initial checkin of SkSL compiler

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1984363002
CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot,Build-Mac-Clang-x86_64-Release-CMake-Trybot

Review-Url: https://codereview.chromium.org/1984363002
diff --git a/src/sksl/ast/SkSLASTParameter.h b/src/sksl/ast/SkSLASTParameter.h
new file mode 100644
index 0000000..8f1b453
--- /dev/null
+++ b/src/sksl/ast/SkSLASTParameter.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+ 
+#ifndef SKSL_ASTPARAMETER
+#define SKSL_ASTPARAMETER
+
+#include "SkSLASTModifiers.h"
+#include "SkSLASTType.h"
+
+namespace SkSL {
+
+/**
+ * A declaration of a parameter, as part of a function declaration.
+ */
+struct ASTParameter : public ASTPositionNode {
+    // 'sizes' is a list of the array sizes appearing on a parameter, in source order. 
+    // e.g. int x[3][1] would have sizes [3, 1].
+    ASTParameter(Position position, ASTModifiers modifiers, std::unique_ptr<ASTType> type, 
+                 std::string name, std::vector<int> sizes)
+    : INHERITED(position)
+    , fModifiers(modifiers)
+    , fType(std::move(type))
+    , fName(std::move(name))
+    , fSizes(std::move(sizes)) {}
+
+    std::string description() const override {
+        std::string result = fModifiers.description() + fType->description() + " " + fName;
+        for (int size : fSizes) {
+            result += "[" + to_string(size) + "]";
+        }
+        return result;
+    }
+
+    const ASTModifiers fModifiers;
+    const std::unique_ptr<ASTType> fType;
+    const std::string fName;
+    const std::vector<int> fSizes;
+
+    typedef ASTPositionNode INHERITED;
+};
+
+} // namespace
+
+#endif