Closes #90: Add inspect predicate match, as extension of value match

Author: hsutter

include/cpp2util.h

@@ -1,6 +1,11 @@
+auto in(int min, int max) {
+    return [=](int x){ return min <= x && x <= max; };
+}
+
+in_2_3: (x: int) -> bool = 2 <= x && x <= 3;
+
 main: ()->int = {
     v: std::variant<double, std::string, double> = ();
-    test(v);
     v = "rev dodgson";
     test(v);
 
@@ -15,6 +20,9 @@ main: ()->int = {
     test(a);
 
     test(0);
+    test(1);
+    test(2);
+    test(3);
     test(-42);
     test("xyzzy" as std::string);
     test(3.14);
@@ -24,6 +32,8 @@ test: (x:_) = {
     forty_two := 42;
     std::cout << inspect x -> std::string {
         is 0           = "zero";
+        is (in(1,2))   = "1 or 2";
+        is (in_2_3)    = "3";
         is (forty_two) = "the answer";
         is int         = "integer " + cpp2::to_string(x);
         is std::string = x as std::string;

regression-tests/pure2-inspect-values.cpp2 renamed to regression-tests/mixed-inspect-values.cpp2

@@ -0,0 +1,12 @@
+rev dodgson
+(no match)
+the answer
+zero
+plugh
+zero
+1 or 2
+1 or 2
+3
+integer -42
+xyzzy
+3

regression-tests/test-results/clang-12/mixed-inspect-values.cpp.execution

@@ -0,0 +1,12 @@
+rev dodgson
+(no match)
+the answer
+zero
+plugh
+zero
+1 or 2
+1 or 2
+3
+integer -42
+xyzzy
+3

regression-tests/test-results/clang-12/pure2-inspect-values.cpp.output renamed to regression-tests/test-results/clang-12/mixed-inspect-values.cpp.output

@@ -1,19 +1,25 @@
 // ----- Cpp2 support -----
-#define CPP2_USE_MODULES         Yes
 #include "cpp2util.h"
 
+#line 1 "mixed-inspect-values.cpp2"
+auto in(int min, int max) {
+    return [=](int x){ return min <= x && x <= max; };
+}
 
-#line 1 "pure2-inspect-values.cpp2"
+[[nodiscard]] auto in_2_3(cpp2::in<int> x) -> bool;
+#line 7 "mixed-inspect-values.cpp2"
 [[nodiscard]] auto main() -> int;
-#line 23 "pure2-inspect-values.cpp2"
+#line 31 "mixed-inspect-values.cpp2"
 auto test(auto const& x) -> void;
 
 //=== Cpp2 definitions ==========================================================
 
-#line 1 "pure2-inspect-values.cpp2"
+#line 4 "mixed-inspect-values.cpp2"
+
+[[nodiscard]] auto in_2_3(cpp2::in<int> x) -> bool { return 2 <= x && x <= 3; }
+
 [[nodiscard]] auto main() -> int{
     std::variant<double,std::string,double> v {  }; 
-    test(v);
     v = "rev dodgson";
     test(std::move(v));
 
@@ -28,6 +34,9 @@ auto test(auto const& x) -> void;
     test(std::move(a));
 
     test(0);
+    test(1);
+    test(2);
+    test(3);
     test(-42);
     test(cpp2::as<  std::string>("xyzzy"));
     test(3.14);
@@ -37,7 +46,9 @@ auto test(auto const& x) -> void{
     auto forty_two { 42 }; 
     std::cout << [&] () -> std::string { auto&& __expr = x;
         if (cpp2::is(__expr, 0)) { if constexpr( requires{"zero";} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("zero")),std::string> ) return "zero"; else return std::string{}; else return std::string{}; }
-        else if (cpp2::is(__expr, (std::move(forty_two)))) { if constexpr( requires{"the answer";} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("the answer")),std::string> ) return "the answer"; else return std::string{}; else return std::string{}; }
+        else if (cpp2::is(__expr, (in(1, 2)))) { if constexpr( requires{"1 or 2";} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("1 or 2")),std::string> ) return "1 or 2"; else return std::string{}; else return std::string{}; }
+        else if (cpp2::is(__expr, in_2_3)) { if constexpr( requires{"3";} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("3")),std::string> ) return "3"; else return std::string{}; else return std::string{}; }
+        else if (cpp2::is(__expr, std::move(forty_two))) { if constexpr( requires{"the answer";} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("the answer")),std::string> ) return "the answer"; else return std::string{}; else return std::string{}; }
         else if (cpp2::is<int>(__expr)) { if constexpr( requires{"integer " + cpp2::to_string(x);} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF(("integer " + cpp2::to_string(x))),std::string> ) return "integer " + cpp2::to_string(x); else return std::string{}; else return std::string{}; }
         else if (cpp2::is<std::string>(__expr)) { if constexpr( requires{cpp2::as<std::string>(x);} ) if constexpr( std::is_convertible_v<CPP2_TYPEOF((cpp2::as<std::string>(x))),std::string> ) return cpp2::as<std::string>(x); else return std::string{}; else return std::string{}; }
         else return "(no match)"; }

regression-tests/test-results/gcc-10/mixed-inspect-values.cpp.execution

@@ -0,0 +1,2 @@
+mixed-inspect-values.cpp2... ok (mixed Cpp1/Cpp2, Cpp2 code passes safety checks)
+

regression-tests/test-results/gcc-10/pure2-inspect-values.cpp.output renamed to regression-tests/test-results/gcc-10/mixed-inspect-values.cpp.output

@@ -0,0 +1,12 @@
+rev dodgson
+(no match)
+the answer
+zero
+plugh
+zero
+1 or 2
+1 or 2
+3
+integer -42
+xyzzy
+3

regression-tests/test-results/pure2-inspect-values.cpp renamed to regression-tests/test-results/mixed-inspect-values.cpp

@@ -0,0 +1 @@
+mixed-inspect-values.cpp

regression-tests/test-results/mixed-inspect-values.cpp2.output

@@ -867,7 +867,7 @@ struct function_type_node
     enum active { empty = 0, id, list };
     std::variant<
         std::monostate,
-        std::unique_ptr<id_expression_node>,
+        std::unique_ptr<type_id_node>,
         std::unique_ptr<parameter_declaration_list_node>
     > returns;
 
@@ -2824,7 +2824,7 @@ class parser
     //G     throws
     //G
     //G return-list:
-    //G     -> id-expression
+    //G     -> type-id
     //G     -> parameter_declaration_list
     //G
     //G contract-seq:
@@ -2853,7 +2853,7 @@ class parser
         {
             next();
 
-            if (auto t = id_expression()) {
+            if (auto t = type_id()) {
                 n->returns = std::move(t);
             }
             else if (auto returns_list = parameter_declaration_list(true)) {