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XLexer.prg
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XLexer.prg
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// XLexer.prg
USING System.Collections.Generic
USING System.Globalization
BEGIN NAMESPACE XSharp.Parsers
ABSTRACT CLASS XLexer
PROTECTED _Source AS STRING
PROTECTED _index := 0 AS LONG
PROTECTED _lastToken := XTokenType.NL AS XTokenType
PROTECTED _hasEos := TRUE AS LOGIC
PROTECTED AllowOldStyleComments AS LOGIC
PROTECTED AllowSingleQuotedStrings AS LOGIC
CONSTRUCTOR(source AS STRING )
SELF:_Source := source
AllowOldStyleComments := TRUE
AllowSingleQuotedStrings := TRUE
PROTECTED METHOD Lb() AS CHAR
RETURN IIF((SELF:_index > 0) , SELF:_Source[SELF:_index - 1] , c'\0')
PROTECTED METHOD La() AS CHAR
RETURN IIF((SELF:_index < SELF:_Source:Length) , SELF:_Source[SELF:_index] , c'\0')
PROTECTED METHOD La(n AS LONG ) AS CHAR
RETURN IIF((SELF:_index + n - 1 < SELF:_Source:Length) , SELF:_Source[SELF:_index + n - 1] , c'\0')
PROTECTED METHOD InRange(c AS CHAR , first AS CHAR , last AS CHAR ) AS LOGIC
RETURN c >= first .AND. c <= last
PROTECTED METHOD Eoi() AS LOGIC
RETURN SELF:_index >= SELF:_Source:Length
PROTECTED METHOD Consume() AS VOID
SELF:_index++
PROTECTED METHOD Consume(n AS LONG ) AS VOID
SELF:_index += n
PROTECTED METHOD Rewind(pos AS LONG ) AS VOID
SELF:_index := pos
PROTECTED METHOD Expect(c AS CHAR ) AS LOGIC
IF SELF:La() == c
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD Expect(c1 AS CHAR , c2 AS CHAR ) AS LOGIC
IF SELF:La() == c1 .AND. SELF:La(2) == c2
SELF:Consume(2)
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD ExpectEol() AS LOGIC
LOCAL r AS LOGIC
r := FALSE
IF SELF:La() == c'\r'
SELF:Consume()
r := TRUE
ENDIF
IF SELF:La() == c'\n'
SELF:Consume()
r := TRUE
ENDIF
RETURN r
PROTECTED METHOD ExpectAny(c1 AS CHAR , c2 AS CHAR ) AS LOGIC
LOCAL c3 AS CHAR
c3 := SELF:La()
IF c3 == c1 .OR. c3 == c2
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD ExpectAny(c1 AS CHAR , c2 AS CHAR , c3 AS CHAR) AS LOGIC
LOCAL c4 AS CHAR
c4 := SELF:La()
IF c4 == c1 .OR. c4 == c2 .OR. c4 == c3
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD ExpectAny(c1 AS CHAR , c2 AS CHAR , c3 AS CHAR , c4 AS CHAR ) AS LOGIC
LOCAL c5 AS CHAR
c5 := SELF:La()
IF c5 == c1 .OR. c5 == c2 .OR. c5 == c3 .OR. c5 == c4
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD ExpectRange(c1 AS CHAR , c2 AS CHAR ) AS LOGIC
IF SELF:InRange(SELF:La(), c1, c2)
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
// copied from the Roslyn C# lexer
PROTECTED STATIC METHOD IsLetterChar(cat AS UnicodeCategory ) AS LOGIC
// letter-character:
// A Unicode character of classes Lu, Ll, Lt, Lm, Lo, or Nl
// A Unicode-escape-sequence representing a character of classes Lu, Ll, Lt, Lm, Lo, or Nl
switch cat
case UnicodeCategory.UppercaseLetter
case UnicodeCategory.LowercaseLetter
case UnicodeCategory.TitlecaseLetter
case UnicodeCategory.ModifierLetter
case UnicodeCategory.OtherLetter
case UnicodeCategory.LetterNumber
return true
end switch
RETURN FALSE
