Implement array types and index expressions.

Some cleanup.  Elem() on PtrType is now just Elem and matches
with ArrayType.  Generators now switch over the result type
instead of the operand type.  Delete unused diag function.

R=rsc
APPROVED=rsc
DELTA=281  (219 added, 18 deleted, 44 changed)
OCL=31876
CL=31891

1 files changed, 182 insertions, 40 deletions

diff --git a/usr/austin/eval/expr.go b/usr/austin/eval/expr.go
index 6ab4ad46e..3368b44fc 100644
--- a/usr/austin/eval/expr.go
+++ b/usr/austin/eval/expr.go
@@ -12,7 +12,7 @@ import (
 	"go/scanner";
 	"go/token";
 	"log";
-"os";
+	"os";
 	"strconv";
 	"strings";
 )
@@ -41,6 +41,7 @@ type exprCompiler struct {
 	evalFloat func(f *Frame) float64;
 	evalIdealFloat func() *bignum.Rational;
 	evalString func(f *Frame) string;
+	evalArray func(f *Frame) ArrayValue;
 	evalPtr func(f *Frame) Value;
 	// Evaluate to the "address of" this value; that is, the
 	// settable Value object.  nil for expressions whose address
@@ -62,6 +63,7 @@ func newExprCompiler(c *exprContext, pos token.Position) *exprCompiler {
 // Operator generators
 // TODO(austin) Remove these forward declarations
 func (a *exprCompiler) genIdentOp(t Type, s *Scope, index int)
+func (a *exprCompiler) genIndexArray(l *exprCompiler, r *exprCompiler)
 func (a *exprCompiler) genStarOp(v *exprCompiler)
 func (a *exprCompiler) genUnaryOpNeg(v *exprCompiler)
 func (a *exprCompiler) genUnaryOpNot(v *exprCompiler)
@@ -78,7 +80,13 @@ func (a *exprCompiler) genBinOpAndNot(l *exprCompiler, r *exprCompiler)
 func (a *exprCompiler) genBinOpShl(l *exprCompiler, r *exprCompiler)
 func (a *exprCompiler) genBinOpShr(l *exprCompiler, r *exprCompiler)
 
-func (a *exprCompiler) fork(x ast.Expr) *exprCompiler {
+func (a *exprCompiler) copy() *exprCompiler {
+	ec := newExprCompiler(a.exprContext, a.pos);
+	ec.desc = a.desc;
+	return ec;
+}
+
+func (a *exprCompiler) copyVisit(x ast.Expr) *exprCompiler {
 	ec := newExprCompiler(a.exprContext, x.Pos());
 	x.Visit(ec);
 	return ec;
@@ -145,6 +153,13 @@ func (a *exprCompiler) asString() (func(f *Frame) string) {
 	return a.evalString;
 }
 
+func (a *exprCompiler) asArray() (func(f *Frame) ArrayValue) {
+	if a.evalArray == nil {
+		log.Crashf("tried to get %v node as ArrayType", a.t);
+	}
+	return a.evalArray;
+}
+
 func (a *exprCompiler) asPtr() (func(f *Frame) Value) {
 	if a.evalPtr == nil {
 		log.Crashf("tried to get %v node as PtrType", a.t);
@@ -152,6 +167,9 @@ func (a *exprCompiler) asPtr() (func(f *Frame) Value) {
 	return a.evalPtr;
 }
 
+// TODO(austin) Move convertTo somewhere more reasonable
+func (a *exprCompiler) convertTo(t Type) *exprCompiler
+
 func (a *exprCompiler) DoBadExpr(x *ast.BadExpr) {
 	// Do nothing.  Already reported by parser.
 }
@@ -274,7 +292,103 @@ func (a *exprCompiler) DoSelectorExpr(x *ast.SelectorExpr) {
 }
 
