an infix operator if
* - it does not follow a blank line, and
* - it is followed by at least one whitespace character and a
* token that can start an expression.
* - if the operator appears on its own line, the next line must have at least
* the same indentation width as the operator. See pos/i12395 for a test where this matters.
* If a leading infix operator is found and the source version is `3.0-migration`, emit a change warning.
*/
def isLeadingInfixOperator(nextWidth: IndentWidth = indentWidth(offset), inConditional: Boolean = true) =
allowLeadingInfixOperators
&& isOperator
&& (isWhitespace(ch) || ch == LF)
&& !pastBlankLine
&& {
// Is current lexeme assumed to start an expression?
// This is the case if the lexime is one of the tokens that
// starts an expression or it is a COLONeol. Furthermore, if
// the previous token is in backticks, the lexeme may not be a binary operator.
// I.e. in
//
// a
// `x` += 1
//
// `+=` is not assumed to start an expression since it follows an identifier
// in backticks and is a binary operator. Hence, `x` is not classified as a
// leading infix operator.
def assumeStartsExpr(lexeme: TokenData) =
(canStartExprTokens.contains(lexeme.token) || lexeme.token == COLONeol)
&& (!lexeme.isOperator || nme.raw.isUnary(lexeme.name))
val lookahead = LookaheadScanner()
lookahead.allowLeadingInfixOperators = false
// force a NEWLINE a after current token if it is on its own line
lookahead.nextToken()
assumeStartsExpr(lookahead)
|| lookahead.token == NEWLINE
&& assumeStartsExpr(lookahead.next)
&& indentWidth(offset) <= indentWidth(lookahead.next.offset)
}
&& {
currentRegion match
case r: Indented =>
r.width <= nextWidth
|| {
r.outer match
case null => true
case ro @ Indented(outerWidth, _, _) =>
outerWidth < nextWidth && !ro.otherIndentWidths.contains(nextWidth)
case outer =>
outer.indentWidth < nextWidth
}
case _ => true
}
&& {
if migrateTo3 then
val (what, previous) =
if inConditional then ("Rest of line", "previous expression in parentheses")
else ("Line", "expression on the previous line")
report.errorOrMigrationWarning(
em"""$what starts with an operator;
|it is now treated as a continuation of the $previous,
|not as a separate statement.""",
sourcePos(), MigrationVersion.Scala2to3)
true
}
/** The indentation width of the given offset. */
def indentWidth(offset: Offset): IndentWidth =
import IndentWidth.{Run, Conc}
def recur(idx: Int, ch: Char, n: Int, k: IndentWidth => IndentWidth): IndentWidth =
if (idx < 0) k(Run(ch, n))
else {
val nextChar = buf(idx)
if (nextChar == LF) k(Run(ch, n))
else if (nextChar == ' ' || nextChar == '\t')
if (nextChar == ch)
recur(idx - 1, ch, n + 1, k)
else {
val k1: IndentWidth => IndentWidth = if (n == 0) k else Conc(_, Run(ch, n))
recur(idx - 1, nextChar, 1, k1)
}
else recur(idx - 1, ' ', 0, identity)
}
recur(offset - 1, ' ', 0, identity)
end indentWidth
/** Handle newlines, possibly inserting an INDENT, OUTDENT, NEWLINE, or NEWLINES token
* in front of the current token. This depends on whether indentation is significant or not.
*
* Indentation is _significant_ if indentSyntax is set, and we are not inside a
* {...}, [...], (...), case ... => pair, nor in a if/while condition
* (i.e. currentRegion is empty).
*
* There are three rules:
*
* 1. Insert NEWLINE or NEWLINES if
*
* - the closest enclosing sepRegion is { ... } or for ... do/yield,
* or we are on the toplevel, i.e. currentRegion is empty, and
* - the previous token can end a statement, and
* - the current token can start a statement, and
* - the current token is not a leading infix operator, and
* - if indentation is significant then the current token starts at the current
* indentation width or to the right of it.
*
* The inserted token is NEWLINES if the current token is preceded by a
* whitespace line, or NEWLINE otherwise.
*
* 2. Insert INDENT if
*
* - indentation is significant, and
* - the last token can start an indentation region.
