javascript - 我有一个代表数组的字符串。如何推送保持格式的元素？

Question

给定一个类的名称 (CustomClass6) 和一个表示具有 ANY 格式的数组的字符串，它应该将类的名称附加到数组中以保持格式。

示例 1:

给定这个字符串:

"""
const arr = [
  CustomClass11,
  CustomClass22,
  CustomClass33,
  CustomClass44,
  CustomClass55
];
"""

函数应该返回:

"""
const arr = [
  CustomClass11,
  CustomClass22,
  CustomClass33,
  CustomClass44,
  CustomClass55,
  CustomClass6
];
"""

示例 2:

给定字符串:

"""
const arr = [CustomClass1, CustomClass2, CustomClass3];
"""

它应该返回:

"""
const arr = [CustomClass1, CustomClass2, CustomClass3, CustomClass6];
"""

示例 3:

"""
const arr = [];
"""

它应该返回:

"""
const arr = [CustomClass6];
"""

这些是我到目前为止所做的功能。我已经能够解决示例 1，但如您所见，我已将分隔符硬编码为 \n:

function getStringWithElementAppended(
  stringWithArray: string,
  classToAppend: string
) {
  const openingBraketIndex = stringWithArray.indexOf('[');
  const closingBracketIndex = getIndexInString(
    stringWithArray,
    ']',
    openingBraketIndex
  );

  const updatedContent = appendElementToArrayInString(
    classToAppend,
    openingBraketIndex,
    closingBracketIndex,
    stringWithArray
  );

  return updatedContent;
}

function getIndexInString(
  String: string,
  stringToLookFor: string,
  startingIndex: number = 0,
  limitIndex: number = String.length,
  lastIndex = false
) {
  const auxString = String.slice(startingIndex, limitIndex);

  if (lastIndex) {
    return startingIndex + auxString.lastIndexOf(stringToLookFor);
  } else {
    return startingIndex + auxString.indexOf(stringToLookFor);
  }
}

function appendElementToArrayInString(
  elementToAppend: string,
  arrayBeginingIndex: number,
  arrayEndIndex: number,
  String: string
) {
  const separationBetweenElements = '\n';
  const endOfArrayIndex = getIndexInString(
    String,
    separationBetweenElements,
    arrayBeginingIndex,
    arrayEndIndex,
    true
  );
  const previousElementEndIndex = getIndexInString(
    String,
    separationBetweenElements,
    arrayBeginingIndex,
    endOfArrayIndex,
    true
  );
  const spaceBetweenElements = String.slice(
    previousElementEndIndex + 1,
    endOfArrayIndex
  );
  const whitespaceIndex = spaceBetweenElements.lastIndexOf(' ');
  const whitespace = spaceBetweenElements.slice(0, whitespaceIndex + 1);
  const contentToAdd =
    ',' +
    separationBetweenElements +
    whitespace +
    elementToAppend +
    separationBetweenElements;
  const updatedString =
    String.slice(0, endOfArrayIndex) + contentToAdd + String.slice(arrayEndIndex);
  return updatedString;
}

归根结底，输出应该遵循输入的格式。我在修改现有文件的脚本中使用此代码，我们不希望我们的 SCM 检测到大量格式更改。

Answer 1

主要的并发症是分隔符。没有内置的方法可以做到这一点。为了检测分隔符，您需要从本质上将字符串解析为语法。

语法将包括:

• 变量声明
• 数组语法
• 前缀填充
• 值(value)观
• 分隔符
• 后缀填充

我们开发的语言将基于这种语法的构造，它本质上是每个片段的简单生成。需要根据设置的值检测分隔符。

// Test data

const inputa = 
`"""
const arr = [
  CustomClass25,
  CustomClass9,
  CustomClass12,
  CustomClass8
];
"""`;

const inputb = 
`"""
const arr = [CustomClass1, CustomClass2, CustomClass3];
"""`;

const inputc = 
`"""
const arr = [];
"""`;

// Main actor
function modifyDeclaration(declaration,addition){

 // Retain starting declaration index
 const startingSyntax = declaration.indexOf('[');

 // Retain ending declaration index
 const endingSyntax = declaration.indexOf('];');

 // Obtain the contained array from syntax
 const arrayOnly = declaration.substring(startingSyntax+1,endingSyntax);

 // Determine the array's prefix padding
 const prefixPadding = arrayOnly.substring(0,arrayOnly.search(/\S|$/));

 // Determine the array's suffix padding
 // by reversing the string and finding
 // the first nonwhitespace character
 const suffixPadding = arrayOnly.substring(arrayOnly.length - arrayOnly.split('').reverse().findIndex(s => /\S/.test(s)));

 // Strip array padding for value insertion
 const values = arrayOnly.substring(prefixPadding.length,arrayOnly.length - suffixPadding.length);

 // Assume base separation is the same
 // as the trailing padding in cases
 // of no set
 let separator = suffixPadding;

 // Gather the index of the first comma for
 // separator detection
 const commaIndex = arrayOnly.indexOf(',');

 // When there are values or a commas
 if(commaIndex > -1 || values.length > 0){

  // Make the separator include a comma
  // as well as the first separator
  separator = ',' + arrayOnly.substring(
    commaIndex+1,
    commaIndex+1 + arrayOnly.substring(commaIndex+1).search(/\S|$/)
  );
 }

 // Return our production value
 return declaration.substring(0,startingSyntax+1) + 
   prefixPadding +
   values +
   separator +
   addition +
   suffixPadding + 
   declaration.substring(endingSyntax)
}

const addition = 'CustomClass42';

console.log(modifyDeclaration(inputa,addition));
console.log(modifyDeclaration(inputb,addition));
console.log(modifyDeclaration(inputc,addition));