Implement comparison opcode

We access existing comparison implementations from CPython byte code. This allows us to provide examples of if-else and while loops. We fix a minor bug this revealed in PyUnicode.
jython · jeff5 · Feb 4, 2023 · Jan 6, 2023 · Jan 6, 2023 · Jan 6, 2023
commit 09729baae082ad779dacd6c82bdf5519dc390eb5
diff --git a/core/src/main/java/org/python/core/CPython38Frame.java b/core/src/main/java/org/python/core/CPython38Frame.java
@@ -1,4 +1,4 @@
-// Copyright (c)2022 Jython Developers.
+// Copyright (c)2023 Jython Developers.
 // Licensed to PSF under a contributor agreement.
 package org.python.core;
 
@@ -246,6 +246,15 @@ Object eval() {
                         s[sp - 1] = Abstract.getAttr(s[sp - 1], name);
                         break;
 
+                    case Opcode.COMPARE_OP:
+                        // v | w | -> | op(v,w) |
+                        // -------^sp -----------^sp
+                        w = s[--sp]; // POP
+                        v = s[sp - 1]; // TOP
+                        s[sp - 1] = Comparison.from(opword & 0xff).apply(v, w);
+                        oparg = 0;
+                        break;
+
                     case Opcode.JUMP_FORWARD:
                         ip += (oparg | opword & 0xff) >> 1;
                         oparg = 0;

diff --git a/core/src/main/java/org/python/core/Comparison.java b/core/src/main/java/org/python/core/Comparison.java
@@ -1,4 +1,4 @@
-// Copyright (c)2021 Jython Developers.
+// Copyright (c)2023 Jython Developers.
 // Licensed to PSF under a contributor agreement.
 package org.python.core;
 
@@ -61,39 +61,48 @@ enum Comparison {
         boolean toBool(int c) { return c >= 0; }
     },
 
-    /** The (reflected) {@code __contains__} operation. */
+    /**
+     * The {@code in} operation (reflected {@code __contains__}). Note
+     * that "{@code v in seq}" compiles to<pre>
+     *    LOAD_NAME    0 (v)
+     *    LOAD_NAME    1 (seq)
+     *    COMPARE_OP   6 (in)
+     * </pre> which must lead to {@code seq.__contains__(v)}.
+     */
     IN("in", Slot.op_contains) {
 
         @Override
         boolean toBool(int c) { return c >= 0; }
 
         @Override
-        Object apply(Object v, Object w) throws Throwable {
-            Operations vOps = Operations.of(v);
+        Object apply(Object v, Object seq) throws Throwable {
+            Operations ops = Operations.of(seq);
             try {
-                MethodHandle contains = slot.getSlot(vOps);
-                return (boolean)contains.invokeExact(w, v);
+                MethodHandle contains = slot.getSlot(ops);
+                return (boolean)contains.invokeExact(seq, v);
             } catch (Slot.EmptyException e) {
-                throw new TypeError(NOT_CONTAINER, vOps.type(v).name);
+                throw new TypeError(NOT_CONTAINER, ops.type(seq).name);
             }
         }
     },
 
-    /** The inverted (reflected) {@code __contains__} operation. */
+    /**
+     * The inverted {@code in} operation (reflected
+     * {@code __contains__}).
+     */
     NOT_IN("not in", Slot.op_contains) {
 
         @Override
         boolean toBool(int c) { return c < 0; }
 
         @Override
-        Object apply(Object v, Object w) throws Throwable {
-            Operations vOps = Operations.of(v);
-            ;
+        Object apply(Object v, Object seq) throws Throwable {
+            Operations ops = Operations.of(seq);
             try {
-                MethodHandle contains = slot.getSlot(vOps);
-                return (boolean)contains.invokeExact(w, v);
+                MethodHandle contains = slot.getSlot(ops);
+                return !(boolean)contains.invokeExact(seq, v);
             } catch (Slot.EmptyException e) {
-                throw new TypeError(NOT_CONTAINER, vOps.type(v).name);
+                throw new TypeError(NOT_CONTAINER, ops.type(seq).name);
             }
         }
     },
@@ -161,7 +170,7 @@ Object apply(Object v, Object w) throws Throwable {
     public String toString() { return text; }
 
