jsdoc2flow/src/fixers/returns_fixer.js

Convert JSDoc comments into Flow/Typescript annotations

"use strict"

class ReturnsFixer {
  constructor({ flowAnnotation }) {
    this.flowAnnotation = flowAnnotation
  }

  getFixes(tag, node, { code, comment }) {
    const fixes = []

    // @returns always applies to things that come after it
    if (node.trailingComments && node.trailingComments.includes(comment)) {
      return fixes
    }

    // @returns can only be applied to FunctionDeclaration, or a
    // FunctionExpression that might be embedded within a VariableDeclaration
    if (
      node.type !== "FunctionDeclaration" &&
      node.type !== "VariableDeclaration" &&
      node.type !== "MethodDefinition" &&
      node.type !== "Property" &&
      node.type !== "ExpressionStatement"
    ) {
      return fixes
    }

    let blockStatementNode = node.body

    if (node.type === "VariableDeclaration") {
      if (node.declarations.length !== 1) {
        return fixes
      }

      const varInit = node.declarations[0].init
      if (varInit.type !== "FunctionExpression" && varInit.type !== "ArrowFunctionExpression") {
        return fixes
      }

      blockStatementNode = varInit.body
    } else if (node.type === "MethodDefinition" || node.type === "Property") {
      if (node.value.type !== "FunctionExpression") {
        return fixes
      }
      blockStatementNode = node.value.body
    } else if (node.type === "ExpressionStatement") {
      if (
        node.expression.type !== "AssignmentExpression" ||
        (node.expression.right.type !== "FunctionExpression" &&
          node.expression.right.type !== "ArrowFunctionExpression")
      ) {
        return fixes
      }
      blockStatementNode = node.expression.right.body
    }

    // Look back to try to find the ending bracket
    let endBracketIndex = -1
    for (let i = blockStatementNode.start; i >= node.start; i--) {
      if (code[i] === ")") {
        endBracketIndex = i
        break
      }
    }

    // If there is no ending bracket, then just ignore and do nothing. This is
    // mainly for arrow functions, which can be declared without brackets.
    if (endBracketIndex < 0) {
      return fixes
    }

    fixes.push(this.flowAnnotation.inline(endBracketIndex + 1, tag.type))
    return fixes
  }
}
module.exports = ReturnsFixer