Add new relational rules to WGSL grammar.

This CL adds the `relational_expression.post.unary_expression` grammar
rule into the WGSL parser. A `shift_expression` helper and a
`relational_expression` helper are also added.

Note, the two helpers have `maybe_` as name prefixes. This will be
dropped when the old parser path is removed which current uses the
other versions of those names.

Bug: tint:1633
Change-Id: I6431edfe8fdb9f5a6eea804a7d6fa9a4982ea04e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/99761
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>

src/tint/reader/wgsl/parser_impl.cc

@@ -2800,6 +2800,19 @@ Maybe<const ast::Expression*> ParserImpl::element_count_expression() {
     return math.value;
 }
 
+// shift_expression
+//   : unary_expression shift_expression.post.unary_expression
+Maybe<const ast::Expression*> ParserImpl::maybe_shift_expression() {
+    auto lhs = unary_expression();
+    if (lhs.errored) {
+        return Failure::kErrored;
+    }
+    if (!lhs.matched) {
+        return Failure::kNoMatch;
+    }
+    return expect_shift_expression_post_unary_expression(lhs.value);
+}
+
 // shift_expression.post.unary_expression
 //   : multiplicative_expression.post.unary_expression?
 //   | SHIFT_LEFT unary_expression
@@ -2835,6 +2848,66 @@ Expect<const ast::Expression*> ParserImpl::expect_shift_expression_post_unary_ex
     return expect_multiplicative_expression_post_unary_expression(lhs);
 }
 
+// relational_expression
+//   : unary_expression relational_expression.post.unary_expression
+Maybe<const ast::Expression*> ParserImpl::maybe_relational_expression() {
+    auto lhs = unary_expression();
+    if (lhs.errored) {
+        return Failure::kErrored;
+    }
+    if (!lhs.matched) {
+        return Failure::kNoMatch;
+    }
+    return expect_relational_expression_post_unary_expression(lhs.value);
+}
+
+// relational_expression.post.unary_expression
+//   : shift_expression.post.unary_expression
+//   | shift_expression.post.unary_expression EQUAL_EQUAL shift_expression
+//   | shift_expression.post.unary_expression GREATER_THAN shift_expression
+//   | shift_expression.post.unary_expression GREATER_THAN_EQUAL shift_expression
+//   | shift_expression.post.unary_expression LESS_THAN shift_expression
+//   | shift_expression.post.unary_expression LESS_THAN_EQUAL shift_expression
+//   | shift_expression.post.unary_expression NOT_EQUAL shift_expression
+//
+// Note, a `shift_expression` element was added to simplify many of the right sides
+Expect<const ast::Expression*> ParserImpl::expect_relational_expression_post_unary_expression(
+    const ast::Expression* lhs) {
+    auto lhs_result = expect_shift_expression_post_unary_expression(lhs);
+    if (lhs_result.errored) {
+        return Failure::kErrored;
+    }
+    lhs = lhs_result.value;
+
+    auto& t = peek();
+    if (match(Token::Type::kEqualEqual) || match(Token::Type::kGreaterThan) ||
+        match(Token::Type::kGreaterThanEqual) || match(Token::Type::kLessThan) ||
+        match(Token::Type::kLessThanEqual) || match(Token::Type::kNotEqual)) {
+        ast::BinaryOp op = ast::BinaryOp::kNone;
+        if (t.Is(Token::Type::kLessThan)) {
+            op = ast::BinaryOp::kLessThan;
+        } else if (t.Is(Token::Type::kGreaterThan)) {
+            op = ast::BinaryOp::kGreaterThan;
+        } else if (t.Is(Token::Type::kLessThanEqual)) {
+            op = ast::BinaryOp::kLessThanEqual;
+        } else if (t.Is(Token::Type::kGreaterThanEqual)) {
+            op = ast::BinaryOp::kGreaterThanEqual;
+        }
+
+        auto& next = peek();
+        auto rhs = maybe_shift_expression();
+        if (rhs.errored) {
+            return Failure::kErrored;
+        }
+        if (!rhs.matched) {
+            return add_error(next, std::string("unable to parse right side of ") +
+                                       std::string(t.to_name()) + " expression");
+        }
+        lhs = create<ast::BinaryExpression>(t.source(), op, lhs, rhs.value);
+    }
+    return lhs;
+}
+
 // singular_expression
 //   : primary_expression postfix_expr
 Maybe<const ast::Expression*> ParserImpl::singular_expression() {

