withTempSet macro

kiss/src/kiss/Macros.hx

@@ -840,6 +840,30 @@ class Macros {
             ]);
         };
 
+        k.doc("withTempSet", 2, null, "(withTempSet [<bindings...>] <body...>)");
+        macros["withTempSet"] = (wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) -> {
+            var b = wholeExp.expBuilder();
+            var bindingList = exps[0].bindingList("withTempSet");
+            var body = exps.slice(1);
+            var bindingPairs = Prelude.groups(bindingList, 2);
+            var exps = [for (pair in bindingPairs) pair[0]];
+            var values = [for (pair in bindingPairs) pair[1]];
+            var oldValueSymbols = [for (i in 0...bindingPairs.length) b.symbol()];
+            var letBindings = Lambda.flatten(Prelude.zipThrow(oldValueSymbols, exps));
+            var setBindings:Array<Array<ReaderExp>> = Prelude.zipThrow(exps, values);
+            var resetBindings:Array<Array<ReaderExp>> = Prelude.zipThrow(exps, oldValueSymbols);
+            var result = b.symbol();
+            b.let(letBindings, [
+                for (pair in setBindings)
+                    b.set(pair[0], pair[1])
+            ].concat([
+                b.let([result, b.begin(body)], [
+                    for (pair in resetBindings)
+                        b.set(pair[0], pair[1])
+                ].concat([result]))
+            ]));
+        };
+
         k.doc("defnew", 1, null, "(defNew [<args...>] [<optional property bindings...>] <optional body...>");
         macros["defnew"] = (wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) -> {
             var args = exps.shift();

kiss/src/test/cases/BasicTestCase.hx

@@ -399,6 +399,10 @@ class BasicTestCase extends Test {
         _testWithFunctions();
     }
 
+    function testWithTempSet() {
+        _testWithTempSet();
+    }
+
     function testPrintMacrosCheck() {
         _testPrintMacrosCheck();
     }

kiss/src/test/cases/BasicTestCase.kiss

@@ -751,6 +751,23 @@ From:[(assert false (+ \"false \" \"should \" \"have \" \"been \" \"true\"))]" m
         (localFunction c [val] (+ (a val) (b val)))
         (Assert.equals 5 (c 1))))
 
+(function _testWithTempSet []  
+    (let [&mut v 5
+            &mut v2 3]
+        (assertEquals 5 v)
+        (assertEquals 3 v2)
+        (withTempSet [v 6]
+            (assertEquals 6 v)
+            (assertEquals 3 v2))
+        (assertEquals 5 v)
+        (assertEquals 3 v2)
+        (withTempSet [v 7 v2 9]
+            (assertEquals 7 v)
+            (assertEquals 9 v2))
+        (assertEquals 5 v)
+        (assertEquals 3 v2))
+    (Assert.pass))
+
 (var anotherNullToPrint null)
 (function _testPrintMacrosCheck []
     (printAllNulls)