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package bjc.pratt.blocks;
import java.util.function.UnaryOperator;
import bjc.pratt.ParserContext;
import bjc.pratt.commands.CommandResult;
import bjc.pratt.commands.CommandResult.Status;
import bjc.pratt.tokens.Token;
import bjc.data.Tree;
import bjc.utils.parserutils.ParserException;
/**
* A parse block that can adjust the state before handling its context.
*
* @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 TriggeredParseBlock<K, V, C> implements ParseBlock<K, V, C> {
private final UnaryOperator<C> onEntr;
private final UnaryOperator<C> onExt;
private final ParseBlock<K, V, C> sourc;
/**
* Create a new triggered parse block.
*
* @param onEnter
* The action to fire before parsing the block.
*
* @param onExit
* The action to fire after parsing the block.
*
* @param source
* The block to use for parsing.
*/
public TriggeredParseBlock(final UnaryOperator<C> onEnter, final UnaryOperator<C> onExit,
final ParseBlock<K, V, C> source) {
onEntr = onEnter;
onExt = onExit;
sourc = source;
}
@Override
public CommandResult<K, V> parse(final ParserContext<K, V, C> ctx) throws ParserException {
final C newState = onEntr.apply(ctx.state);
final ParserContext<K, V, C> newCtx = new ParserContext<>(ctx.tokens, ctx.parse, newState);
final CommandResult<K,V> res = sourc.parse(newCtx);
if (res.status != Status.SUCCESS) return res;
ctx.state = onExt.apply(newState);
return res;
}
}
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