private static Expression add(String symbol1, String symbol2) { return add(nameReference(symbol1), nameReference(symbol2)); }
private static Expression multiply(String symbol1, String symbol2) { return multiply(nameReference(symbol1), nameReference(symbol2)); }
private static Expression equals(String symbol1, String symbol2) { return equals(nameReference(symbol1), nameReference(symbol2)); }
private static Expression someExpression(String symbol1, String symbol2) { return someExpression(nameReference(symbol1), nameReference(symbol2)); }
private static void addEquality(String symbol1, String symbol2, EqualityInference.Builder builder) { builder.addEquality(nameReference(symbol1), nameReference(symbol2)); }
@Test public void testEqualityGeneration() { EqualityInference.Builder builder = new EqualityInference.Builder(); builder.addEquality(nameReference("a1"), add("b", "c")); // a1 = b + c builder.addEquality(nameReference("e1"), add("b", "d")); // e1 = b + d addEquality("c", "d", builder); EqualityInference inference = builder.build(); Expression scopedCanonical = inference.getScopedCanonical(nameReference("e1"), symbolBeginsWith("a")); assertEquals(scopedCanonical, nameReference("a1")); }
@Test public void testSubExpressionRewrites() { EqualityInference.Builder builder = new EqualityInference.Builder(); builder.addEquality(nameReference("a1"), add("b", "c")); // a1 = b + c builder.addEquality(nameReference("a2"), multiply(nameReference("b"), add("b", "c"))); // a2 = b * (b + c) builder.addEquality(nameReference("a3"), multiply(nameReference("a1"), add("b", "c"))); // a3 = a1 * (b + c) EqualityInference inference = builder.build(); // Expression (b + c) should get entirely rewritten as a1 assertEquals(inference.rewriteExpression(add("b", "c"), symbolBeginsWith("a")), nameReference("a1")); // Only the sub-expression (b + c) should get rewritten in terms of a* assertEquals(inference.rewriteExpression(multiply(nameReference("ax"), add("b", "c")), symbolBeginsWith("a")), multiply(nameReference("ax"), nameReference("a1"))); // To be compliant, could rewrite either the whole expression, or just the sub-expression. Rewriting larger expressions are preferred assertEquals(inference.rewriteExpression(multiply(nameReference("a1"), add("b", "c")), symbolBeginsWith("a")), nameReference("a3")); }
@Test public void testExtractInferrableEqualities() { EqualityInference inference = new EqualityInference.Builder() .extractInferenceCandidates(ExpressionUtils.and(equals("a1", "b1"), equals("b1", "c1"), someExpression("c1", "d1"))) .build(); // Able to rewrite to c1 due to equalities assertEquals(nameReference("c1"), inference.rewriteExpression(nameReference("a1"), matchesSymbols("c1"))); // But not be able to rewrite to d1 which is not connected via equality assertNull(inference.rewriteExpression(nameReference("a1"), matchesSymbols("d1"))); }
@Test public void testExpressionsThatMayReturnNullOnNonNullInput() { List<Expression> candidates = ImmutableList.of( new Cast(nameReference("b"), "BIGINT", true), // try_cast new FunctionCall(QualifiedName.of("try"), ImmutableList.of(nameReference("b"))), new NullIfExpression(nameReference("b"), number(1)), new IfExpression(nameReference("b"), number(1), new NullLiteral()), new DereferenceExpression(nameReference("b"), identifier("x")), new InPredicate(nameReference("b"), new InListExpression(ImmutableList.of(new NullLiteral()))), new SearchedCaseExpression(ImmutableList.of(new WhenClause(new IsNotNullPredicate(nameReference("b")), new NullLiteral())), Optional.empty()), new SimpleCaseExpression(nameReference("b"), ImmutableList.of(new WhenClause(number(1), new NullLiteral())), Optional.empty()), new SubscriptExpression(new ArrayConstructor(ImmutableList.of(new NullLiteral())), nameReference("b"))); for (Expression candidate : candidates) { EqualityInference.Builder builder = new EqualityInference.Builder(); builder.extractInferenceCandidates(equals(nameReference("b"), nameReference("x"))); builder.extractInferenceCandidates(equals(nameReference("a"), candidate)); EqualityInference inference = builder.build(); List<Expression> equalities = inference.generateEqualitiesPartitionedBy(matchesSymbols("b")).getScopeStraddlingEqualities(); assertEquals(equalities.size(), 1); assertTrue(equalities.get(0).equals(equals(nameReference("x"), nameReference("b"))) || equalities.get(0).equals(equals(nameReference("b"), nameReference("x")))); } }
