From 0a0f48020db5b5aedff516bd220c268b1ad77da9 Mon Sep 17 00:00:00 2001
From: Leonhard Spiegelberg <leonhard_spiegelberg@brown.edu>
Date: Mon, 6 Dec 2021 23:17:52 -0500
Subject: [PATCH] is keyword fix for integers etc.

---
 tuplex/codegen/src/BlockGeneratorVisitor.cc | 32 ++++++++++++++++++++-
 tuplex/test/core/DataFrameOperations.cc     | 24 ++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/tuplex/codegen/src/BlockGeneratorVisitor.cc b/tuplex/codegen/src/BlockGeneratorVisitor.cc
index 1c6a7fa5a..cbcffab6d 100644
--- a/tuplex/codegen/src/BlockGeneratorVisitor.cc
+++ b/tuplex/codegen/src/BlockGeneratorVisitor.cc
@@ -961,12 +961,42 @@ namespace tuplex {
             assert(R);
 
             if(tt == TokenType::IS || tt == TokenType::ISNOT) {
+
+                // special case: left/right is not boolean
+                // --> Python allows that, it's bad coding style though.
+                // compile and hint.
+                if(leftType != python::Type::BOOLEAN || rightType != python::Type::BOOLEAN) {
+                    _logger.warn("SyntaxWarning: UDF contains is comparison between " + leftType.desc() + " and "
+                    + rightType.desc() + ". Better avoid, is should be only used to test against booleans or None.");
+
+                    // though upcast may be defined, for is this will be ignored.
+
+                    // only for integers there's actual code. Else, assume always false due to memory
+                    // address issue
+                    if(leftType == rightType && leftType == python::Type::I64) {
+                        _logger.warn("SyntaxWarning: Emitting code for integer is comparison, i.e. for integers in range [-5, 256] is behaves like ==");
+
+                        // result is: L == R && -5 <= L <= 256
+                        assert(L && R);
+                        auto equal = builder.CreateICmpEQ(L, R);
+                        auto upperBound = builder.CreateICmpSLE(L, _env->i64Const(256));
+                        auto lowerBound = builder.CreateICmpSGE(L, _env->i64Const(-5));
+                        // could short-circuit here, but & does fine as well...
+                        auto resValue = builder.CreateAnd(equal, builder.CreateAnd(upperBound, lowerBound));
+                        return _env->upcastToBoolean(builder, resValue);
+                    } else {
+                        return _env->boolConst(false);
+                    }
+                }
+
+                // rest of the code is for the boolean case
                 assert(leftType == python::Type::BOOLEAN || rightType == python::Type::BOOLEAN);
+
                 // one of the types must be boolean, otherwise compareInst with _isnull would've taken care.
                 if((leftType == python::Type::BOOLEAN) != (rightType == python::Type::BOOLEAN)) {
                     // one of the types is boolean, other isn't. comparison results in false.
                     return _env->boolConst(tt == TokenType::ISNOT);
-                } 
+                }
                 
                 // both must be boolean.
                 auto cmpPredicate = (tt == TokenType::ISNOT) ? llvm::CmpInst::Predicate::ICMP_NE : llvm::CmpInst::Predicate::ICMP_EQ;
diff --git a/tuplex/test/core/DataFrameOperations.cc b/tuplex/test/core/DataFrameOperations.cc
index 8d018da45..fdd21f55a 100644
--- a/tuplex/test/core/DataFrameOperations.cc
+++ b/tuplex/test/core/DataFrameOperations.cc
@@ -407,4 +407,28 @@ TEST_F(DataFrameTest, RenameColumns) {
     // check now fuzzy matching
     auto& err_ds = ds3.renameColumn("secund", "+1");
     EXPECT_TRUE(err_ds.isError());
+}
+
+TEST_F(DataFrameTest, IsKeywordAndFilter) {
+    // Following causes a bug (https://github.com/tuplex/tuplex/issues/54), this test is to fix it.
+    // c = Context()
+    // c.parallelize([1, 2, 3]).filter(lambda x: x is 2).collect()
+
+    using namespace tuplex;
+    Context c(microTestOptions());
+
+    // rename test, position based:
+    auto& ds = c.parallelize({Row(1), Row(2), Row(3)}).filter(UDF("lambda x: x is 2"));
+    ASSERT_FALSE(ds.isError());
+
+    // for integers -5 <= x <= 256 python is weird, is acts like equality!
+    auto v = ds.collectAsVector();
+    ASSERT_EQ(v.size(), 1);
+    EXPECT_EQ(v.front().getInt(0), 2);
+
+    // also check here floats to be sure the filter doesn't screw things up.
+    ds = c.parallelize({Row(1.0), Row(2.0), Row(3.0)}).filter(UDF("lambda x: x is 2.0"));
+    ASSERT_FALSE(ds.isError());
+    v = ds.collectAsVector();
+    ASSERT_EQ(v.size(), 0);
 }
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