1 //===--- StringSwitch.h - Switch-on-literal-string Construct --------------===/
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===/
9 // This file implements the StringSwitch template, which mimics a switch()
10 // statement whose cases are string literals.
12 //===----------------------------------------------------------------------===/
13 #ifndef LLVM_ADT_STRINGSWITCH_H
14 #define LLVM_ADT_STRINGSWITCH_H
16 #include "llvm/ADT/StringRef.h"
22 /// \brief A switch()-like statement whose cases are string literals.
24 /// The StringSwitch class is a simple form of a switch() statement that
25 /// determines whether the given string matches one of the given string
26 /// literals. The template type parameter \p T is the type of the value that
27 /// will be returned from the string-switch expression. For example,
28 /// the following code switches on the name of a color in \c argv[i]:
31 /// Color color = StringSwitch<Color>(argv[i])
33 /// .Case("orange", Orange)
34 /// .Case("yellow", Yellow)
35 /// .Case("green", Green)
36 /// .Case("blue", Blue)
37 /// .Case("indigo", Indigo)
38 /// .Cases("violet", "purple", Violet)
39 /// .Default(UnknownColor);
41 template<typename T, typename R = T>
43 /// \brief The string we are matching.
46 /// \brief The pointer to the result of this switch statement, once known,
51 explicit StringSwitch(StringRef S)
52 : Str(S), Result(nullptr) { }
55 StringSwitch& Case(const char (&S)[N], const T& Value) {
56 if (!Result && N-1 == Str.size() &&
57 (std::memcmp(S, Str.data(), N-1) == 0)) {
65 StringSwitch& EndsWith(const char (&S)[N], const T &Value) {
66 if (!Result && Str.size() >= N-1 &&
67 std::memcmp(S, Str.data() + Str.size() + 1 - N, N-1) == 0) {
75 StringSwitch& StartsWith(const char (&S)[N], const T &Value) {
76 if (!Result && Str.size() >= N-1 &&
77 std::memcmp(S, Str.data(), N-1) == 0) {
84 template<unsigned N0, unsigned N1>
85 StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
87 return Case(S0, Value).Case(S1, Value);
90 template<unsigned N0, unsigned N1, unsigned N2>
91 StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
92 const char (&S2)[N2], const T& Value) {
93 return Case(S0, Value).Case(S1, Value).Case(S2, Value);
96 template<unsigned N0, unsigned N1, unsigned N2, unsigned N3>
97 StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
98 const char (&S2)[N2], const char (&S3)[N3],
100 return Case(S0, Value).Case(S1, Value).Case(S2, Value).Case(S3, Value);
103 template<unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4>
104 StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
105 const char (&S2)[N2], const char (&S3)[N3],
106 const char (&S4)[N4], const T& Value) {
107 return Case(S0, Value).Case(S1, Value).Case(S2, Value).Case(S3, Value)
111 R Default(const T& Value) const {
119 assert(Result && "Fell off the end of a string-switch");
124 } // end namespace llvm
126 #endif // LLVM_ADT_STRINGSWITCH_H