initial checkin of SkSL compiler

src/sksl/ir/SkSLSymbolTable.h

+/*
+ * 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_SYMBOLTABLE
+#define SKSL_SYMBOLTABLE
+
+#include <memory>
+#include <unordered_map>
+#include "SkSLErrorReporter.h"
+#include "SkSLSymbol.h"
+#include "SkSLUnresolvedFunction.h"
+
+namespace SkSL {
+
+/**
+ * Maps identifiers to symbols. Functions, in particular, are mapped to either FunctionDeclaration
+ * or UnresolvedFunction depending on whether they are overloaded or not.
+ */
+class SymbolTable {
+public:
+    SymbolTable(ErrorReporter& errorReporter)
+    : fErrorReporter(errorReporter) {}
+
+    SymbolTable(std::shared_ptr<SymbolTable> parent, ErrorReporter& errorReporter)
+    : fParent(parent)
+    , fErrorReporter(errorReporter) {}
+
+    std::shared_ptr<Symbol> operator[](const std::string& name);
+
+    void add(const std::string& name, std::shared_ptr<Symbol> symbol);
+
+    const std::shared_ptr<SymbolTable> fParent;
+
+private:
+    static std::vector<std::shared_ptr<FunctionDeclaration>> GetFunctions(
+                                                                  const std::shared_ptr<Symbol>& s);
+
+    std::unordered_map<std::string, std::shared_ptr<Symbol>> fSymbols;
+
+    ErrorReporter& fErrorReporter;
+};
+
+} // namespace
+
+#endif