add bigint class

Author: devsnek

doc/bigint.md

@@ -0,0 +1,93 @@
+# BigInt
+
+A JavaScript BigInt value.
+
+## Methods
+
+### New
+
+```cpp
+static BigInt New(Napi::Env env, int64_t value);
+static BigInt New(Napi::Env env, uint64_t value);
+```
+
+ - `[in] env`: The `napi_env` Environment
+ - `[in] value`: The value the JavaScript BigInt will contain
+
+These APIs convert the C `int64_t` and `uint64_t` types to the JavaScript
+`BigInt` type.
+
+```cpp
+static BigInt New(Napi::Env env,
+                  int sign_bit,
+                  size_t word_count,
+                  const uint64_t* words);
+```
+
+ - `[in] env`: The `napi_env` Environment
+ - `[in] sign_bit`: Determines if the resulting BigInt will be positive or negative.
+ - `[in] word_count`: The length of the words array.
+ - `[in] words`: An array of `uint64_t` little-endian 64-bit words.
+
+This API converts an array of unsigned 64-bit words into a single `BigInt`
+value.
+
+The resulting `BigInt` is calculated as: (–1)<sup>`sign_bit`</sup> (`words[0]`
+× (2<sup>64</sup>)<sup>0</sup> + `words[1]` × (2<sup>64</sup>)<sup>1</sup> + …)
+
+### Constructor
+
+```cpp
+Napi::BigInt();
+```
+
+Returns a new empty JavaScript BigInt.
+
+
+### Int64Value
+
+```cpp
+int64_t Int64Value(bool* lossless) const;
+```
+
+ - `[out] lossless`: Indicates whether the BigInt value was converted
+   losslessly.
+
+This API returns the C `int64_t` primitive equivalent of the given JavaScript
+BigInt. If needed it will truncate the value, setting lossless to false.
+
+### Uint64Value
+
+```cpp
+uint64_t Uint64Value(bool* lossless) const;
+```
+
+ - `[out] lossless`: Indicates whether the BigInt value was converted
+   losslessly.
+
+This API returns the C `uint64_t` primitive equivalent of the given JavaScript
+BigInt. If needed it will truncate the value, setting lossless to false.
+
+### WordCount
+
+```cpp
+size_t WordCount() const;
+```
+
+Returns the number of words needed to store this BigInt value.
+
+### ToWords
+
+```cpp
+void ToWords(size_t* word_count, int* sign_bit, uint64_t* words);
+```
+
+ - `[out] sign_bit`: Integer representing if the JavaScript BigInt is positive
+   or negative.
+ - `[in/out] word_count`: Must be initialized to the length of the words array.
+   Upon return, it will be set to the actual number of words that would be
+   needed to store this BigInt.
+ - `[out] words`: Pointer to a pre-allocated 64-bit word array.
+
+This API converts a single BigInt value into a sign bit, 64-bit little-endian
+array, and the number of elements in the array.

napi-inl.h

@@ -287,6 +287,12 @@ inline bool Value::IsNumber() const {
   return Type() == napi_number;
 }
 
+#ifdef NAPI_EXPERIMENTAL
+inline bool Value::IsBigInt() const {
+  return Type() == napi_bigint;
+}
+#endif  // NAPI_EXPERIMENTAL
+
 inline bool Value::IsString() const {
   return Type() == napi_string;
 }
@@ -505,6 +511,69 @@ inline double Number::DoubleValue() const {
   return result;
 }
 
