v8/src/ast-value-factory.h

// Copyright 2014 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
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//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef V8_AST_VALUE_FACTORY_H_
#define V8_AST_VALUE_FACTORY_H_

#include "src/api.h"
#include "src/hashmap.h"
#include "src/utils.h"

// AstString, AstValue and AstValueFactory are for storing strings and values
// independent of the V8 heap and internalizing them later. During parsing,
// AstStrings and AstValues are created and stored outside the heap, in
// AstValueFactory. After parsing, the strings and values are internalized
// (moved into the V8 heap).
namespace v8 {
namespace internal {

class AstString : public ZoneObject {
 public:
  virtual ~AstString() {}

  virtual int length() const = 0;
  bool IsEmpty() const { return length() == 0; }

  // Puts the string into the V8 heap.
  virtual void Internalize(Isolate* isolate) = 0;

  // This function can be called after internalizing.
  V8_INLINE Handle<String> string() const {
    DCHECK(!string_.is_null());
    return string_;
  }

 protected:
  // This is null until the string is internalized.
  Handle<String> string_;
};


class AstRawString : public AstString {
 public:
  virtual int length() const OVERRIDE {
    if (is_one_byte_)
      return literal_bytes_.length();
    return literal_bytes_.length() / 2;
  }

  virtual void Internalize(Isolate* isolate) OVERRIDE;

  bool AsArrayIndex(uint32_t* index) const;

  // The string is not null-terminated, use length() to find out the length.
  const unsigned char* raw_data() const {
    return literal_bytes_.start();
  }
  bool is_one_byte() const { return is_one_byte_; }
  bool IsOneByteEqualTo(const char* data) const;
  uint16_t FirstCharacter() const {
    if (is_one_byte_)
      return literal_bytes_[0];
    const uint16_t* c =
        reinterpret_cast<const uint16_t*>(literal_bytes_.start());
    return *c;
  }

  // For storing AstRawStrings in a hash map.
  uint32_t hash() const {
    return hash_;
  }
  static bool Compare(void* a, void* b);

 private:
  friend class AstValueFactory;
  friend class AstRawStringInternalizationKey;

  AstRawString(bool is_one_byte, const Vector<const byte>& literal_bytes,
            uint32_t hash)
      : is_one_byte_(is_one_byte), literal_bytes_(literal_bytes), hash_(hash) {}

  AstRawString()
      : is_one_byte_(true),
        hash_(0) {}

  bool is_one_byte_;

  // Points to memory owned by Zone.
  Vector<const byte> literal_bytes_;
  uint32_t hash_;
};


class AstConsString : public AstString {
 public:
  AstConsString(const AstString* left, const AstString* right)
      : left_(left),
        right_(right) {}

  virtual int length() const OVERRIDE {
    return left_->length() + right_->length();
  }

  virtual void Internalize(Isolate* isolate) OVERRIDE;

 private:
  friend class AstValueFactory;

  const AstString* left_;
  const AstString* right_;
};


// AstValue is either a string, a number, a string array, a boolean, or a
// special value (null, undefined, the hole).
class AstValue : public ZoneObject {
 public:
  bool IsString() const {
    return type_ == STRING;
  }

  bool IsNumber() const {
    return type_ == NUMBER || type_ == SMI;
  }

  const AstRawString* AsString() const {
    if (type_ == STRING)
      return string_;
    UNREACHABLE();
    return 0;
  }

  double AsNumber() const {
    if (type_ == NUMBER)
      return number_;
    if (type_ == SMI)
      return smi_;
    UNREACHABLE();
    return 0;
  }

  bool EqualsString(const AstRawString* string) const {
    return type_ == STRING && string_ == string;
  }

  bool IsPropertyName() const;

  bool BooleanValue() const;

  void Internalize(Isolate* isolate);

  // Can be called after Internalize has been called.
  V8_INLINE Handle<Object> value() const {
    if (type_ == STRING) {
      return string_->string();
    }
    DCHECK(!value_.is_null());
    return value_;
  }

 private:
  friend class AstValueFactory;

  enum Type {
    STRING,
    SYMBOL,
    NUMBER,
    SMI,
    BOOLEAN,
    STRING_ARRAY,
    NULL_TYPE,
    UNDEFINED,
    THE_HOLE
  };

  explicit AstValue(const AstRawString* s) : type_(STRING) { string_ = s; }

  explicit AstValue(const char* name) : type_(SYMBOL) { symbol_name_ = name; }

  explicit AstValue(double n) : type_(NUMBER) { number_ = n; }

  AstValue(Type t, int i) : type_(t) {
    DCHECK(type_ == SMI);
    smi_ = i;
  }

  explicit AstValue(bool b) : type_(BOOLEAN) { bool_ = b; }

  explicit AstValue(ZoneList<const AstRawString*>* s) : type_(STRING_ARRAY) {
    strings_ = s;
  }

  explicit AstValue(Type t) : type_(t) {
    DCHECK(t == NULL_TYPE || t == UNDEFINED || t == THE_HOLE);
  }

