text: /*
   * 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_SWIZZLE
  #define SKSL_SWIZZLE
  
  #include "include/private/SkSLDefines.h"
  #include "src/sksl/SkSLContext.h"
  #include "src/sksl/SkSLIRGenerator.h"
  #include "src/sksl/SkSLUtil.h"
  #include "src/sksl/ir/SkSLConstructor.h"
  #include "src/sksl/ir/SkSLExpression.h"
  
  namespace SkSL {
  
  /**
   * Represents a vector swizzle operation such as 'float3(1, 2, 3).zyx'.
   */
  struct Swizzle final : public Expression {
      static constexpr Kind kExpressionKind = Kind::kSwizzle;
  
      Swizzle(const Context& context, std::unique_ptr<Expression> base,
              const ComponentArray& components)
              : INHERITED(base->fOffset, kExpressionKind,
                          &base->type().componentType().toCompound(context, components.size(), 1))
              , fBase(std::move(base))
              , fComponents(components) {
          SkASSERT(this->components().size() >= 1 && this->components().size() <= 4);
      }
  
      // Swizzle::Convert permits component arrays containing ZERO or ONE, does typechecking, reports
      // errors via ErrorReporter, and returns an expression that combines constructors and native
      // swizzles (comprised solely of X/Y/W/Z).
      static std::unique_ptr<Expression> Convert(const Context& context,
                                                 std::unique_ptr<Expression> base,
                                                 ComponentArray inComponents);
  
      static std::unique_ptr<Expression> Convert(const Context& context,
                                                 std::unique_ptr<Expression> base,
                                                 skstd::string_view maskString);
  
      // Swizzle::Make does not permit ZERO or ONE in the component array, just X/Y/Z/W; errors are
      // reported via ASSERT.
      static std::unique_ptr<Expression> Make(const Context& context,
                                              std::unique_ptr<Expression> expr,
                                              ComponentArray inComponents);
  
      std::unique_ptr<Expression>& base() {
          return fBase;
      }
  
      const std::unique_ptr<Expression>& base() const {
          return fBase;
      }
  
      const ComponentArray& components() const {
          return fComponents;
      }
  
      bool hasProperty(Property property) const override {
          return this->base()->hasProperty(property);
      }
  
      std::unique_ptr<Expression> clone() const override {
          return std::unique_ptr<Expression>(new Swizzle(&this->type(), this->base()->clone(),
                                                         this->components()));
      }
  
      String description() const override {
          String result = this->base()->description() + ".";
          for (int x : this->components()) {
              result += "xyzw"[x];
          }
          return result;
      }
  
  private:
      static std::unique_ptr<Expression> Convert(const Context& context,
                                                 std::unique_ptr<Expression> base,
                                                 ComponentArray inComponents,
                                                 skstd::string_view maskString);
  
      Swizzle(const Type* type, std::unique_ptr<Expression> base, const ComponentArray& components)
          : INHERITED(base->fOffset, kExpressionKind, type)
          , fBase(std::move(base))
          , fComponents(components) {
          SkASSERT(this->components().size() >= 1 && this->components().size() <= 4);
      }
  
      std::unique_ptr<Expression> fBase;
      ComponentArray fComponents;
  
      using INHERITED = Expression;
  };
  
  }  // namespace SkSL
  
  #endif
  