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package bjc.dicelang.ast;
import bjc.dicelang.ComplexDice;
import bjc.dicelang.ast.nodes.DiceASTType;
import bjc.dicelang.ast.nodes.DiceLiteralNode;
import bjc.dicelang.ast.nodes.DiceLiteralType;
import bjc.dicelang.ast.nodes.IDiceASTNode;
import bjc.dicelang.ast.nodes.ILiteralDiceNode;
import bjc.dicelang.ast.nodes.IntegerLiteralNode;
import bjc.dicelang.ast.nodes.OperatorDiceNode;
import bjc.dicelang.ast.nodes.VariableDiceNode;
import bjc.utils.data.IPair;
import bjc.utils.data.LazyPair;
import bjc.utils.data.Pair;
import bjc.utils.funcdata.FunctionalMap;
import bjc.utils.funcdata.IFunctionalList;
import bjc.utils.funcdata.IFunctionalMap;
import bjc.utils.funcdata.ITree;
import bjc.utils.funcdata.Tree;
/**
* Evaluate a dice AST to an integer value
*
* @author ben
*
*/
public class DiceASTEvaluator {
/**
* Build the map of operations to use when collapsing the AST
*
* @param enviroment
* The enviroment to evaluate bindings and such against
* @return The operations to use when collapsing the AST
*/
private static IFunctionalMap<IDiceASTNode, IOperatorCollapser>
buildOperations(
IFunctionalMap<String, ITree<IDiceASTNode>> enviroment) {
IFunctionalMap<IDiceASTNode, IOperatorCollapser> operatorCollapsers =
new FunctionalMap<>();
operatorCollapsers.put(OperatorDiceNode.ADD,
new ArithmeticCollapser(OperatorDiceNode.ADD,
(left, right) -> left + right));
operatorCollapsers.put(OperatorDiceNode.SUBTRACT,
new ArithmeticCollapser(OperatorDiceNode.SUBTRACT,
(left, right) -> left - right));
operatorCollapsers.put(OperatorDiceNode.MULTIPLY,
new ArithmeticCollapser(OperatorDiceNode.MULTIPLY,
(left, right) -> left * right));
operatorCollapsers.put(OperatorDiceNode.DIVIDE,
new ArithmeticCollapser(OperatorDiceNode.DIVIDE,
(left, right) -> left / right));
operatorCollapsers.put(OperatorDiceNode.ASSIGN, (nodes) -> {
return parseBinding(enviroment, nodes);
});
operatorCollapsers.put(OperatorDiceNode.COMPOUND,
DiceASTEvaluator::parseCompound);
operatorCollapsers.put(OperatorDiceNode.GROUP,
DiceASTEvaluator::parseGroup);
return operatorCollapsers;
}
/**
* Evaluate the provided AST to a numeric value
*
* @param expression
* The expression to evaluate
* @param enviroment
* The enviroment to look up variables in
* @return The integer value of the expression
*/
public static int evaluateAST(ITree<IDiceASTNode> expression,
IFunctionalMap<String, ITree<IDiceASTNode>> enviroment) {
IFunctionalMap<IDiceASTNode, IOperatorCollapser> collapsers =
buildOperations(enviroment);
return expression.collapse(
(node) -> evaluateLeaf(node, enviroment), collapsers::get,
(pair) -> pair.getLeft());
}
private static IPair<Integer, ITree<IDiceASTNode>> evaluateLeaf(
IDiceASTNode leafNode,
IFunctionalMap<String, ITree<IDiceASTNode>> enviroment) {
ITree<IDiceASTNode> returnedAST = new Tree<>(leafNode);
switch (leafNode.getType()) {
case LITERAL:
return new Pair<>(evaluateLiteral(leafNode), returnedAST);
case VARIABLE:
return new LazyPair<>(() -> {
return bindLiteralValue(leafNode, enviroment);
}, () -> returnedAST);
case OPERATOR:
default:
throw new UnsupportedOperationException(
"Node '" + leafNode + "' cannot be a leaf.");
}
}
private static Integer bindLiteralValue(IDiceASTNode leafNode,
IFunctionalMap<String, ITree<IDiceASTNode>> enviroment) {
String variableName = ((VariableDiceNode) leafNode).getVariable();