 func (a *exprCompiler) DoIndexExpr(x *ast.IndexExpr) {
-	log.Crash("Not implemented");
+	l, r := a.copyVisit(x.X), a.copyVisit(x.Index);
+	if l.t == nil || r.t == nil {
+		return;
+	}
+
+	// Type check object
+	if lt, ok := l.t.literal().(*PtrType); ok {
+		if et, ok := lt.Elem.literal().(*ArrayType); ok {
+			// Automatic dereference
+			nl := l.copy();
+			nl.t = et;
+			nl.genStarOp(l);
+			l = nl;
+		}
+	}
+
+	var at Type;
+	intIndex := false;
+	var maxIndex int64 = -1;
+
+	switch lt := l.t.literal().(type) {
+	case *ArrayType:
+		at = lt.Elem;
+		intIndex = true;
+		maxIndex = lt.Len;
+
+	// TODO(austin) Uncomment when there is a SliceType
+	// case *SliceType:
+	// 	a.t = lt.Elem;
+	// 	intIndex = true;
+
+	case *stringType:
+		at = Uint8Type;
+		intIndex = true;
+
+	// TODO(austin) Uncomment when there is a MapType
+	// case *MapType:
+	// 	log.Crash("Index into map not implemented");
+
+	default:
+		a.diag("cannot index into %v", l.t);
+		return;
+	}
+
+	// Type check index and convert to int if necessary
+	if intIndex {
+		// XXX(Spec) It's unclear if ideal floats with no
+		// fractional part are allowed here.  6g allows it.  I
+		// believe that's wrong.
+		switch _ := r.t.literal().(type) {
+		case *idealIntType:
+			val := r.asIdealInt()();
+			if val.IsNeg() || (maxIndex != -1 && val.Cmp(bignum.Int(maxIndex)) >= 0) {
+				a.diag("array index out of bounds");
+				return;
+			}
+			r = r.convertTo(IntType);
+			if r == nil {
+				return;
+			}
+
+		case *uintType:
+			// Convert to int
+			nr := r.copy();
+			nr.t = IntType;
+			rf := r.asUint();
+			nr.evalInt = func(f *Frame) int64 {
+				return int64(rf(f));
+			};
+			r = nr;
+
+		case *intType:
+			// Good as is
+
+		default:
+			a.diag("illegal operand type for index\n\t%v", r.t);
+			return;
+		}
+	}
+
+	a.t = at;
+
+	// Compile
+	switch lt := l.t.literal().(type) {
+	case *ArrayType:
+		a.t = lt.Elem;
+		// TODO(austin) Bounds check
+		a.genIndexArray(l, r);
+		lf := l.asArray();
+		rf := r.asInt();
+		a.evalAddr = func(f *Frame) Value {
+			return lf(f).Elem(rf(f));
+		};
+
+	default:
+		log.Crashf("Compilation of index into %T not implemented", l.t.literal());
+	}
 }
 
 func (a *exprCompiler) DoTypeAssertExpr(x *ast.TypeAssertExpr) {
@@ -286,14 +400,16 @@ func (a *exprCompiler) DoCallExpr(x *ast.CallExpr) {
 }
 
 func (a *exprCompiler) DoStarExpr(x *ast.StarExpr) {
-	v := a.fork(x.X);
+	v := a.copyVisit(x.X);
 	if v.t == nil {
 		return;
 	}
 
-	switch vt := v.t.(type) {
+	switch vt := v.t.literal().(type) {
 	case *PtrType:
-		a.t = vt.Elem();
+		// TODO(austin) If this is vt.Elem() I get a
+		// "call of a non-function: Type" error
+		a.t = vt.Elem;
 		a.genStarOp(v);
 		vf := v.asPtr();
 		a.evalAddr = func(f *Frame) Value { return vf(f) };
@@ -307,7 +423,7 @@ func (a *exprCompiler) DoStarExpr(x *ast.StarExpr) {
 var unaryOpDescs = make(map[token.Token] string)
 
 func (a *exprCompiler) DoUnaryExpr(x *ast.UnaryExpr) {
-	v := a.fork(x.X);
+	v := a.copyVisit(x.X);
 	if v.t == nil {
 		return;
 	}
@@ -431,9 +547,8 @@ func (a *exprCompiler) convertTo(t Type) *exprCompiler {
 	}
 
