Merge pull request #422 from MikeBeller/compare

Implement polymorphic compare

src/boot/boot.janet

@@ -667,6 +667,66 @@
   [xs]
   (get xs (- (length xs) 1)))
 
+## Polymorphic comparisons
+
+(defn compare-primitive
+  "Compare x and y using primitive operators.
+   Returns -1,0,1 for x < y, x = y, x > y respectively.
+   Present mostly for constructing 'compare' methods in prototypes."
+  [x y]
+  (cond
+    (= x y) 0
+    (< x y) -1
+    (> x y) 1))
+
+(defn compare
+  "Polymorphic compare.  Returns -1,0,1 for x < y, x = y, x > y respectively.
+   Differs from the primitive comparators in that it first checks to
+   see whether either x or y implement a 'compare' method which can
+   compare x and y.  If so it uses that compare method.  If not, it
+   delegates to the primitive comparators."
+  [x y]
+  (or
+    (when-let [f (get x :compare)] (f x y))
+    (when-let [f (get y :compare)
+               fyx (f y x)] (- fyx))
+    (compare-primitive x y)))
+
+(defn compare-reduce- [op xs]
+  (var r true)
+  (loop [i :range [0 (- (length xs) 1)]
+         :let [c (compare (xs i) (xs (+ i 1)))
+               ok (op c 0)]
+         :when (not ok)]
+    (set r false)
+    (break))
+  r)
+
+(defn compare=
+  "Equivalent of '=' but using compare function instead of primitive comparator"
+  [& xs]
+  (compare-reduce- = xs))
+
+(defn compare<
+  "Equivalent of '<' but using compare function instead of primitive comparator"
+  [& xs]
+  (compare-reduce- < xs))
+
+(defn compare<=
+  "Equivalent of '<=' but using compare function instead of primitive comparator"
+  [& xs]
+  (compare-reduce- <= xs))
+
+(defn compare>
+  "Equivalent of '>' but using compare function instead of primitive comparator"
+  [& xs]
+  (compare-reduce- > xs))
+
+(defn compare>=
+  "Equivalent of '>=' but using compare function instead of primitive comparator"
+  [& xs]
+  (compare-reduce- >= xs))
+
 ###
 ###
 ### Indexed Combinators

src/core/inttypes.c

@@ -197,6 +197,122 @@ static Janet cfun_it_u64_new(int32_t argc, Janet *argv) {
     return janet_wrap_u64(janet_unwrap_u64(argv[0]));
 }
 
