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package bjc.pratt.blocks;
import java.util.Set;
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.data.SimpleTree;
import bjc.utils.parserutils.ParserException;
/**
* A {@link ParseBlock} for a series of parse blocks, linked by a set of tokens.
*
* Roughly analogous to Perl 6s list associative operators.
*
* @author bjculkin
*
* @param <K>
* The token key type.
*
* @param <V>
* The token value type.
*
* @param <C>
* The parser state type.
*
*/
public class ChainParseBlock<K, V, C> implements ParseBlock<K, V, C> {
private ParseBlock<K, V, C> iner;
private Set<K> indicators;
private Token<K, V> trm;
/**
* Create a new chain parser block.
*
* @param inner
* The block for the chains interior.
*
* @param chainIndicators
* The set of markers that indicate continuing the chain
*
* @param term
* The node in the AST for the expression.
*/
public ChainParseBlock(ParseBlock<K, V, C> inner, Set<K> chainIndicators, Token<K, V> term) {
iner = inner;
indicators = chainIndicators;
trm = term;
}
@Override
public CommandResult<K, V> parse(ParserContext<K, V, C> ctx) throws ParserException {
CommandResult<K,V> resOuter = iner.parse(ctx);
if (resOuter.status != Status.SUCCESS) return resOuter;
Tree<Token<K, V>> expression = resOuter.success();
Token<K, V> currentToken = ctx.tokens.current();
if(indicators.contains(currentToken.getKey())) {
Tree<Token<K, V>> res = new SimpleTree<>(trm);
res.addChild(expression);
while(indicators.contains(currentToken.getKey())) {
res.addChild(new SimpleTree<>(currentToken));
ctx.tokens.next();
CommandResult<K,V> resInner = iner.parse(ctx);
if (resInner.status != Status.SUCCESS) return resInner;
Tree<Token<K, V>> innerExpression = resInner.success();
res.addChild(innerExpression);
currentToken = ctx.tokens.current();
}
return CommandResult.success(res);
}
return resOuter;
}
}
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