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src: Initial implementation of DataView class
This is an initial implementation of DataView class. This change includes the following things: - DataView::New() methods - Getters for DataView (ArrayBuffer(), ByteOffset(), ByteLength()) - Tests for them PR-URL: nodejs/node-addon-api#205 Reviewed-By: Michael Dawson <[email protected]> Reviewed-By: Kyle Farnung <[email protected]>
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‎napi-inl.h‎

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@@ -1171,6 +1171,88 @@ inline void ArrayBuffer::EnsureInfo() const {
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}
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}
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#if NAPI_DATA_VIEW_FEATURE
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////////////////////////////////////////////////////////////////////////////////
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// DataView class
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////////////////////////////////////////////////////////////////////////////////
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inline DataView DataView::New(napi_env env,
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Napi::ArrayBuffer arrayBuffer) {
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return New(env, arrayBuffer, 0, arrayBuffer.ByteLength());
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}
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inline DataView DataView::New(napi_env env,
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Napi::ArrayBuffer arrayBuffer,
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size_t byteOffset) {
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if (byteOffset > arrayBuffer.ByteLength()) {
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NAPI_THROW(RangeError::New(env,
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"Start offset is outside the bounds of the buffer"));
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return DataView();
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}
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return New(env, arrayBuffer, byteOffset,
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arrayBuffer.ByteLength() - byteOffset);
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}
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inline DataView DataView::New(napi_env env,
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Napi::ArrayBuffer arrayBuffer,
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size_t byteOffset,
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size_t byteLength) {
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if (byteOffset + byteLength > arrayBuffer.ByteLength()) {
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NAPI_THROW(RangeError::New(env, "Invalid DataView length"));
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return DataView();
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}
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napi_value value;
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napi_status status = napi_create_dataview(
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env, byteLength, arrayBuffer, byteOffset, &value);
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NAPI_THROW_IF_FAILED(env, status, DataView());
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return DataView(env, value);
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}
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inline DataView::DataView() : Object() {
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}
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inline DataView::DataView(napi_env env, napi_value value) : Object(env, value) {
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}
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inline Napi::ArrayBuffer DataView::ArrayBuffer() const {
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napi_value arrayBuffer;
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napi_status status = napi_get_dataview_info(
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_env,
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_value /* dataView */,
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nullptr /* byteLength */,
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nullptr /* data */,
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&arrayBuffer /* arrayBuffer */,
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nullptr /* byteOffset */);
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NAPI_THROW_IF_FAILED(_env, status, Napi::ArrayBuffer());
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return Napi::ArrayBuffer(_env, arrayBuffer);
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}
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inline size_t DataView::ByteOffset() const {
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size_t byteOffset;
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napi_status status = napi_get_dataview_info(
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_env,
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_value /* dataView */,
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nullptr /* byteLength */,
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nullptr /* data */,
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nullptr /* arrayBuffer */,
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&byteOffset /* byteOffset */);
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NAPI_THROW_IF_FAILED(_env, status, 0);
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return byteOffset;
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}
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inline size_t DataView::ByteLength() const {
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size_t byteLength;
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napi_status status = napi_get_dataview_info(
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_env,
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_value /* dataView */,
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&byteLength /* byteLength */,
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nullptr /* data */,
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nullptr /* arrayBuffer */,
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nullptr /* byteOffset */);
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NAPI_THROW_IF_FAILED(_env, status, 0);
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return byteLength;
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}
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#endif
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////////////////////////////////////////////////////////////////////////////////
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// TypedArray class
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////////////////////////////////////////////////////////////////////////////////

‎napi.h‎

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@@ -778,6 +778,36 @@ namespace Napi {
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T* data);
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};
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#if NAPI_DATA_VIEW_FEATURE
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/// The DataView provides a low-level interface for reading/writing multiple
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/// number types in an ArrayBuffer irrespective of the platform's endianness.
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class DataView : public Object {
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public:
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static DataView New(napi_env env,
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Napi::ArrayBuffer arrayBuffer);
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static DataView New(napi_env env,
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Napi::ArrayBuffer arrayBuffer,
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size_t byteOffset);
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static DataView New(napi_env env,
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Napi::ArrayBuffer arrayBuffer,
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size_t byteOffset,
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size_t byteLength);
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DataView(); ///< Creates a new _empty_ DataView instance.
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DataView(napi_env env, napi_value value); ///< Wraps a N-API value primitive.
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Napi::ArrayBuffer ArrayBuffer() const; ///< Gets the backing array buffer.
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size_t ByteOffset() const; ///< Gets the offset into the buffer where the array starts.
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size_t ByteLength() const; ///< Gets the length of the array in bytes.
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// TODO: This class isn't a complete implementation yet, and will
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// incrementally add additional methods to read/write data into buffer.
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// Currently, this class is wrapped by the NAPI_DATA_VIEW_FEATURE macro flag
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// and this should be enabled only in the tests until the implementation is
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// completed.
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};
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#endif
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class Function : public Object {
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public:
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/// Callable must implement operator() accepting a const CallbackInfo&

