case handle null. close #14

src/kiss/Macros.hx

@@ -645,7 +645,6 @@ class Macros {
             var bindingList = exps[0].bindingList(funcName);
             var firstPattern = bindingList.shift();
             var firstValue = bindingList.shift();
-            var firstValueSymbol = b.symbol();
 
             var thenExp = if (assertLet) b.begin(exps.slice(1)) else exps[1];
             var elseExp = if (!assertLet && exps.length > 2) {
@@ -656,29 +655,20 @@ class Macros {
                 b.symbol("null");
             };
 
-            return b.callSymbol("let", [
-                b.list([firstValueSymbol, firstValue]),
-                b.callSymbol("if", [
-                    firstValueSymbol,
-                    b.call(
-                        b.symbol("case"), [
-                            firstValueSymbol,
-                            b.call(
-                                firstPattern, [
-                                    if (bindingList.length == 0) {
-                                        thenExp;
-                                    } else {
-                                        ifLet(assertLet, wholeExp, [
-                                            b.list(bindingList)
-                                        ].concat(exps.slice(1)), k);
-                                    }
-                                ]),
-                            b.call(
-                                b.symbol("otherwise"), [
-                                    elseExp
-                                ])
-                        ]),
-                    elseExp
+            return b.callSymbol("case", [
+                firstValue,
+                b.call(
+                    firstPattern, [
+                        if (bindingList.length == 0) {
+                            thenExp;
+                        } else {
+                            ifLet(assertLet, wholeExp, [
+                                b.list(bindingList)
+                            ].concat(exps.slice(1)), k);
+                        }
+                    ]),
+                b.callSymbol("otherwise", [
+                        elseExp
                 ])
             ]);
         }
@@ -1109,7 +1099,8 @@ class Macros {
             return b.callSymbol("case", [
                 b.callField(funcName, exps.shift(), exps),
                 b.callSymbol("-1", [b.symbol("haxe.ds.Option.None")]),
-                b.callSymbol("other", [b.callSymbol("haxe.ds.Option.Some", [b.symbol("other")])])
+                b.callSymbol("other", [b.callSymbol("haxe.ds.Option.Some", [b.symbol("other")])]),
+                b.callSymbol("null", [b.callSymbol("throw", [b.str("Haxe indexOf is broken")])])
             ]);
         }
         macros["indexOf"] = indexOfMacro.bind(false);

src/kiss/SpecialForms.hx

@@ -12,6 +12,7 @@ using kiss.Reader;
 using kiss.Helpers;
 using kiss.Prelude;
 using kiss.Kiss;
+using tink.MacroApi;
 
 // Special forms convert Kiss reader expressions into Haxe macro expressions
 typedef SpecialFormFunction = (wholeExp:ReaderExp, args:Array<ReaderExp>, k:KissState) -> Expr;
@@ -285,6 +286,14 @@ class SpecialForms {
             // Therefore only one case is required in a case statement, because one case could be enough
             // to cover all patterns.
             wholeExp.checkNumArgs(2, null, '(case [expression] [cases...] [optional: (otherwise [default])])');
+
+            var isTupleCase = switch (args[0].def) {
+                case ListExp(_):
+                    true;
+                default:
+                    false;
+            }
+
             var b = wholeExp.expBuilder();
             var defaultExpr = switch (args[-1].def) {
                 case CallExp({pos: _, def: Symbol("otherwise")}, otherwiseExps):
@@ -293,7 +302,32 @@ class SpecialForms {
                 default:
                     null;
             };
-            ESwitch(k.withoutListWrapping().convert(args[0]), args.slice(1).map(Helpers.makeSwitchCase.bind(_, k)), defaultExpr).withMacroPosOf(wholeExp);
+
+            var cases = args.slice(1);
+            // case also override's haxe's switch() behavior by refusing to match null values against <var> patterns.
+            if (!isTupleCase) {
+                var nullExpr = defaultExpr;
+                var idx = 0;
+                for (arg in cases) {
+                    switch (arg.def) {
+                        case CallExp({pos: _, def: Symbol("null")}, nullExps):
+                            cases.splice(idx, 1);
+                            nullExpr = k.convert(b.begin(nullExps));
+                            break;
+                        default:
+                    }
+                    ++idx;
+                }
+
+                if (nullExpr == null) {
+                    throw CompileError.fromExp(wholeExp, "Unmatched pattern: null");
+                }
+
+                var nullCase = b.callSymbol("null", [b.raw(nullExpr.toString())]);
+                cases.insert(0, nullCase);
+            }
+
+            ESwitch(k.withoutListWrapping().convert(args[0]), cases.map(Helpers.makeSwitchCase.bind(_, k)), defaultExpr).withMacroPosOf(wholeExp);
         };
 
         // Type check syntax:

src/test/cases/BasicTestCase.hx

@@ -327,6 +327,10 @@ class BasicTestCase extends Test {
         _testEvalStatic();
         _testEval();
     }
+
+    function testCaseOnNull() {
+        _testCaseOnNull();
+    }
 }
 
 class BasicObject {

src/test/cases/BasicTestCase.kiss

@@ -351,7 +351,7 @@
 (function _testCase []
     (case (toOption [])
         (None (Assert.pass))
-        ((Some value) (Assert.fail)))
+        (otherwise (Assert.fail)))
     (case (toOption "hey")
         (None (Assert.fail))
         ((Some "hey") (Assert.pass))
@@ -589,4 +589,9 @@
 
 (function _testEvalStatic []
     (Assert.equals 9 (eval 'staticValue))
-    (assertThrows (eval 'value)))
+    (assertThrows (eval 'value)))
+
+(function _testCaseOnNull []
+    (Assert.equals 5 (case null (v 10) (null 5)))
+    (Assert.equals 5 (case null (v 10) (null 5) (otherwise 6)))
+    (Assert.equals 5 (case null (v 10) (otherwise 5))))