29 struct Effect {  struct
35   Effect() : modality(DEFINITE) {}  in Effect()  argument
36   explicit Effect(Bounds b, Modality m = DEFINITE) : modality(m), bounds(b) {}  in modality()  argument
39   static Effect Unknown(Zone* zone) {  in Unknown()  argument
40     return Effect(Bounds::Unbounded(zone), POSSIBLE);  in Unknown()
43   static Effect Forget(Zone* zone) {  in Forget()  argument
44     return Effect(Bounds::Unbounded(zone), DEFINITE);  in Forget()
48   static Effect Seq(Effect e1, Effect e2, Zone* zone) {  in Seq()  argument
50     return Effect(Bounds::Either(e1.bounds, e2.bounds, zone), e1.modality);  in Seq()
54   static Effect Alt(Effect e1, Effect e2, Zone* zone) {  in Alt()  argument
55     return Effect(  in Alt()
83   Effect Lookup(Var var) {  in Lookup()
86         ? locator.value() : Effect::Unknown(Base::zone());  in Lookup()
90     Effect effect = Lookup(var);  in LookupBounds()
91     return effect.modality == Effect::DEFINITE  in LookupBounds()
96   void Seq(Var var, Effect effect) {  in Seq()
99       effect = Effect::Seq(locator.value(), effect, Base::zone());  in Seq()
110   void Alt(Var var, Effect effect) {  in Alt()
113       effect = Effect::Alt(locator.value(), effect, Base::zone());  in Alt()
128         Effect::Forget(Base::zone()), Effects(Base::zone()) };  in Forget()
138     void Call(Var var, Effect effect) { self.Seq(var, effect); }  in Call()
144     void Call(Var var, Effect effect) { self.Alt(var, effect); }  in Call()
150     void Call(Var var, Effect effect) {  in Call()
151       if (effect.modality == Effect::DEFINITE && !other.Contains(var)) {  in Call()
152         effect.modality = Effect::POSSIBLE;  in Call()
163     void Call(Var var, Effect effect) { effects.Seq(var, new_effect); }  in Call()
164     Effect new_effect;
189     typedef Effect Value;
191     static Effect NoValue() { return Effect(); }  in NoValue()