     /**
-     * Translate CPython {@code Opcode.COMPARE_OP} opcode argument to
+     * Translate CPython {@link Opcode#COMPARE_OP} opcode argument to
      * Comparison constant.
      *
      * @param oparg opcode argument

diff --git a/core/src/main/java/org/python/core/PyUnicode.java b/core/src/main/java/org/python/core/PyUnicode.java
@@ -1,4 +1,4 @@
-// Copyright (c)2021 Jython Developers.
+// Copyright (c)2023 Jython Developers.
 // Licensed to PSF under a contributor agreement.
 package org.python.core;
 
@@ -409,14 +409,17 @@ private static boolean __contains__(String self, Object o) {
 
     private static boolean contains(CodepointDelegate s, Object o) {
         try {
-            CodepointDelegate p = adapt(s);
+            CodepointDelegate p = adapt(o);
             PySlice.Indices slice = getSliceIndices(s, null, null);
             return find(s, p, slice) >= 0;
         } catch (NoConversion nc) {
-            throw Abstract.requiredTypeError("a string", o);
+            throw Abstract.typeError(IN_STRING_TYPE, o);
         }
     }
 
+    private static final String IN_STRING_TYPE =
+            "'in <string>' requires string as left operand, not %s";
+
     /*
     @ExposedMethod(type = MethodType.BINARY, doc = BuiltinDocs.unicode___add___doc)
     */
@@ -2730,7 +2733,7 @@ static final Object __format__(Object self, Object formatSpec) {
      * object to format and output. If {@code field_name} is not
      * {@code None}, it is looked up, formatted with {@code format_spec}
      * and {@code conversion} and then used.
-     * 
+     *
      * @param formatString to parse
      * @return an iterator of format {@code tuple}s
      */
@@ -2745,7 +2748,7 @@ static Object formatter_parser(Object formatString) {
 
     /**
      * Implementation of {@code _string.formatter_field_name_split}.
-     * 
+     *
      * @param fieldName to split into components
      * @return a tuple of the first field name component and the rest
      */
@@ -4476,7 +4479,7 @@ public double atof() {
      */
     @Deprecated // See _PyUnicode_TransformDecimalAndSpaceToASCII
     private String encodeDecimal() {
-        
+
         // XXX This all has a has a Jython 2 smell: bytes/str confusion.
         // XXX Also, String and PyUnicode implementations are needed.
         // XXX Follow CPython _PyUnicode_TransformDecimalAndSpaceToASCII
@@ -4910,7 +4913,7 @@ public static PyLong atol(String self, int base) {
      * @param value the format string when {@code enclosingIterator} is not null
      * @return the formatted string based on the arguments
      * @throws TypeError if {@code __repr__} or {@code __str__} conversions returned a non-string.
-     * @throws Throwable from other errors in 
+     * @throws Throwable from other errors in {@code __repr__} or {@code __str__}
      */
     // XXX make this support format(String) too
     private String buildFormattedString(Object[] args, String[] keywords,

diff --git a/core/src/test/java/org/python/core/CPython38CodeTest.java b/core/src/test/java/org/python/core/CPython38CodeTest.java
@@ -126,7 +126,7 @@ void co_consts() {
     @DisplayName("We can execute simple ...")
     @ParameterizedTest(name = "{0}.py")
     @ValueSource(strings = {"load_store_name", "unary_op", "binary_op", "bool_left_arith",
-            "bool_right_arith", "tuple_index", "list_index", "call_method_builtin"})
+            "bool_right_arith", "comparison", "tuple_index", "list_index", "call_method_builtin"})
     void executeSimple(String name) {
         CPython38Code code = readCode(name);
         PyDict globals = new PyDict();
@@ -140,9 +140,10 @@ void executeSimple(String name) {
      * @param name of the Python example
      */
     @SuppressWarnings("static-method")
-    @DisplayName("We can execute branches ...")
+    @DisplayName("We can execute branches and while loops ...")
     @ParameterizedTest(name = "{0}.py")
-    @ValueSource(strings = {"simple_if", "multi_if"})
+    @ValueSource(strings = {"simple_if", "multi_if", "simple_loop", "tuple_dot_product",
+            "list_dot_product"})
     void executeBranchAndLoop(String name) {
         CPython38Code code = readCode(name);
         PyDict globals = new PyDict();