+#ifdef NAPI_EXPERIMENTAL
+////////////////////////////////////////////////////////////////////////////////
+// BigInt Class
+////////////////////////////////////////////////////////////////////////////////
+
+inline BigInt BigInt::New(napi_env env, int64_t val) {
+  napi_value value;
+  napi_status status = napi_create_bigint_int64(env, val, &value);
+  NAPI_THROW_IF_FAILED(env, status, BigInt());
+  return BigInt(env, value);
+}
+
+inline BigInt BigInt::New(napi_env env, uint64_t val) {
+  napi_value value;
+  napi_status status = napi_create_bigint_uint64(env, val, &value);
+  NAPI_THROW_IF_FAILED(env, status, BigInt());
+  return BigInt(env, value);
+}
+
+inline BigInt BigInt::New(napi_env env, int sign_bit, size_t word_count, const uint64_t* words) {
+  napi_value value;
+  napi_status status = napi_create_bigint_words(env, sign_bit, word_count, words, &value);
+  NAPI_THROW_IF_FAILED(env, status, BigInt());
+  return BigInt(env, value);
+}
+
+inline BigInt::BigInt() : Value() {
+}
+
+inline BigInt::BigInt(napi_env env, napi_value value) : Value(env, value) {
+}
+
+inline int64_t BigInt::Int64Value(bool* lossless) const {
+  int64_t result;
+  napi_status status = napi_get_value_bigint_int64(
+      _env, _value, &result, lossless);
+  NAPI_THROW_IF_FAILED(_env, status, 0);
+  return result;
+}
+
+inline uint64_t BigInt::Uint64Value(bool* lossless) const {
+  uint64_t result;
+  napi_status status = napi_get_value_bigint_uint64(
+      _env, _value, &result, lossless);
+  NAPI_THROW_IF_FAILED(_env, status, 0);
+  return result;
+}
+
+inline size_t BigInt::WordCount() const {
+  size_t word_count;
+  napi_status status = napi_get_value_bigint_words(
+      _env, _value, nullptr, &word_count, nullptr);
+  NAPI_THROW_IF_FAILED(_env, status, 0);
+  return word_count;
+}
+
+inline void BigInt::ToWords(int* sign_bit, size_t* word_count, uint64_t* words) {
+  napi_status status = napi_get_value_bigint_words(
+      _env, _value, sign_bit, word_count, words);
+  NAPI_THROW_IF_FAILED(_env, status);
+}
+#endif  // NAPI_EXPERIMENTAL
+
 ////////////////////////////////////////////////////////////////////////////////
 // Name class
 ////////////////////////////////////////////////////////////////////////////////

napi.h

@@ -52,6 +52,9 @@ namespace Napi {
   class Value;
   class Boolean;
   class Number;
+#ifdef NAPI_EXPERIMENTAL
+  class BigInt;
+#endif  // NAPI_EXPERIMENTAL
   class String;
   class Object;
   class Array;
@@ -72,6 +75,10 @@ namespace Napi {
   typedef TypedArrayOf<uint32_t> Uint32Array; ///< Typed-array of unsigned 32-bit integers
   typedef TypedArrayOf<float> Float32Array;   ///< Typed-array of 32-bit floating-point values
   typedef TypedArrayOf<double> Float64Array;  ///< Typed-array of 64-bit floating-point values
+#ifdef NAPI_EXPERIMENTAL
+  typedef TypedArrayOf<int64_t> BigInt64Array;   ///< Typed array of signed 64-bit integers
+  typedef TypedArrayOf<uint64_t> BigUint64Array; ///< Typed array of unsigned 64-bit integers
+#endif  // NAPI_EXPERIMENTAL
 
   /// Defines the signature of a N-API C++ module's registration callback (init) function.
   typedef Object (*ModuleRegisterCallback)(Env env, Object exports);
@@ -171,6 +178,9 @@ namespace Napi {
     bool IsNull() const;        ///< Tests if a value is a null JavaScript value.
     bool IsBoolean() const;     ///< Tests if a value is a JavaScript boolean.
     bool IsNumber() const;      ///< Tests if a value is a JavaScript number.
+#ifdef NAPI_EXPERIMENTAL
+    bool IsBigInt() const;      ///< Tests if a value is a JavaScript bigint.
+#endif  // NAPI_EXPERIMENTAL
     bool IsString() const;      ///< Tests if a value is a JavaScript string.
     bool IsSymbol() const;      ///< Tests if a value is a JavaScript symbol.
     bool IsArray() const;       ///< Tests if a value is a JavaScript array.
@@ -242,6 +252,47 @@ namespace Napi {
     double DoubleValue() const;   ///< Converts a Number value to a 64-bit floating-point value.
   };
 
