1 files changed, 195 insertions, 0 deletions
diff --git a/dice-lang/src/bjc/utils/dice/ast/DiceASTExpression.java b/dice-lang/src/bjc/utils/dice/ast/DiceASTExpression.java
new file mode 100644
index 0000000..89adb65
--- /dev/null
+++ b/dice-lang/src/bjc/utils/dice/ast/DiceASTExpression.java
@@ -0,0 +1,195 @@
+package bjc.utils.dice.ast;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.BinaryOperator;
+
+import org.apache.commons.lang3.StringUtils;
+
+import bjc.utils.data.Pair;
+import bjc.utils.dice.ComplexDice;
+import bjc.utils.dice.CompoundDice;
+import bjc.utils.dice.IDiceExpression;
+import bjc.utils.parserutils.AST;
+
+/**
+ * An implementation of {@link IDiceExpression} backed by an AST of
+ * {@link IDiceASTNode}s
+ * 
+ * @author ben
+ *
+ */
+public class DiceASTExpression implements IDiceExpression {
+
+	/**
+	 * Build the map of operations to use when collapsing the AST
+	 * 
+	 * @param env
+	 *            The enviroment to evaluate bindings and such against
+	 * @return The operations to use when collapsing the AST
+	 */
+	private static
+			Map<IDiceASTNode, BinaryOperator<Pair<Integer, AST<IDiceASTNode>>>>
+			buildOperations(Map<String, DiceASTExpression> env) {
+		Map<IDiceASTNode, BinaryOperator<Pair<Integer, AST<IDiceASTNode>>>> opCollapsers =
+				new HashMap<>();
+
+		opCollapsers.put(OperatorDiceNode.ADD, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+				return new Pair<>(lval + rval,
+						new AST<>(OperatorDiceNode.ADD, last, rast));
+			}));
+
+		});
+		opCollapsers.put(OperatorDiceNode.SUBTRACT, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+				return new Pair<>(lval - rval,
+						new AST<>(OperatorDiceNode.SUBTRACT, last, rast));
+			}));
+
+		});
+		opCollapsers.put(OperatorDiceNode.MULTIPLY, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+				return new Pair<>(lval * rval,
+						new AST<>(OperatorDiceNode.MULTIPLY, last, rast));
+			}));
+
+		});
+		opCollapsers.put(OperatorDiceNode.DIVIDE, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+				return new Pair<>(lval / rval,
+						new AST<>(OperatorDiceNode.DIVIDE, last, rast));
+			}));
+		});
+
+		opCollapsers.put(OperatorDiceNode.ASSIGN, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+				String nam = last.collapse((nod) -> {
+					return ((VariableDiceNode) nod).getVariable();
+				} , (v) -> (lv, rv) -> null, (r) -> r);
+
+				env.put(nam, new DiceASTExpression(rast, env));
+
+				return new Pair<>(rval,
+						new AST<>(OperatorDiceNode.ASSIGN, last, rast));
+			}));
+		});
+
+		opCollapsers.put(OperatorDiceNode.COMPOUND, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+				int ival = Integer.parseInt(
+						Integer.toString(lval) + Integer.toString(rval));
+
+				return new Pair<>(ival,
+						new AST<>(OperatorDiceNode.COMPOUND, last, rast));
+			}));
+		});
+		opCollapsers.put(OperatorDiceNode.GROUP, (left, right) -> {
+			return left.merge((lval, last) -> right.merge((rval, rast) -> {
+
+				return new Pair<>(new ComplexDice(lval, rval).roll(),
+						new AST<>(OperatorDiceNode.GROUP, last, rast));
+			}));
+		});
+
+		return opCollapsers;
+	}
+
+	/**
+	 * The AST this expression will evaluate
+	 */
+	private AST<IDiceASTNode>				ast;
+
+	/**
+	 * The enviroment to evaluate bindings and such against
+	 */
+	private Map<String, DiceASTExpression>	env;
+
+	/**
+	 * Create a new dice expression backed by an AST
+	 * 
+	 * @param ast
+	 *            The AST backing this expression
+	 * @param env
+	 *            The enviroment to evaluate bindings against
+	 */
+	public DiceASTExpression(AST<IDiceASTNode> ast,
+			Map<String, DiceASTExpression> env) {
+		this.ast = ast;
+		this.env = env;
+	}
+
+	/**
+	 * Expand a leaf AST token into a pair for evaluation
+	 * 
+	 * @param tokn
+	 *            The token to evaluate
+	 * @return A pair consisting of the token's value and the AST it
+	 *         represents
+	 */
+	private Pair<Integer, AST<IDiceASTNode>> evalLeaf(IDiceASTNode tokn) {
+		if (tokn instanceof VariableDiceNode) {
+			String varName = ((VariableDiceNode) tokn).getVariable();
+
+			if (env.containsKey(varName)) {
+				return new Pair<>(env.get(varName).roll(),
+						new AST<>(tokn));
+			} else {
+				// Handle special case for defining variables
+				return new Pair<>(0, new AST<>(tokn));
+			}
+		} else {
+			LiteralDiceNode lnod = (LiteralDiceNode) tokn;
+			String dat = lnod.getData();
+
+			if (StringUtils.countMatches(dat, 'c') == 1
+					&& !dat.equalsIgnoreCase("c")) {
+				String[] strangs = dat.split("c");
+				return new Pair<>(new CompoundDice(strangs).roll(),
+						new AST<>(tokn));
+			} else if (StringUtils.countMatches(dat, 'd') == 1
+					&& !dat.equalsIgnoreCase("d")) {
+				/*
+				 * Handle dice groups
+				 */
+				return new Pair<>(ComplexDice.fromString(dat).roll(),
+						new AST<>(tokn));
+			} else {
+				return new Pair<>(Integer.parseInt(dat), new AST<>(tokn));
+			}
+		}
+	}
+
+	/**
+	 * Get the AST bound to this expression
+	 * 
+	 * @return the ast
+	 */
+	public AST<IDiceASTNode> getAst() {
+		return ast;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see bjc.utils.dice.IDiceExpression#roll()
+	 */
+	@Override
+	public int roll() {
+		Map<IDiceASTNode, BinaryOperator<Pair<Integer, AST<IDiceASTNode>>>> operations =
+				buildOperations(env);
+
+		return ast.collapse(this::evalLeaf, operations::get,
+				(r) -> r.merge((left, right) -> left));
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return ast.toString();
+	}
+}