* - the indentation of the current token is strictly greater than the previous
* indentation width, or the two widths are the same and the current token is
* one of `:` or `match`.
*
* The following tokens can start an indentation region:
*
* : = => <- if then else while do try catch
* finally for yield match throw return with
*
* Inserting an INDENT starts a new indentation region with the indentation of the current
* token as indentation width.
*
* 3. Insert OUTDENT if
*
* - indentation is significant, and
* - the indentation of the current token is strictly less than the
* previous indentation width,
* - the current token is not a leading infix operator.
*
* Inserting an OUTDENT closes an indentation region. In this case, issue an error if
* the indentation of the current token does not match the indentation of some previous
* line in an enclosing indentation region.
*
* If a token is inserted and consumed, the original source token is still considered to
* start a new line, so the process that inserts an OUTDENT might repeat several times.
*
* Indentation widths are strings consisting of spaces and tabs, ordered by the prefix relation.
* I.e. `a <= b` iff `b.startsWith(a)`. If indentation is significant it is considered an error
* if the current indentation width and the indentation of the current token are incomparable.
*/
def handleNewLine(lastToken: Token) =
var indentIsSignificant = false
var newlineIsSeparating = false
var lastWidth = IndentWidth.Zero
var indentPrefix = EMPTY
val nextWidth = indentWidth(offset)
// If nextWidth is an indentation level not yet seen by enclosing indentation
// region, invoke `handler`.
inline def handleNewIndentWidth(r: Region, inline handler: Indented => Unit): Unit = r match
case r @ Indented(curWidth, prefix, outer)
if curWidth < nextWidth && !r.otherIndentWidths.contains(nextWidth) && nextWidth != lastWidth =>
handler(r)
case _ =>
/** Is this line seen as a continuation of last line? We assume that
* - last line ended in a token that can end a statement
* - current line starts with a token that can start a statement
* - current line does not start with a leading infix operator
* The answer is different for Scala-2 and Scala-3.
* - In Scala 2: Only `{` is treated as continuing, irrespective of indentation.
* But this is in fact handled by Parser.argumentStart which skips a NEWLINE,
* so we always assume false here.
* - In Scala 3: Only indented statements are treated as continuing, as long as
* they start with `(`, `[` or `{`, or the last statement ends in a `return`.
* The Scala 2 rules apply under source `3.0-migration` or under `-no-indent`.
*/
inline def isContinuing =
lastWidth < nextWidth
&& (openParensTokens.contains(token) || lastToken == RETURN)
&& !pastBlankLine
&& !migrateTo3
&& !noindentSyntax
currentRegion match
case r: Indented =>
indentIsSignificant = indentSyntax
lastWidth = r.width
newlineIsSeparating = lastWidth <= nextWidth || r.isOutermost
indentPrefix = r.prefix
case _: InString => ()
case r =>
indentIsSignificant = indentSyntax
r.proposeKnownWidth(nextWidth, lastToken)
lastWidth = r.knownWidth
newlineIsSeparating = r.isInstanceOf[InBraces]
// can emit OUTDENT if line is not non-empty blank line at EOF
inline def isTrailingBlankLine: Boolean =
token == EOF && {
val end = buf.length - 1 // take terminal NL as empty last line
val prev = buf.lastIndexWhere(!isWhitespace(_), end = end)
prev < 0 || end - prev > 0 && isLineBreakChar(buf(prev))
}
inline def canDedent: Boolean =
lastToken != INDENT
&& !isLeadingInfixOperator(nextWidth)
&& !statCtdTokens.contains(lastToken)
&& !isTrailingBlankLine
if newlineIsSeparating
&& canEndStatTokens.contains(lastToken)
&& canStartStatTokens.contains(token)
&& !isLeadingInfixOperator(nextWidth)
&& !isContinuing
then
insert(if (pastBlankLine) NEWLINES else NEWLINE, lineOffset)
else if indentIsSignificant then
if nextWidth < lastWidth
|| nextWidth == lastWidth && (indentPrefix == MATCH || indentPrefix == CATCH) && token != CASE then
if currentRegion.isOutermost then
if nextWidth < lastWidth then currentRegion = topLevelRegion(nextWidth)
else if canDedent then
currentRegion match
case r: Indented =>
insert(OUTDENT, offset)
handleNewIndentWidth(r.enclosing, ir =>
if next.token == DOT
&& !nextWidth.isClose(r.indentWidth)
&& !nextWidth.isClose(ir.indentWidth)
then
ir.otherIndentWidths += nextWidth
else
val lw = lastWidth
errorButContinue(
em"""The start of this line does not match any of the previous indentation widths.
