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package bjc.pratt.blocks;
import java.util.function.Function;
import bjc.data.Tree;
import bjc.pratt.ParserContext;
import bjc.pratt.PrattParser;
import bjc.pratt.commands.CommandResult;
import bjc.pratt.tokens.Token;
import bjc.pratt.tokens.TokenStream;
import bjc.typeclasses.Isomorphism;
import bjc.data.Tree;
import bjc.functypes.*;
import bjc.utils.parserutils.ParserException;
/**
* A {@link ParseBlock} that parses an expression from a 'inner' grammar.
*
* @author bjculkin
*
* @param <K> The key type of the outer tokens.
*
* @param <V> The value type of the outer tokens.
*
* @param <C> The state type of the outer parser.
*
* @param <K2> The key type of the inner tokens.
*
* @param <V2> The value type of the inner tokens.
*
* @param <C2> The state type of the outer parser.
*/
public class GrammarParseBlock<K, V, C, K2, V2, C2> implements ParseBlock<K, V, C> {
private final PrattParser<K2, V2, C2> innr;
private final int prcedence;
private final boolean isStatemnt;
private final Function<TokenStream<K, V>, TokenStream<K2, V2>> tkenTransform;
private final Isomorphism<C, C2> stteTransform;
private final Function<Tree<Token<K2, V2>>, Tree<Token<K, V>>> xpressionTransform;
/**
* Create a new grammar parser block.
*
* @param inner The inner grammar to parse.
* @param precedence The precedence of the expression to parse.
* @param isStatement Is the expression being parsed in statement
* context?
* @param tokenTransform Function to transform to the new token type.
* @param stateTransform Function to toggle between state types.
* @param expressionTransform Function to transform back to the normal token
* type.
*/
public GrammarParseBlock(final PrattParser<K2, V2, C2> inner, final int precedence, final boolean isStatement,
final Function<TokenStream<K, V>, TokenStream<K2, V2>> tokenTransform,
final Isomorphism<C, C2> stateTransform,
final Function<Tree<Token<K2, V2>>, Tree<Token<K, V>>> expressionTransform) {
innr = inner;
prcedence = precedence;
isStatemnt = isStatement;
tkenTransform = tokenTransform;
stteTransform = stateTransform;
xpressionTransform = expressionTransform;
}
@Override
public CommandResult<K, V> parse(final ParserContext<K, V, C> ctx) throws ParserException {
final C2 newState = stteTransform.to(ctx.state);
final TokenStream<K2, V2> newTokens = tkenTransform.apply(ctx.tokens);
final CommandResult<K2, V2> res = innr.parseExpression(prcedence, newTokens, newState, isStatemnt);
switch (res.status) {
case SUCCESS:
break;
case FAIL:
return CommandResult.fail();
case BACKTRACK:
return CommandResult.backtrack();
default:
throw new IllegalStateException("Unhandled status " + res.status);
}
Tree<Token<K2, V2>> expression = res.success();
ctx.state = stteTransform.from(newState);
return CommandResult.success(xpressionTransform.apply(expression));
}
}
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