typedoc-better-json/src/getSignature/getFunctionSignature.ts

Transforms typedoc's json output to a format that is better for creating custom documentation website

import {
  FunctionSignature,
  TypeInfo,
  TokenInfo,
  FunctionParameter,
} from "../types";
import { getTypeParamSignature } from "./getTypeParamSignature";

export function getFunctionSignature(
  name: string,
  signature: FunctionSignature,
): TypeInfo {
  const tokens: TokenInfo[] = [];

  const collectTokens = (typeInfo: TypeInfo | undefined) => {
    typeInfo?.tokens?.forEach((t) => tokens.push(t));
  };

  const returnType = signature.returns?.type?.code ?? "void";
  collectTokens(signature.returns?.type);

  let paramList = "";

  if (signature.parameters) {
    const output = getParametersSignature(signature.parameters);
    paramList = output.code;
    output.tokens?.forEach((t) => tokens.push(t));
  }

  let typeParams = "";

  if (signature.typeParameters) {
    const output = getTypeParamSignature(signature.typeParameters);
    typeParams = output.code;
    output.tokens?.forEach((t) => tokens.push(t));
  }

  return {
    code: `function ${name}${typeParams}(${paramList}) : ${returnType}`,
    tokens,
  };
}

export function getParametersSignature(
  parameters: FunctionParameter[],
): TypeInfo {
  const tokens: TokenInfo[] = [];

  const collectTokens = (typeInfo: TypeInfo | undefined) => {
    typeInfo?.tokens?.forEach((t) => tokens.push(t));
  };

  const paramCode = parameters
    .map((param) => {
      const postfix = param.flags?.isOptional ? "?" : "";
      const prefix = param.flags?.isRest ? "..." : "";
      collectTokens(param.type);
      return `${prefix}${param.name}${postfix}: ${param.type?.code}`;
    })
    .join(", ");

  return {
    code: paramCode,
    tokens,
  };
}