先核來源與已訂規則
這份假設檔案約定 UTF-16LE,每組兩字節須完整。41 00 42 00 在此是 AB,當作 BE 就變字。本例先核檔案聲明及雙數字節,不自行估次序。
| 紀錄 | 輸入 JSON |
|---|---|
| 原例輸入 | {"encoding":"utf-16le","bytes":[65,0,66,0]} |
比較兩條實際路徑
更正為 AB。此檔案若聲明 BE 要停,是本例格式約定,並不表示 BE 編碼本身無效。
| 路徑 | 輸出 JSON |
|---|---|
| 錯誤路徑 | {"accepted":true,"text":"䄀䈀"} |
| 更正路徑 | {"accepted":true,"text":"AB"} |
import {DatabaseSync} from 'node:sqlite';
import {TextDecoder} from 'node:util';
import {inflateSync} from 'node:zlib';
import {posix} from 'node:path';
import {createHash} from 'node:crypto';
const rows=(db,sql)=>db.prepare(sql).all().map(r=>({...r}));
const failed=(action)=>{try{action();return null;}catch(e){return {code:e.errcode??e.code??e.name};}};
import assert from 'node:assert/strict';
const run=function run(i,corrected=true){
if(corrected&&(i.encoding!=='utf-16le'||i.bytes.length%2!==0))return {accepted:false,error:'encoding-contract'};
try{return {accepted:true,text:new TextDecoder(corrected?i.encoding:'utf-16be',{fatal:true}).decode(Uint8Array.from(i.bytes))};}
catch{return {accepted:false,error:'invalid-encoded-text'};}
};
const cases=[{"label":"misleading base","input":{"encoding":"utf-16le","bytes":[65,0,66,0]},"expected":{"accepted":true,"text":"䄀䈀"},"corrected":false},{"label":"corrected base","input":{"encoding":"utf-16le","bytes":[65,0,66,0]},"expected":{"accepted":true,"text":"AB"},"corrected":true},{"label":"contradictory declaration","input":{"encoding":"utf-16be","bytes":[65,0]},"expected":{"accepted":false,"error":"encoding-contract"},"corrected":true},{"label":"odd trailing byte","input":{"encoding":"utf-16le","bytes":[65]},"expected":{"accepted":false,"error":"encoding-contract"},"corrected":true}];
for(const test of cases){
const actual=run(test.input,test.corrected);
assert.deepEqual(actual,test.expected,test.label);
console.log(test.label,actual);
}
下次載入前核邊界
聲明不符與只剩單字節,兩者都在收紀錄前擋住。
| 情況 | 輸入 JSON | 預期輸出 JSON |
|---|---|---|
| 字節次序聲明相反 | {"encoding":"utf-16be","bytes":[65,0]} | {"accepted":false,"error":"encoding-contract"} |
| 不足一組字節 | {"encoding":"utf-16le","bytes":[65]} | {"accepted":false,"error":"encoding-contract"} |
次序錯但看似有字,可否照匯入?
查看參考答案
不可,有字不等於依正確編碼。此來源須 LE 及完整字節組,結果應 AB。