  Type type_;

  // Uninternalized value.
  union {
    const AstRawString* string_;
    double number_;
    int smi_;
    bool bool_;
    ZoneList<const AstRawString*>* strings_;
    const char* symbol_name_;
  };

  // Internalized value (empty before internalized).
  Handle<Object> value_;
};


// For generating string constants.
#define STRING_CONSTANTS(F)                           \
  F(anonymous_function, "(anonymous function)")       \
  F(arguments, "arguments")                           \
  F(constructor, "constructor")                       \
  F(done, "done")                                     \
  F(dot, ".")                                         \
  F(dot_for, ".for")                                  \
  F(dot_generator, ".generator")                      \
  F(dot_generator_object, ".generator_object")        \
  F(dot_iterator, ".iterator")                        \
  F(dot_module, ".module")                            \
  F(dot_result, ".result")                            \
  F(empty, "")                                        \
  F(eval, "eval")                                     \
  F(initialize_const_global, "initializeConstGlobal") \
  F(initialize_var_global, "initializeVarGlobal")     \
  F(make_reference_error, "MakeReferenceError")       \
  F(make_syntax_error, "MakeSyntaxError")             \
  F(make_type_error, "MakeTypeError")                 \
  F(module, "module")                                 \
  F(native, "native")                                 \
  F(next, "next")                                     \
  F(proto, "__proto__")                               \
  F(prototype, "prototype")                           \
  F(this, "this")                                     \
  F(use_asm, "use asm")                               \
  F(use_strict, "use strict")                         \
  F(value, "value")


class AstValueFactory {
 public:
  AstValueFactory(Zone* zone, uint32_t hash_seed)
      : string_table_(AstRawString::Compare),
        zone_(zone),
        isolate_(NULL),
        hash_seed_(hash_seed) {
#define F(name, str) \
    name##_string_ = NULL;
    STRING_CONSTANTS(F)
#undef F
  }

  const AstRawString* GetOneByteString(Vector<const uint8_t> literal);
  const AstRawString* GetOneByteString(const char* string) {
    return GetOneByteString(Vector<const uint8_t>(
        reinterpret_cast<const uint8_t*>(string), StrLength(string)));
  }
  const AstRawString* GetTwoByteString(Vector<const uint16_t> literal);
  const AstRawString* GetString(Handle<String> literal);
  const AstConsString* NewConsString(const AstString* left,
                                     const AstString* right);

  void Internalize(Isolate* isolate);
  bool IsInternalized() {
    return isolate_ != NULL;
  }

#define F(name, str) \
  const AstRawString* name##_string() { \
    if (name##_string_ == NULL) { \
      const char* data = str; \
      name##_string_ = GetOneByteString( \
          Vector<const uint8_t>(reinterpret_cast<const uint8_t*>(data), \
                                static_cast<int>(strlen(data)))); \
    } \
    return name##_string_; \
  }
  STRING_CONSTANTS(F)
#undef F

  const AstValue* NewString(const AstRawString* string);
  // A JavaScript symbol (ECMA-262 edition 6).
  const AstValue* NewSymbol(const char* name);
  const AstValue* NewNumber(double number);
  const AstValue* NewSmi(int number);
  const AstValue* NewBoolean(bool b);
  const AstValue* NewStringList(ZoneList<const AstRawString*>* strings);
  const AstValue* NewNull();
  const AstValue* NewUndefined();
  const AstValue* NewTheHole();

 private:
  const AstRawString* GetString(uint32_t hash, bool is_one_byte,
                                Vector<const byte> literal_bytes);

  // All strings are copied here, one after another (no NULLs inbetween).
  HashMap string_table_;
  // For keeping track of all AstValues and AstRawStrings we've created (so that
  // they can be internalized later).
  List<AstValue*> values_;
  List<AstString*> strings_;
  Zone* zone_;
  Isolate* isolate_;

  uint32_t hash_seed_;

#define F(name, str) \
  const AstRawString* name##_string_;
  STRING_CONSTANTS(F)
#undef F
};

} }  // namespace v8::internal

#undef STRING_CONSTANTS

#endif  // V8_AST_VALUE_FACTORY_H_