1 files changed, 92 insertions, 0 deletions
diff --git a/JPratt/src/main/java/com/ashardalon/pratt/blocks/GrammarParseBlock.java b/JPratt/src/main/java/com/ashardalon/pratt/blocks/GrammarParseBlock.java
new file mode 100644
index 0000000..048e9f6
--- /dev/null
+++ b/JPratt/src/main/java/com/ashardalon/pratt/blocks/GrammarParseBlock.java
@@ -0,0 +1,92 @@
+package com.ashardalon.pratt.blocks;
+
+import java.util.function.Function;
+
+import com.ashardalon.pratt.ParserContext;
+import com.ashardalon.pratt.PrattParser;
+import com.ashardalon.pratt.commands.CommandResult;
+import com.ashardalon.pratt.tokens.Token;
+import com.ashardalon.pratt.tokens.TokenStream;
+
+import bjc.data.Tree;
+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));
+	}
+}
+\ No newline at end of file