src/tint/reader/wgsl/parser_impl.h

@@ -667,11 +667,22 @@ class ParserImpl {
     /// Parses an `element_count_expression` grammar element
     /// @returns the parsed expression or nullptr
     Maybe<const ast::Expression*> element_count_expression();
+    /// Parses a `unary_expression shift.post.unary_expression`
+    /// @returns the parsed expression or nullptr
+    Maybe<const ast::Expression*> maybe_shift_expression();
     /// Parses a `shift_expression.post.unary_expression` grammar element
     /// @param lhs the left side of the expression
     /// @returns the parsed expression or `lhs` if no match
     Expect<const ast::Expression*> expect_shift_expression_post_unary_expression(
         const ast::Expression* lhs);
+    /// Parses a `unary_expression relational_expression.post.unary_expression`
+    /// @returns the parsed expression or nullptr
+    Maybe<const ast::Expression*> maybe_relational_expression();
+    /// Parses a `relational_expression.post.unary_expression` grammar element
+    /// @param lhs the left side of the expression
+    /// @returns the parsed expression or `lhs` if no match
+    Expect<const ast::Expression*> expect_relational_expression_post_unary_expression(
+        const ast::Expression* lhs);
     /// Parse the `additive_operator` grammar element
     /// @returns the parsed operator if successful
     Maybe<ast::BinaryOp> additive_operator();

src/tint/reader/wgsl/parser_impl_relational_expression_test.cc

@@ -17,7 +17,7 @@
 namespace tint::reader::wgsl {
 namespace {
 
-TEST_F(ParserImplTest, RelationalExpression_Parses_LessThan) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_Parses_LessThan) {
     auto p = parser("a < true");
     auto e = p->relational_expression();
     EXPECT_TRUE(e.matched);
@@ -42,7 +42,7 @@ TEST_F(ParserImplTest, RelationalExpression_Parses_LessThan) {
     ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
 }
 
-TEST_F(ParserImplTest, RelationalExpression_Parses_GreaterThan) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_Parses_GreaterThan) {
     auto p = parser("a > true");
     auto e = p->relational_expression();
     EXPECT_TRUE(e.matched);
@@ -67,7 +67,7 @@ TEST_F(ParserImplTest, RelationalExpression_Parses_GreaterThan) {
     ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
 }
 
-TEST_F(ParserImplTest, RelationalExpression_Parses_LessThanEqual) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_Parses_LessThanEqual) {
     auto p = parser("a <= true");
     auto e = p->relational_expression();
     EXPECT_TRUE(e.matched);
@@ -92,7 +92,7 @@ TEST_F(ParserImplTest, RelationalExpression_Parses_LessThanEqual) {
     ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
 }
 
-TEST_F(ParserImplTest, RelationalExpression_Parses_GreaterThanEqual) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_Parses_GreaterThanEqual) {
     auto p = parser("a >= true");
     auto e = p->relational_expression();
     EXPECT_TRUE(e.matched);
@@ -117,7 +117,7 @@ TEST_F(ParserImplTest, RelationalExpression_Parses_GreaterThanEqual) {
     ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
 }
 
-TEST_F(ParserImplTest, RelationalExpression_InvalidLHS) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_InvalidLHS) {
     auto p = parser("if (a) {} < true");
     auto e = p->relational_expression();
     EXPECT_FALSE(e.matched);
@@ -126,7 +126,7 @@ TEST_F(ParserImplTest, RelationalExpression_InvalidLHS) {
     EXPECT_EQ(e.value, nullptr);
 }
 
-TEST_F(ParserImplTest, RelationalExpression_InvalidRHS) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_InvalidRHS) {
     auto p = parser("true < if (a) {}");
     auto e = p->relational_expression();
     ASSERT_TRUE(p->has_error());
@@ -134,7 +134,7 @@ TEST_F(ParserImplTest, RelationalExpression_InvalidRHS) {
     EXPECT_EQ(p->error(), "1:8: unable to parse right side of < expression");
 }
 
