1 files changed, 146 insertions, 0 deletions
diff --git a/dice-lang/src/main/java/bjc/dicelang/old/ast/DiceASTParser.java b/dice-lang/src/main/java/bjc/dicelang/old/ast/DiceASTParser.java
new file mode 100644
index 0000000..d8e13f7
--- /dev/null
+++ b/dice-lang/src/main/java/bjc/dicelang/old/ast/DiceASTParser.java
@@ -0,0 +1,146 @@
+package bjc.dicelang.old.ast;
+
+import java.util.Deque;
+import java.util.LinkedList;
+import java.util.function.Function;
+
+import org.apache.commons.lang3.StringUtils;
+
+import bjc.dicelang.ast.nodes.IDiceASTNode;
+import bjc.dicelang.ast.nodes.LiteralDiceNode;
+import bjc.dicelang.ast.nodes.OperatorDiceNode;
+import bjc.dicelang.ast.nodes.VariableDiceNode;
+import bjc.utils.data.IPair;
+import bjc.utils.data.Pair;
+import bjc.utils.funcdata.FunctionalStringTokenizer;
+import bjc.utils.funcdata.IFunctionalList;
+import bjc.utils.funcutils.ListUtils;
+import bjc.utils.parserutils.AST;
+import bjc.utils.parserutils.ShuntingYard;
+import bjc.utils.parserutils.TreeConstructor;
+
+/**
+ * Create an AST from a string expression
+ * 
+ * @author ben
+ *
+ */
+public class DiceASTParser {
+	private static final class NodeBaker
+			implements Function<String, IDiceASTNode> {
+		@Override
+		public IDiceASTNode apply(String tok) {
+			if (isOperator(tok)) {
+				return OperatorDiceNode.fromString(tok);
+			} else if (NodeBaker.isLiteral(tok)) {
+				return new LiteralDiceNode(tok);
+			} else {
+				return new VariableDiceNode(tok);
+			}
+		}
+
+		/**
+		 * Check if a token represents a literal
+		 * 
+		 * @param tok
+		 *            The token to check
+		 * @return Whether or not the token represents a literal
+		 */
+		private static boolean isLiteral(String tok) {
+			if (StringUtils.countMatches(tok, 'c') == 1
+					&& !tok.equalsIgnoreCase("c")) {
+				return true;
+			} else if (StringUtils.countMatches(tok, 'd') == 1
+					&& !tok.equalsIgnoreCase("d")) {
+				return true;
+			} else {
+				try {
+					Integer.parseInt(tok);
+					return true;
+				} catch (@SuppressWarnings("unused") NumberFormatException nfex) {
+					// We don't care about details
+					return false;
+				}
+			}
+		}
+	}
+
+	/**
+	 * The yard to use for shunting expressions
+	 */
+	private static ShuntingYard<String> yard;
+
+	static {
+		yard = new ShuntingYard<>();
+
+		yard.addOp("d", 5); // dice operator: use for creating variable
+		// size dice groups
+		yard.addOp("c", 6); // compound operator: use for creating compound
+		// dice from expressions
+		yard.addOp(":=", 0); // binding operator: Bind a name to a variable
+		// expression
+	}
+
+	/**
+	 * Build an AST from a string expression
+	 * 
+	 * @param exp
+	 *            The string to build from
+	 * @return An AST built from the passed in string
+	 */
+	public static AST<IDiceASTNode> buildAST(String exp) {
+		IFunctionalList<String> tokens = FunctionalStringTokenizer
+				.fromString(exp).toList();
+
+		Deque<IPair<String, String>> ops = new LinkedList<>();
+
+		ops.add(new Pair<>("+", "\\+"));
+		ops.add(new Pair<>("-", "-"));
+		ops.add(new Pair<>("*", "\\*"));
+		ops.add(new Pair<>("/", "/"));
+		ops.add(new Pair<>(":=", ":="));
+
+		IFunctionalList<String> semiExpandedTokens = ListUtils
+				.splitTokens(tokens, ops);
+
+		ops = new LinkedList<>();
+
+		ops.add(new Pair<>("(", "\\("));
+		ops.add(new Pair<>(")", "\\)"));
+
+		IFunctionalList<String> fullyExpandedTokens = ListUtils
+				.deAffixTokens(semiExpandedTokens, ops);
+
+		IFunctionalList<String> shunted = yard.postfix(fullyExpandedTokens,
+				(s) -> s);
+
+		AST<String> rawAST = TreeConstructor.constructTree(shunted,
+				DiceASTParser::isOperator);
+
+		AST<IDiceASTNode> bakedAST = rawAST.transmuteAST(new NodeBaker());
+
+		return bakedAST;
+	}
+
+	/**
+	 * Check if a token represents an operator
+	 * 
+	 * @param tok
+	 *            The token to check if it represents an operator
+	 * @return Whether or not the token represents an operator
+	 */
+	private static boolean isOperator(String tok) {
+		switch (tok) {
+			case ":=":
+			case "+":
+			case "-":
+			case "*":
+			case "/":
+			case "c":
+			case "d":
+				return true;
+			default:
+				return false;
+		}
+	}
+}