1 files changed, 144 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/ImmutableString.h b/gfx/angle/checkout/src/compiler/translator/ImmutableString.h
new file mode 100644
index 0000000000..5f08ea06cc
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/ImmutableString.h
@@ -0,0 +1,144 @@
+//
+// Copyright (c) 2018 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// ImmutableString.h: Wrapper for static or pool allocated char arrays, that are guaranteed to be
+// valid and unchanged for the duration of the compilation.
+//
+
+#ifndef COMPILER_TRANSLATOR_IMMUTABLESTRING_H_
+#define COMPILER_TRANSLATOR_IMMUTABLESTRING_H_
+
+#include <string>
+
+#include "common/string_utils.h"
+#include "compiler/translator/Common.h"
+
+namespace sh
+{
+
+namespace
+{
+constexpr size_t constStrlen(const char *str)
+{
+    if (str == nullptr)
+    {
+        return 0u;
+    }
+    size_t len = 0u;
+    while (*(str + len) != '\0')
+    {
+        ++len;
+    }
+    return len;
+}
+}  // namespace
+
+class ImmutableString
+{
+  public:
+    // The data pointer passed in must be one of:
+    //  1. nullptr (only valid with length 0).
+    //  2. a null-terminated static char array like a string literal.
+    //  3. a null-terminated pool allocated char array. This can't be c_str() of a local TString,
+    //     since when a TString goes out of scope it clears its first character.
+    explicit constexpr ImmutableString(const char *data) : mData(data), mLength(constStrlen(data))
+    {}
+
+    constexpr ImmutableString(const char *data, size_t length) : mData(data), mLength(length) {}
+
+    ImmutableString(const std::string &str)
+        : mData(AllocatePoolCharArray(str.c_str(), str.size())), mLength(str.size())
+    {}
+
+    constexpr ImmutableString(const ImmutableString &) = default;
+
+    ImmutableString &operator=(const ImmutableString &) = default;
+
+    constexpr const char *data() const { return mData ? mData : ""; }
+    constexpr size_t length() const { return mLength; }
+
+    char operator[](size_t index) const { return data()[index]; }
+
+    constexpr bool empty() const { return mLength == 0; }
+    bool beginsWith(const char *prefix) const { return angle::BeginsWith(data(), prefix); }
+    constexpr bool beginsWith(const ImmutableString &prefix) const
+    {
+        return mLength >= prefix.length() && memcmp(data(), prefix.data(), prefix.length()) == 0;
+    }
+    bool contains(const char *substr) const { return strstr(data(), substr) != nullptr; }
+
+    constexpr bool operator==(const ImmutableString &b) const
+    {
+        if (mLength != b.mLength)
+        {
+            return false;
+        }
+        return memcmp(data(), b.data(), mLength) == 0;
+    }
+    constexpr bool operator!=(const ImmutableString &b) const { return !(*this == b); }
+    constexpr bool operator==(const char *b) const
+    {
+        if (b == nullptr)
+        {
+            return empty();
+        }
+        return strcmp(data(), b) == 0;
+    }
+    constexpr bool operator!=(const char *b) const { return !(*this == b); }
+    bool operator==(const std::string &b) const
+    {
+        return mLength == b.length() && memcmp(data(), b.c_str(), mLength) == 0;
+    }
+    bool operator!=(const std::string &b) const { return !(*this == b); }
+
+    constexpr bool operator<(const ImmutableString &b) const
+    {
+        if (mLength < b.mLength)
+        {
+            return true;
+        }
+        if (mLength > b.mLength)
+        {
+            return false;
+        }
+        return (memcmp(data(), b.data(), mLength) < 0);
+    }
+
+    template <size_t hashBytes>
+    struct FowlerNollVoHash
+    {
+        static const size_t kFnvOffsetBasis;
+        static const size_t kFnvPrime;
+
+        constexpr size_t operator()(const ImmutableString &a) const
+        {
+            const char *data = a.data();
+            size_t hash      = kFnvOffsetBasis;
+            while ((*data) != '\0')
+            {
+                hash = hash ^ (*data);
+                hash = hash * kFnvPrime;
+                ++data;
+            }
+            return hash;
+        }
+    };
+
+    // This hash encodes the opening parentheses location (if any), name length and whether the name
+    // contains { or [ characters in addition to a 19-bit hash. This way the hash is more useful for
+    // lookups. The string passed in should be at most 63 characters.
+    uint32_t mangledNameHash() const;
+
+  private:
+    const char *mData;
+    size_t mLength;
+};
+
+constexpr ImmutableString kEmptyImmutableString("");
+}  // namespace sh
+
+std::ostream &operator<<(std::ostream &os, const sh::ImmutableString &str);
+
+#endif  // COMPILER_TRANSLATOR_IMMUTABLESTRING_H_