From 41c2a41eaf3c2dd158a2a51947180f402918229e Mon Sep 17 00:00:00 2001
From: bjculkin <bjculkin@mix.wvu.edu>
Date: Fri, 24 Mar 2017 09:54:17 -0400
Subject: Implement Pratt parser.

---
 .../bjc/utils/parserutils/pratt/NullCommands.java  | 115 +++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/NullCommands.java

(limited to 'BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/NullCommands.java')

diff --git a/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/NullCommands.java b/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/NullCommands.java
new file mode 100644
index 0000000..cf57241
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/parserutils/pratt/NullCommands.java
@@ -0,0 +1,115 @@
+package bjc.utils.parserutils.pratt;
+
+import bjc.utils.data.ITree;
+import bjc.utils.data.Tree;
+import bjc.utils.parserutils.ParserException;
+
+/**
+ * * Contains factory methods for producing common implementations of
+ * {@link NullCommand}
+ * 
+ * @author EVE
+ *
+ */
+public class NullCommands {
+	private static abstract class AbstractNullCommand<K, V, C> extends NullCommand<K, V, C> {
+		@Override
+		public ITree<Token<K, V>> nullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
+				throws ParserException {
+			//tokens.next();
+
+			return intNullDenotation(operator, ctx);
+		}
+
+		protected abstract ITree<Token<K, V>> intNullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
+				throws ParserException;
+
+	}
+
+	private static class UnaryCommand<K, V, C> extends AbstractNullCommand<K, V, C> {
+		private final int nullPwer;
+
+		public UnaryCommand(int nullPower) {
+			nullPwer = nullPower;
+		}
+
+		@Override
+		protected ITree<Token<K, V>> intNullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
+				throws ParserException {
+			ITree<Token<K, V>> opr = ctx.parse.parseExpression(nullPwer, ctx.tokens, ctx.state);
+
+			return new Tree<>(operator, opr);
+		}
+	}
+
+	private static class GroupingCommand<K, V, C> extends AbstractNullCommand<K, V, C> {
+		private K		term;
+		private Token<K, V>	mark;
+		private int		inner;
+
+		public GroupingCommand(int innerPrec, K terminator, Token<K, V> marker) {
+			inner = innerPrec;
+			term = terminator;
+			mark = marker;
+		}
+
+		@SuppressWarnings("unchecked")
+		@Override
+		protected ITree<Token<K, V>> intNullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
+				throws ParserException {
+			ITree<Token<K, V>> opr = ctx.parse.parseExpression(inner, ctx.tokens, ctx.state);
+
+			ctx.tokens.expect(term);
+
+			return new Tree<>(mark, opr);
+		}
+	}
+
+	private static class LeafCommand<K, V, C> extends NullCommand<K, V, C> {
+		@Override
+		public ITree<Token<K, V>> nullDenotation(Token<K, V> operator, ParserContext<K, V, C> ctx)
+				throws ParserException {
+
+			return new Tree<>(operator);
+		}
+	}
+
+	/**
+	 * Create a new unary operator.
+	 * 
+	 * @param precedence
+	 *                The precedence of the operator.
+	 * 
+	 * @return A command implementing that operator.
+	 */
+	public static <K, V, C> NullCommand<K, V, C> unary(int precedence) {
+		return new UnaryCommand<>(precedence);
+	}
+
+	/**
+	 * Create a new grouping operator.
+	 * 
+	 * @param precedence
+	 *                The precedence of the expression in the operator.
+	 * 
+	 * @param term
+	 *                The type that closes the group.
+	 * 
+	 * @param mark
+	 *                The token for the AST node of the group.
+	 * 
+	 * @return A command implementing the operator.
+	 */
+	public static <K, V, C> NullCommand<K, V, C> grouping(int precedence, K term, Token<K, V> mark) {
+		return new GroupingCommand<>(precedence, term, mark);
+	}
+
+	/**
+	 * Create a new leaf operator.
+	 * 
+	 * @return A command implementing the operator.
+	 */
+	public static <K, V, C> NullCommand<K, V, C> leaf() {
+		return new LeafCommand<>();
+	}
+}
-- 
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