Update Pratt parser

1 files changed, 101 insertions, 0 deletions

diff --git a/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/blocks/SimpleParseBlock.java b/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/blocks/SimpleParseBlock.java
new file mode 100644
index 0000000..c2e9e54
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/blocks/SimpleParseBlock.java
@@ -0,0 +1,101 @@
+package bjc.utils.parserutils.pratt.blocks;
+
+import java.util.function.Predicate;
+
+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;
+
+/**
+ * Simple implementation of {@link ParseBlock}
+ * 
+ * @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 SimpleParseBlock<K, V, C> implements ParseBlock<K, V, C> {
+	private int pow;
+
+	private K term;
+
+	private Predicate<ITree<Token<K, V>>> validatr;
+
+	/**
+	 * Create a new block.
+	 * 
+	 * @param precedence
+	 *                The precedence of this block.
+	 * 
+	 * @param terminator
+	 *                The token type that terminates the block. If this is
+	 *                null, don't check for a terminator.
+	 * 
+	 * @param validator
+	 *                The predicate to apply to blocks.
+	 */
+	public SimpleParseBlock(int precedence, K terminator, Predicate<ITree<Token<K, V>>> validator) {
+		if (precedence < 0) throw new IllegalArgumentException("Precedence must be non-negative");
+
+		pow = precedence;
+		term = terminator;
+		validatr = validator;
+	}
+
+	@Override
+	public ITree<Token<K, V>> parse(ParserContext<K, V, C> ctx) throws ParserException {
+		ITree<Token<K, V>> res = ctx.parse.parseExpression(pow, ctx.tokens, ctx.state, false);
+
+		if (term != null) {
+			ctx.tokens.expect(term);
+		}
+
+		if (validatr == null || validatr.test(res)) {
+			return res;
+		}
+
+		throw new ParserException("Block failed validation");
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+
+		int result = 1;
+
+		result = prime * result + pow;
+		result = prime * result + ((term == null) ? 0 : term.hashCode());
+
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (!(obj instanceof SimpleParseBlock)) return false;
+
+		SimpleParseBlock<?, ?, ?> other = (SimpleParseBlock<?, ?, ?>) obj;
+
+		if (pow != other.pow) return false;
+
+		if (term == null) {
+			if (other.term != null) return false;
+		} else if (!term.equals(other.term)) return false;
+
+		return true;
+	}
+
+	@Override
+	public String toString() {
+		return String.format("ParseBlock [pow=%s, term='%s']", pow, term);
+	}
+}
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