[libc-commits] [libc] 187099d - [reland][NFC][libc] standardize string_view

Guillaume Chatelet via libc-commits libc-commits at lists.llvm.org
Tue Aug 23 03:56:10 PDT 2022


Author: Guillaume Chatelet
Date: 2022-08-23T10:55:57Z
New Revision: 187099da1c415bd8f717eb5adc75bb1d73c7a0ba

URL: https://github.com/llvm/llvm-project/commit/187099da1c415bd8f717eb5adc75bb1d73c7a0ba
DIFF: https://github.com/llvm/llvm-project/commit/187099da1c415bd8f717eb5adc75bb1d73c7a0ba.diff

LOG: [reland][NFC][libc] standardize string_view

Added: 
    

Modified: 
    libc/src/__support/CPP/string_view.h
    libc/src/stdio/printf_core/core_structs.h
    libc/test/src/__support/CPP/stringview_test.cpp
    libc/test/src/dirent/dirent_test.cpp
    libc/utils/MPFRWrapper/MPFRUtils.cpp

Removed: 
    


################################################################################
diff  --git a/libc/src/__support/CPP/string_view.h b/libc/src/__support/CPP/string_view.h
index 6c17e9b3dbe0c..b6e9a2d0e3843 100644
--- a/libc/src/__support/CPP/string_view.h
+++ b/libc/src/__support/CPP/string_view.h
@@ -33,30 +33,41 @@ class string_view {
     return 0;
   }
 
+  static constexpr size_t length(const char *Str) {
+    for (const char *End = Str;; ++End)
+      if (*End == '\0')
+        return End - Str;
+  }
+
+  bool equals(string_view Other) const {
+    return (Len == Other.Len &&
+            compareMemory(Data, Other.Data, Other.Len) == 0);
+  }
+
 public:
+  using value_type = char;
+  using size_type = size_t;
+  using 
diff erence_type = ptr
diff _t;
+  using pointer = char *;
+  using const_pointer = const char *;
+  using reference = char &;
+  using const_reference = const char &;
+  using const_iterator = char *;
+  using iterator = const_iterator;
+
   // special value equal to the maximum value representable by the type
   // size_type.
-  static constexpr size_t npos = -1;
+  inline static constexpr size_t npos = -1;
 
   constexpr string_view() : Data(nullptr), Len(0) {}
 
   // Assumes Str is a null-terminated string. The length of the string does
   // not include the terminating null character.
-  explicit constexpr string_view(const char *Str) : Data(Str), Len(0) {
-    if (Str == nullptr)
-      return;
-    for (const char *D = Data; *D != '\0'; ++D, ++Len)
-      ;
-    if (Len == 0)
-      Data = nullptr;
-  }
+  // Preconditions: [Str, Str + ​length(Str)) is a valid range.
+  constexpr string_view(const char *Str) : Data(Str), Len(length(Str)) {}
 
-  explicit constexpr string_view(const char *Str, size_t N)
-      : Data(N ? Str : nullptr), Len(Str == nullptr ? 0 : N) {}
-
-  // Ctor for raw literal.
-  template <size_t N>
-  constexpr string_view(const char (&Str)[N]) : string_view(Str, N - 1) {}
+  // Preconditions: [Str, Str + N) is a valid range.
+  constexpr string_view(const char *Str, size_t N) : Data(Str), Len(N) {}
 
   constexpr const char *data() const { return Data; }
 
@@ -90,16 +101,14 @@ class string_view {
     return Len < Other.Len ? -1 : 1;
   }
 