-TEST_F(ParserImplTest, RelationalExpression_NoOr_ReturnsLHS) {
+TEST_F(ParserImplTest, RelationalExpression_Orig_NoOr_ReturnsLHS) {
     auto p = parser("a true");
     auto e = p->relational_expression();
     EXPECT_TRUE(e.matched);
@@ -144,5 +144,163 @@ TEST_F(ParserImplTest, RelationalExpression_NoOr_ReturnsLHS) {
     ASSERT_TRUE(e->Is<ast::IdentifierExpression>());
 }
 
+TEST_F(ParserImplTest, RelationalExpression_PostUnary_Parses_LessThan) {
+    auto p = parser("a < true");
+    auto lhs = p->unary_expression();
+    auto e = p->expect_relational_expression_post_unary_expression(lhs.value);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+
+    EXPECT_EQ(e->source.range.begin.line, 1u);
+    EXPECT_EQ(e->source.range.begin.column, 3u);
+    EXPECT_EQ(e->source.range.end.line, 1u);
+    EXPECT_EQ(e->source.range.end.column, 4u);
+
+    ASSERT_TRUE(e->Is<ast::BinaryExpression>());
+    auto* rel = e->As<ast::BinaryExpression>();
+    EXPECT_EQ(ast::BinaryOp::kLessThan, rel->op);
+
+    ASSERT_TRUE(rel->lhs->Is<ast::IdentifierExpression>());
+    auto* ident = rel->lhs->As<ast::IdentifierExpression>();
+    EXPECT_EQ(ident->symbol, p->builder().Symbols().Register("a"));
+
+    ASSERT_TRUE(rel->rhs->Is<ast::BoolLiteralExpression>());
+    ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_PostUnary_Parses_GreaterThan) {
+    auto p = parser("a > true");
+    auto lhs = p->unary_expression();
+    auto e = p->expect_relational_expression_post_unary_expression(lhs.value);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+
+    EXPECT_EQ(e->source.range.begin.line, 1u);
+    EXPECT_EQ(e->source.range.begin.column, 3u);
+    EXPECT_EQ(e->source.range.end.line, 1u);
+    EXPECT_EQ(e->source.range.end.column, 4u);
+
+    ASSERT_TRUE(e->Is<ast::BinaryExpression>());
+    auto* rel = e->As<ast::BinaryExpression>();
+    EXPECT_EQ(ast::BinaryOp::kGreaterThan, rel->op);
+
+    ASSERT_TRUE(rel->lhs->Is<ast::IdentifierExpression>());
+    auto* ident = rel->lhs->As<ast::IdentifierExpression>();
+    EXPECT_EQ(ident->symbol, p->builder().Symbols().Register("a"));
+
+    ASSERT_TRUE(rel->rhs->Is<ast::BoolLiteralExpression>());
+    ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_PostUnary_Parses_LessThanEqual) {
+    auto p = parser("a <= true");
+    auto lhs = p->unary_expression();
+    auto e = p->expect_relational_expression_post_unary_expression(lhs.value);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+
+    EXPECT_EQ(e->source.range.begin.line, 1u);
+    EXPECT_EQ(e->source.range.begin.column, 3u);
+    EXPECT_EQ(e->source.range.end.line, 1u);
+    EXPECT_EQ(e->source.range.end.column, 5u);
+
+    ASSERT_TRUE(e->Is<ast::BinaryExpression>());
+    auto* rel = e->As<ast::BinaryExpression>();
+    EXPECT_EQ(ast::BinaryOp::kLessThanEqual, rel->op);
+
+    ASSERT_TRUE(rel->lhs->Is<ast::IdentifierExpression>());
+    auto* ident = rel->lhs->As<ast::IdentifierExpression>();
+    EXPECT_EQ(ident->symbol, p->builder().Symbols().Register("a"));
+
+    ASSERT_TRUE(rel->rhs->Is<ast::BoolLiteralExpression>());
+    ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_PostUnary_Parses_GreaterThanEqual) {
+    auto p = parser("a >= true");
+    auto lhs = p->unary_expression();
+    auto e = p->expect_relational_expression_post_unary_expression(lhs.value);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+
