private void processDeclarations(Env<String, Type> env) {
// The declarations type the pattern variables...
for (Dec dec : decs) env = env.bind(dec.getName(), dec.getDeclaredType());
for (BArm arm : arms) {
arm.processDeclarations(env);
}
}
public int maxLocals() {
// Be sure to add in local slots for each of the expression values...
int maxLocals = 0;
for (AST exp : exps) maxLocals = Math.max(maxLocals, exp.maxLocals());
for (BArm arm : arms) maxLocals = Math.max(maxLocals, arm.maxLocals());
return maxLocals + exps.length;
}
public Type type(Env<String, Type> env) {
// The case expression may include declarations that
// type the bound variables in patterns. The pattern
// variables are updated...
processDeclarations(env);
// Get the types of the supplied values...
Type[] suppliedTypes = new Type[exps.length];
Type[] expectedTypes = new Type[exps.length];
for (int i = 0; i < exps.length; i++) {
suppliedTypes[i] = exps[i].type(env);
expectedTypes[i] = ast.types.Void.VOID;
}
// The return type. Any void return types are ignored...
Type resultType = null;
for (BArm arm : arms) {
int lineStart = arm.patterns[0].getLineStart();
int lineEnd = arm.patterns[0].getLineEnd();
if (arm.patterns.length == exps.length) {
HandlerType handlerType = arm.type(env);
for (int i = 0; i < exps.length; i++) {
if (!Term.equals(handlerType.getTypes()[i], suppliedTypes[i], env)) {
throw new TypeMatchError(
lineStart, lineEnd, suppliedTypes[i], handlerType.getTypes()[i]);
}
}
if (resultType == null) resultType = handlerType.getResult();
else if (!Type.equals(resultType, handlerType.getResult(), env))
throw new TypeError(
lineStart,
lineEnd,
"incompatible case arm return types "
+ resultType
+ " and "
+ handlerType.getResult());
} else throw new TypeError(lineStart, lineEnd, "incorrect number of arm patterns.");
}
return resultType;
}
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);
}
public void setPath(String path) {
for (AST exp : exps) exp.setPath(path);
for (BArm arm : arms) arm.setPath(path);
}
public void DV(HashSet<String> vars) {
for (AST exp : exps) exp.DV(vars);
for (BArm arm : arms) arm.DV(vars);
}
