added basic dataflow analysis to skslc

src/sksl/ir/SkSLVarDeclaration.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_VARDECLARATIONS
-#define SKSL_VARDECLARATIONS
-
-#include "SkSLExpression.h"
-#include "SkSLStatement.h"
-#include "SkSLVariable.h"
-
-namespace SkSL {
-
-/**
- * A single variable declaration within a var declaration statement. For instance, the statement
- * 'int x = 2, y[3];' is a VarDeclarations statement containing two individual VarDeclaration 
- * instances.
- */
-struct VarDeclaration {
-    VarDeclaration(const Variable* var,
-                   std::vector<std::unique_ptr<Expression>> sizes,
-                   std::unique_ptr<Expression> value)
-    : fVar(var)
-    , fSizes(std::move(sizes))
-    , fValue(std::move(value)) {}
-
-    std::string description() const {
-        std::string result = fVar->fName;
-        for (const auto& size : fSizes) {
-            if (size) {
-                result += "[" + size->description() + "]";
-            } else {
-                result += "[]";
-            }
-        }
-        if (fValue) {
-            result += " = " + fValue->description();
-        }
-        return result;        
-    }
-
-    const Variable* fVar;
-    std::vector<std::unique_ptr<Expression>> fSizes;
-    std::unique_ptr<Expression> fValue;
-};
-
-/**
- * A variable declaration statement, which may consist of one or more individual variables.
- */
-struct VarDeclarations : public ProgramElement {
-    VarDeclarations(Position position, const Type* baseType, 
-                    std::vector<VarDeclaration> vars)
-    : INHERITED(position, kVar_Kind)
-    , fBaseType(*baseType)
-    , fVars(std::move(vars)) {}
-
-    std::string description() const override {
-        if (!fVars.size()) {
-            return "";
-        }
-        std::string result = fVars[0].fVar->fModifiers.description() + fBaseType.description() + 
-                             " ";
-        std::string separator = "";
-        for (const auto& var : fVars) {
-            result += separator;
-            separator = ", ";
-            result += var.description();
-        }
-        return result;
-    }
-
-    const Type& fBaseType;
-    const std::vector<VarDeclaration> fVars;
-
-    typedef ProgramElement INHERITED;
-};
-
-} // namespace
-
-#endif