-  // An equivalent method is not available in std::string_view.
-  bool equals(string_view Other) const {
-    return (Len == Other.Len &&
-            compareMemory(Data, Other.Data, Other.Len) == 0);
-  }
-
   inline bool operator==(string_view Other) const { return equals(Other); }
   inline bool operator!=(string_view Other) const { return !(*this == Other); }
-  inline bool operator<(string_view Other) const { return compare(Other) == -1; }
-  inline bool operator<=(string_view Other) const { return compare(Other) != 1; }
+  inline bool operator<(string_view Other) const {
+    return compare(Other) == -1;
+  }
+  inline bool operator<=(string_view Other) const {
+    return compare(Other) != 1;
+  }
   inline bool operator>(string_view Other) const { return compare(Other) == 1; }
   inline bool operator>=(string_view Other) const {
     return compare(Other) != -1;
@@ -116,16 +125,6 @@ class string_view {
   // The behavior is undefined if n > size().
   void remove_suffix(size_t N) { Len -= N; }
 
-  // An equivalent method is not available in std::string_view.
-  string_view trim(const char C) const {
-    string_view Copy = *this;
-    while (Copy.starts_with(C))
-      Copy = Copy.drop_front();
-    while (Copy.ends_with(C))
-      Copy = Copy.drop_back();
-    return Copy;
-  }
-
   // Check if this string starts with the given Prefix.
   bool starts_with(string_view Prefix) const {
     return Len >= Prefix.Len &&
@@ -162,129 +161,27 @@ class string_view {
     return string_view(Data + Start, min(N, Len - Start));
   }
 
-  // Search for the first character matching the character
-  //
-  // Returns The index of the first character satisfying the character starting
-  // from From, or npos if not found.
-  size_t find_first_of(const char c, size_t From = 0) const noexcept {
-    string_view S = drop_front(From);
-    while (!S.empty()) {
-      if (S.front() == c)
-        return size() - S.size();
-      S = S.drop_front();
-    }
-    return npos;
-  }
-
-  // Search for the last character matching the character
-  //
-  // Return the index of the last character equal to the |c| before End.
-  size_t find_last_of(const char c, size_t End = npos) const {
-    End = End > size() ? size() : End + 1;
-    string_view S = drop_back(size() - End);
-    while (!S.empty()) {
-      if (S.back() == c)
-        return S.size() - 1;
-      S = S.drop_back();
-    }
-    return npos;
-  }
-
-  // Search for the first character satisfying the predicate Function
-  //
-  // Returns The index of the first character satisfying Function starting from
-  // From, or npos if not found.
-  template <typename F> size_t find_if(F Function, size_t From = 0) const {
-    string_view S = drop_front(From);
-    while (!S.empty()) {
-      if (Function(S.front()))
-        return size() - S.size();
-      S = S.drop_front();
-    }
-    return npos;
-  }
-
-  // Search for the first character not satisfying the predicate Function
-  // Returns The index of the first character not satisfying Function starting
-  // from From, or npos if not found.
-  template <typename F> size_t find_if_not(F Function, size_t From = 0) const {
-    return find_if([Function](char c) { return !Function(c); }, From);
-  }
-
   // front - Get the first character in the string.
   char front() const { return Data[0]; }
 
   // back - Get the last character in the string.
   char back() const { return Data[Len - 1]; }
 