|Indentation width of current line : $nextWidth
|This falls between previous widths: ${ir.width} and $lw"""))
case r =>
if skipping then
if r.enclosing.isClosedByUndentAt(nextWidth) then
insert(OUTDENT, offset)
else if r.isInstanceOf[InBraces] && !closingRegionTokens.contains(token) then
report.warning("Line is indented too far to the left, or a `}` is missing", sourcePos())
else if lastWidth < nextWidth
|| lastWidth == nextWidth && (lastToken == MATCH || lastToken == CATCH) && token == CASE then
if canStartIndentTokens.contains(lastToken) then
currentRegion = Indented(nextWidth, lastToken, currentRegion)
insert(INDENT, offset)
else if lastToken == SELFARROW then
currentRegion.knownWidth = nextWidth
else if (lastWidth != nextWidth)
val lw = lastWidth
errorButContinue(spaceTabMismatchMsg(lw, nextWidth))
if token != OUTDENT then
handleNewIndentWidth(currentRegion, _.otherIndentWidths += nextWidth)
if next.token == EMPTY then
profile.recordNewLine()
end handleNewLine
def spaceTabMismatchMsg(lastWidth: IndentWidth, nextWidth: IndentWidth): Message =
em"""Incompatible combinations of tabs and spaces in indentation prefixes.
|Previous indent : $lastWidth
|Latest indent : $nextWidth"""
def observeColonEOL(inTemplate: Boolean): Unit =
val enabled =
if token == COLONop && inTemplate then
report.deprecationWarning(em"`:` after symbolic operator is deprecated; use backticks around operator instead", sourcePos(offset))
true
else token == COLONfollow && (inTemplate || sourceVersion.enablesFewerBraces)
if enabled then
peekAhead()
val atEOL = isAfterLineEnd || token == EOF
reset()
if atEOL then token = COLONeol
// consume => and insert <indent> if applicable. Used to detect colon arrow: x =>
def observeArrowIndented(): Unit =
if isArrow && indentSyntax then
peekAhead()
val atEOL = isAfterLineEnd
val atEOF = token == EOF
reset()
if atEOF then
token = EOF
else if atEOL then
val nextWidth = indentWidth(next.offset)
val lastWidth = currentRegion.indentWidth
if lastWidth < nextWidth then
currentRegion = Indented(nextWidth, COLONeol, currentRegion)
offset = next.offset
token = INDENT
def observeIndented(): Unit =
if indentSyntax && isNewLine then
val nextWidth = indentWidth(next.offset)
val lastWidth = currentRegion.indentWidth
if lastWidth < nextWidth then
currentRegion = Indented(nextWidth, COLONeol, currentRegion)
offset = next.offset
token = INDENT
/** Insert an <outdent> token if next token closes an indentation region.
* Exception: continue if indentation region belongs to a `match` and next token is `case`.
