Пример #1
0
  public void compile(
      List<FrameVar> locals, List<DynamicVar> dynamics, CodeBox code, boolean isLast) {

    // The expressions matched by the case arms are set in the stack frame as
    // locals...

    int base = locals.length();
    int index = 0;
    for (AST exp : exps) {
      exp.compile(locals, dynamics, code, false);
      locals = locals.cons(new FrameVar("$case-" + (index++), locals.length()));
      code.add(new SetFrame(getLineStart(), locals.length() - 1), locals, dynamics);
      code.add(new Pop(getLineStart()), locals, dynamics);
    }
    compileArms(base, locals, dynamics, code, isLast);
  }
Пример #2
0
  public void compileArms(
      int varIndex,
      List<FrameVar> locals,
      List<DynamicVar> dynamics,
      CodeBox code,
      boolean isLast) {

    boolean useSwitchTable = isDisjointArms() && arms.length > 3;
    SwitchTable switchTableInstr = new SwitchTable(getLineStart(), varIndex);
    if (useSwitchTable) code.add(switchTableInstr, locals, dynamics);

    // Define the dynamic vars up front ... then remove them at the end...

    // Compile each arm independently...

    Vector<CodeBox> armCode = new Vector<CodeBox>();
    Vector<HashSet<String>> armBV = new Vector<HashSet<String>>();
    Vector<HashSet<String>> armDV = new Vector<HashSet<String>>();

    for (BArm arm : arms) {

      // Work out which variables bound by patterns should be local and which
      // should be dynamic...

      HashSet<String> DV = new HashSet<String>();
      HashSet<String> BV = new HashSet<String>();

      for (Pattern p : arm.patterns) p.vars(BV);
      arm.exp.DV(DV);
      arm.guard.DV(DV);

      armBV.add(BV);
      armDV.add(DV);
    }

    for (int i = 0; i < arms.length; i++) {

      BArm arm = arms[i];
      HashSet<String> BV = armBV.get(i);
      HashSet<String> DV = armDV.get(i);

      List<FrameVar> armLocals = locals;
      List<DynamicVar> armDynamics = dynamics;

      CodeBox instrs = new CodeBox("", 0);

      // We have just failed to here so remove the dynamic variables from the
      // previous arm...

      if (i > 0) {
        for (String v : armBV.get(i - 1)) {
          if (armDV.get(i - 1).contains(v)) {
            instrs.add(new PopDynamic(getLineStart()), locals, dynamics);
            dynamics = dynamics.getTail();
          }
        }
      }
      for (String v : BV) {
        if (DV.contains(v)) {
          armDynamics = armDynamics.map(DynamicVar::incDynamic).cons(new DynamicVar(v, 0));
          instrs.add(new Null(getLineStart()), locals, dynamics);
          instrs.add(new NewDynamic(getLineStart()), locals, dynamics);
        } else armLocals = armLocals.cons(new FrameVar(v, armLocals.length()));
      }
      arm.compile(varIndex, armLocals, armDynamics, instrs, isLast && i == arms.length - 1);
      for (String v : BV) {
        if (DV.contains(v)) {
          instrs.add(new PopDynamic(getLineStart()), locals, dynamics);
          dynamics = dynamics.getTail();
        }
      }
      armCode.add(instrs);
    }

    // Now insert the TRY...SKIP instructions between the arms...

    for (int i = 0; i < armCode.size(); i++) {
      int length = code.getCode().size();
      instrs.patterns.Try tryArm = new instrs.patterns.Try(getLineStart(), 0, i == 0);
      code.add(tryArm, locals, dynamics);
      int base = code.getCode().size();
      CodeBox armCodeBox = armCode.get(i);
      if (useSwitchTable) switchTableInstr.processArm(arms[i], code.getCode().size());
      for (Instr instr : armCodeBox.getCode()) {
        if (instr instanceof Goto) {
          Goto g = (Goto) instr;
          g.setAddress(g.getAddress() + base);
        }
        code.add(
            instr,
            armCodeBox.getLocalsAt(armCodeBox.indexOf(instr)),
            armCodeBox.getDynamicsAt(armCodeBox.indexOf(instr)));
      }
      // Jump over the rest of the case arms and the end error message...
      int distance = distance(armCode, i + 1) + 2;
      Skip jmp = new Skip(getLineStart(), distance);
      code.add(jmp, locals, dynamics);
      int offset = code.getCode().size() - length;
      tryArm.setOffset(offset - 1);
      if (useSwitchTable) switchTableInstr.processError(arms[i], offset - 1);
    }

    // Add in the error at the end of the case...

    code.add(new instrs.patterns.CaseError(getLineStart(), this, varIndex), locals, dynamics);
  }