@Test public void testConstantEqualities() { EqualityInference.Builder builder = new EqualityInference.Builder(); addEquality("a1", "b1", builder); addEquality("b1", "c1", builder); builder.addEquality(nameReference("c1"), number(1)); EqualityInference inference = builder.build(); // Should always prefer a constant if available (constant is part of all scopes) assertEquals(inference.rewriteExpression(nameReference("a1"), matchesSymbols("a1", "b1")), number(1)); // All scope equalities should utilize the constant if possible EqualityInference.EqualityPartition equalityPartition = inference.generateEqualitiesPartitionedBy(matchesSymbols("a1", "b1")); assertEquals(equalitiesAsSets(equalityPartition.getScopeEqualities()), set(set(nameReference("a1"), number(1)), set(nameReference("b1"), number(1)))); assertEquals(equalitiesAsSets(equalityPartition.getScopeComplementEqualities()), set(set(nameReference("c1"), number(1)))); // There should be no scope straddling equalities as the full set of equalities should be already represented by the scope and inverse scope assertTrue(equalityPartition.getScopeStraddlingEqualities().isEmpty()); }
builder.addEquality(nameReference("a1"), nameReference("b1")); builder.addEquality(add("a1", "a1"), multiply(nameReference("a1"), number(2))); builder.addEquality(nameReference("b1"), nameReference("c1")); builder.addEquality(add("a1", "a1"), nameReference("c1")); builder.addEquality(add("a1", "b1"), nameReference("c1"));
inference.getScopedCanonical(nameReference("a2"), matchesSymbols("c2", "d2")), inference.getScopedCanonical(nameReference("b2"), matchesSymbols("c2", "d2"))); Expression canonical = inference.getScopedCanonical(nameReference("a2"), matchesSymbols("c2", "d2"));
private static Expression add(String symbol1, String symbol2) { return add(nameReference(symbol1), nameReference(symbol2)); }
private static Expression someExpression(String symbol1, String symbol2) { return someExpression(nameReference(symbol1), nameReference(symbol2)); }
private static Expression multiply(String symbol1, String symbol2) { return multiply(nameReference(symbol1), nameReference(symbol2)); }
private static Expression equals(String symbol1, String symbol2) { return equals(nameReference(symbol1), nameReference(symbol2)); }
private static void addEquality(String symbol1, String symbol2, EqualityInference.Builder builder) { builder.addEquality(nameReference(symbol1), nameReference(symbol2)); }
@Test public void testEqualityGeneration() throws Exception { EqualityInference.Builder builder = new EqualityInference.Builder(); builder.addEquality(nameReference("a1"), add("b", "c")); // a1 = b + c builder.addEquality(nameReference("e1"), add("b", "d")); // e1 = b + d addEquality("c", "d", builder); EqualityInference inference = builder.build(); Expression scopedCanonical = inference.getScopedCanonical(nameReference("e1"), symbolBeginsWith("a")); assertEquals(scopedCanonical, nameReference("a1")); }
@Test public void testSubExpressionRewrites() throws Exception { EqualityInference.Builder builder = new EqualityInference.Builder(); builder.addEquality(nameReference("a1"), add("b", "c")); // a1 = b + c builder.addEquality(nameReference("a2"), multiply(nameReference("b"), add("b", "c"))); // a2 = b * (b + c) builder.addEquality(nameReference("a3"), multiply(nameReference("a1"), add("b", "c"))); // a3 = a1 * (b + c) EqualityInference inference = builder.build(); // Expression (b + c) should get entirely rewritten as a1 assertEquals(inference.rewriteExpression(add("b", "c"), symbolBeginsWith("a")), nameReference("a1")); // Only the sub-expression (b + c) should get rewritten in terms of a* assertEquals(inference.rewriteExpression(multiply(nameReference("ax"), add("b", "c")), symbolBeginsWith("a")), multiply(nameReference("ax"), nameReference("a1"))); // To be compliant, could rewrite either the whole expression, or just the sub-expression. Rewriting larger expressions are preferred assertEquals(inference.rewriteExpression(multiply(nameReference("a1"), add("b", "c")), symbolBeginsWith("a")), nameReference("a3")); }
@Test public void testExtractInferrableEqualities() throws Exception { EqualityInference inference = new EqualityInference.Builder() .extractInferenceCandidates(ExpressionUtils.and(equals("a1", "b1"), equals("b1", "c1"), someExpression("c1", "d1"))) .build(); // Able to rewrite to c1 due to equalities assertEquals(nameReference("c1"), inference.rewriteExpression(nameReference("a1"), matchesSymbols("c1"))); // But not be able to rewrite to d1 which is not connected via equality assertNull(inference.rewriteExpression(nameReference("a1"), matchesSymbols("d1"))); }