 	// Convert rat to type t.
-	res := newExprCompiler(a.exprContext, a.pos);
+	res := a.copy();
 	res.t = t;
-	res.desc = a.desc;
 	switch t := t.(type) {
 	case *uintType:
 		n, d := rat.Value();
@@ -465,7 +580,7 @@ func (a *exprCompiler) convertTo(t Type) *exprCompiler {
 var binOpDescs = make(map[token.Token] string)
 
 func (a *exprCompiler) DoBinaryExpr(x *ast.BinaryExpr) {
-	l, r := a.fork(x.X), a.fork(x.Y);
+	l, r := a.copyVisit(x.X), a.copyVisit(x.Y);
 	if l.t == nil || r.t == nil {
 		return;
 	}
@@ -852,6 +967,8 @@ func (a *exprCompiler) genIdentOp(t Type, s *Scope, index int) {
 		a.evalFloat = func(f *Frame) float64 { return f.Get(s, index).(FloatValue).Get() };
 	case *stringType:
 		a.evalString = func(f *Frame) string { return f.Get(s, index).(StringValue).Get() };
+	case *ArrayType:
+		a.evalArray = func(f *Frame) ArrayValue { return f.Get(s, index).(ArrayValue).Get() };
 	case *PtrType:
 		a.evalPtr = func(f *Frame) Value { return f.Get(s, index).(PtrValue).Get() };
 	default:
@@ -859,9 +976,32 @@ func (a *exprCompiler) genIdentOp(t Type, s *Scope, index int) {
 	}
 }
 
