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[ADT] Allow arbitrary number of cases in StringSwitch #163117

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Merged
merged 1 commit into from
Oct 13, 2025
Merged

[ADT] Allow arbitrary number of cases in StringSwitch #163117

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52 changes: 34 additions & 18 deletions llvm/include/llvm/ADT/StringSwitch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include "llvm/Support/ErrorHandling.h"
#include <cassert>
#include <cstring>
#include <initializer_list>
#include <optional>

namespace llvm {
Expand Down Expand Up @@ -85,55 +86,60 @@ class StringSwitch {
return *this;
}

StringSwitch &Cases(std::initializer_list<StringLiteral> CaseStrings,
T Value) {
return CasesImpl(Value, CaseStrings);
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, T Value) {
return CasesImpl(Value, S0, S1);
return CasesImpl(Value, {S0, S1});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
T Value) {
return CasesImpl(Value, S0, S1, S2);
return CasesImpl(Value, {S0, S1, S2});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, T Value) {
return CasesImpl(Value, S0, S1, S2, S3);
return CasesImpl(Value, {S0, S1, S2, S3});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, T Value) {
return CasesImpl(Value, S0, S1, S2, S3, S4);
return CasesImpl(Value, {S0, S1, S2, S3, S4});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
T Value) {
return CasesImpl(Value, S0, S1, S2, S3, S4, S5);
return CasesImpl(Value, {S0, S1, S2, S3, S4, S5});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, T Value) {
return CasesImpl(Value, S0, S1, S2, S3, S4, S5, S6);
return CasesImpl(Value, {S0, S1, S2, S3, S4, S5, S6});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, StringLiteral S7, T Value) {
return CasesImpl(Value, S0, S1, S2, S3, S4, S5, S6, S7);
return CasesImpl(Value, {S0, S1, S2, S3, S4, S5, S6, S7});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, StringLiteral S7, StringLiteral S8,
T Value) {
return CasesImpl(Value, S0, S1, S2, S3, S4, S5, S6, S7, S8);
return CasesImpl(Value, {S0, S1, S2, S3, S4, S5, S6, S7, S8});
}

StringSwitch &Cases(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, StringLiteral S5,
StringLiteral S6, StringLiteral S7, StringLiteral S8,
StringLiteral S9, T Value) {
return CasesImpl(Value, S0, S1, S2, S3, S4, S5, S6, S7, S8, S9);
return CasesImpl(Value, {S0, S1, S2, S3, S4, S5, S6, S7, S8, S9});
}

// Case-insensitive case matchers.
Expand All @@ -156,23 +162,28 @@ class StringSwitch {
return *this;
}

StringSwitch &CasesLower(std::initializer_list<StringLiteral> CaseStrings,
T Value) {
return CasesLowerImpl(Value, CaseStrings);
}

StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, T Value) {
return CasesLowerImpl(Value, S0, S1);
return CasesLowerImpl(Value, {S0, S1});
}

StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
T Value) {
return CasesLowerImpl(Value, S0, S1, S2);
return CasesLowerImpl(Value, {S0, S1, S2});
}

StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, T Value) {
return CasesLowerImpl(Value, S0, S1, S2, S3);
return CasesLowerImpl(Value, {S0, S1, S2, S3});
}

StringSwitch &CasesLower(StringLiteral S0, StringLiteral S1, StringLiteral S2,
StringLiteral S3, StringLiteral S4, T Value) {
return CasesLowerImpl(Value, S0, S1, S2, S3, S4);
return CasesLowerImpl(Value, {S0, S1, S2, S3, S4});
}

[[nodiscard]] R Default(T Value) {
Expand Down Expand Up @@ -211,16 +222,21 @@ class StringSwitch {
return false;
}

template <typename... Args> StringSwitch &CasesImpl(T &Value, Args... Cases) {
StringSwitch &CasesImpl(T &Value,
std::initializer_list<StringLiteral> Cases) {
// Stop matching after the string is found.
(... || CaseImpl(Value, Cases));
for (StringLiteral S : Cases)
if (CaseImpl(Value, S))
break;
return *this;
}

template <typename... Args>
StringSwitch &CasesLowerImpl(T &Value, Args... Cases) {
StringSwitch &CasesLowerImpl(T &Value,
std::initializer_list<StringLiteral> Cases) {
// Stop matching after the string is found.
(... || CaseLowerImpl(Value, Cases));
for (StringLiteral S : Cases)
if (CaseLowerImpl(Value, S))
break;
return *this;
}
};
Expand Down
13 changes: 11 additions & 2 deletions llvm/unittests/ADT/StringSwitchTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -153,13 +153,14 @@ TEST(StringSwitchTest, EndsWithLower) {
}

TEST(StringSwitchTest, Cases) {
enum class OSType { Windows, Linux, Unknown };
enum class OSType { Windows, Linux, MacOS, Unknown };

auto Translate = [](StringRef S) {
return llvm::StringSwitch<OSType>(S)
.Cases(StringLiteral::withInnerNUL("wind\0ws"), "win32", "winnt",
OSType::Windows)
.Cases("linux", "unix", "*nix", "posix", OSType::Linux)
.Cases({"macos", "osx"}, OSType::MacOS)
.Default(OSType::Unknown);
};

Expand All @@ -172,21 +173,26 @@ TEST(StringSwitchTest, Cases) {
EXPECT_EQ(OSType::Linux, Translate("*nix"));
EXPECT_EQ(OSType::Linux, Translate("posix"));

EXPECT_EQ(OSType::MacOS, Translate("macos"));
EXPECT_EQ(OSType::MacOS, Translate("osx"));

// Note that the whole null-terminator embedded string is required for the
// case to match.
EXPECT_EQ(OSType::Unknown, Translate("wind"));
EXPECT_EQ(OSType::Unknown, Translate("Windows"));
EXPECT_EQ(OSType::Unknown, Translate("MacOS"));
EXPECT_EQ(OSType::Unknown, Translate(""));
}

TEST(StringSwitchTest, CasesLower) {
enum class OSType { Windows, Linux, Unknown };
enum class OSType { Windows, Linux, MacOS, Unknown };

auto Translate = [](StringRef S) {
return llvm::StringSwitch<OSType>(S)
.CasesLower(StringLiteral::withInnerNUL("wind\0ws"), "win32", "winnt",
OSType::Windows)
.CasesLower("linux", "unix", "*nix", "posix", OSType::Linux)
.CasesLower({"macos", "osx"}, OSType::MacOS)
.Default(OSType::Unknown);
};

Expand All @@ -202,6 +208,9 @@ TEST(StringSwitchTest, CasesLower) {
EXPECT_EQ(OSType::Windows, Translate(llvm::StringRef("wind\0ws", 7)));
EXPECT_EQ(OSType::Linux, Translate("linux"));

EXPECT_EQ(OSType::MacOS, Translate("macOS"));
EXPECT_EQ(OSType::MacOS, Translate("OSX"));

EXPECT_EQ(OSType::Unknown, Translate("wind"));
EXPECT_EQ(OSType::Unknown, Translate(""));
}
Expand Down