babel/packages/babel-generator/src/generators/expressions.js

import * as t from "babel-types";
import * as n from "../node";

export function UnaryExpression(node: Object) {
  if (
    node.operator === "void" ||
    node.operator === "delete" ||
    node.operator === "typeof"
  ) {
    this.word(node.operator);
    this.space();
  } else {
    this.token(node.operator);
  }

  this.print(node.argument, node);
}

export function DoExpression(node: Object) {
  this.word("do");
  this.space();
  this.print(node.body, node);
}

export function ParenthesizedExpression(node: Object) {
  this.token("(");
  this.print(node.expression, node);
  this.token(")");
}

export function UpdateExpression(node: Object) {
  if (node.prefix) {
    this.token(node.operator);
    this.print(node.argument, node);
  } else {
    this.print(node.argument, node);
    this.token(node.operator);
  }
}

export function ConditionalExpression(node: Object) {
  this.print(node.test, node);
  this.space();
  this.token("?");
  this.space();
  this.print(node.consequent, node);
  this.space();
  this.token(":");
  this.space();
  this.print(node.alternate, node);
}

export function NewExpression(node: Object, parent: Object) {
  this.word("new");
  this.space();
  this.print(node.callee, node);
  if (
    this.format.minified &&
    node.arguments.length === 0 &&
    !node.optional &&
    !t.isCallExpression(parent, { callee: node }) &&
    !t.isMemberExpression(parent) &&
    !t.isNewExpression(parent)
  ) {
    return;
  }

  if (node.optional) {
    this.token("?.");
  }
  this.token("(");
  this.printList(node.arguments, node);
  this.token(")");
}

export function SequenceExpression(node: Object) {
  this.printList(node.expressions, node);
}

export function ThisExpression() {
  this.word("this");
}

export function Super() {
  this.word("super");
}

export function Decorator(node: Object) {
  this.token("@");
  this.print(node.expression, node);
  this.newline();
}

function commaSeparatorNewline() {
  this.token(",");
  this.newline();

  if (!this.endsWith("\n")) this.space();
}

export function CallExpression(node: Object) {
  this.print(node.callee, node);

  if (node.optional) {
    this.token("?.");
  }
  this.token("(");

  const isPrettyCall = node._prettyCall;

  let separator;
  if (isPrettyCall) {
    separator = commaSeparatorNewline;
    this.newline();
    this.indent();
  }

  this.printList(node.arguments, node, { separator });

  if (isPrettyCall) {
    this.newline();
    this.dedent();
  }

  this.token(")");
}

export function Import() {
  this.word("import");
}

function buildYieldAwait(keyword: string) {
  return function(node: Object) {
    this.word(keyword);

    if (node.delegate) {
      this.token("*");
    }

    if (node.argument) {
      this.space();
      const terminatorState = this.startTerminatorless();
      this.print(node.argument, node);
      this.endTerminatorless(terminatorState);
    }
  };
}

export const YieldExpression = buildYieldAwait("yield");
export const AwaitExpression = buildYieldAwait("await");

export function EmptyStatement() {
  this.semicolon(true /* force */);
}

export function ExpressionStatement(node: Object) {
  this.print(node.expression, node);
  this.semicolon();
}

export function AssignmentPattern(node: Object) {
  this.print(node.left, node);
  if (node.left.optional) this.token("?");
  this.print(node.left.typeAnnotation, node);
  this.space();
  this.token("=");
  this.space();
  this.print(node.right, node);
}

export function AssignmentExpression(node: Object, parent: Object) {
  // Somewhere inside a for statement `init` node but doesn't usually
  // needs a paren except for `in` expressions: `for (a in b ? a : b;;)`
  const parens =
    this.inForStatementInitCounter &&
    node.operator === "in" &&
    !n.needsParens(node, parent);

  if (parens) {
    this.token("(");
  }

  this.print(node.left, node);

  this.space();
  if (node.operator === "in" || node.operator === "instanceof") {
    this.word(node.operator);
  } else {
    this.token(node.operator);
  }
  this.space();

  this.print(node.right, node);

  if (parens) {
    this.token(")");
  }
}

export function BindExpression(node: Object) {
  this.print(node.object, node);
  this.token("::");
  this.print(node.callee, node);
}

export {
  AssignmentExpression as BinaryExpression,
  AssignmentExpression as LogicalExpression,
};

export function MemberExpression(node: Object) {
  this.print(node.object, node);

  if (!node.computed && t.isMemberExpression(node.property)) {
    throw new TypeError("Got a MemberExpression for MemberExpression property");
  }

  let computed = node.computed;
  if (t.isLiteral(node.property) && typeof node.property.value === "number") {
    computed = true;
  }

  if (node.optional) {
    this.token("?.");
  }
  if (computed) {
    this.token("[");
    this.print(node.property, node);
    this.token("]");
  } else {
    if (!node.optional) {
      this.token(".");
    }
    this.print(node.property, node);
  }
}

export function MetaProperty(node: Object) {
  this.print(node.meta, node);
  this.token(".");
  this.print(node.property, node);
}