*/
def observeOutdented(): Unit = currentRegion match
case r: Indented
if !r.isOutermost
&& closingRegionTokens.contains(token)
&& !(token == CASE && r.prefix == MATCH)
&& next.token == EMPTY // can be violated for ill-formed programs, e.g. neg/i12605.scala
=>
insert(OUTDENT, offset)
case _ =>
def peekAhead() =
prev.copyFrom(this)
getNextToken(token)
if token == END && !isEndMarker then token = IDENTIFIER
def reset() =
next.copyFrom(this)
this.copyFrom(prev)
def closeIndented() = currentRegion match
case r: Indented if !r.isOutermost => insert(OUTDENT, offset)
case _ =>
/** - Join CASE + CLASS => CASECLASS, CASE + OBJECT => CASEOBJECT
* SEMI + ELSE => ELSE, COLON following id/)/] => COLONfollow
* - Insert missing OUTDENTs at EOF
*/
def postProcessToken(lastToken: Token, lastName: SimpleName): Unit = {
def fuse(tok: Int) = {
token = tok
offset = prev.offset
lastOffset = prev.lastOffset
lineOffset = prev.lineOffset
}
(token: @switch) match {
case CASE =>
peekAhead()
if (token == CLASS) fuse(CASECLASS)
else if (token == OBJECT) fuse(CASEOBJECT)
else reset()
case SEMI =>
peekAhead()
if (token != ELSE) reset()
case COMMA =>
def isEnclosedInParens(r: Region): Boolean = r match
case r: Indented => isEnclosedInParens(r.outer)
case _: InParens => true
case _ => false
currentRegion match
case r: Indented if isEnclosedInParens(r.outer) =>
insert(OUTDENT, offset)
case _ =>
peekAhead()
if isAfterLineEnd
&& currentRegion.commasExpected
&& (token == RPAREN || token == RBRACKET || token == RBRACE || token == OUTDENT)
then
// encountered a trailing comma
// reset only the lastOffset
// so that the tree's span is correct
lastOffset = prev.lastOffset
else
reset()
case END =>
if !isEndMarker then token = IDENTIFIER
case COLONop =>
if lastToken == IDENTIFIER && lastName != null && isIdentifierStart(lastName.head)
|| colonEOLPredecessors.contains(lastToken)
then token = COLONfollow
case RBRACE | RPAREN | RBRACKET =>
closeIndented()
case EOF =>
if !source.maybeIncomplete then closeIndented()
case _ =>
}
}
protected def isEndMarker: Boolean =
if indentSyntax && isAfterLineEnd then
val endLine = source.offsetToLine(offset)
val lookahead = new LookaheadScanner():
override def isEndMarker = false
lookahead.nextToken()
if endMarkerTokens.contains(lookahead.token)
&& source.offsetToLine(lookahead.offset) == endLine
then
lookahead.nextToken()
if lookahead.token == EOF
|| source.offsetToLine(lookahead.offset) > endLine
then return true
false
/** Is there a blank line between the last token and the current one?
* A blank line is a sequence of only characters <= ' ', between two LFs (or FFs).
*/
private def pastBlankLine: Boolean =
val end = offset
def recur(idx: Offset, isBlank: Boolean): Boolean =
idx < end && {
val ch = buf(idx)
if ch == LF || ch == FF then isBlank || recur(idx + 1, isBlank = true)
else recur(idx + 1, isBlank = isBlank && ch <= ' ')
}
recur(lastOffset, isBlank = false)
import Character.{isHighSurrogate, isLowSurrogate, isUnicodeIdentifierPart, isUnicodeIdentifierStart, isValidCodePoint, toCodePoint}
// f"\\u$c%04x" or f"${"\\"}u$c%04x"
private def toUnicode(c: Char): String = { val s = c.toInt.toHexString; "\\u" + "0" * (4 - s.length) + s }
// given char (ch) is high surrogate followed by low, codepoint passes predicate.
// true means supplementary chars were put to buffer.
// strict to require low surrogate (if not in string literal).
private def isSupplementary(high: Char, test: Int => Boolean, strict: Boolean = true): Boolean =
isHighSurrogate(high) && {
var res = false
val low = lookaheadChar()
if isLowSurrogate(low) then
val codepoint = toCodePoint(high, low)
if isValidCodePoint(codepoint) then
if test(codepoint) then
putChar(high)
putChar(low)
nextChar()
nextChar()
res = true
else
error(em"illegal character '${toUnicode(high)}${toUnicode(low)}'")
else if !strict then
putChar(high)
nextChar()
res = true
else
error(em"illegal character '${toUnicode(high)}' missing low surrogate")
res
}
private def atSupplementary(ch: Char, f: Int => Boolean): Boolean =
isHighSurrogate(ch) && {
val hi = ch
val lo = lookaheadChar()
isLowSurrogate(lo) && {
val codepoint = toCodePoint(hi, lo)
isValidCodePoint(codepoint) && f(codepoint)
}
}
/** read next token, filling TokenData fields of Scanner.