‎test/binding.cc‎

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@@ -7,6 +7,7 @@ Object InitAsyncWorker(Env env);
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Object InitBasicTypesNumber(Env env);
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Object InitBasicTypesValue(Env env);
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Object InitBuffer(Env env);
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Object InitDataView(Env env);
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Object InitError(Env env);
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Object InitExternal(Env env);
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Object InitFunction(Env env);
@@ -22,6 +23,7 @@ Object Init(Env env, Object exports) {
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exports.Set("basic_types_number", InitBasicTypesNumber(env));
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exports.Set("basic_types_value", InitBasicTypesValue(env));
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exports.Set("buffer", InitBuffer(env));
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exports.Set("dataview", InitDataView(env));
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exports.Set("error", InitError(env));
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exports.Set("external", InitExternal(env));
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exports.Set("function", InitFunction(env));

‎test/binding.gyp‎

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@@ -7,6 +7,7 @@
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'basic_types/value.cc',
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'binding.cc',
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'buffer.cc',
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'dataview/dataview.cc',
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'error.cc',
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'external.cc',
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'function.cc',

‎test/dataview/dataview.cc‎

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#include "napi.h"
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using namespace Napi;
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static Value CreateDataView1(const CallbackInfo& info) {
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ArrayBuffer arrayBuffer = info[0].As<ArrayBuffer>();
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return DataView::New(info.Env(), arrayBuffer);
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}
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static Value CreateDataView2(const CallbackInfo& info) {
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ArrayBuffer arrayBuffer = info[0].As<ArrayBuffer>();
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size_t byteOffset = info[1].As<Number>().Uint32Value();
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return DataView::New(info.Env(), arrayBuffer, byteOffset);
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}
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static Value CreateDataView3(const CallbackInfo& info) {
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ArrayBuffer arrayBuffer = info[0].As<ArrayBuffer>();
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size_t byteOffset = info[1].As<Number>().Uint32Value();
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size_t byteLength = info[2].As<Number>().Uint32Value();
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return DataView::New(info.Env(), arrayBuffer, byteOffset, byteLength);
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}
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static Value GetArrayBuffer(const CallbackInfo& info) {
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return info[0].As<DataView>().ArrayBuffer();
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}
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static Value GetByteOffset(const CallbackInfo& info) {
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return Number::New(info.Env(), info[0].As<DataView>().ByteOffset());
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}
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static Value GetByteLength(const CallbackInfo& info) {
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return Number::New(info.Env(), info[0].As<DataView>().ByteLength());
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}
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Object InitDataView(Env env) {
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Object exports = Object::New(env);
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exports["createDataView1"] = Function::New(env, CreateDataView1);
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exports["createDataView2"] = Function::New(env, CreateDataView2);
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exports["createDataView3"] = Function::New(env, CreateDataView3);
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exports["getArrayBuffer"] = Function::New(env, GetArrayBuffer);
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exports["getByteOffset"] = Function::New(env, GetByteOffset);
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exports["getByteLength"] = Function::New(env, GetByteLength);
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return exports;
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}

‎test/dataview/dataview.js‎

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'use strict';
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const buildType = process.config.target_defaults.default_configuration;
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const assert = require('assert');
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test(require(`../build/${buildType}/binding.node`));
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test(require(`../build/${buildType}/binding_noexcept.node`));
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function test(binding) {
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function testDataViewCreation(factory, arrayBuffer, offset, length) {
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const view = factory(arrayBuffer, offset, length);
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offset = offset ? offset : 0;
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assert.ok(dataview.getArrayBuffer(view) instanceof ArrayBuffer);
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assert.strictEqual(dataview.getArrayBuffer(view), arrayBuffer);
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assert.strictEqual(dataview.getByteOffset(view), offset);
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assert.strictEqual(dataview.getByteLength(view),
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length ? length : arrayBuffer.byteLength - offset);
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}
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function testInvalidRange(factory, arrayBuffer, offset, length) {
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assert.throws(() => {
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factory(arrayBuffer, offset, length);
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}, RangeError);
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}
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const dataview = binding.dataview;
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const arrayBuffer = new ArrayBuffer(10);
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testDataViewCreation(dataview.createDataView1, arrayBuffer);
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testDataViewCreation(dataview.createDataView2, arrayBuffer, 2);
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testDataViewCreation(dataview.createDataView2, arrayBuffer, 10);
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testDataViewCreation(dataview.createDataView3, arrayBuffer, 2, 4);
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testDataViewCreation(dataview.createDataView3, arrayBuffer, 10, 0);
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testInvalidRange(dataview.createDataView2, arrayBuffer, 11);
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testInvalidRange(dataview.createDataView3, arrayBuffer, 11, 0);
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testInvalidRange(dataview.createDataView3, arrayBuffer, 6, 5);
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}

‎test/index.js‎

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@@ -13,6 +13,7 @@ let testModules = [
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'basic_types/number',
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'basic_types/value',
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'buffer',
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'dataview/dataview',
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'error',
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'external',
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'function',

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