Update Pratt parser

1 files changed, 61 insertions, 0 deletions

diff --git a/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/blocks/TriggeredParseBlock.java b/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/blocks/TriggeredParseBlock.java
new file mode 100644
index 0000000..fbfc61b
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/blocks/TriggeredParseBlock.java
@@ -0,0 +1,61 @@
+package bjc.utils.parserutils.pratt.blocks;
+
+import java.util.function.UnaryOperator;
+
+import bjc.utils.data.ITree;
+import bjc.utils.parserutils.ParserException;
+import bjc.utils.parserutils.pratt.ParseBlock;
+import bjc.utils.parserutils.pratt.ParserContext;
+import bjc.utils.parserutils.pratt.Token;
+
+/**
+ * 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 UnaryOperator<C>	onEnter;
+	private UnaryOperator<C>	onExit;
+
+	private ParseBlock<K, V, C> source;
+
+	/**
+	 * 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(UnaryOperator<C> onEnter, UnaryOperator<C> onExit, ParseBlock<K, V, C> source) {
+		super();
+		this.onEnter = onEnter;
+		this.onExit = onExit;
+		this.source = source;
+	}
+
+	@Override
+	public ITree<Token<K, V>> parse(ParserContext<K, V, C> ctx) throws ParserException {
+		C newState = onEnter.apply(ctx.state);
+
+		ParserContext<K, V, C> newCtx = new ParserContext<>(ctx.tokens, ctx.parse, newState);
+
+		ITree<Token<K, V>> res = source.parse(newCtx);
+
+		ctx.state = onExit.apply(newState);
+
+		return res;
+	}
+
+}