feat(functions): add logical functions

lib/src/functions/logical.dart

@@ -0,0 +1,110 @@
+import '../evaluator.dart';
+import '../values.dart';
+import 'helpers.dart';
+
+void registerLogical(Map<String, CellFunction> registry) {
+  registry['IF'] = (args, ctx) {
+    arity(args, 2, 3);
+    if (ctx.asBoolean(ctx.eval(args[0]))) return ctx.eval(args[1]);
+    if (args.length == 3) return ctx.eval(args[2]);
+    return const BooleanValue(false);
+  };
+
+  registry['IFS'] = (args, ctx) {
+    arity(args, 2);
+    if (args.length.isOdd) throw const EvalException(ErrorValue(ErrorKind.value));
+    for (var i = 0; i < args.length; i += 2) {
+      if (ctx.asBoolean(ctx.eval(args[i]))) return ctx.eval(args[i + 1]);
+    }
+    throw const EvalException(ErrorValue(ErrorKind.na));
+  };
+
+  registry['SWITCH'] = (args, ctx) {
+    arity(args, 3);
+    final subject = ctx.eval(args[0]);
+    var i = 1;
+    while (i + 1 < args.length) {
+      if (ctx.compare(subject, ctx.eval(args[i])) == 0) return ctx.eval(args[i + 1]);
+      i += 2;
+    }
+    if (i < args.length) return ctx.eval(args[i]);
+    throw const EvalException(ErrorValue(ErrorKind.na));
+  };
+
+  registry['AND'] = (args, ctx) {
+    arity(args, 1);
+    var seen = false;
+    var accumulated = true;
+    for (final value in ctx.flatten(args)) {
+      if (value is BlankValue) continue;
+      accumulated = accumulated && ctx.asBoolean(value);
+      seen = true;
+    }
+    if (!seen) throw const EvalException(ErrorValue(ErrorKind.value));
+    return BooleanValue(accumulated);
+  };
+
+  registry['OR'] = (args, ctx) {
+    arity(args, 1);
+    var seen = false;
+    var accumulated = false;
+    for (final value in ctx.flatten(args)) {
+      if (value is BlankValue) continue;
+      accumulated = accumulated || ctx.asBoolean(value);
+      seen = true;
+    }
+    if (!seen) throw const EvalException(ErrorValue(ErrorKind.value));
+    return BooleanValue(accumulated);
+  };
+
+  registry['XOR'] = (args, ctx) {
+    arity(args, 1);
+    var trueCount = 0;
+    var seen = false;
+    for (final value in ctx.flatten(args)) {
+      if (value is BlankValue) continue;
+      if (ctx.asBoolean(value)) trueCount++;
+      seen = true;
+    }
+    if (!seen) throw const EvalException(ErrorValue(ErrorKind.value));
+    return BooleanValue(trueCount.isOdd);
+  };
+
+  registry['NOT'] = (args, ctx) {
+    arity(args, 1, 1);
+    return BooleanValue(!ctx.asBoolean(ctx.eval(args[0])));
+  };
+
+  registry['TRUE'] = (args, ctx) {
+    arity(args, 0, 0);
+    return const BooleanValue(true);
+  };
+
+  registry['FALSE'] = (args, ctx) {
+    arity(args, 0, 0);
+    return const BooleanValue(false);
+  };
+
+  registry['IFERROR'] = (args, ctx) {
+    arity(args, 2, 2);
+    try {
+      final value = ctx.eval(args[0]);
+      if (value is ErrorValue) return ctx.eval(args[1]);
+      return value;
+    } on EvalException {
+      return ctx.eval(args[1]);
+    }
+  };
+
+  registry['IFNA'] = (args, ctx) {
+    arity(args, 2, 2);
+    try {
+      final value = ctx.eval(args[0]);
+      if (value is ErrorValue && value.kind == ErrorKind.na) return ctx.eval(args[1]);
+      return value;
+    } on EvalException catch (error) {
+      if (error.kind == ErrorKind.na) return ctx.eval(args[1]);
+      rethrow;
+    }
+  };
+}