This is Coco/R (http://ssw.jku.at/Coco/) for Oberon

Based on implementation taken from A2 (Coco/R V2.2)

Modifications based on current C# version (Apr 19, 2011)

Usage

echo '*' > par

./CocoCompile file.ATG

Modifications done

• most important:

  • IF (LL(1)-resolver):

    • CR.ATG: Resolver introduced (based on C# Coco.atg); Coco.Error updated

    • CRT: Resolver introduced (based on C# Tab.cs)

    • CRX: Resolver introduced (based on C# ParserGen.cs)

      TODO?:

      • what is correct 2nd arg of GenCond in case of CRT.opt in GenCode ?
      • CRT.any case in GenCode: implementation differs from C# version

  • CRT.LL1Test: LL1Error(4) added, based on C# Tab.cs CheckLL1(); DelSubGraph() introduced

  • literals:

    • CRX: new procedure: GenTokens
    • CR.ATG: modified
    • CRDriver.FRM: semantic error 27 introduced ("token string declared twice")
    • CRDriver.FRM: semantic error 28 introduced ("undefined string in production")
    • CRT: new procedures: NewLit, FindLit

  • Driver generation:

    • CRX.GenCompiler: modified
    • Driver.FRM: created
    • Coco.Mod renamed to CRDriver.FRM and modified

  • CR.ATG.FixString: "literal tokens must not contain blanks" semantic check inserted

• CRA.GenComment.GenBody: "ch = r.eot" -> "ch = EOF"

• CR.ATG: SHORT inserted in 2 places in SimSet production

• input ATG linesep related:

  • CR.ATG: eol -> lf, cr
  • Scanner.FRM: "EOL = 0DX" -> "EOL = 0AX"

• unused:

  • CRT: unused import of SYSTEM removed
  • Scanner.FRM: unused import of SYSTEM commented
  • CR.ATG: name variable commented in SetDDT (it not used)
  • CR.ATG: "gn: CRT.GraphNode" commented in CR production (it not used)
  • CR.ATG: c variable commented in Factor production (it not used)

• optimizations:

  • CRT.Length: s -> CONST s
  • CRA.Length: s -> CONST s
  • CRX.Length: s -> CONST s

• typos:

  • spaces:

    • Scanner.FRM: extra space removed in first line "(* scanner module..."
    • redundant spaces removed in some places

Features candidates

IF() LL(1)-resolver	implemented
multi-symbol lookahead	I will not implement it
literals	implemented

Notes

• line separators:

  • generated code:

    Texts.WriteLn always emits CR

    CRA.GenLiterals: CHR(13)

  • input ATG:

    CR.ATG: eol token

    Scanner.FRM: EOL (line counter)

  • CRX.EOL: 0DX

• lookahead-related:

  new	old	comment
  la.kind	sym	often used
  la.val	S.GetName(S.nextPos, S.nextLen, nextName)
  t.kind	???	rarely used? may be easy implemented in Parser.FRM?
  t.val	S.GetName(S.pos, S.len, name)	often used

• it is possible to write: (. IF ... THEN .) ... (. END .) :)

TODO

• do Coco regression tests

  TestResOK (EOF related)

• number of reported errors does not correspond to number of displayed errors

• trace:

  does not work now

  literals