text: // Copyright 2020 The Tint Authors.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #ifndef SRC_WRITER_HLSL_GENERATOR_IMPL_H_
  #define SRC_WRITER_HLSL_GENERATOR_IMPL_H_
  
  #include <string>
  #include <unordered_map>
  #include <unordered_set>
  
  #include "src/ast/array_accessor_expression.h"
  #include "src/ast/assignment_statement.h"
  #include "src/ast/binary_expression.h"
  #include "src/ast/bitcast_expression.h"
  #include "src/ast/break_statement.h"
  #include "src/ast/call_expression.h"
  #include "src/ast/case_statement.h"
  #include "src/ast/continue_statement.h"
  #include "src/ast/discard_statement.h"
  #include "src/ast/identifier_expression.h"
  #include "src/ast/if_statement.h"
  #include "src/ast/intrinsic.h"
  #include "src/ast/literal.h"
  #include "src/ast/loop_statement.h"
  #include "src/ast/member_accessor_expression.h"
  #include "src/ast/return_statement.h"
  #include "src/ast/scalar_constructor_expression.h"
  #include "src/ast/switch_statement.h"
  #include "src/ast/type_constructor_expression.h"
  #include "src/ast/unary_op_expression.h"
  #include "src/program.h"
  #include "src/scope_stack.h"
  #include "src/type/struct_type.h"
  #include "src/writer/hlsl/namer.h"
  
  namespace tint {
  namespace writer {
  namespace hlsl {
  
  /// Implementation class for HLSL generator
  class GeneratorImpl {
   public:
    /// Constructor
    /// @param program the program to generate
    explicit GeneratorImpl(const Program* program);
    ~GeneratorImpl();
  
    /// Increment the emitter indent level
    void increment_indent() { indent_ += 2; }
    /// Decrement the emiter indent level
    void decrement_indent() {
      if (indent_ < 2) {
        indent_ = 0;
        return;
      }
      indent_ -= 2;
    }
  
    /// Writes the current indent to the output stream
    /// @param out the output stream
    void make_indent(std::ostream& out);
  
    /// @returns the error
    std::string error() const { return error_; }
  
    /// @param out the output stream
    /// @returns true on successful generation; false otherwise
    bool Generate(std::ostream& out);
  
