From: Zachary Turner Date: Sun, 25 Sep 2016 03:27:29 +0000 (+0000) Subject: Add some predicated searching functions to StringRef. X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=568a8f4a4de56dd51a118dd7559b497cee8f8b96;p=llvm Add some predicated searching functions to StringRef. This adds 4 new functions to StringRef, which can be used to take or drop characters while a certain condition is met, or until a certain condition is met. They are: take_while - Return characters until a condition is not met. take_until - Return characters until a condition is met. drop_while - Remove characters until a condition is not met. drop_until - Remove characters until a condition is met. Internally, all of these functions delegate to two additional helper functions which can be used to search for the position of a character meeting or not meeting a condition, which are: find_if - Find the first character matching a predicate. find_if_not - Find the first character not matching a predicate. Differential Revision: https://reviews.llvm.org/D24842 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282346 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/ADT/StringRef.h b/include/llvm/ADT/StringRef.h index 44b14d20dee..f6a348e8ab4 100644 --- a/include/llvm/ADT/StringRef.h +++ b/include/llvm/ADT/StringRef.h @@ -10,6 +10,7 @@ #ifndef LLVM_ADT_STRINGREF_H #define LLVM_ADT_STRINGREF_H +#include "llvm/ADT/STLExtras.h" #include "llvm/ADT/iterator_range.h" #include "llvm/Support/Compiler.h" #include @@ -276,6 +277,32 @@ namespace llvm { return npos; } + /// Search for the first character satisfying the predicate \p F + /// + /// \returns The index of the first character satisfying \p F starting from + /// \p From, or npos if not found. + LLVM_ATTRIBUTE_ALWAYS_INLINE + LLVM_ATTRIBUTE_UNUSED_RESULT + size_t find_if(function_ref F, size_t From = 0) const { + StringRef S = drop_front(From); + while (!S.empty()) { + if (F(S.front())) + return size() - S.size(); + S = S.drop_front(); + } + return npos; + } + + /// Search for the first character not satisfying the predicate \p F + /// + /// \returns The index of the first character not satisfying \p F starting + /// from \p From, or npos if not found. + LLVM_ATTRIBUTE_ALWAYS_INLINE + LLVM_ATTRIBUTE_UNUSED_RESULT + size_t find_if_not(function_ref F, size_t From = 0) const { + return find_if([F](char c) { return !F(c); }, From); + } + /// Search for the first string \p Str in the string. /// /// \returns The index of the first occurrence of \p Str, or npos if not @@ -352,6 +379,9 @@ namespace llvm { LLVM_ATTRIBUTE_ALWAYS_INLINE bool contains(StringRef Other) const { return find(Other) != npos; } + LLVM_ATTRIBUTE_ALWAYS_INLINE + bool contains(char C) const { return find_first_of(C) != npos; } + /// @} /// @name Helpful Algorithms /// @{ @@ -496,6 +526,22 @@ namespace llvm { return drop_front(size() - N); } + /// Return the longest prefix of 'this' such that every character + /// in the prefix satisfies the given predicate. + LLVM_ATTRIBUTE_ALWAYS_INLINE + LLVM_ATTRIBUTE_UNUSED_RESULT + StringRef take_while(function_ref F) const { + return substr(0, find_if_not(F)); + } + + /// Return the longest prefix of 'this' such that no character in + /// the prefix satisfies the given predicate. + LLVM_ATTRIBUTE_ALWAYS_INLINE + LLVM_ATTRIBUTE_UNUSED_RESULT + StringRef take_until(function_ref F) const { + return substr(0, find_if(F)); + } + /// Return a StringRef equal to 'this' but with the first \p N elements /// dropped. LLVM_ATTRIBUTE_ALWAYS_INLINE @@ -514,6 +560,22 @@ namespace llvm { return substr(0, size()-N); } + /// Return a StringRef equal to 'this', but with all characters satisfying + /// the given predicate dropped from the beginning of the string. + LLVM_ATTRIBUTE_ALWAYS_INLINE + LLVM_ATTRIBUTE_UNUSED_RESULT + StringRef drop_while(function_ref F) const { + return substr(find_if_not(F)); + } + + /// Return a StringRef equal to 'this', but with all characters not + /// satisfying the given predicate dropped from the beginning of the string. + LLVM_ATTRIBUTE_ALWAYS_INLINE + LLVM_ATTRIBUTE_UNUSED_RESULT + StringRef drop_until(function_ref F) const { + return substr(find_if(F)); + } + /// Returns true if this StringRef has the given prefix and removes that /// prefix. LLVM_ATTRIBUTE_ALWAYS_INLINE diff --git a/unittests/ADT/StringRefTest.cpp b/unittests/ADT/StringRefTest.cpp index 39ed71b77e9..e1f54967572 100644 --- a/unittests/ADT/StringRefTest.cpp +++ b/unittests/ADT/StringRefTest.cpp @@ -864,4 +864,60 @@ TEST(StringRefTest, Take) { EXPECT_TRUE(Taken.empty()); } +TEST(StringRefTest, FindIf) { + StringRef Punct("Test.String"); + StringRef NoPunct("ABCDEFG"); + StringRef Empty; + + auto IsPunct = [](char c) { return ::ispunct(c); }; + auto IsAlpha = [](char c) { return ::isalpha(c); }; + EXPECT_EQ(4, Punct.find_if(IsPunct)); + EXPECT_EQ(StringRef::npos, NoPunct.find_if(IsPunct)); + EXPECT_EQ(StringRef::npos, Empty.find_if(IsPunct)); + + EXPECT_EQ(4, Punct.find_if_not(IsAlpha)); + EXPECT_EQ(StringRef::npos, NoPunct.find_if_not(IsAlpha)); + EXPECT_EQ(StringRef::npos, Empty.find_if_not(IsAlpha)); +} + +TEST(StringRefTest, TakeWhileUntil) { + StringRef Test("String With 1 Number"); + + StringRef Taken = Test.take_while([](char c) { return ::isdigit(c); }); + EXPECT_EQ("", Taken); + + Taken = Test.take_until([](char c) { return ::isdigit(c); }); + EXPECT_EQ("String With ", Taken); + + Taken = Test.take_while([](char c) { return true; }); + EXPECT_EQ(Test, Taken); + + Taken = Test.take_until([](char c) { return true; }); + EXPECT_EQ("", Taken); + + Test = ""; + Taken = Test.take_while([](char c) { return true; }); + EXPECT_EQ("", Taken); +} + +TEST(StringRefTest, DropWhileUntil) { + StringRef Test("String With 1 Number"); + + StringRef Taken = Test.drop_while([](char c) { return ::isdigit(c); }); + EXPECT_EQ(Test, Taken); + + Taken = Test.drop_until([](char c) { return ::isdigit(c); }); + EXPECT_EQ("1 Number", Taken); + + Taken = Test.drop_while([](char c) { return true; }); + EXPECT_EQ("", Taken); + + Taken = Test.drop_until([](char c) { return true; }); + EXPECT_EQ(Test, Taken); + + StringRef EmptyString = ""; + Taken = EmptyString.drop_while([](char c) { return true; }); + EXPECT_EQ("", Taken); +} + } // end anonymous namespace