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package bjc.dicelang.old.ast;
import java.util.Deque;
import java.util.LinkedList;
import java.util.function.Function;
import bjc.dicelang.old.ast.nodes.IDiceASTNode;
import bjc.dicelang.old.ast.nodes.LiteralDiceNode;
import bjc.dicelang.old.ast.nodes.OperatorDiceNode;
import bjc.dicelang.old.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 (LiteralDiceNode.isLiteral(tok)) {
return new LiteralDiceNode(tok);
} else {
return new VariableDiceNode(tok);
}
}
}
/**
* 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;
}
}
}
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