Add operator precedence parser. (#464)

2026-10-05 17:31:07 +01:00 · 2021-04-15 18:23:36 -07:00
parent 82d5a25caa
commit 09763653b7
9 changed files with 656 additions and 6 deletions
@@ -0,0 +1,116 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include "parser/precedence.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "lexer/token_kind.h"
+
+namespace Carbon {
+namespace {
+
+using ::testing::Eq;
+using ::testing::Ne;
+
+TEST(PrecedenceTest, OperatorsAreRecognized) {
+  EXPECT_TRUE(PrecedenceGroup::ForLeading(TokenKind::Minus()).hasValue());
+  EXPECT_TRUE(PrecedenceGroup::ForLeading(TokenKind::Tilde()).hasValue());
+  EXPECT_FALSE(PrecedenceGroup::ForLeading(TokenKind::Slash()).hasValue());
+  EXPECT_FALSE(PrecedenceGroup::ForLeading(TokenKind::Identifier()).hasValue());
+
+  EXPECT_TRUE(PrecedenceGroup::ForTrailing(TokenKind::Minus()).hasValue());
+  EXPECT_FALSE(PrecedenceGroup::ForTrailing(TokenKind::Tilde()).hasValue());
+  EXPECT_TRUE(PrecedenceGroup::ForTrailing(TokenKind::Slash()).hasValue());
+  EXPECT_FALSE(
+      PrecedenceGroup::ForTrailing(TokenKind::Identifier()).hasValue());
+
+  EXPECT_TRUE(PrecedenceGroup::ForTrailing(TokenKind::Minus())->is_binary);
+  EXPECT_FALSE(
+      PrecedenceGroup::ForTrailing(TokenKind::MinusMinus())->is_binary);
+}
+
+TEST(PrecedenceTest, Associativity) {
+  EXPECT_THAT(
+      PrecedenceGroup::ForLeading(TokenKind::Minus())->GetAssociativity(),
+      Eq(Associativity::RightToLeft));
+  EXPECT_THAT(PrecedenceGroup::ForTrailing(TokenKind::PlusPlus())
+                  ->level.GetAssociativity(),
+              Eq(Associativity::LeftToRight));
+  EXPECT_THAT(
+      PrecedenceGroup::ForTrailing(TokenKind::Plus())->level.GetAssociativity(),
+      Eq(Associativity::LeftToRight));
+  EXPECT_THAT(PrecedenceGroup::ForTrailing(TokenKind::Equal())
+                  ->level.GetAssociativity(),
+              Eq(Associativity::RightToLeft));
+  EXPECT_THAT(PrecedenceGroup::ForTrailing(TokenKind::PlusEqual())
+                  ->level.GetAssociativity(),
+              Eq(Associativity::None));
+}
+
+TEST(PrecedenceTest, DirectRelations) {
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Star())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::Plus())->level),
+              Eq(OperatorPriority::LeftFirst));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Plus())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::Star())->level),
+              Eq(OperatorPriority::RightFirst));
+
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Amp())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::Less())->level),
+              Eq(OperatorPriority::LeftFirst));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Less())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::Amp())->level),
+              Eq(OperatorPriority::RightFirst));
+}
+
+TEST(PrecedenceTest, IndirectRelations) {
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Star())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::OrKeyword())->level),
+              Eq(OperatorPriority::LeftFirst));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::OrKeyword())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::Star())->level),
+              Eq(OperatorPriority::RightFirst));
+
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  *PrecedenceGroup::ForLeading(TokenKind::Tilde()),
+                  PrecedenceGroup::ForTrailing(TokenKind::Equal())->level),
+              Eq(OperatorPriority::LeftFirst));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Equal())->level,
+                  *PrecedenceGroup::ForLeading(TokenKind::Tilde())),
+              Eq(OperatorPriority::RightFirst));
+}
+
+TEST(PrecedenceTest, IncomparableOperators) {
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  *PrecedenceGroup::ForLeading(TokenKind::Tilde()),
+                  *PrecedenceGroup::ForLeading(TokenKind::NotKeyword())),
+              Eq(OperatorPriority::Ambiguous));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  *PrecedenceGroup::ForLeading(TokenKind::Tilde()),
+                  *PrecedenceGroup::ForLeading(TokenKind::Minus())),
+              Eq(OperatorPriority::Ambiguous));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  *PrecedenceGroup::ForLeading(TokenKind::Minus()),
+                  PrecedenceGroup::ForTrailing(TokenKind::Amp())->level),
+              Eq(OperatorPriority::Ambiguous));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Equal())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::PipeEqual())->level),
+              Eq(OperatorPriority::Ambiguous));
+  EXPECT_THAT(PrecedenceGroup::GetPriority(
+                  PrecedenceGroup::ForTrailing(TokenKind::Plus())->level,
+                  PrecedenceGroup::ForTrailing(TokenKind::Amp())->level),
+              Eq(OperatorPriority::Ambiguous));
+}
+
+}  // namespace
+}  // namespace Carbon