if (enviroment.containsKey(variableName)) {
int result =
evaluateAST(enviroment.get(variableName), enviroment);
return result;
}
// Value to allow for assignments
return 0;
}
private static int evaluateLiteral(IDiceASTNode leafNode) {
DiceLiteralType literalType =
((ILiteralDiceNode) leafNode).getLiteralType();
switch (literalType) {
case DICE:
return ((DiceLiteralNode) leafNode).getValue();
case INTEGER:
return ((IntegerLiteralNode) leafNode).getValue();
default:
throw new UnsupportedOperationException("Literal value '"
+ leafNode + "' is of a type (" + literalType
+ ") not currently supported.");
}
}
private static IPair<Integer, ITree<IDiceASTNode>> parseBinding(
IFunctionalMap<String, ITree<IDiceASTNode>> enviroment,
IFunctionalList<IPair<Integer, ITree<IDiceASTNode>>> nodes) {
if (nodes.getSize() != 2) {
throw new UnsupportedOperationException(
"Can only bind nodes with two children. Problem children are "
+ nodes);
}
IPair<Integer, ITree<IDiceASTNode>> nameNode = nodes.getByIndex(0);
IPair<Integer, ITree<IDiceASTNode>> valueNode =
nodes.getByIndex(1);
// Force valueNode to materialize for debugging purposes
valueNode.merge((l, r) -> null);
return nameNode.bindRight((nameTree) -> {
return valueNode.bind((valueValue, valueTree) -> {
if (containsSimpleVariable(nameTree)) {
String varName = nameTree.transformHead((nameNod) -> {
return ((VariableDiceNode) nameNod).getVariable();
});
enviroment.put(varName, valueTree);
return new Pair<>(valueValue, nameTree);
}
throw new IllegalStateException(
"Statement that shouldn't be hit was hit.");
});
});
}
private static boolean
containsSimpleVariable(ITree<IDiceASTNode> nameTree) {
return nameTree.transformHead((nameNod) -> {
if (nameNod.getType() != DiceASTType.VARIABLE) {
throw new UnsupportedOperationException(
"Assigning to complex variables isn't supported. Problem node is "
+ nameNod);
}
return true;
});
}
private static IPair<Integer, ITree<IDiceASTNode>> parseCompound(
IFunctionalList<IPair<Integer, ITree<IDiceASTNode>>> nodes) {
if (nodes.getSize() != 2) {
throw new UnsupportedOperationException(
"Can only form a group from two dice");
}
IPair<Integer, ITree<IDiceASTNode>> leftDiceNode =
nodes.getByIndex(0);
IPair<Integer, ITree<IDiceASTNode>> rightDiceNode =
nodes.getByIndex(1);
return leftDiceNode.bind((leftDiceValue, leftDiceTree) -> {
return rightDiceNode.bind((rightDiceValue, rightDiceTree) -> {
Integer result =
Integer.parseInt(Integer.toString(leftDiceValue)
+ Integer.toString(rightDiceValue));
return new Pair<>(result,
new Tree<>(OperatorDiceNode.GROUP, leftDiceTree,
rightDiceTree));
});
});
}
private static IPair<Integer, ITree<IDiceASTNode>> parseGroup(
IFunctionalList<IPair<Integer, ITree<IDiceASTNode>>> nodes) {
if (nodes.getSize() != 2) {
throw new UnsupportedOperationException(
"Can only form a group from two dice");
}
IPair<Integer, ITree<IDiceASTNode>> numberDiceNode =
nodes.getByIndex(0);
IPair<Integer, ITree<IDiceASTNode>> diceTypeNode =
nodes.getByIndex(1);
return numberDiceNode.bind((numberDiceValue, numberDiceTree) -> {
return diceTypeNode.bind((diceTypeValue, diceTypeTree) -> {
ComplexDice cDice =
new ComplexDice(numberDiceValue, diceTypeValue);
return new Pair<>(cDice.roll(),
new Tree<>(OperatorDiceNode.GROUP, numberDiceTree,
diceTypeTree));
});
});
}
}
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