+    EXPECT_EQ(e->source.range.begin.line, 1u);
+    EXPECT_EQ(e->source.range.begin.column, 3u);
+    EXPECT_EQ(e->source.range.end.line, 1u);
+    EXPECT_EQ(e->source.range.end.column, 5u);
+
+    ASSERT_TRUE(e->Is<ast::BinaryExpression>());
+    auto* rel = e->As<ast::BinaryExpression>();
+    EXPECT_EQ(ast::BinaryOp::kGreaterThanEqual, rel->op);
+
+    ASSERT_TRUE(rel->lhs->Is<ast::IdentifierExpression>());
+    auto* ident = rel->lhs->As<ast::IdentifierExpression>();
+    EXPECT_EQ(ident->symbol, p->builder().Symbols().Register("a"));
+
+    ASSERT_TRUE(rel->rhs->Is<ast::BoolLiteralExpression>());
+    ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_PostUnary_InvalidRHS) {
+    auto p = parser("true < if (a) {}");
+    auto lhs = p->unary_expression();
+    auto e = p->expect_relational_expression_post_unary_expression(lhs.value);
+    ASSERT_TRUE(p->has_error());
+    EXPECT_EQ(e.value, nullptr);
+    EXPECT_EQ(p->error(), "1:8: unable to parse right side of < expression");
+}
+
+TEST_F(ParserImplTest, RelationalExpression_PostUnary_NoMatch_ReturnsLHS) {
+    auto p = parser("a true");
+    auto lhs = p->unary_expression();
+    auto e = p->expect_relational_expression_post_unary_expression(lhs.value);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+    EXPECT_EQ(lhs.value, e.value);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_Matches) {
+    auto p = parser("a >= true");
+    auto e = p->maybe_relational_expression();
+    EXPECT_TRUE(e.matched);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+
+    ASSERT_TRUE(e->Is<ast::BinaryExpression>());
+    auto* rel = e->As<ast::BinaryExpression>();
+    EXPECT_EQ(ast::BinaryOp::kGreaterThanEqual, rel->op);
+
+    ASSERT_TRUE(rel->lhs->Is<ast::IdentifierExpression>());
+    auto* ident = rel->lhs->As<ast::IdentifierExpression>();
+    EXPECT_EQ(ident->symbol, p->builder().Symbols().Register("a"));
+
+    ASSERT_TRUE(rel->rhs->Is<ast::BoolLiteralExpression>());
+    ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_InvalidLHS) {
+    auto p = parser("if (a) {}< 3");
+    auto e = p->maybe_relational_expression();
+    ASSERT_FALSE(e.matched);
+    EXPECT_FALSE(e.errored);
+    ASSERT_FALSE(p->has_error()) << p->error();
+    EXPECT_EQ(e.value, nullptr);
+}
+
+TEST_F(ParserImplTest, RelationalExpression_InvalidRHS) {
+    auto p = parser("true < if (a) {}");
+    auto e = p->maybe_relational_expression();
+    ASSERT_FALSE(e.matched);
+    EXPECT_TRUE(e.errored);
+    ASSERT_TRUE(p->has_error());
+    EXPECT_EQ(e.value, nullptr);
+    EXPECT_EQ(p->error(), "1:8: unable to parse right side of < expression");
+}
+
 }  // namespace
 }  // namespace tint::reader::wgsl

src/tint/reader/wgsl/parser_impl_shift_expression_test.cc

@@ -114,7 +114,7 @@ TEST_F(ParserImplTest, ShiftExpression_Orig_NoOr_ReturnsLHS) {
     ASSERT_TRUE(e->Is<ast::IdentifierExpression>());
 }
 
-TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftLeft) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_Parses_ShiftLeft) {
     auto p = parser("a << true");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -139,7 +139,7 @@ TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftLeft) {
     ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
 }
 
-TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftRight) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_Parses_ShiftRight) {
     auto p = parser("a >> true");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -164,7 +164,7 @@ TEST_F(ParserImplTest, ShiftExpression_Parses_ShiftRight) {
     ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
 }
 
-TEST_F(ParserImplTest, ShiftExpression_Parses_Multiplicative) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_Parses_Multiplicative) {
     auto p = parser("a * b");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -185,7 +185,7 @@ TEST_F(ParserImplTest, ShiftExpression_Parses_Multiplicative) {
     EXPECT_EQ(ident->symbol, p->builder().Symbols().Get("b"));
 }
 
-TEST_F(ParserImplTest, ShiftExpression_InvalidSpaceLeft) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_InvalidSpaceLeft) {
     auto p = parser("a < < true");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -194,7 +194,7 @@ TEST_F(ParserImplTest, ShiftExpression_InvalidSpaceLeft) {
     EXPECT_FALSE(e.value->Is<ast::BinaryExpression>());
 }
 
-TEST_F(ParserImplTest, ShiftExpression_InvalidSpaceRight) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_InvalidSpaceRight) {
     auto p = parser("a > > true");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -203,7 +203,7 @@ TEST_F(ParserImplTest, ShiftExpression_InvalidSpaceRight) {
     EXPECT_FALSE(e.value->Is<ast::BinaryExpression>());
 }
 
-TEST_F(ParserImplTest, ShiftExpression_InvalidRHS) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_InvalidRHS) {
     auto p = parser("a << if (a) {}");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -213,7 +213,7 @@ TEST_F(ParserImplTest, ShiftExpression_InvalidRHS) {
     EXPECT_EQ(p->error(), "1:3: unable to parse right side of << expression");
 }
 
-TEST_F(ParserImplTest, ShiftExpression_NoOr_ReturnsLHS) {
+TEST_F(ParserImplTest, ShiftExpression_PostUnary_NoOr_ReturnsLHS) {
     auto p = parser("a true");
     auto lhs = p->unary_expression();
     auto e = p->expect_shift_expression_post_unary_expression(lhs.value);
@@ -223,5 +223,45 @@ TEST_F(ParserImplTest, ShiftExpression_NoOr_ReturnsLHS) {
     ASSERT_EQ(lhs.value, e.value);
 }
 
+TEST_F(ParserImplTest, ShiftExpression_Parses) {
+    auto p = parser("a << true");
+    auto e = p->maybe_shift_expression();
+    EXPECT_TRUE(e.matched);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_NE(e.value, nullptr);
+
+    ASSERT_TRUE(e->Is<ast::BinaryExpression>());
+    auto* rel = e->As<ast::BinaryExpression>();
+    EXPECT_EQ(ast::BinaryOp::kShiftLeft, rel->op);
+
+    ASSERT_TRUE(rel->lhs->Is<ast::IdentifierExpression>());
+    auto* ident = rel->lhs->As<ast::IdentifierExpression>();
+    EXPECT_EQ(ident->symbol, p->builder().Symbols().Get("a"));
+
+    ASSERT_TRUE(rel->rhs->Is<ast::BoolLiteralExpression>());
+    ASSERT_TRUE(rel->rhs->As<ast::BoolLiteralExpression>()->value);
+}
+
+TEST_F(ParserImplTest, ShiftExpression_Invalid_Unary) {
+    auto p = parser("if >> true");
+    auto e = p->maybe_shift_expression();
+    EXPECT_FALSE(e.matched);
+    EXPECT_FALSE(e.errored);
+    EXPECT_FALSE(p->has_error()) << p->error();
+    ASSERT_EQ(e.value, nullptr);
+}
+
+TEST_F(ParserImplTest, ShiftExpression_Inavlid_ShiftExpressionPostUnary) {
+    auto p = parser("a * if (a) {}");
+    auto e = p->maybe_shift_expression();
+    EXPECT_FALSE(e.matched);
+    EXPECT_TRUE(e.errored);
+    EXPECT_TRUE(p->has_error());
+    ASSERT_EQ(e.value, nullptr);
+
+    EXPECT_EQ(p->error(), "1:5: unable to parse right side of * expression");
+}
+
 }  // namespace
 }  // namespace tint::reader::wgsl