    /// Handles generating a constructed type
    /// @param out the output stream
    /// @param ty the constructed type to generate
    /// @returns true if the constructed type was emitted
    bool EmitConstructedType(std::ostream& out, const type::Type* ty);
    /// Handles an array accessor expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the expression to emit
    /// @returns true if the array accessor was emitted
    bool EmitArrayAccessor(std::ostream& pre,
                           std::ostream& out,
                           ast::ArrayAccessorExpression* expr);
    /// Handles an assignment statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted successfully
    bool EmitAssign(std::ostream& out, ast::AssignmentStatement* stmt);
    /// Handles generating a binary expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the binary expression
    /// @returns true if the expression was emitted, false otherwise
    bool EmitBinary(std::ostream& pre,
                    std::ostream& out,
                    ast::BinaryExpression* expr);
    /// Handles generating a bitcast expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the as expression
    /// @returns true if the bitcast was emitted
    bool EmitBitcast(std::ostream& pre,
                     std::ostream& out,
                     ast::BitcastExpression* expr);
    /// Handles a block statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted successfully
    bool EmitBlock(std::ostream& out, const ast::BlockStatement* stmt);
    /// Handles a block statement with a newline at the end
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted successfully
    bool EmitIndentedBlockAndNewline(std::ostream& out,
                                     ast::BlockStatement* stmt);
    /// Handles a block statement with a newline at the end
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted successfully
    bool EmitBlockAndNewline(std::ostream& out, const ast::BlockStatement* stmt);
    /// Handles a break statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted successfully
    bool EmitBreak(std::ostream& out, ast::BreakStatement* stmt);
    /// Handles generating a call expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the call expression
    /// @returns true if the call expression is emitted
    bool EmitCall(std::ostream& pre,
                  std::ostream& out,
                  ast::CallExpression* expr);
    /// Handles generating a call to a texture function (`textureSample`,
    /// `textureSampleGrad`, etc)
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the call expression
    /// @returns true if the call expression is emitted
    bool EmitTextureCall(std::ostream& pre,
                         std::ostream& out,
                         ast::CallExpression* expr);
    /// Handles a case statement
    /// @param out the output stream
    /// @param stmt the statement
    /// @returns true if the statment was emitted successfully
    bool EmitCase(std::ostream& out, ast::CaseStatement* stmt);
    /// Handles generating constructor expressions
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the constructor expression
    /// @returns true if the expression was emitted
    bool EmitConstructor(std::ostream& pre,
                         std::ostream& out,
                         ast::ConstructorExpression* expr);
    /// Handles generating a discard statement
    /// @param out the output stream
    /// @param stmt the discard statement
    /// @returns true if the statement was successfully emitted
    bool EmitDiscard(std::ostream& out, ast::DiscardStatement* stmt);
    /// Handles generating a scalar constructor
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the scalar constructor expression
    /// @returns true if the scalar constructor is emitted
    bool EmitScalarConstructor(std::ostream& pre,
                               std::ostream& out,
                               ast::ScalarConstructorExpression* expr);
    /// Handles emitting a type constructor
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the type constructor expression
    /// @returns true if the constructor is emitted
    bool EmitTypeConstructor(std::ostream& pre,
                             std::ostream& out,
                             ast::TypeConstructorExpression* expr);
    /// Handles a continue statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted successfully
    bool EmitContinue(std::ostream& out, ast::ContinueStatement* stmt);
    /// Handles generate an Expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the expression
    /// @returns true if the expression was emitted
    bool EmitExpression(std::ostream& pre,
                        std::ostream& out,
                        ast::Expression* expr);
    /// Handles generating a function
    /// @param out the output stream
    /// @param func the function to generate
    /// @returns true if the function was emitted
    bool EmitFunction(std::ostream& out, ast::Function* func);
    /// Internal helper for emitting functions
    /// @param out the output stream
    /// @param func the function to emit
    /// @param emit_duplicate_functions set true if we need to duplicate per entry
    /// point
    /// @param ep_sym the current entry point or symbol::kInvalid if none set
    /// @returns true if the function was emitted.
    bool EmitFunctionInternal(std::ostream& out,
                              ast::Function* func,
                              bool emit_duplicate_functions,
                              Symbol ep_sym);
    /// Handles emitting information for an entry point
    /// @param out the output stream
    /// @param func the entry point
    /// @param emitted_globals the set of globals emitted over all entry points
    /// @returns true if the entry point data was emitted
    bool EmitEntryPointData(std::ostream& out,
                            ast::Function* func,
                            std::unordered_set<Symbol>& emitted_globals);
    /// Handles emitting the entry point function
    /// @param out the output stream
    /// @param func the entry point
    /// @returns true if the entry point function was emitted
    bool EmitEntryPointFunction(std::ostream& out, ast::Function* func);
    /// Handles an if statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was successfully emitted
    bool EmitIf(std::ostream& out, ast::IfStatement* stmt);
    /// Handles a literal
    /// @param out the output stream
    /// @param lit the literal to emit
    /// @returns true if the literal was successfully emitted
    bool EmitLiteral(std::ostream& out, ast::Literal* lit);
    /// Handles a loop statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted
    bool EmitLoop(std::ostream& out, ast::LoopStatement* stmt);
    /// Handles generating an identifier expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the identifier expression
    /// @returns true if the identifeir was emitted
    bool EmitIdentifier(std::ostream& pre,
                        std::ostream& out,
                        ast::IdentifierExpression* expr);
    /// Handles a member accessor expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the member accessor expression
    /// @returns true if the member accessor was emitted
    bool EmitMemberAccessor(std::ostream& pre,
                            std::ostream& out,
                            ast::MemberAccessorExpression* expr);
    /// Handles a storage buffer accessor expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the storage buffer accessor expression
    /// @param rhs the right side of a store expression. Set to nullptr for a load
    /// @returns true if the storage buffer accessor was emitted
    bool EmitStorageBufferAccessor(std::ostream& pre,
                                   std::ostream& out,
                                   ast::Expression* expr,
                                   ast::Expression* rhs);
    /// Handles return statements
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was successfully emitted
    bool EmitReturn(std::ostream& out, ast::ReturnStatement* stmt);
    /// Handles statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted
    bool EmitStatement(std::ostream& out, ast::Statement* stmt);
    /// Handles generating a switch statement
    /// @param out the output stream
    /// @param stmt the statement to emit
    /// @returns true if the statement was emitted
    bool EmitSwitch(std::ostream& out, ast::SwitchStatement* stmt);
    /// Handles generating type
    /// @param out the output stream
    /// @param type the type to generate
    /// @param name the name of the variable, only used for array emission
    /// @returns true if the type is emitted
    bool EmitType(std::ostream& out, type::Type* type, const std::string& name);
    /// Handles generating a structure declaration
    /// @param out the output stream
    /// @param ty the struct to generate
    /// @param name the struct name
    /// @returns true if the struct is emitted
    bool EmitStructType(std::ostream& out,
                        const type::Struct* ty,
                        const std::string& name);
    /// Handles a unary op expression
    /// @param pre the preamble for the expression stream
    /// @param out the output of the expression stream
    /// @param expr the expression to emit
    /// @returns true if the expression was emitted
    bool EmitUnaryOp(std::ostream& pre,
                     std::ostream& out,
                     ast::UnaryOpExpression* expr);
    /// Emits the zero value for the given type
    /// @param out the output stream
    /// @param type the type to emit the value for
    /// @returns true if the zero value was successfully emitted.
    bool EmitZeroValue(std::ostream& out, type::Type* type);
    /// Handles generating a variable
    /// @param out the output stream
    /// @param var the variable to generate
    /// @param skip_constructor set true if the constructor should be skipped
    /// @returns true if the variable was emitted
    bool EmitVariable(std::ostream& out,
                      ast::Variable* var,
                      bool skip_constructor);
    /// Handles generating a program scope constant variable
    /// @param out the output stream
    /// @param var the variable to emit
    /// @returns true if the variable was emitted
    bool EmitProgramConstVariable(std::ostream& out, const ast::Variable* var);
  