+// Code to support polymorphic comparison.
+//
+// int/u64 and int/s64 support a "compare" method that allows
+// comparison to each other, and to Janet numbers, using the
+// "compare" "compare<" ... functions.
+//
+// In the following code explicit casts are sometimes used to help
+// make it clear when int/float conversions are happening.
+//
+static int64_t compare_double_double(double x, double y) {
+    return (x < y) ? -1 : ((x > y) ? 1 : 0);
+}
+
+static int64_t compare_int64_double(int64_t x, double y) {
+    if (isnan(y)) {
+        return 0; // clojure and python do this
+    } else if ((y > ((double) -MAX_INT_IN_DBL)) && (y < ((double) MAX_INT_IN_DBL))) {
+        double dx = (double) x;
+        return compare_double_double(dx, y);
+    } else if (y > ((double) INT64_MAX)) {
+        return -1;
+    } else if (y < ((double) INT64_MIN)) {
+        return 1;
+    } else {
+        int64_t yi = (int64_t) y;
+        return (x < yi) ? -1 : ((x > yi) ? 1 : 0);
+    }
+}
+
+static int64_t compare_uint64_double(uint64_t x, double y) {
+    if (isnan(y)) {
+        return 0; // clojure and python do this
+    } else if (y < 0) {
+        return 1;
+    } else if ((y >= 0) && (y < ((double) MAX_INT_IN_DBL))) {
+        double dx = (double) x;
+        return compare_double_double(dx, y);
+    } else if (y > ((double) UINT64_MAX)) {
+        return -1;
+    } else {
+        uint64_t yi = (uint64_t) y;
+        return (x < yi) ? -1 : ((x > yi) ? 1 : 0);
+    }
+}
+
+
+static Janet cfun_it_s64_compare(int32_t argc, Janet *argv) {
+    janet_fixarity(argc, 2);
+    if (janet_is_int(argv[0]) != JANET_INT_S64)
+        janet_panic("compare method requires int/s64 as first argument");
+    int64_t x = janet_unwrap_s64(argv[0]);
+    switch (janet_type(argv[1])) {
+        default:
+            break;
+        case JANET_NUMBER : {
+            double y = janet_unwrap_number(argv[1]);
+            return janet_wrap_number(compare_int64_double(x, y));
+        }
+        case JANET_ABSTRACT: {
+            void *abst = janet_unwrap_abstract(argv[1]);
+            if (janet_abstract_type(abst) == &janet_s64_type) {
+                int64_t y = *(int64_t *)abst;
+                return janet_wrap_number((x < y) ? -1 : (x > y ? 1 : 0));
+            } else if (janet_abstract_type(abst) == &janet_u64_type) {
+                // comparing signed to unsigned -- be careful!
+                uint64_t y = *(uint64_t *)abst;
+                if (x < 0) {
+                    return janet_wrap_number(-1);
+                } else if (y > INT64_MAX) {
+                    return janet_wrap_number(-1);
+                } else {
+                    int64_t y2 = (int64_t) y;
+                    return janet_wrap_number((x < y2) ? -1 : (x > y2 ? 1 : 0));
+                }
+            }
+            break;
+        }
+    }
+    return janet_wrap_nil();
+}
+
+static Janet cfun_it_u64_compare(int32_t argc, Janet *argv) {
+    janet_fixarity(argc, 2);
+    if (janet_is_int(argv[0]) != JANET_INT_U64)  // is this needed?
+        janet_panic("compare method requires int/u64 as first argument");
+    uint64_t x = janet_unwrap_u64(argv[0]);
+    switch (janet_type(argv[1])) {
+        default:
+            break;
+        case JANET_NUMBER : {
+            double y = janet_unwrap_number(argv[1]);
+            return janet_wrap_number(compare_uint64_double(x, y));
+        }
+        case JANET_ABSTRACT: {
+            void *abst = janet_unwrap_abstract(argv[1]);
+            if (janet_abstract_type(abst) == &janet_u64_type) {
+                uint64_t y = *(uint64_t *)abst;
+                return janet_wrap_number((x < y) ? -1 : (x > y ? 1 : 0));
+            } else if (janet_abstract_type(abst) == &janet_s64_type) {
+                // comparing unsigned to signed -- be careful!
+                int64_t y = *(int64_t *)abst;
+                if (y < 0) {
+                    return janet_wrap_number(1);
+                } else if (x > INT64_MAX) {
+                    return janet_wrap_number(1);
+                } else {
+                    int64_t x2 = (int64_t) x;
+                    return janet_wrap_number((x2 < y) ? -1 : (x2 > y ? 1 : 0));
+                }
+            }
+            break;
+        }
+    }
+    return janet_wrap_nil();
+}
+
 #define OPMETHOD(T, type, name, oper) \
 static Janet cfun_it_##type##_##name(int32_t argc, Janet *argv) { \
     janet_arity(argc, 2, -1); \
@@ -266,14 +382,6 @@ static Janet cfun_it_##type##_##name(int32_t argc, Janet *argv) { \
     return janet_wrap_abstract(box); \
 } \
 
-#define COMPMETHOD(T, type, name, oper) \
-static Janet cfun_it_##type##_##name(int32_t argc, Janet *argv) { \
-    janet_fixarity(argc, 2); \
-    T v1 = janet_unwrap_##type(argv[0]); \
-    T v2 = janet_unwrap_##type(argv[1]); \
-    return janet_wrap_boolean(v1 oper v2); \
-}
-
 static Janet cfun_it_s64_mod(int32_t argc, Janet *argv) {
     janet_arity(argc, 2, -1);
     int64_t *box = janet_abstract(&janet_s64_type, sizeof(int64_t));
@@ -316,13 +424,6 @@ OPMETHOD(int64_t, s64, or, |)
 OPMETHOD(int64_t, s64, xor, ^)
 OPMETHOD(int64_t, s64, lshift, <<)
 OPMETHOD(int64_t, s64, rshift, >>)
-COMPMETHOD(int64_t, s64, lt, <)
-COMPMETHOD(int64_t, s64, gt, >)
-COMPMETHOD(int64_t, s64, le, <=)
-COMPMETHOD(int64_t, s64, ge, >=)
-COMPMETHOD(int64_t, s64, eq, ==)
-COMPMETHOD(int64_t, s64, ne, !=)
-
 OPMETHOD(uint64_t, u64, add, +)
 OPMETHOD(uint64_t, u64, sub, -)
 OPMETHODINVERT(uint64_t, u64, subi, -)
@@ -336,18 +437,13 @@ OPMETHOD(uint64_t, u64, or, |)
 OPMETHOD(uint64_t, u64, xor, ^)
 OPMETHOD(uint64_t, u64, lshift, <<)
 OPMETHOD(uint64_t, u64, rshift, >>)
-COMPMETHOD(uint64_t, u64, lt, <)
-COMPMETHOD(uint64_t, u64, gt, >)
-COMPMETHOD(uint64_t, u64, le, <=)
-COMPMETHOD(uint64_t, u64, ge, >=)
-COMPMETHOD(uint64_t, u64, eq, ==)
-COMPMETHOD(uint64_t, u64, ne, !=)
 
