107 lines
3.6 KiB
Java
107 lines
3.6 KiB
Java
package expression.common;
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import java.util.function.Function;
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/**
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* @author Georgiy Korneev (kgeorgiy@kgeorgiy.info)
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*/
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public abstract class Node<T> {
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private Node() {
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}
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public abstract <R> R get(Const<T, R> con, Nullary<R> nul, Unary<Node<T>, R> un, Binary<Node<T>, R> bin);
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public abstract <R> R cata(Const<T, R> con, Nullary<R> nul, Unary<R, R> un, Binary<R, R> bin);
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public final String toPolish() {
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return cata(
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T::toString,
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name -> name,
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(name, priority, a) -> a + " " + name + ":1",
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(name, a1, a2) -> a1 + " " + a2 + " " + name + ":2"
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);
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}
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@Override
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public final String toString() {
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return cata(
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T::toString,
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name -> name,
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(name, priority, a) -> name.equals("[") ? "[" + a + "]" :
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(priority & 1) == 1 ? "(" + name + " " + a + ")" : "(" + a + " " + name + ")",
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(name, a1, a2) -> "(" + a1 + " " + name + " " + a2 + ")"
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);
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}
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public static <T> Node<T> constant(final T value) {
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return new Node<>() {
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@Override
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public <R> R get(final Const<T, R> con, final Nullary<R> nul, final Unary<Node<T>, R> un, final Binary<Node<T>, R> bin) {
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return con.apply(value);
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}
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@Override
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public <R> R cata(final Const<T, R> con, final Nullary<R> nul, final Unary<R, R> un, final Binary<R, R> bin) {
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return con.apply(value);
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}
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};
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}
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public static <T> Node<T> op(final String name) {
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return new Node<>() {
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@Override
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public <R> R get(final Const<T, R> con, final Nullary<R> nul, final Unary<Node<T>, R> un, final Binary<Node<T>, R> bin) {
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return nul.apply(name);
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}
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@Override
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public <R> R cata(final Const<T, R> con, final Nullary<R> nul, final Unary<R, R> un, final Binary<R, R> bin) {
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return nul.apply(name);
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}
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};
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}
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public static <T> Node<T> op(final String name, final int priority, final Node<T> arg) {
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return new Node<>() {
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@Override
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public <R> R get(final Const<T, R> con, final Nullary<R> nul, final Unary<Node<T>, R> un, final Binary<Node<T>, R> bin) {
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return un.apply(name, priority, arg);
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}
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@Override
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public <R> R cata(final Const<T, R> con, final Nullary<R> nul, final Unary<R, R> un, final Binary<R, R> bin) {
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return un.apply(name, priority, arg.cata(con, nul, un, bin));
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}
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};
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}
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public static <T> Node<T> op(final String name, final Node<T> arg1, final Node<T> arg2) {
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return new Node<>() {
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@Override
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public <R> R get(final Const<T, R> con, final Nullary<R> nul, final Unary<Node<T>, R> un, final Binary<Node<T>, R> bin) {
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return bin.apply(name, arg1, arg2);
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}
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@Override
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public <R> R cata(final Const<T, R> con, final Nullary<R> nul, final Unary<R, R> un, final Binary<R, R> bin) {
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return bin.apply(name, arg1.cata(con, nul, un, bin), arg2.cata(con, nul, un, bin));
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}
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};
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}
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@FunctionalInterface
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public interface Const<T, R> extends Function<T, R> {}
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@FunctionalInterface
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public interface Nullary<R> extends Function<String, R> {}
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@FunctionalInterface
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public interface Unary<T, R> {
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R apply(String name, int priority, T arg);
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}
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@FunctionalInterface
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public interface Binary<T, R> {
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R apply(String name, T arg1, T arg2);
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}
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}
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