feat(interpreter): support array access expressions

unnamed · Dec 27, 2023 · 8a8b1c2 · 8a8b1c2
1 parent 5893f92
commit 8a8b1c2
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diff --git a/src/main/java/team/unnamed/mocha/runtime/ExpressionEvaluatorImpl.java b/src/main/java/team/unnamed/mocha/runtime/ExpressionEvaluatorImpl.java
@@ -188,6 +188,19 @@ public T entity() {
         return val;
     }
 
+    @Override
+    public @NotNull Value visitArrayAccess(final @NotNull ArrayAccessExpression expression) {
+        final Value array = expression.array().visit(this);
+        final Value index = expression.index().visit(this);
+        if (!(array instanceof ArrayValue)) {
+            return Value.nil();
+        } else {
+            final Value[] values = ((ArrayValue) array).values();
+            final int validIndex = Math.max(0, (int) index.getAsNumber()) % values.length;
+            return values[validIndex];
+        }
+    }
+
     @Override
     public @NotNull Value visitAccess(final @NotNull AccessExpression expression) {
         final Value objectValue = expression.object().visit(this);

diff --git a/src/test/java/team/unnamed/mocha/MochaAssertions.java b/src/test/java/team/unnamed/mocha/MochaAssertions.java
@@ -6,6 +6,7 @@
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.UnaryOperator;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.fail;
@@ -56,4 +57,15 @@ public static void assertParseError(final @NotNull String expr, final int column
             assertEquals(column, e.cursor().column(), "Expected parse error at column " + column + " for expression: '" + expr + "'");
         }
     }
+
+    public static void assertEvaluates(final double expected, final @NotNull String expr, final @NotNull UnaryOperator<MochaEngine<?>> configurer) {
+        MochaEngine<?> engine = MochaEngine.createStandard();
+        engine = configurer.apply(engine);
+        final double result = engine.eval(expr);
+        assertEquals(expected, result, 0.0001, () -> "Expression: '" + expr + "' evaluated to " + result + ", expected " + expected);
+    }
+
+    public static void assertEvaluates(final double expected, final @NotNull String expr) {
+        assertEvaluates(expected, expr, engine -> engine);
+    }
 }
diff --git a/src/test/java/team/unnamed/mocha/runtime/ArrayAccessRuntimeTest.java b/src/test/java/team/unnamed/mocha/runtime/ArrayAccessRuntimeTest.java
@@ -0,0 +1,34 @@
+package team.unnamed.mocha.runtime;
+
+import org.junit.jupiter.api.Test;
+import team.unnamed.mocha.MochaEngine;
+import team.unnamed.mocha.runtime.value.ArrayValue;
+import team.unnamed.mocha.runtime.value.NumberValue;
+
+import java.util.function.UnaryOperator;
+
+import static team.unnamed.mocha.MochaAssertions.assertEvaluates;
+
+class ArrayAccessRuntimeTest {
+    @Test
+    void test() {
+        final UnaryOperator<MochaEngine<?>> configurer = engine -> {
+            engine.scope().query().set("values", ArrayValue.of(
+                    NumberValue.of(5D),
+                    NumberValue.of(10D),
+                    NumberValue.of(100D)
+            ));
+            return engine;
+        };
+
+        assertEvaluates(5D, "query.values[0]", configurer);
+        assertEvaluates(10D, "query.values[1]", configurer);
+        assertEvaluates(100D, "query.values[2]", configurer);
+        assertEvaluates(100D, "q.values[20 + 3]", configurer);
+        assertEvaluates(5D, "query.values[-1]", configurer);
+        assertEvaluates(5D, "q.values[-1000]", configurer);
+        assertEvaluates(5D, "q.values[0.5]", configurer);
+        assertEvaluates(10D, "q.values[0.5 + 0.5]", configurer);
+        assertEvaluates(100D, "q.values[math.pi - 1]", configurer);
+    }
+}