1 files changed, 80 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/ImmutableStringBuilder.h b/gfx/angle/checkout/src/compiler/translator/ImmutableStringBuilder.h
new file mode 100644
index 0000000000..2af963821c
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/ImmutableStringBuilder.h
@@ -0,0 +1,80 @@
+//
+// Copyright 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.
+//
+// ImmutableStringBuilder.h: Stringstream-like utility for building pool allocated strings where the
+// maximum length is known in advance.
+//
+
+#ifndef COMPILER_TRANSLATOR_IMMUTABLESTRINGBUILDER_H_
+#define COMPILER_TRANSLATOR_IMMUTABLESTRINGBUILDER_H_
+
+#include "compiler/translator/ImmutableString.h"
+
+namespace sh
+{
+
+class ImmutableStringBuilder
+{
+  public:
+    ImmutableStringBuilder(size_t maxLength)
+        : mPos(0u), mMaxLength(maxLength), mData(AllocateEmptyPoolCharArray(maxLength))
+    {}
+
+    ImmutableStringBuilder &operator<<(const ImmutableString &str);
+
+    ImmutableStringBuilder &operator<<(const char *str);
+
+    ImmutableStringBuilder &operator<<(const char &c);
+
+    // This invalidates the ImmutableStringBuilder, so it should only be called once.
+    operator ImmutableString();
+
+    void appendDecimal(const uint32_t &i);
+
+    template <typename T>
+    void appendHex(T number)
+    {
+        ASSERT(mData != nullptr);
+        ASSERT(mPos + sizeof(T) * 2u <= mMaxLength);
+        int index = static_cast<int>(sizeof(T)) * 2 - 1;
+        // Loop through leading zeroes.
+        while (((number >> (index * 4)) & 0xfu) == 0 && index > 0)
+        {
+            --index;
+        }
+        // Write the rest of the hex digits.
+        while (index >= 0)
+        {
+            char digit     = static_cast<char>((number >> (index * 4)) & 0xfu);
+            char digitChar = (digit < 10) ? (digit + '0') : (digit + ('a' - 10));
+            mData[mPos++]  = digitChar;
+            --index;
+        }
+    }
+
+    template <typename T>
+    static constexpr size_t GetHexCharCount()
+    {
+        return sizeof(T) * 2;
+    }
+
+  private:
+    inline static char *AllocateEmptyPoolCharArray(size_t strLength)
+    {
+        size_t requiredSize = strLength + 1u;
+        return static_cast<char *>(GetGlobalPoolAllocator()->allocate(requiredSize));
+    }
+
+    size_t mPos;
+    size_t mMaxLength;
+    char *mData;
+};
+
+// GLSL ES 3.00.6 section 3.9: the maximum length of an identifier is 1024 characters.
+constexpr unsigned int kESSLMaxIdentifierLength = 1024u;
+
+}  // namespace sh
+
+#endif  // COMPILER_TRANSLATOR_IMMUTABLESTRINGBUILDER_H_