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package bjc.utils.parserutils.pratt;
import bjc.utils.data.ITree;
import bjc.utils.data.Tree;
import bjc.utils.parserutils.ParserException;
/**
* * Contains factory methods for producing common implementations of
* {@link NullCommand}
*
* @author EVE
*
*/
public class NullCommands {
private static abstract class AbstractNullCommand<K, V, C> extends NullCommand<K, V, C> {
@Override
public ITree<Token<K, V>> nullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
throws ParserException {
//tokens.next();
return intNullDenotation(operator, ctx);
}
protected abstract ITree<Token<K, V>> intNullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
throws ParserException;
}
private static class UnaryCommand<K, V, C> extends AbstractNullCommand<K, V, C> {
private final int nullPwer;
public UnaryCommand(int nullPower) {
nullPwer = nullPower;
}
@Override
protected ITree<Token<K, V>> intNullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
throws ParserException {
ITree<Token<K, V>> opr = ctx.parse.parseExpression(nullPwer, ctx.tokens, ctx.state);
return new Tree<>(operator, opr);
}
}
private static class GroupingCommand<K, V, C> extends AbstractNullCommand<K, V, C> {
private K term;
private Token<K, V> mark;
private int inner;
public GroupingCommand(int innerPrec, K terminator, Token<K, V> marker) {
inner = innerPrec;
term = terminator;
mark = marker;
}
@SuppressWarnings("unchecked")
@Override
protected ITree<Token<K, V>> intNullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
throws ParserException {
ITree<Token<K, V>> opr = ctx.parse.parseExpression(inner, ctx.tokens, ctx.state);
ctx.tokens.expect(term);
return new Tree<>(mark, opr);
}
}
private static class LeafCommand<K, V, C> extends NullCommand<K, V, C> {
@Override
public ITree<Token<K, V>> nullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
throws ParserException {
return new Tree<>(operator);
}
}
/**
* Create a new unary operator.
*
* @param precedence
* The precedence of the operator.
*
* @return A command implementing that operator.
*/
public static <K, V, C> NullCommand<K, V, C> unary(int precedence) {
return new UnaryCommand<>(precedence);
}
/**
* Create a new grouping operator.
*
* @param precedence
* The precedence of the expression in the operator.
*
* @param term
* The type that closes the group.
*
* @param mark
* The token for the AST node of the group.
*
* @return A command implementing the operator.
*/
public static <K, V, C> NullCommand<K, V, C> grouping(int precedence, K term, Token<K, V> mark) {
return new GroupingCommand<>(precedence, term, mark);
}
/**
* Create a new leaf operator.
*
* @return A command implementing the operator.
*/
public static <K, V, C> NullCommand<K, V, C> leaf() {
return new LeafCommand<>();
}
}
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