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n-api: remove napi_get_value_string_length()
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This API doesn't serve much purpose, and is only likely to cause
confusion and bugs. The intention was that this would return the
number of characters in a string independent of encoding, but
that's not generally useful. In almost all cases, one of the
encoding-specific napi_get_value_string_* APIs is more correct.
(Pass a null buffer if only the encoded length is desired.)

Anyway the current implementation of napi_get_value_string_length()
is technically wrong: it returns the number of 2-byte code units of
the UTF-16 encoding, but there are actually some characters that
are encoded as two UTF-16 code units.

Note the JavaScript String.prototype.length property returns the
number of UTF-16 code units, which may be different from the number
of characters. So, getting the true character count is not common
with JavaScript, and is probably best left to specialized
internationalization libraries.

Backport-PR-URL: #19447
PR-URL: #12496
Fixes: nodejs/abi-stable-node#226
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
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@jasongin @MylesBorins
jasongin authored and MylesBorins committed Apr 16, 2018
1 parent d9f3e0d commit f5cfa09
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Showing 4 changed files with 10 additions and 30 deletions.
15 changes: 0 additions & 15 deletions src/node_api.cc
View file
Expand Up @@ -1720,21 +1720,6 @@ napi_status napi_get_value_bool(napi_env env, napi_value value, bool* result) {
return napi_ok;
}

// Gets the number of CHARACTERS in the string.
napi_status napi_get_value_string_length(napi_env env,
napi_value value,
size_t* result) {
NAPI_PREAMBLE(env);
CHECK_ARG(env, result);

v8::Local<v8::Value> val = v8impl::V8LocalValueFromJsValue(value);
RETURN_STATUS_IF_FALSE(env, val->IsString(), napi_string_expected);

*result = val.As<v8::String>()->Length();

return GET_RETURN_STATUS(env);
}

// Copies a JavaScript string into a LATIN-1 string buffer. The result is the
// number of bytes (excluding the null terminator) copied into buf.
// A sufficient buffer size should be greater than the length of string,
Expand Down
5 changes: 0 additions & 5 deletions src/node_api.h
View file
Expand Up @@ -171,11 +171,6 @@ NAPI_EXTERN napi_status napi_get_value_bool(napi_env env,
napi_value value,
bool* result);

// Gets the number of CHARACTERS in the string.
NAPI_EXTERN napi_status napi_get_value_string_length(napi_env env,
napi_value value,
size_t* result);

// Copies LATIN-1 encoded bytes from a string into a buffer.
NAPI_EXTERN napi_status napi_get_value_string_latin1(napi_env env,
napi_value value,
Expand Down
14 changes: 7 additions & 7 deletions test/addons-napi/test_string/test.js
View file
Expand Up @@ -9,7 +9,7 @@ const empty = '';
assert.strictEqual(test_string.TestLatin1(empty), empty);
assert.strictEqual(test_string.TestUtf8(empty), empty);
assert.strictEqual(test_string.TestUtf16(empty), empty);
assert.strictEqual(test_string.Length(empty), 0);
assert.strictEqual(test_string.Utf16Length(empty), 0);
assert.strictEqual(test_string.Utf8Length(empty), 0);

const str1 = 'hello world';
Expand All @@ -19,7 +19,7 @@ assert.strictEqual(test_string.TestUtf16(str1), str1);
assert.strictEqual(test_string.TestLatin1Insufficient(str1), str1.slice(0, 3));
assert.strictEqual(test_string.TestUtf8Insufficient(str1), str1.slice(0, 3));
assert.strictEqual(test_string.TestUtf16Insufficient(str1), str1.slice(0, 3));
assert.strictEqual(test_string.Length(str1), 11);
assert.strictEqual(test_string.Utf16Length(str1), 11);
assert.strictEqual(test_string.Utf8Length(str1), 11);

const str2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
Expand All @@ -29,7 +29,7 @@ assert.strictEqual(test_string.TestUtf16(str2), str2);
assert.strictEqual(test_string.TestLatin1Insufficient(str2), str2.slice(0, 3));
assert.strictEqual(test_string.TestUtf8Insufficient(str2), str2.slice(0, 3));
assert.strictEqual(test_string.TestUtf16Insufficient(str2), str2.slice(0, 3));
assert.strictEqual(test_string.Length(str2), 62);
assert.strictEqual(test_string.Utf16Length(str2), 62);
assert.strictEqual(test_string.Utf8Length(str2), 62);

