geforkt von Mirrors/FastAsyncWorldEdit
Added while loops to the expression parser.
Also added a test case. Iterations are currently limited to 256 maximum.
Dieser Commit ist enthalten in:
Ursprung
aa43975e34
Commit
f217be0bdf
@ -107,7 +107,7 @@ public class Lexer {
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characterTokens.add(';');
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}
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private static final Set<String> keywords = new HashSet<String>(Arrays.asList("if", "else"));
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private static final Set<String> keywords = new HashSet<String>(Arrays.asList("if", "else", "while", "do"));
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private static final Pattern numberPattern = Pattern.compile("^([0-9]*(?:\\.[0-9]+)?(?:[eE][+-]?[0-9]+)?)");
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private static final Pattern identifierPattern = Pattern.compile("^([A-Za-z][0-9A-Za-z_]*)");
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@ -36,6 +36,7 @@ import com.sk89q.worldedit.expression.runtime.Functions;
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import com.sk89q.worldedit.expression.runtime.RValue;
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import com.sk89q.worldedit.expression.runtime.Sequence;
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import com.sk89q.worldedit.expression.runtime.Variable;
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import com.sk89q.worldedit.expression.runtime.While;
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/**
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* Processes a list of tokens into an executable tree.
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@ -112,7 +113,7 @@ public class Parser {
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case 'k':
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final String keyword = ((KeywordToken) current).value;
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switch (keyword.charAt(0)) {
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case 'i': // if
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case 'i': { // if
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++position;
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final RValue condition = parseBracket();
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final RValue truePart = parseStatements(true);
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@ -128,6 +129,31 @@ public class Parser {
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statements.add(new Conditional(current.getPosition(), condition, truePart, falsePart));
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break;
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}
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case 'w': { // while
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++position;
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final RValue condition = parseBracket();
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final RValue body = parseStatements(true);
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statements.add(new While(current.getPosition(), condition, body, false));
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break;
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}
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case 'd': { // do
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++position;
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final RValue body = parseStatements(true);
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final Token next = peek();
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if (!(next instanceof KeywordToken) || !((KeywordToken) next).value.equals("while")) {
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throw new ParserException(current.getPosition(), "Expected while");
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}
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++position;
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final RValue condition = parseBracket();
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statements.add(new While(current.getPosition(), condition, body, true));
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break;
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}
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default:
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throw new ParserException(current.getPosition(), "Unimplemented keyword '" + keyword + "'");
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@ -30,8 +30,12 @@ public class Conditional extends Node {
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@Override
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public String toString() {
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if (falsePart == null) {
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return "if ("+condition+") { "+truePart+" }";
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} else {
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return "if ("+condition+") { "+truePart+" } else { "+falsePart+" }";
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}
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}
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//TODO: optimizer
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}
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57
src/main/java/com/sk89q/worldedit/expression/runtime/While.java
Normale Datei
57
src/main/java/com/sk89q/worldedit/expression/runtime/While.java
Normale Datei
@ -0,0 +1,57 @@
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package com.sk89q.worldedit.expression.runtime;
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public class While extends Node {
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RValue condition;
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RValue body;
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boolean footChecked;
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public While(int position, RValue condition, RValue body, boolean footChecked) {
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super(position);
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this.condition = condition;
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this.body = body;
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this.footChecked = footChecked;
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}
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@Override
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public double getValue() throws EvaluationException {
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int iterations = 0;
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double ret = 0.0;
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if (footChecked) {
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do {
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ret = body.getValue();
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++iterations;
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if (iterations > 256) {
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throw new EvaluationException(getPosition(), "Loop exceeded 256 iterations.");
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}
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} while (condition.getValue() > 0.0);
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} else {
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while (condition.getValue() > 0.0) {
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ret = body.getValue();
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++iterations;
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if (iterations > 256) {
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throw new EvaluationException(getPosition(), "Loop exceeded 256 iterations.");
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}
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}
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}
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return ret;
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}
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@Override
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public char id() {
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return 't';
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}
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@Override
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public String toString() {
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if (footChecked) {
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return "do { "+body+" } while ("+condition+")";
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} else {
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return "while ("+condition+") { "+body+" }";
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}
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}
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//TODO: optimizer
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}
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@ -84,7 +84,12 @@ public class ExpressionTest {
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final Expression expression2 = Expression.compile("if (0) if (1) x=5; y=4;", "x", "y");
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expression2.evaluate(1, 2);
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assertEquals(4, expression2.getVariable("y").getValue(), 0);
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}
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@Test
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public void testWhile() throws ExpressionException {
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assertEquals(5, simpleEval("c=5; a=0; while (c > 0) { ++a; --c; } a"), 0);
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assertEquals(5, simpleEval("c=5; a=0; do { ++a; --c; } while (c > 0) a"), 0);
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}
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private double simpleEval(String expression) throws ExpressionException {
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