export function processStringToChildren()

in packages/eui/src/components/i18n/i18n_util.tsx [41:122]

• 40 lines of code
• 10 McCabe index (conditional complexity)

export function processStringToChildren(
  input: string,
  values: RenderableValues,
  i18nMappingFunc?: (token: string) => string
): string | ReactNode[] {
  const children: ReactNode[] = [];

  let child: Child;

  function appendCharToChild(char: string) {
    if (child === undefined) {
      // starting a new string literal
      child = char;
    } else if (typeof child === 'string') {
      // existing string literal
      child = child + char;
    } else if (hasPropName(child)) {
      // adding to the propName of a values lookup
      child.propName = child.propName + char;
    }
  }

  function appendValueToChildren(value: Child) {
    if (value === undefined) {
      return;
    } else if (isElement(value)) {
      // an array with any ReactElements will be kept as an array
      // so they need to be assigned a key
      children.push(cloneElement(value, { key: children.length }));
    } else if (hasPropName(value)) {
      // this won't be called, propName children are converted to a ReactChild before calling this
    } else {
      // everything else can go straight in
      if (i18nMappingFunc !== undefined && typeof value === 'string') {
        value = i18nMappingFunc(value);
      }
      children.push(value);
    }
  }

  // if we don't encounter a non-primitive
  // then `children` can be concatenated together at the end
  let encounteredNonPrimitive = false;
  for (let i = 0; i < input.length; i++) {
    const char = input[i];

    if (char === '\\') {
      // peek at the next character to know if this is an escape
      const nextChar = input[i + 1];
      let charToAdd = char; // if this isn't an escape sequence then we will add the backslash

      if (nextChar === '{' || nextChar === '}') {
        // escaping a brace
        i += 1; // advance passed the brace
        charToAdd = input[i];
      }
      appendCharToChild(charToAdd);
    } else if (char === '{') {
      appendValueToChildren(child);
      child = { propName: '' };
    } else if (char === '}') {
      const propName = (child as { propName: string }).propName;
      if (!values.hasOwnProperty(propName)) {
        throw new Error(
          `Key "${propName}" not found in ${JSON.stringify(values, null, 2)}`
        );
      }
      const propValue = values[propName];
      encounteredNonPrimitive =
        encounteredNonPrimitive || !isPrimitive(propValue);
      appendValueToChildren(propValue);
      child = undefined;
    } else {
      appendCharToChild(char);
    }
  }

  // include any remaining child value
  appendValueToChildren(child);

  return encounteredNonPrimitive ? children : children.join('');
}