-  // Return a string_view equal to 'this' but with the first N elements
-  // dropped.
-  string_view drop_front(size_t N = 1) const { return substr(N); }
-
-  // Return a string_view equal to 'this' but with the last N elements
-  // dropped.
-  string_view drop_back(size_t N = 1) const { return substr(0, size() - N); }
-
-  // Return a string_view equal to 'this' but with only the first N
-  // elements remaining.  If N is greater than the length of the
-  // string, the entire string is returned.
-  string_view take_front(size_t N = 1) const {
-    if (N >= size())
-      return *this;
-    return drop_back(size() - N);
-  }
-
-  // Return a string_view equal to 'this' but with only the last N
-  // elements remaining.  If N is greater than the length of the
-  // string, the entire string is returned.
-  string_view take_back(size_t N = 1) const {
-    if (N >= size())
-      return *this;
-    return drop_front(size() - N);
-  }
-
-  // Return the longest prefix of 'this' such that every character
-  // in the prefix satisfies the given predicate.
-  template <typename F> string_view take_while(F Function) const {
-    return substr(0, find_if_not(Function));
-  }
-
-  // Return the longest prefix of 'this' such that no character in
-  // the prefix satisfies the given predicate.
-  template <typename F> string_view take_until(F Function) const {
-    return substr(0, find_if(Function));
-  }
-
-  // Return a string_view equal to 'this', but with all characters satisfying
-  // the given predicate dropped from the beginning of the string.
-  template <typename F> string_view drop_while(F Function) const {
-    return substr(find_if_not(Function));
-  }
-
-  // Return a string_view equal to 'this', but with all characters not
-  // satisfying the given predicate dropped from the beginning of the string.
-  template <typename F> string_view drop_until(F Function) const {
-    return substr(find_if(Function));
-  }
-
-  // Returns true if this string_view has the given prefix and removes that
-  // prefix.
-  bool consume_front(string_view Prefix) {
-    if (!starts_with(Prefix))
-      return false;
-
-    *this = drop_front(Prefix.size());
-    return true;
+  // Finds the first occurence of c in this view, starting at position From.
+  size_t find_first_of(const char c, size_t From = 0) const {
+    for (size_t Pos = From; Pos < size(); ++Pos)
+      if ((*this)[Pos] == c)
+        return Pos;
+    return npos;
   }
 
-  // Returns true if this string_view has the given suffix and removes that
-  // suffix.
-  bool consume_back(string_view Suffix) {
-    if (!ends_with(Suffix))
-      return false;
-
-    *this = drop_back(Suffix.size());
-    return true;
+  // Finds the last occurence of c in this view, ending at position End.
+  size_t find_last_of(const char c, size_t End = npos) const {
+    End = End > size() ? size() : End + 1;
+    for (; End > 0; --End)
+      if ((*this)[End - 1] == c)
+        return End - 1;
+    return npos;
   }
 };
 

diff  --git a/libc/src/stdio/printf_core/core_structs.h b/libc/src/stdio/printf_core/core_structs.h
index c229096039feb..25e530337eec4 100644
--- a/libc/src/stdio/printf_core/core_structs.h
+++ b/libc/src/stdio/printf_core/core_structs.h
@@ -58,8 +58,8 @@ struct FormatSection {
     if (has_conv != other.has_conv)
       return false;
 
-    if (!cpp::string_view(raw_string, raw_len)
-             .equals(cpp::string_view(other.raw_string, other.raw_len)))
+    if (cpp::string_view(raw_string, raw_len) !=
+        cpp::string_view(other.raw_string, other.raw_len))
       return false;
 
     if (has_conv) {

diff  --git a/libc/test/src/__support/CPP/stringview_test.cpp b/libc/test/src/__support/CPP/stringview_test.cpp
index 87853d8b1cfc7..bd6b614218bb4 100644
--- a/libc/test/src/__support/CPP/stringview_test.cpp
+++ b/libc/test/src/__support/CPP/stringview_test.cpp
@@ -1,4 +1,5 @@
-//===-- Unittests for string_view ------------------------------------------===//
+//===-- Unittests for string_view
+//------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -18,19 +19,11 @@ TEST(LlvmLibcStringViewTest, InitializeCheck) {
 
   v = string_view("");
   ASSERT_EQ(v.size(), size_t(0));
-  ASSERT_TRUE(v.data() == nullptr);
-
-  v = string_view(nullptr);
-  ASSERT_EQ(v.size(), size_t(0));
-  ASSERT_TRUE(v.data() == nullptr);
-
-  v = string_view(nullptr, 10);
-  ASSERT_EQ(v.size(), size_t(0));
-  ASSERT_TRUE(v.data() == nullptr);
+  ASSERT_TRUE(v.data() != nullptr);
 
   v = string_view("abc", 0);
   ASSERT_EQ(v.size(), size_t(0));
-  ASSERT_TRUE(v.data() == nullptr);
+  ASSERT_TRUE(v.data() != nullptr);
 
   v = string_view("123456789");
   ASSERT_EQ(v.size(), size_t(9));
@@ -38,13 +31,13 @@ TEST(LlvmLibcStringViewTest, InitializeCheck) {
 