    /// Returns true if the accessor is accessing a storage buffer.
    /// @param expr the expression to check
    /// @returns true if the accessor is accessing a storage buffer for which
    /// we need to execute a Load instruction.
    bool is_storage_buffer_access(ast::MemberAccessorExpression* expr);
    /// Returns true if the accessor is accessing a storage buffer.
    /// @param expr the expression to check
    /// @returns true if the accessor is accessing a storage buffer
    bool is_storage_buffer_access(ast::ArrayAccessorExpression* expr);
    /// Registers the given global with the generator
    /// @param global the global to register
    void register_global(ast::Variable* global);
    /// Checks if the global variable is in an input or output struct
    /// @param var the variable to check
    /// @returns true if the global is in an input or output struct
    bool global_is_in_struct(ast::Variable* var) const;
    /// Creates a text string representing the index into a storage buffer
    /// @param pre the pre stream
    /// @param expr the expression to use as the index
    /// @returns the index string, or blank if unable to generate
    std::string generate_storage_buffer_index_expression(std::ostream& pre,
                                                         ast::Expression* expr);
    /// Generates an intrinsic name from the given name
    /// @param intrinsic the intrinsic to convert to a name
    /// @returns the intrinsic name or blank on error
    std::string generate_intrinsic_name(ast::Intrinsic intrinsic);
    /// Handles generating a builtin method name
    /// @param expr the expression
    /// @returns the name or "" if not valid
    std::string generate_builtin_name(ast::CallExpression* expr);
    /// Converts a builtin to an attribute name
    /// @param builtin the builtin to convert
    /// @returns the string name of the builtin or blank on error
    std::string builtin_to_attribute(ast::Builtin builtin) const;
    /// Determines if the function needs the input struct passed to it.
    /// @param func the function to check
    /// @returns true if there are input struct variables used in the function
    bool has_referenced_in_var_needing_struct(ast::Function* func);
    /// Determines if the function needs the output struct passed to it.
    /// @param func the function to check
    /// @returns true if there are output struct variables used in the function
    bool has_referenced_out_var_needing_struct(ast::Function* func);
    /// Determines if any used program variable requires an input or output
    /// struct.
    /// @param func the function to check
    /// @returns true if an input or output struct is required.
    bool has_referenced_var_needing_struct(ast::Function* func);
  
    /// @returns the namer for testing
    Namer* namer_for_testing() { return &namer_; }
  
    /// Generate a unique name
    /// @param prefix the name prefix
    /// @returns a unique name
    std::string generate_name(const std::string& prefix);
  
   private:
    enum class VarType { kIn, kOut };
  
    struct EntryPointData {
      std::string struct_name;
      std::string var_name;
    };
  
    std::string current_ep_var_name(VarType type);
    std::string get_buffer_name(ast::Expression* expr);
  
    std::string error_;
    size_t indent_ = 0;
  
    Namer namer_;
    const Program* program_ = nullptr;
    type::Manager types_;
    Symbol current_ep_sym_;
    bool generating_entry_point_ = false;
    uint32_t loop_emission_counter_ = 0;
    ScopeStack<ast::Variable*> global_variables_;
    std::unordered_map<Symbol, EntryPointData> ep_sym_to_in_data_;
    std::unordered_map<Symbol, EntryPointData> ep_sym_to_out_data_;
  
    // This maps an input of "<entry_point_name>_<function_name>" to a remapped
    // function name. If there is no entry for a given key then function did
    // not need to be remapped for the entry point and can be emitted directly.
    std::unordered_map<std::string, std::string> ep_func_name_remapped_;
  };
  
  }  // namespace hlsl
  }  // namespace writer
  }  // namespace tint
  
  #endif  // SRC_WRITER_HLSL_GENERATOR_IMPL_H_
  