[libc-commits] [PATCH] D129618: Add support for two more string_view functions

[Jeff Bailey via Phabricator via libc-commits]

jeffbailey created this revision.
jeffbailey added a reviewer: gchatelet.
Herald added projects: libc-project, All.
Herald added a subscriber: libc-commits.
jeffbailey requested review of this revision.

1. Support starts_with(char)
2. Support find_first_of(char, size_t)

Tested:
New unit tests.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D129618

Files:
  libc/src/__support/CPP/StringView.h
  libc/test/src/__support/CPP/stringview_test.cpp


Index: libc/test/src/__support/CPP/stringview_test.cpp
===================================================================
--- libc/test/src/__support/CPP/stringview_test.cpp
+++ libc/test/src/__support/CPP/stringview_test.cpp
@@ -49,11 +49,13 @@
 
 TEST(LlvmLibcStringViewTest, startsWith) {
   StringView v("abc");
+  ASSERT_TRUE(v.starts_with('a'));
   ASSERT_TRUE(v.starts_with(StringView("a")));
   ASSERT_TRUE(v.starts_with(StringView("ab")));
   ASSERT_TRUE(v.starts_with(StringView("abc")));
   ASSERT_TRUE(v.starts_with(StringView()));
   ASSERT_TRUE(v.starts_with(StringView("")));
+  ASSERT_FALSE(v.starts_with('1'));
   ASSERT_FALSE(v.starts_with(StringView("123")));
   ASSERT_FALSE(v.starts_with(StringView("abd")));
   ASSERT_FALSE(v.starts_with(StringView("aaa")));
@@ -176,3 +178,17 @@
   ASSERT_TRUE(Tmp.consume_back("bc"));
   ASSERT_TRUE(Tmp.equals("a"));
 }
+
+TEST(LlvmLibcStringViewTest, FindFirstOf) {
+  StringView Tmp("abca");
+  ASSERT_TRUE(Tmp.find_first_of('a') == 0);
+  ASSERT_TRUE(Tmp.find_first_of('d') == StringView::npos);
+  ASSERT_TRUE(Tmp.find_first_of('b') == 1);
+  ASSERT_TRUE(Tmp.find_first_of('a', 0) == 0);
+  ASSERT_TRUE(Tmp.find_first_of('b', 1) == 1);
+  ASSERT_TRUE(Tmp.find_first_of('a', 1) == 3);
+  ASSERT_TRUE(Tmp.find_first_of('a', 42) == StringView::npos);
+  ASSERT_FALSE(Tmp.find_first_of('c') == 1);
+  ASSERT_FALSE(Tmp.find_first_of('c', 0) == 1);
+  ASSERT_FALSE(Tmp.find_first_of('c', 1) == 1);
+}
Index: libc/src/__support/CPP/StringView.h
===================================================================
--- libc/src/__support/CPP/StringView.h
+++ libc/src/__support/CPP/StringView.h
@@ -137,6 +137,11 @@
            compareMemory(Data, Prefix.Data, Prefix.Len) == 0;
   }
 
+  // Check if this string starts with the given Prefix.
+  bool starts_with(const char Prefix) const {
+    return Len >= 1 && Data[0] == Prefix;
+  }
+
   // Check if this string ends with the given Suffix.
   bool ends_with(StringView Suffix) const {
     return Len >= Suffix.Len &&
@@ -157,6 +162,20 @@
     return StringView(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 {
+    StringView S = drop_front(From);
+    while (!S.empty()) {
+      if (S.front() == c)
+        return size() - S.size();
+      S = S.drop_front();
+    }
+    return npos;
+  }
+
   // Search for the first character satisfying the predicate Function
   //
   // Returns The index of the first character satisfying Function starting from


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