 TEST(LlvmLibcStringViewTest, Equals) {
   string_view v("abc");
-  ASSERT_TRUE(v.equals(string_view("abc")));
-  ASSERT_FALSE(v.equals(string_view()));
-  ASSERT_FALSE(v.equals(string_view("")));
-  ASSERT_FALSE(v.equals(string_view("123")));
-  ASSERT_FALSE(v.equals(string_view("abd")));
-  ASSERT_FALSE(v.equals(string_view("aaa")));
-  ASSERT_FALSE(v.equals(string_view("abcde")));
+  ASSERT_EQ(v, string_view("abc"));
+  ASSERT_NE(v, string_view());
+  ASSERT_NE(v, string_view(""));
+  ASSERT_NE(v, string_view("123"));
+  ASSERT_NE(v, string_view("abd"));
+  ASSERT_NE(v, string_view("aaa"));
+  ASSERT_NE(v, string_view("abcde"));
 }
 
 TEST(LlvmLibcStringViewTest, startsWith) {
@@ -81,12 +74,12 @@ TEST(LlvmLibcStringViewTest, RemovePrefix) {
   string_view a("123456789");
   a.remove_prefix(0);
   ASSERT_EQ(a.size(), size_t(9));
-  ASSERT_TRUE(a.equals(string_view("123456789")));
+  ASSERT_TRUE(a == "123456789");
 
   string_view b("123456789");
   b.remove_prefix(4);
   ASSERT_EQ(b.size(), size_t(5));
-  ASSERT_TRUE(b.equals(string_view("56789")));
+  ASSERT_TRUE(b == "56789");
 
   string_view c("123456789");
   c.remove_prefix(9);
@@ -97,59 +90,18 @@ TEST(LlvmLibcStringViewTest, RemoveSuffix) {
   string_view a("123456789");
   a.remove_suffix(0);
   ASSERT_EQ(a.size(), size_t(9));
-  ASSERT_TRUE(a.equals(string_view("123456789")));
+  ASSERT_TRUE(a == "123456789");
 
   string_view b("123456789");
   b.remove_suffix(4);
   ASSERT_EQ(b.size(), size_t(5));
-  ASSERT_TRUE(b.equals(string_view("12345")));
+  ASSERT_TRUE(b == "12345");
 
   string_view c("123456789");
   c.remove_suffix(9);
   ASSERT_EQ(c.size(), size_t(0));
 }
 
-TEST(LlvmLibcStringViewTest, TrimSingleChar) {
-  string_view v("     123456789   ");
-  auto t = v.trim(' ');
-  ASSERT_EQ(t.size(), size_t(9));
-  ASSERT_TRUE(t.equals(string_view("123456789")));
-
-  v = string_view("====12345==");
-  t = v.trim(' ');
-  ASSERT_EQ(v.size(), size_t(11));
-  ASSERT_TRUE(t.equals(string_view("====12345==")));
-
-  t = v.trim('=');
-  ASSERT_EQ(t.size(), size_t(5));
-  ASSERT_TRUE(t.equals(string_view("12345")));
-
-  v = string_view("12345===");
-  t = v.trim('=');
-  ASSERT_EQ(t.size(), size_t(5));
-  ASSERT_TRUE(t.equals(string_view("12345")));
-
-  v = string_view("===========12345");
-  t = v.trim('=');
-  ASSERT_EQ(t.size(), size_t(5));
-  ASSERT_TRUE(t.equals(string_view("12345")));
-
-  v = string_view("============");
-  t = v.trim('=');
-  ASSERT_EQ(t.size(), size_t(0));
-  ASSERT_TRUE(t.data() == nullptr);
-
-  v = string_view();
-  t = v.trim(' ');
-  ASSERT_EQ(t.size(), size_t(0));
-  ASSERT_TRUE(t.data() == nullptr);
-
-  v = string_view("");
-  t = v.trim(' ');
-  ASSERT_EQ(t.size(), size_t(0));
-  ASSERT_TRUE(t.data() == nullptr);
-}
-
 TEST(LlvmLibcStringViewTest, Observer) {
   string_view ABC("abc");
   ASSERT_EQ(ABC.size(), size_t(3));
@@ -160,32 +112,6 @@ TEST(LlvmLibcStringViewTest, Observer) {
 