+func (a *exprCompiler) genIndexArray(l *exprCompiler, r *exprCompiler) {
+	lf := l.asArray();
+	rf := r.asInt();
+	switch _ := a.t.literal().(type) {
+	case *boolType:
+		a.evalBool = func(f *Frame) bool { return lf(f).Elem(rf(f)).(BoolValue).Get() };
+	case *uintType:
+		a.evalUint = func(f *Frame) uint64 { return lf(f).Elem(rf(f)).(UintValue).Get() };
+	case *intType:
+		a.evalInt = func(f *Frame) int64 { return lf(f).Elem(rf(f)).(IntValue).Get() };
+	case *floatType:
+		a.evalFloat = func(f *Frame) float64 { return lf(f).Elem(rf(f)).(FloatValue).Get() };
+	case *stringType:
+		a.evalString = func(f *Frame) string { return lf(f).Elem(rf(f)).(StringValue).Get() };
+	case *ArrayType:
+		a.evalArray = func(f *Frame) ArrayValue { return lf(f).Elem(rf(f)).(ArrayValue).Get() };
+	case *PtrType:
+		a.evalPtr = func(f *Frame) Value { return lf(f).Elem(rf(f)).(PtrValue).Get() };
+	default:
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
+	}
+}
+
 func (a *exprCompiler) genStarOp(v *exprCompiler) {
 	vf := v.asPtr();
-	switch _ := v.t.literal().(*PtrType).Elem().literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *boolType:
 		a.evalBool = func(f *Frame) bool { return vf(f).(BoolValue).Get() };
 	case *uintType:
@@ -872,15 +1012,17 @@ func (a *exprCompiler) genStarOp(v *exprCompiler) {
 		a.evalFloat = func(f *Frame) float64 { return vf(f).(FloatValue).Get() };
 	case *stringType:
 		a.evalString = func(f *Frame) string { return vf(f).(StringValue).Get() };
+	case *ArrayType:
+		a.evalArray = func(f *Frame) ArrayValue { return vf(f).(ArrayValue).Get() };
 	case *PtrType:
 		a.evalPtr = func(f *Frame) Value { return vf(f).(PtrValue).Get() };
 	default:
-		log.Crashf("unexpected operand type %v at %v", v.t.literal().(*PtrType).Elem().literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", v.t.literal().(*PtrType).Elem.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genUnaryOpNeg(v *exprCompiler) {
-	switch _ := v.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		vf := v.asUint();
 		a.evalUint = func(f *Frame) uint64 { return -vf(f) };
@@ -899,22 +1041,22 @@ func (a *exprCompiler) genUnaryOpNeg(v *exprCompiler) {
 		val := vf().Neg();
 		a.evalIdealFloat = func() *bignum.Rational { return val };
 	default:
-		log.Crashf("unexpected operand type %v at %v", v.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", v.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genUnaryOpNot(v *exprCompiler) {
-	switch _ := v.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *boolType:
 		vf := v.asBool();
 		a.evalBool = func(f *Frame) bool { return !vf(f) };
 	default:
-		log.Crashf("unexpected operand type %v at %v", v.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", v.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genUnaryOpXor(v *exprCompiler) {
-	switch _ := v.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		vf := v.asUint();
 		a.evalUint = func(f *Frame) uint64 { return ^vf(f) };
@@ -926,12 +1068,12 @@ func (a *exprCompiler) genUnaryOpXor(v *exprCompiler) {
 		val := vf().Neg().Sub(bignum.Int(1));
 		a.evalIdealInt = func() *bignum.Integer { return val };
 	default:
-		log.Crashf("unexpected operand type %v at %v", v.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", v.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpAdd(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -959,12 +1101,12 @@ func (a *exprCompiler) genBinOpAdd(l *exprCompiler, r *exprCompiler) {
 		rf := r.asString();
 		a.evalString = func(f *Frame) string { return lf(f) + rf(f) };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpSub(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -988,12 +1130,12 @@ func (a *exprCompiler) genBinOpSub(l *exprCompiler, r *exprCompiler) {
 		val := lf().Sub(rf());
 		a.evalIdealFloat = func() *bignum.Rational { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpMul(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1017,12 +1159,12 @@ func (a *exprCompiler) genBinOpMul(l *exprCompiler, r *exprCompiler) {
 		val := lf().Mul(rf());
 		a.evalIdealFloat = func() *bignum.Rational { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpQuo(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1046,12 +1188,12 @@ func (a *exprCompiler) genBinOpQuo(l *exprCompiler, r *exprCompiler) {
 		val := lf().Quo(rf());
 		a.evalIdealFloat = func() *bignum.Rational { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpRem(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1066,12 +1208,12 @@ func (a *exprCompiler) genBinOpRem(l *exprCompiler, r *exprCompiler) {
 		val := lf().Rem(rf());
 		a.evalIdealInt = func() *bignum.Integer { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpAnd(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1086,12 +1228,12 @@ func (a *exprCompiler) genBinOpAnd(l *exprCompiler, r *exprCompiler) {
 		val := lf().And(rf());
 		a.evalIdealInt = func() *bignum.Integer { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpOr(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1106,12 +1248,12 @@ func (a *exprCompiler) genBinOpOr(l *exprCompiler, r *exprCompiler) {
 		val := lf().Or(rf());
 		a.evalIdealInt = func() *bignum.Integer { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpXor(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1126,12 +1268,12 @@ func (a *exprCompiler) genBinOpXor(l *exprCompiler, r *exprCompiler) {
 		val := lf().Xor(rf());
 		a.evalIdealInt = func() *bignum.Integer { return val };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpAndNot(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1141,12 +1283,12 @@ func (a *exprCompiler) genBinOpAndNot(l *exprCompiler, r *exprCompiler) {
 		rf := r.asInt();
 		a.evalInt = func(f *Frame) int64 { return lf(f) &^ rf(f) };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpShl(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1156,12 +1298,12 @@ func (a *exprCompiler) genBinOpShl(l *exprCompiler, r *exprCompiler) {
 		rf := r.asUint();
 		a.evalInt = func(f *Frame) int64 { return lf(f) << rf(f) };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }
 
 func (a *exprCompiler) genBinOpShr(l *exprCompiler, r *exprCompiler) {
-	switch _ := l.t.literal().(type) {
+	switch _ := a.t.literal().(type) {
 	case *uintType:
 		lf := l.asUint();
 		rf := r.asUint();
@@ -1171,6 +1313,6 @@ func (a *exprCompiler) genBinOpShr(l *exprCompiler, r *exprCompiler) {
 		rf := r.asUint();
 		a.evalInt = func(f *Frame) int64 { return lf(f) >> rf(f) };
 	default:
-		log.Crashf("unexpected left operand type %v at %v", l.t.literal(), a.pos);
+		log.Crashf("unexpected result type %v at %v", l.t.literal(), a.pos);
 	}
 }