diff --git a/core/src/test/java/org/python/core/PyListTest.java b/core/src/test/java/org/python/core/PyListTest.java
@@ -1,3 +1,5 @@
+// Copyright (c)2023 Jython Developers.
+// Licensed to PSF under a contributor agreement.
 package org.python.core;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -159,7 +161,7 @@ private static Arguments sortExample(List<Object> sorted, long seed,
 
         /**
          * A toString that limits the array size
-         * 
+         *
          * @param a the array to return as a string
          * @param n maximum number of array elements to show
          * @return string representation of {@code a}
@@ -176,7 +178,7 @@ private static String shortString(ArrayList<Object> a, int n) {
 
     /**
      * Randomise the order of elements in a list.
-     * 
+     *
      * @param m to randomise
      * @param r random generator
      */

diff --git a/core/src/test/pythonExample/comparison.py b/core/src/test/pythonExample/comparison.py
@@ -0,0 +1,55 @@
+# comparison.py
+
+# Tests of the order comparisons
+
+a = 2
+b = 4
+
+lt = a < b
+le = a <= b
+eq = a == b
+ne = a != b
+ge = a >= b
+gt = a > b
+
+
+a = 4
+b = 2
+
+lt1 = a < b
+le1 = a <= b
+eq1 = a == b
+ne1 = a != b
+ge1 = a >= b
+gt1 = a > b
+
+
+a = 2
+b = 2
+
+lt2 = a < b
+le2 = a <= b
+eq2 = a == b
+ne2 = a != b
+ge2 = a >= b
+gt2 = a > b
+
+# Tests of 'in'
+
+t = ("cow", 2, "pig", None, 42.0)
+f0 = 1 in t
+f1 = "c" in t
+t1x = "c" not in t
+f2 = 42.1 in t
+f3 = (2,) in t
+f4 = "c" in t[2]
+
+
+t0 = 2 in t
+t1 = "pig" in t
+f1x = "pig" not in t
+t2 = None in t
+t3 = 42 in t
+t4 = "p" in t[2]
+
+
diff --git a/core/src/test/pythonExample/list_dot_product.py b/core/src/test/pythonExample/list_dot_product.py
@@ -0,0 +1,17 @@
+# list_dot_product.py
+
+# Multiply-add of float vectors (without for loops)
+# Also, multiplication as repetition.
+
+n = 2
+
+a = [1.2, 3.4, 5.6, 7.8] * (3 * n)
+b = (4 * n) * [1.2, 4.5, 7.8]
+n = 12 * n  # lists are this long
+
+i = 0
+sum = 0.0
+
+while i < n:
+    sum = sum + a[i] * b[i]
+    i = i + 1
diff --git a/core/src/test/pythonExample/simple_loop.py b/core/src/test/pythonExample/simple_loop.py
@@ -0,0 +1,10 @@
+# simple_loop.py
+
+n = 6
+
+# ? n, sum
+sum = 0
+while n > 0:
+    sum = sum + n
+    n = n - 1
+
diff --git a/core/src/test/pythonExample/tuple_dot_product.py b/core/src/test/pythonExample/tuple_dot_product.py
@@ -0,0 +1,25 @@
+# tuple_dot_product.py
+
+# Multiply-add of int and float vectors (without for loops)
+
+a = (2, 3, 4)
+b = (3, 4, 6)
+n = 3
+
+# ? sum
+
+sum = a[0] * b[0]
+i = 1
+while i < n:
+    sum = sum + a[i] * b[i]
+    i = i + 1
+
+a= (1., 2., 3., 4.)
+b = (4., 3., 4., 5.)
+n = 4
+
+sum2 = a[0] * b[0]
+i = 1
+while i < n:
+    sum2 = sum2 + a[i] * b[i]
+    i = i + 1