// copied from the Roslyn C# lexer
PUBLIC STATIC METHOD IsIdentifierPartCharacter(ch AS CHAR ) AS LOGIC
// identifier-part-character:
// letter-character
// decimal-digit-character
// connecting-character
// combining-character
// formatting-character
//
IF ch < c'a' // '\u0061'
IF ch < c'A' // '\u0041'
RETURN ch >= c'0' ; // '\u0030'
.AND. ch <= c'9' // '\u0039'
ENDIF
RETURN ch <= c'Z' ; // '\u005A'
.OR. ch == c'_' // '\u005F'
ENDIF
IF ch <= c'z' // '\u007A'
RETURN TRUE
ENDIF
IF ch <= c'\u007f' // max ASCII
RETURN FALSE
ENDIF
VAR cat := CharUnicodeInfo.GetUnicodeCategory(ch)
RETURN IsLetterChar(cat) ;
.OR. cat == UnicodeCategory.DecimalDigitNumber ;
.OR. cat == UnicodeCategory.ConnectorPunctuation ;
.OR. cat == UnicodeCategory.NonSpacingMark;
.OR. cat == UnicodeCategory.SpacingCombiningMark;
.OR. (ch > c'\u007f' .AND. cat == UnicodeCategory.Format)
// copied from the Roslyn C# lexer
PUBLIC STATIC METHOD IsIdentifierStartCharacter(ch AS CHAR ) AS LOGIC
// identifier-start-character:
// letter-character
// _ (the underscore character U+005F)
IF ch < c'a' // '\u0061'
IF ch < c'A' // '\u0041'
RETURN FALSE
ENDIF
RETURN ch <= c'Z' ; // '\u005A'
.OR. ch == c'_' // '\u005F'
ENDIF
IF ch <= c'z' // '\u007A'
RETURN TRUE
ENDIF
IF ch <= c'\u007f' // max ASCII
RETURN FALSE
ENDIF
RETURN IsLetterChar(CharUnicodeInfo.GetUnicodeCategory(ch))
PROTECTED METHOD ExpectIdStart() AS LOGIC
LOCAL c AS CHAR
c := SELF:La()
IF IsIdentifierStartCharacter(c)
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD ExpectIdChar() AS LOGIC
LOCAL c AS CHAR
c := SELF:La()
IF IsIdentifierPartCharacter(c)
SELF:Consume()
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD ExpectLower(s AS STRING ) AS LOGIC
IF Char.ToLower(SELF:La()) == s[0]
FOR VAR i := 1 TO s:Length
IF Char.ToLower(SELF:La(i)) != s[i - 1]
RETURN FALSE
ENDIF
NEXT
SELF:Consume(s:Length)
RETURN TRUE
ENDIF
RETURN FALSE
PROTECTED METHOD Reach(c AS CHAR ) AS LOGIC
IF !SELF:Eoi() .AND. SELF:La() != c
SELF:Consume()
RETURN FALSE
ENDIF
RETURN TRUE
PROTECTED METHOD ReachEsc(c AS CHAR ) AS LOGIC
LOCAL esc AS LOGIC
IF !SELF:Eoi() .AND. SELF:La() != c
esc := SELF:La() == c'\\'
SELF:Consume()
IF !SELF:Eoi() .AND. esc
SELF:Consume()
ENDIF
RETURN FALSE
ENDIF
RETURN TRUE
PROTECTED METHOD ConsumeToEol() AS VOID
DO WHILE !SELF:ReachEol()
NOP
ENDDO
RETURN
PROTECTED METHOD ReachEol() AS LOGIC
LOCAL c AS CHAR
IF !SELF:Eoi()
c := SELF:La()
IF c != c'\r' .AND. c != c'\n'
SELF:Consume()
RETURN FALSE
ENDIF
ENDIF
RETURN TRUE
PROTECTED METHOD Reach(c1 AS CHAR , c2 AS CHAR ) AS LOGIC
IF !SELF:Eoi()
IF SELF:La() != c1 .OR. SELF:La(2) != c2
SELF:Consume()
RETURN FALSE
ENDIF
ENDIF
RETURN TRUE
METHOD Reset() AS VOID
SELF:_lastToken := XTokenType.NL
SELF:_index := 0
METHOD AllTokens() AS IList<XToken>
LOCAL t AS XToken
VAR i := List<XToken>{}
DO WHILE (t := SELF:NextToken()) != NULL
i:Add(t)
ENDDO
RETURN i
METHOD GetText(t AS XToken ) AS STRING
RETURN SELF:_Source:Substring(t:Start, t:Length)
ABSTRACT METHOD NextToken AS XToken
ABSTRACT METHOD LookupKeyword(strKeyword AS STRING) AS XTokenType
END CLASS
END NAMESPACE