const str3 = '?!@#$%^&*()_+-=[]{}/.,<>\'"\\';
Expand All @@ -39,7 +39,7 @@ assert.strictEqual(test_string.TestUtf16(str3), str3);
assert.strictEqual(test_string.TestLatin1Insufficient(str3), str3.slice(0, 3));
assert.strictEqual(test_string.TestUtf8Insufficient(str3), str3.slice(0, 3));
assert.strictEqual(test_string.TestUtf16Insufficient(str3), str3.slice(0, 3));
assert.strictEqual(test_string.Length(str3), 27);
assert.strictEqual(test_string.Utf16Length(str3), 27);
assert.strictEqual(test_string.Utf8Length(str3), 27);

const str4 = '¡¢£¤¥¦§¨©ª«¬­®¯°±²³´µ¶·¸¹º»¼½¾¿';
Expand All @@ -49,7 +49,7 @@ assert.strictEqual(test_string.TestUtf16(str4), str4);
assert.strictEqual(test_string.TestLatin1Insufficient(str4), str4.slice(0, 3));
assert.strictEqual(test_string.TestUtf8Insufficient(str4), str4.slice(0, 1));
assert.strictEqual(test_string.TestUtf16Insufficient(str4), str4.slice(0, 3));
assert.strictEqual(test_string.Length(str4), 31);
assert.strictEqual(test_string.Utf16Length(str4), 31);
assert.strictEqual(test_string.Utf8Length(str4), 62);

const str5 = 'ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþ';
Expand All @@ -59,13 +59,13 @@ assert.strictEqual(test_string.TestUtf16(str5), str5);
assert.strictEqual(test_string.TestLatin1Insufficient(str5), str5.slice(0, 3));
assert.strictEqual(test_string.TestUtf8Insufficient(str5), str5.slice(0, 1));
assert.strictEqual(test_string.TestUtf16Insufficient(str5), str5.slice(0, 3));
assert.strictEqual(test_string.Length(str5), 63);
assert.strictEqual(test_string.Utf16Length(str5), 63);
assert.strictEqual(test_string.Utf8Length(str5), 126);

const str6 = '\u{2003}\u{2101}\u{2001}\u{202}\u{2011}';
assert.strictEqual(test_string.TestUtf8(str6), str6);
assert.strictEqual(test_string.TestUtf16(str6), str6);
assert.strictEqual(test_string.TestUtf8Insufficient(str6), str6.slice(0, 1));
assert.strictEqual(test_string.TestUtf16Insufficient(str6), str6.slice(0, 3));
assert.strictEqual(test_string.Length(str6), 5);
assert.strictEqual(test_string.Utf16Length(str6), 5);
assert.strictEqual(test_string.Utf8Length(str6), 14);
6 changes: 3 additions & 3 deletions test/addons-napi/test_string/test_string.c
View file
Expand Up @@ -157,7 +157,7 @@ napi_value TestUtf16Insufficient(napi_env env, napi_callback_info info) {
return output;
}

napi_value Length(napi_env env, napi_callback_info info) {
napi_value Utf16Length(napi_env env, napi_callback_info info) {
size_t argc = 1;
napi_value args[1];
NAPI_CALL(env, napi_get_cb_info(env, info, &argc, args, NULL, NULL));
Expand All @@ -171,7 +171,7 @@ napi_value Length(napi_env env, napi_callback_info info) {
"Wrong type of argment. Expects a string.");

size_t length;
NAPI_CALL(env, napi_get_value_string_length(env, args[0], &length));
NAPI_CALL(env, napi_get_value_string_utf16(env, args[0], NULL, 0, &length));

napi_value output;
NAPI_CALL(env, napi_create_number(env, (double)length, &output));
Expand Down Expand Up @@ -209,7 +209,7 @@ void Init(napi_env env, napi_value exports, napi_value module, void* priv) {
DECLARE_NAPI_PROPERTY("TestUtf8Insufficient", TestUtf8Insufficient),
DECLARE_NAPI_PROPERTY("TestUtf16", TestUtf16),
DECLARE_NAPI_PROPERTY("TestUtf16Insufficient", TestUtf16Insufficient),
DECLARE_NAPI_PROPERTY("Length", Length),
DECLARE_NAPI_PROPERTY("Utf16Length", Utf16Length),
DECLARE_NAPI_PROPERTY("Utf8Length", Utf8Length),
};

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