demangle: Update to llvm/llvm-project@ecbc812e0c

externals/demangle/llvm/Demangle/StringView.h

@@ -1,5 +1,5 @@
-//===--- StringView.h -------------------------------------------*- C++ -*-===//
-//
+//===--- StringView.h ----------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-FileCopyrightText: Part of the LLVM Project
@@ -8,6 +8,9 @@
 //===----------------------------------------------------------------------===//
 //
 // FIXME: Use std::string_view instead when we support C++17.
+// There are two copies of this file in the source tree.  The one under
+// libcxxabi is the original and the one under llvm is the copy.  Use
+// cp-to-llvm.sh to update the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
@@ -15,7 +18,6 @@
 #define DEMANGLE_STRINGVIEW_H
 
 #include "DemangleConfig.h"
-#include <algorithm>
 #include <cassert>
 #include <cstring>
 
@@ -37,29 +39,23 @@ public:
   StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
   StringView() : First(nullptr), Last(nullptr) {}
 
-  StringView substr(size_t From) const {
-    return StringView(begin() + From, size() - From);
+  StringView substr(size_t Pos, size_t Len = npos) const {
+    assert(Pos <= size());
+    if (Len > size() - Pos)
+      Len = size() - Pos;
+    return StringView(begin() + Pos, Len);
   }
 
   size_t find(char C, size_t From = 0) const {
-    size_t FindBegin = std::min(From, size());
     // Avoid calling memchr with nullptr.
-    if (FindBegin < size()) {
+    if (From < size()) {
       // Just forward to memchr, which is faster than a hand-rolled loop.
-      if (const void *P = ::memchr(First + FindBegin, C, size() - FindBegin))
+      if (const void *P = ::memchr(First + From, C, size() - From))
         return size_t(static_cast<const char *>(P) - First);
     }
     return npos;
   }
 
-  StringView substr(size_t From, size_t To) const {
-    if (To >= size())
-      To = size() - 1;
-    if (From >= size())
-      From = size() - 1;
-    return StringView(First + From, First + To);
-  }
-
   StringView dropFront(size_t N = 1) const {
     if (N >= size())
       N = size();
@@ -106,7 +102,7 @@ public:
   bool startsWith(StringView Str) const {
     if (Str.size() > size())
       return false;
-    return std::equal(Str.begin(), Str.end(), begin());
+    return std::strncmp(Str.begin(), begin(), Str.size()) == 0;
   }
 
   const char &operator[](size_t Idx) const { return *(begin() + Idx); }
@@ -119,7 +115,7 @@ public:
 
 inline bool operator==(const StringView &LHS, const StringView &RHS) {
   return LHS.size() == RHS.size() &&
-         std::equal(LHS.begin(), LHS.end(), RHS.begin());
+         std::strncmp(LHS.begin(), RHS.begin(), LHS.size()) == 0;
 }
 
 DEMANGLE_NAMESPACE_END