 #undef OPMETHOD
 #undef DIVMETHOD
 #undef DIVMETHOD_SIGNED
 #undef COMPMETHOD
 
+
 static JanetMethod it_s64_methods[] = {
     {"+", cfun_it_s64_add},
     {"r+", cfun_it_s64_add},
@@ -361,12 +457,6 @@ static JanetMethod it_s64_methods[] = {
     {"rmod", cfun_it_s64_modi},
     {"%", cfun_it_s64_rem},
     {"r%", cfun_it_s64_remi},
-    {"<", cfun_it_s64_lt},
-    {">", cfun_it_s64_gt},
-    {"<=", cfun_it_s64_le},
-    {">=", cfun_it_s64_ge},
-    {"=", cfun_it_s64_eq},
-    {"!=", cfun_it_s64_ne},
     {"&", cfun_it_s64_and},
     {"r&", cfun_it_s64_and},
     {"|", cfun_it_s64_or},
@@ -375,6 +465,7 @@ static JanetMethod it_s64_methods[] = {
     {"r^", cfun_it_s64_xor},
     {"<<", cfun_it_s64_lshift},
     {">>", cfun_it_s64_rshift},
+    {"compare", cfun_it_s64_compare},
 
     {NULL, NULL}
 };
@@ -392,12 +483,6 @@ static JanetMethod it_u64_methods[] = {
     {"rmod", cfun_it_u64_modi},
     {"%", cfun_it_u64_mod},
     {"r%", cfun_it_u64_modi},
-    {"<", cfun_it_u64_lt},
-    {">", cfun_it_u64_gt},
-    {"<=", cfun_it_u64_le},
-    {">=", cfun_it_u64_ge},
-    {"=", cfun_it_u64_eq},
-    {"!=", cfun_it_u64_ne},
     {"&", cfun_it_u64_and},
     {"r&", cfun_it_u64_and},
     {"|", cfun_it_u64_or},
@@ -406,6 +491,7 @@ static JanetMethod it_u64_methods[] = {
     {"r^", cfun_it_u64_xor},
     {"<<", cfun_it_u64_lshift},
     {">>", cfun_it_u64_rshift},
+    {"compare", cfun_it_u64_compare},
 
     {NULL, NULL}
 };

test/suite0.janet

@@ -334,5 +334,86 @@
 (assert (deep= @{:a 3 :b 2} @{:a 1 :b 2 :a 3}) "table literal duplicate keys")
 (assert (deep= @{:a 3 :b 2} (table :a 1 :b 2 :a 3)) "table constructor duplicate keys")
 
