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/SkSLASTCallSuffix.h b/src/sksl/ast/SkSLASTCallSuffix.h
new file mode 100644
index 0000000..5cff6f6
--- /dev/null
+++ b/src/sksl/ast/SkSLASTCallSuffix.h
@@ -0,0 +1,44 @@
+/*
+ * 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_ASTCALLSUFFIX
+#define SKSL_ASTCALLSUFFIX
+
+#include <sstream>
+#include <vector>
+#include "SkSLASTSuffix.h"
+
+namespace SkSL {
+
+/**
+ * A parenthesized list of arguments following an expression, indicating a function call. 
+ */
+struct ASTCallSuffix : public ASTSuffix {
+    ASTCallSuffix(Position position, std::vector<std::unique_ptr<ASTExpression>> arguments) 
+    : INHERITED(position, ASTSuffix::kCall_Kind)
+    , fArguments(std::move(arguments)) {}
+
+    std::string description() const override {
+        std::string result("(");
+        std::string separator = "";
+        for (size_t i = 0; i < fArguments.size(); ++i) {
+            result += separator;
+            separator = ", ";
+            result += fArguments[i]->description();
+        }
+        result += ")";
+        return result;
+    }
+
+    std::vector<std::unique_ptr<ASTExpression>> fArguments;
+
+    typedef ASTSuffix INHERITED;
+};
+
+} // namespace
+
+#endif