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package bjc.pratt.commands.impls;
import bjc.pratt.ParserContext;
import bjc.pratt.blocks.ParseBlock;
import bjc.pratt.commands.BinaryPostCommand;
import bjc.pratt.tokens.Token;
import bjc.data.Tree;
import bjc.data.SimpleTree;
import bjc.utils.parserutils.ParserException;
/**
* A ternary command, like C's ?:
*
* @author bjculkin
*
* @param <K>
* The key type of the tokens.
*
* @param <V>
* The value type of the tokens.
*
* @param <C>
* The state type of the parser.
*/
public class TernaryCommand<K, V, C> extends BinaryPostCommand<K, V, C> {
private final ParseBlock<K, V, C> innerBlck;
private final Token<K, V> mark;
private final boolean nonassoc;
/**
* Create a new ternary command.
*
* @param precedence
* The precedence of this operator.
*
* @param innerBlock
* The representation of the inner block of the expression.
*
* @param marker
* The token to use as the root of the AST node.
*
* @param isNonassoc
* Whether or not the conditional is associative.
*/
public TernaryCommand(final int precedence, final ParseBlock<K, V, C> innerBlock, final Token<K, V> marker,
final boolean isNonassoc) {
super(precedence);
if(innerBlock == null)
throw new NullPointerException("Inner block must not be null");
else if(marker == null) throw new NullPointerException("Marker must not be null");
innerBlck = innerBlock;
mark = marker;
nonassoc = isNonassoc;
}
@Override
public Tree<Token<K, V>> denote(final Tree<Token<K, V>> operand, final Token<K, V> operator,
final ParserContext<K, V, C> ctx) throws ParserException {
final Tree<Token<K, V>> inner = innerBlck.parse(ctx);
final Tree<Token<K, V>> outer = ctx.parse.parseExpression(1 + leftBinding(), ctx.tokens, ctx.state,
false);
return new SimpleTree<>(mark, inner, operand, outer);
}
@Override
public int nextBinding() {
if(nonassoc) return leftBinding() - 1;
return leftBinding();
}
}
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