+#ifdef NAPI_EXPERIMENTAL
+  /// A JavaScript bigint value.
+  class BigInt : public Value {
+  public:
+    static BigInt New(
+      napi_env env, ///< N-API environment
+      int64_t value ///< Number value
+    );
+    static BigInt New(
+      napi_env env,  ///< N-API environment
+      uint64_t value ///< Number value
+    );
+
+    /// Creates a new BigInt object using a specified sign bit and a
+    /// specified list of digits/words.
+    /// The resulting number is calculated as:
+    /// (-1)^sign_bit * (words[0] * (2^64)^0 + words[1] * (2^64)^1 + ...)
+    static BigInt New(
+      napi_env env,          ///< N-API environment
+      int sign_bit,          ///< Sign bit. 1 if negative.
+      size_t word_count,     ///< Number of words in array
+      const uint64_t* words  ///< Array of words
+    );
+
+    BigInt();                               ///< Creates a new _empty_ BigInt instance.
+    BigInt(napi_env env, napi_value value); ///< Wraps a N-API value primitive.
+
+    int64_t Int64Value(bool* lossless) const;   ///< Converts a BigInt value to a 64-bit signed integer value.
+    uint64_t Uint64Value(bool* lossless) const; ///< Converts a BigInt value to a 64-bit unsigned integer value.
+
+    size_t WordCount() const; ///< The number of 64-bit words needed to store the result of ToWords().
+
+    /// Writes the contents of this BigInt to a specified memory location.
+    /// `sign_bit` must be provided and will be set to 1 if this BigInt is negative.
+    /// `*word_count` has to be initialized to the length of the `words` array.
+    /// Upon return, it will be set to the actual number of words that would
+    /// be needed to store this BigInt (i.e. the return value of `WordCount()`).
+    void ToWords(int* sign_bit, size_t* word_count, uint64_t* words);
+  };
+#endif  // NAPI_EXPERIMENTAL
+
   /// A JavaScript string or symbol value (that can be used as a property name).
   class Name : public Value {
   public:
@@ -705,6 +756,10 @@ namespace Napi {
         : std::is_same<T, uint32_t>::value ? napi_uint32_array
         : std::is_same<T, float>::value ? napi_float32_array
         : std::is_same<T, double>::value ? napi_float64_array
+#ifdef NAPI_EXPERIMENTAL
+        : std::is_same<T, int64_t>::value ? napi_bigint64_array
+        : std::is_same<T, uint64_t>::value ? napi_biguint64_array
+#endif  // NAPI_EXPERIMENTAL
         : unknown_array_type;
     }
     /// !endcond
@@ -1551,9 +1606,9 @@ namespace Napi {
     std::string _error;
   };
 
-  // Memory management. 
+  // Memory management.
   class MemoryManagement {
-    public: 
+    public:
       static int64_t AdjustExternalMemory(Env env, int64_t change_in_bytes);
   };
 

test/bigint.cc

@@ -0,0 +1,76 @@
+#define NAPI_EXPERIMENTAL
+#include "napi.h"
+
+using namespace Napi;
+
+namespace {
+
+Value IsLossless(const CallbackInfo& info) {
+  Env env = info.Env();
+
+  BigInt big = info[0].As<BigInt>();
+  bool is_signed = info[1].ToBoolean().Value();
+
+  bool lossless;
+  if (is_signed) {
+    big.Int64Value(&lossless);
+  } else {
+    big.Uint64Value(&lossless);
+  }
+
+  return Boolean::New(env, lossless);
+}
+
+Value TestInt64(const CallbackInfo& info) {
+  bool lossless;
+  int64_t input = info[0].As<BigInt>().Int64Value(&lossless);
+
+  return BigInt::New(info.Env(), input);
+}
+
+Value TestUint64(const CallbackInfo& info) {
+  bool lossless;
+  uint64_t input = info[0].As<BigInt>().Uint64Value(&lossless);
+
+  return BigInt::New(info.Env(), input);
+}
+
+Value TestWords(const CallbackInfo& info) {
+  BigInt big = info[0].As<BigInt>();
+
+  size_t expected_word_count = big.WordCount();
+
+  int sign_bit;
+  size_t word_count = 10;
+  uint64_t words[10];
+
+  big.ToWords(&sign_bit, &word_count, words);
+
+  if (word_count != expected_word_count) {
+    Error::New(info.Env(), "word count did not match").ThrowAsJavaScriptException();
+    return;
+  }
+
+  return BigInt::New(info.Env(), sign_bit, word_count, words);
+}
+
+Value TestTooBigBigInt(const CallbackInfo& info) {
+  int sign_bit = 0;
+  size_t word_count = SIZE_MAX;
+  uint64_t words[10];
+
+  return BigInt::New(info.Env(), sign_bit, word_count, words);
+}
+
+}  // anonymous namespace
+
+Object InitBigInt(Env env) {
+  Object exports = Object::New(env);
+  exports["IsLossless"] = Function::New(env, IsLossless);
+  exports["TestInt64"] = Function::New(env, TestInt64);
+  exports["TestUint64"] = Function::New(env, TestUint64);
+  exports["TestWords"] = Function::New(env, TestWords);
+  exports["TestTooBigBigInt"] = Function::New(env, TestTooBigBigInt);
+
+  return exports;
+}