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Copy pathParser.java
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72 lines (60 loc) · 1.82 KB
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package com.company;
import java.util.ArrayList;
import java.util.function.Function;
import static com.company.Tuple.*;
class ParseResults<A> extends ArrayList<Tuple<A,Text>> {
public static <A> ParseResults<A> result(Tuple<A,Text> t){
ParseResults<A> pr = new ParseResults<A>();
pr.add(t);
return pr;
}
public static <A> ParseResults<A> empty(){
ParseResults<A> pr = new ParseResults<A>();
return pr;
}
}
class Parser<A> {
private final Function<Text,ParseResults<A>> f;
public Parser(Function<Text,ParseResults<A>> f){
this.f =f;
}
public Parser<A> alt(Parser<A> a){
return new Parser<>(s->{
ParseResults<A> r = parse(this).apply(s);
if (r.size() > 0){
return r;
} else {
return parse(a).apply(s);
}
});
}
public <B> Parser<B> bind(Function<A,Parser<B>> f){
return new Parser<B>(s-> {
ParseResults<A> results = parse(this).apply(s);
ParseResults<B> prb = ParseResults.empty();
for (Tuple<A,Text> r : results){
Parser<B> pb = f.apply(r.getA());
ParseResults<B> bResults = parse(pb).apply(r.getB());
for (Tuple<B,Text> br : bResults){
prb.add(br);
}
}
return prb;
});
}
public static <A> Parser<A> empty(){
return new Parser<A>(s -> {
return new ParseResults<A>();
});
}
public static <B> Parser<B> pure(B b){
return new Parser<B>(s -> {
ParseResults<B> list = new ParseResults<B>();
list.add(t(b,s));
return list;
});
}
public static <A> Function<Text,ParseResults<A>> parse(Parser<A> p){
return p.f;
}
}