 bool isDigit(char c) { return c >= '0' && c <= '9'; }
 
-TEST(LlvmLibcStringViewTest, Transform) {
-  ASSERT_TRUE(string_view("123abc").drop_back(3).equals("123"));
-  ASSERT_TRUE(string_view("123abc").drop_front(3).equals("abc"));
-  ASSERT_TRUE(string_view("123abc").take_back(3).equals("abc"));
-  ASSERT_TRUE(string_view("123abc").take_front(3).equals("123"));
-
-  ASSERT_TRUE(string_view("123abc").take_while(&isDigit).equals("123"));
-  ASSERT_TRUE(string_view("abc123").take_until(&isDigit).equals("abc"));
-  ASSERT_TRUE(string_view("123abc").drop_while(&isDigit).equals("abc"));
-  ASSERT_TRUE(string_view("abc123").drop_until(&isDigit).equals("123"));
-}
-
-TEST(LlvmLibcStringViewTest, ConsumeFront) {
-  string_view Tmp("abc");
-  ASSERT_FALSE(Tmp.consume_front("###"));
-  ASSERT_TRUE(Tmp.consume_front("ab"));
-  ASSERT_TRUE(Tmp.equals("c"));
-}
-
-TEST(LlvmLibcStringViewTest, ConsumeBack) {
-  string_view Tmp("abc");
-  ASSERT_FALSE(Tmp.consume_back("###"));
-  ASSERT_TRUE(Tmp.consume_back("bc"));
-  ASSERT_TRUE(Tmp.equals("a"));
-}
-
 TEST(LlvmLibcStringViewTest, FindFirstOf) {
   string_view Tmp("abca");
   ASSERT_TRUE(Tmp.find_first_of('a') == 0);

diff  --git a/libc/test/src/dirent/dirent_test.cpp b/libc/test/src/dirent/dirent_test.cpp
index 5fb32052ce032..82fb09acedd56 100644
--- a/libc/test/src/dirent/dirent_test.cpp
+++ b/libc/test/src/dirent/dirent_test.cpp
@@ -33,13 +33,13 @@ TEST(LlvmLibcDirentTest, SimpleOpenAndRead) {
     struct ::dirent *d = __llvm_libc::readdir(dir);
     if (d == nullptr)
       break;
-    if (string_view(&d->d_name[0]).equals("file1.txt"))
+    if (string_view(&d->d_name[0]) == "file1.txt")
       file1 = d;
-    if (string_view(&d->d_name[0]).equals("file2.txt"))
+    if (string_view(&d->d_name[0]) == "file2.txt")
       file2 = d;
-    if (string_view(&d->d_name[0]).equals("dir1"))
+    if (string_view(&d->d_name[0]) == "dir1")
       dir1 = d;
-    if (string_view(&d->d_name[0]).equals("dir2"))
+    if (string_view(&d->d_name[0]) == "dir2")
       dir2 = d;
   }
 

diff  --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index 60651dacd7421..b5e4de10a066c 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -380,7 +380,12 @@ class MPFRNumber {
     char buffer[printBufSize];
     mpfr_snprintf(buffer, printBufSize, "%100.50Rf", value);
     cpp::string_view view(buffer);
-    view = view.trim(' ');
+    // Trim whitespaces
+    const char whitespace = ' ' ;
+    while (!view.empty() && view.front() == whitespace)
+      view = view.drop_front();
+    while (!view.empty() && view.back() == whitespace)
+      view = view.drop_back();
     return std::string(view.data());
   }
 


        


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