+## Polymorphic comparison -- Issue #272
+
+# confirm polymorphic comparison delegation to primitive comparators:
+(assert (= 0 (compare-primitive 3 3)) "compare-primitive integers (1)")
+(assert (= -1 (compare-primitive 3 5)) "compare-primitive integers (2)")
+(assert (= 1 (compare-primitive "foo" "bar")) "compare-primitive strings")
+(assert (= 0 (compare 1 1)) "compare integers (1)")
+(assert (= -1 (compare 1 2)) "compare integers (2)")
+(assert (= 1 (compare "foo" "bar")) "compare strings (1)")
+
+(assert (compare< 1 2 3 4 5 6) "compare less than integers")
+(assert (not (compare> 1 2 3 4 5 6)) "compare not greater than integers")
+(assert (compare< 1.0 2.0 3.0 4.0 5.0 6.0) "compare less than reals")
+(assert (compare> 6 5 4 3 2 1) "compare greater than integers")
+(assert (compare> 6.0 5.0 4.0 3.0 2.0 1.0) "compare greater than reals")
+(assert (not (compare< 6.0 5.0 4.0 3.0 2.0 1.0)) "compare less than reals")
+(assert (compare<= 1 2 3 3 4 5 6) "compare less than or equal to integers")
+(assert (compare<= 1.0 2.0 3.0 3.0 4.0 5.0 6.0) "compare less than or equal to reals")
+(assert (compare>= 6 5 4 4 3 2 1) "compare greater than or equal to integers")
+(assert (compare>= 6.0 5.0 4.0 4.0 3.0 2.0 1.0) "compare greater than or equal to reals")
+(assert (compare< 1.0 nil false true
+           (fiber/new (fn [] 1))
+           "hi"
+           (quote hello)
+           :hello
+           (array 1 2 3)
+           (tuple 1 2 3)
+           (table "a" "b" "c" "d")
+           (struct 1 2 3 4)
+           (buffer "hi")
+           (fn [x] (+ x x))
+           print) "compare type ordering")
+
+# test polymorphic compare with 'objects' (table/setproto)
+(def mynum
+  @{:type :mynum :v 0 :compare
+    (fn [self other]
+      (case (type other)
+      :number (compare-primitive (self :v) other)
+      :table (when (= (get other :type) :mynum)
+               (compare-primitive (self :v) (other :v)))))})
+
+(let [n3 (table/setproto @{:v 3} mynum)]
+  (assert (= 0 (compare 3 n3)) "compare num to object (1)")
+  (assert (= -1 (compare n3 4)) "compare object to num (2)")
+  (assert (= 1 (compare (table/setproto @{:v 4} mynum) n3)) "compare object to object")
+  (assert (compare< 2 n3 4) "compare< poly")
+  (assert (compare> 4 n3 2) "compare> poly")
+  (assert (compare<= 2 3 n3 4) "compare<= poly")
+  (assert (compare= 3 n3 (table/setproto @{:v 3} mynum)) "compare= poly")
+  (assert (deep= (sorted @[4 5 n3 2] compare<) @[2 n3 4 5]) "polymorphic sort"))
+
+(let [
+      MAX_INT_64_STRING "9223372036854775807"
+      MAX_UINT_64_STRING "18446744073709551615"
+      MAX_INT_IN_DBL_STRING "9007199254740991"
+      NAN (math/log -1)
+      INF (/ 1 0)
+      MINUS_INF (/ -1 0)
+
+      compare-poly-tests
+      [
+       [(int/s64 3) (int/u64 3) 0]
+       [(int/s64 -3) (int/u64 3) -1]
+       [(int/s64 3) (int/u64 2) 1] 
+       [(int/s64 3) 3 0] [(int/s64 3) 4 -1] [(int/s64 3) -9 1]
+       [(int/u64 3) 3 0] [(int/u64 3) 4 -1] [(int/u64 3) -9 1]
+       [3 (int/s64 3) 0] [3 (int/s64 4) -1] [3 (int/s64 -5) 1]
+       [3 (int/u64 3) 0] [3 (int/u64 4) -1] [3 (int/u64 2) 1]
+       [(int/s64 MAX_INT_64_STRING) (int/u64 MAX_UINT_64_STRING) -1]
+       [(int/s64 MAX_INT_IN_DBL_STRING) (scan-number MAX_INT_IN_DBL_STRING) 0]
+       [(int/u64 MAX_INT_IN_DBL_STRING) (scan-number MAX_INT_IN_DBL_STRING) 0]
+       [(+ 1 (int/u64 MAX_INT_IN_DBL_STRING)) (scan-number MAX_INT_IN_DBL_STRING) 1]
+       [(int/s64 0) INF -1] [(int/u64 0) INF -1]
+       [MINUS_INF (int/u64 0) -1] [MINUS_INF (int/s64 0) -1] 
+       [(int/s64 1) NAN 0] [NAN (int/u64 1) 0]
+       ]]
+  (each [x y c] compare-poly-tests
+    (assert (= c (compare x y)) (string/format "compare polymorphic %q %q %d" x y c)))
+  )
+
 (end-suite)