Add java evaluator

1 files changed, 74 insertions, 0 deletions

diff --git a/java/LCEvaluatorTest.java b/java/LCEvaluatorTest.java
new file mode 100644
index 0000000..ec2f027
--- /dev/null
+++ b/java/LCEvaluatorTest.java
@@ -0,0 +1,74 @@
+package org.lambdanantes.lcgoji;
+
+import org.junit.Test;
+import org.lambdanantes.lcgoji.ast.Term;
+import org.lambdanantes.lcgoji.ast.Var;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.lambdanantes.lcgoji.LCEvaluator.evaluate;
+import static org.lambdanantes.lcgoji.ast.Abs.IDENTITY;
+import static org.lambdanantes.lcgoji.ast.Abs.λ;
+import static org.lambdanantes.lcgoji.ast.App.apply;
+import static org.lambdanantes.lcgoji.ast.Var.var;
+
+public class LCEvaluatorTest {
+
+    Var x = var("x");
+    Var y = var("y");
+    Var z = var("z");
+
+    @Test
+    public void l_evaluation_d_une_variable_rend_la_meme_variable() {
+        // evaluate(x) == x
+        assertEvalTo(x, x);
+    }
+
+    @Test
+    public void l_evaluation_d_une_abstraction_rend_la_meme_abstraction() {
+        // evaluate(λx.x) == λx.x
+        assertEvalTo(IDENTITY, IDENTITY);
+    }
+
+    @Test
+    public void l_evaluation_de_l_application_de_deux_vars_rend_la_meme_application() {
+        // evaluate(x y) == x y
+        assertEvalTo(apply(x, y), apply(x, y));
+    }
+
+    @Test
+    public void l_evaluation_de_l_application_de_l_identite_sur_un_argument_rend_l_argument() {
+        // evaluate((λx.x) y) == y
+        assertEvalTo(apply(IDENTITY, y), y);
+    }
+
+    @Test
+    public void l_evaluation_de_l_application_d_une_abstraction_substitue_son_argument() {
+        // evaluate((λx.x x) y ) == y y
+        assertEvalTo(apply(λ("x", apply(x, x)), y), apply(y, y));
+    }
+
+    @Test
+    public void l_evaluation_de_l_application_d_une_abstraction_d_abstraction_substitue_recursivement_son_argument() {
+        // evaluate((λx.λy.x) z) == λy.z
+        assertEvalTo(apply(λ("x", λ("y", x)), z), λ("y", z));
+    }
+
+    @Test
+    public void l_evaluation_de_l_application_d_une_abstraction_ne_substitue_pas_ses_variables_libres() {
+        // evaluate((λx.y) z) == y
+        assertEvalTo(apply(λ("x", y), z), y);
+    }
+
+    @Test
+    public void l_evaluation_de_l_application_d_une_abstraction_d_abstraction_ne_substitue_pas_les_variables_redefinies() {
+        // evaluate((λx.λx.x) z) == λx.x
+        assertEvalTo(apply(λ("x", λ("x", x)), z), λ("x", x));
+    }
+
+    /////
+
+    private static void assertEvalTo(Term termToEvaluate, Term result) {
+        assertThat(evaluate(termToEvaluate), is(result));
+    }
+}