*/
protected final def fetchToken(): Unit = {
offset = charOffset - 1
lineOffset = if (lastOffset < lineStartOffset) lineStartOffset else -1
name = null
(ch: @switch) match {
case ' ' | '\t' | CR | LF | FF =>
nextChar()
fetchToken()
case 'A' | 'B' | 'C' | 'D' | 'E' |
'F' | 'G' | 'H' | 'I' | 'J' |
'K' | 'L' | 'M' | 'N' | 'O' |
'P' | 'Q' | 'R' | 'S' | 'T' |
'U' | 'V' | 'W' | 'X' | 'Y' |
'Z' | '$' | '_' |
'a' | 'b' | 'c' | 'd' | 'e' |
'f' | 'g' | 'h' | 'i' | 'j' |
'k' | 'l' | 'm' | 'n' | 'o' |
'p' | 'q' | 'r' | 's' | 't' |
'u' | 'v' | 'w' | 'x' | 'y' |
'z' =>
putChar(ch)
nextChar()
getIdentRest()
if (ch == '"' && token == IDENTIFIER)
token = INTERPOLATIONID
case '<' => // is XMLSTART?
def fetchLT() = {
val last = if (charOffset >= 2) buf(charOffset - 2) else ' '
nextChar()
last match {
case ' ' | '\t' | '\n' | '{' | '(' | '>' if xml.Utility.isNameStart(ch) || ch == '!' || ch == '?' =>
token = XMLSTART
case _ =>
// Console.println("found '<', but last is '" + in.last +"'"); // DEBUG
putChar('<')
getOperatorRest()
}
}
fetchLT()
case '~' | '!' | '@' | '#' | '%' |
'^' | '*' | '+' | '-' | /*'<' | */
'>' | '?' | ':' | '=' | '&' |
'|' | '\\' =>
putChar(ch)
nextChar()
getOperatorRest()
case '/' =>
if (skipComment())
fetchToken()
else {
putChar('/')
getOperatorRest()
}
case '0' =>
def fetchLeadingZero(): Unit = {
nextChar()
ch match {
case 'x' | 'X' => base = 16 ; nextChar()
case 'b' | 'B' => base = 2 ; nextChar()
case _ => base = 10 ; putChar('0')
}
if (base != 10 && !isNumberSeparator(ch) && digit2int(ch, base) < 0)
error(em"invalid literal number")
}
fetchLeadingZero()
getNumber()
case '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' =>
base = 10
getNumber()
case '`' =>
getBackquotedIdent()
case '\"' =>
def stringPart(multiLine: Boolean) = {
getStringPart(multiLine)
currentRegion = InString(multiLine, currentRegion)
}
def fetchDoubleQuote() =
if (token == INTERPOLATIONID) {
nextRawChar()
if (ch == '\"') {
if (lookaheadChar() == '\"') {
nextRawChar()
nextRawChar()
stringPart(multiLine = true)
}
else {
nextChar()
token = STRINGLIT
strVal = ""
}
}
else {
stringPart(multiLine = false)
}
}
else {
nextChar()
if (ch == '\"') {
nextChar()
if (ch == '\"') {
nextRawChar()
getRawStringLit()
}
else {
token = STRINGLIT
strVal = ""
}
}
else
getStringLit()
}
fetchDoubleQuote()
case '\'' =>
def fetchSingleQuote(): Unit = {
nextChar()
if isIdentifierStart(ch) then
charLitOr { getIdentRest(); QUOTEID }
else if isOperatorPart(ch) && ch != '\\' then
charLitOr { getOperatorRest(); QUOTEID }
else ch match {
case '{' | '[' | ' ' | '\t' if lookaheadChar() != '\'' =>
token = QUOTE
case _ if !isAtEnd && ch != SU && ch != CR && ch != LF =>
val isEmptyCharLit = (ch == '\'')
getLitChar()
if ch == '\'' then
if isEmptyCharLit then error(em"empty character literal (use '\\'' for single quote)")
else if litBuf.length != 1 then error(em"illegal codepoint in Char constant: ${litBuf.toString.map(toUnicode).mkString("'", "", "'")}")
else finishCharLit()
else if isEmptyCharLit then error(em"empty character literal")
else error(em"unclosed character literal")
case _ =>
error(em"unclosed character literal")
}
}
fetchSingleQuote()
case '.' =>
nextChar()
if ('0' <= ch && ch <= '9') {