/obc-Coco

Coco/R for Oxford Oberon-2 compiler runtime

Primary LanguageMathematica

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