[llvm] f198e0b - [StringView] remove dropFront

[Nick Desaulniers via llvm-commits]

Author: Nick Desaulniers
Date: 2023-04-14T10:24:10-07:00
New Revision: f198e0b594aa697d5aeacf6abe3399c37b446830

URL: https://github.com/llvm/llvm-project/commit/f198e0b594aa697d5aeacf6abe3399c37b446830
DIFF: https://github.com/llvm/llvm-project/commit/f198e0b594aa697d5aeacf6abe3399c37b446830.diff

LOG: [StringView] remove dropFront

Towards converting our use of llvm::StringView to std::string_view,
remove a method that std::string_view doesn't have.
llvm::StringView::dropFront is semantically similar to
std::string_view::substr but with the input clamped to the size. No code
was relying on clamping other than the rust demangler, which I fixed in
https://reviews.llvm.org/D148272.  Removing this method makes it easier
to switch over code later.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D148348

Added: 
    

Modified: 
    llvm/include/llvm/Demangle/ItaniumDemangle.h
    llvm/include/llvm/Demangle/StringView.h
    llvm/lib/Demangle/MicrosoftDemangle.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Demangle/ItaniumDemangle.h b/llvm/include/llvm/Demangle/ItaniumDemangle.h
index 21fd95b7988fb..15760cc3e717b 100644
--- a/llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ b/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -1583,7 +1583,7 @@ class SpecialSubstitution final : public ExpandedSpecialSubstitution {
     if (isInstantiation()) {
       // The instantiations are typedefs that drop the "basic_" prefix.
       assert(SV.startsWith("basic_"));
-      SV = SV.dropFront(sizeof("basic_") - 1);
+      SV.remove_prefix(sizeof("basic_") - 1);
     }
     return SV;
   }
@@ -1838,7 +1838,7 @@ class SubobjectExpr : public Node {
       OB += "0";
     } else if (Offset[0] == 'n') {
       OB += "-";
-      OB += Offset.dropFront();
+      OB += Offset.substr(1);
     } else {
       OB += Offset;
     }
@@ -2264,7 +2264,7 @@ class EnumLiteral : public Node {
     OB.printClose();
 
     if (Integer[0] == 'n')
-      OB << "-" << Integer.dropFront(1);
+      OB << '-' << Integer.substr(1);
     else
       OB << Integer;
   }
@@ -2287,10 +2287,9 @@ class IntegerLiteral : public Node {
       OB.printClose();
     }
 
-    if (Value[0] == 'n') {
-      OB += '-';
-      OB += Value.dropFront(1);
-    } else
+    if (Value[0] == 'n')
+      OB << '-' << Value.substr(1);
+    else
       OB += Value;
 
     if (Type.size() <= 3)
@@ -2632,7 +2631,7 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
       if (Kind < Unnameable) {
         assert(Res.startsWith("operator") &&
                "operator name does not start with 'operator'");
-        Res = Res.dropFront(sizeof("operator") - 1);
+        Res.remove_prefix(sizeof("operator") - 1);
         Res.consumeFront(' ');
       }
       return Res;
@@ -3706,7 +3705,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseQualifiedType() {
 
     // extension            ::= U <objc-name> <objc-type>  # objc-type<identifier>
     if (Qual.startsWith("objcproto")) {
-      StringView ProtoSourceName = Qual.dropFront(std::strlen("objcproto"));
+      StringView ProtoSourceName = Qual.substr(std::strlen("objcproto"));
       StringView Proto;
       {
         ScopedOverride<const char *> SaveFirst(First, ProtoSourceName.begin()),

diff  --git a/llvm/include/llvm/Demangle/StringView.h b/llvm/include/llvm/Demangle/StringView.h
index a5d4baeb7a41c..51d9e25cd8ab8 100644
--- a/llvm/include/llvm/Demangle/StringView.h
+++ b/llvm/include/llvm/Demangle/StringView.h
@@ -55,12 +55,6 @@ class StringView {
     return npos;
   }
 
-  StringView dropFront(size_t N = 1) const {
-    if (N >= size())
-      N = size();
-    return StringView(First + N, Last);
-  }
-
   void remove_prefix(size_t N) {
     assert(size() >= N);
     First += N;
@@ -88,14 +82,14 @@ class StringView {
   bool consumeFront(char C) {
     if (!startsWith(C))
       return false;
-    *this = dropFront(1);
+    remove_prefix(1);
     return true;
   }
 
   bool consumeFront(StringView S) {
     if (!startsWith(S))
       return false;
-    *this = dropFront(S.size());
+    remove_prefix(S.size());
     return true;
   }
 

diff  --git a/llvm/lib/Demangle/MicrosoftDemangle.cpp b/llvm/lib/Demangle/MicrosoftDemangle.cpp
index 284daee88f4bf..4230deaeaa96d 100644
--- a/llvm/lib/Demangle/MicrosoftDemangle.cpp
+++ b/llvm/lib/Demangle/MicrosoftDemangle.cpp
@@ -765,7 +765,7 @@ SymbolNode *Demangler::demangleMD5Name(StringView &MangledName) {
     return nullptr;
   }
   const char *Start = MangledName.begin();
-  MangledName = MangledName.dropFront(MD5Last + 1);
+  MangledName.remove_prefix(MD5Last + 1);
 
   // There are two additional special cases for MD5 names:
   // 1. For complete object locators where the object name is long enough
@@ -902,7 +902,7 @@ std::pair<uint64_t, bool> Demangler::demangleNumber(StringView &MangledName) {
 
   if (startsWithDigit(MangledName)) {
     uint64_t Ret = MangledName[0] - '0' + 1;
-    MangledName = MangledName.dropFront(1);
+    MangledName.remove_prefix(1);
     return {Ret, IsNegative};
   }
 
@@ -910,7 +910,7 @@ std::pair<uint64_t, bool> Demangler::demangleNumber(StringView &MangledName) {
   for (size_t i = 0; i < MangledName.size(); ++i) {
     char C = MangledName[i];
     if (C == '@') {
-      MangledName = MangledName.dropFront(i + 1);
+      MangledName.remove_prefix(i + 1);
       return {Ret, IsNegative};
     }
     if ('A' <= C && C <= 'P') {
@@ -1050,7 +1050,7 @@ uint8_t Demangler::demangleCharLiteral(StringView &MangledName) {
     // Don't append the null terminator.
     uint8_t C1 = rebasedHexDigitToNumber(Nibbles[0]);
     uint8_t C2 = rebasedHexDigitToNumber(Nibbles[1]);
-    MangledName = MangledName.dropFront(2);
+    MangledName.remove_prefix(2);
     return (C1 << 4) | C2;
   }
 
@@ -1310,7 +1310,7 @@ Demangler::demangleStringLiteral(StringView &MangledName) {
   if (CrcEndPos == StringView::npos)
     goto StringLiteralError;
   CRC = MangledName.substr(0, CrcEndPos);
-  MangledName = MangledName.dropFront(CrcEndPos + 1);
+  MangledName.remove_prefix(CrcEndPos + 1);
   if (MangledName.empty())
     goto StringLiteralError;
 
@@ -1391,7 +1391,7 @@ StringView Demangler::demangleSimpleString(StringView &MangledName,
     if (i == 0)
       break;
     S = MangledName.substr(0, i);
-    MangledName = MangledName.dropFront(i + 1);
+    MangledName.remove_prefix(i + 1);
 
     if (Memorize)
       memorizeString(S);