prettier/src/printer.js

var assert = require("assert");
var sourceMap = require("source-map");
var printComments = require("./comments").printComments;
var pp = require("./pp");
var fromString = pp.fromString;
var concat = pp.concat;
var isEmpty = pp.isEmpty;
var join = pp.join;
var line = pp.line;
var hardline = pp.hardline;
var softline = pp.softline;
var literalline = pp.literalline;
var group = pp.group;
var multilineGroup = pp.multilineGroup;
var indent = pp.indent;
var getFirstString = pp.getFirstString;
var hasHardLine = pp.hasHardLine;
var conditionalGroup = pp.conditionalGroup;
var normalizeOptions = require("./options").normalize;
var types = require("ast-types");
var namedTypes = types.namedTypes;
var isString = types.builtInTypes.string;
var isObject = types.builtInTypes.object;
var FastPath = require("./fast-path");
var util = require("./util");

function PrintResult(code, sourceMap) {
  assert.ok(this instanceof PrintResult);

  isString.assert(code);

  this.code = code;

  if (sourceMap) {
    isObject.assert(sourceMap);

    this.map = sourceMap;
  }
}

var PRp = PrintResult.prototype;
var warnedAboutToString = false;

PRp.toString = function() {
  if (!warnedAboutToString) {
    console.warn(
      "Deprecation warning: recast.print now returns an object with " +
        "a .code property. You appear to be treating the object as a " +
        "string, which might still work but is strongly discouraged."
    );

    warnedAboutToString = true;
  }

  return this.code;
};

var emptyPrintResult = new PrintResult("");

function Printer(originalOptions) {
  assert.ok(this instanceof Printer);

  var explicitTabWidth = originalOptions && originalOptions.tabWidth;
  var options = normalizeOptions(originalOptions);

  assert.notStrictEqual(options, originalOptions);

  // It's common for client code to pass the same options into both
  // recast.parse and recast.print, but the Printer doesn't need (and
  // can be confused by) options.sourceFileName, so we null it out.
  options.sourceFileName = null;

  function printWithComments(path) {
    assert.ok(path instanceof FastPath);

    return printComments(path, print);
  }

  function print(path, includeComments) {
    if (includeComments)
      return printWithComments(path);

    assert.ok(path instanceof FastPath);

    if (!explicitTabWidth) {
      var oldTabWidth = options.tabWidth;
      var loc = path.getNode().loc;

      if (loc && loc.lines && loc.lines.guessTabWidth) {
        options.tabWidth = loc.lines.guessTabWidth();

        var lines = maybeReprint(path);

        options.tabWidth = oldTabWidth;

        return lines;
      }
    }

    return maybeReprint(path);
  }

  function maybeReprint(path) {
    // TODO: remove this function entirely as we don't ever keep the
    // previous formatting
    return printRootGenerically(path);
  }

  // Print the root node generically, but then resume reprinting its
  // children non-generically.
  function printRootGenerically(path, includeComments) {
    return (includeComments ? printComments(
      path,
      printRootGenerically
    ) : genericPrint(path, options, printWithComments));
  }

  // Print the entire AST generically.
  function printGenerically(path) {
    // return genericPrint(path, options, printGenerically);
    return printComments(path, p => genericPrint(p, options, printGenerically));
  }

  this.print = function(ast) {
    if (!ast) {
      return emptyPrintResult;
    }

    var lines = print(FastPath.from(ast), true);
    return new PrintResult(
      lines.toString(options),
      util.composeSourceMaps(
        options.inputSourceMap,
        lines.getSourceMap(options.sourceMapName, options.sourceRoot)
      )
    );
  };

  this.printGenerically = function(ast) {
    if (!ast) {
      return emptyPrintResult;
    }

    var path = FastPath.from(ast);
    var oldReuseWhitespace = options.reuseWhitespace;

    // Do not reuse whitespace (or anything else, for that matter)
    // when printing generically.
    options.reuseWhitespace = false;

    var res = printGenerically(path);
    var pr = new PrintResult(pp.print(options.printWidth, res));

    options.reuseWhitespace = oldReuseWhitespace;

    return pr;
  };
}

exports.Printer = Printer;

function maybeAddParens(path, lines) {
  return (path.needsParens() ? concat([ "(", lines, ")" ]) : lines);
}

function genericPrint(path, options, printPath) {
  assert.ok(path instanceof FastPath);

  var node = path.getValue();
  var parts = [];
  var needsParens = false;
  var linesWithoutParens = genericPrintNoParens(path, options, printPath);

  if (!node || isEmpty(linesWithoutParens)) {
    return linesWithoutParens;
  }

  if (
    node.decorators && node.decorators.length > 0 &&
      // If the parent node is an export declaration, it will be
      // responsible for printing node.decorators.
      !util.getParentExportDeclaration(path)
  ) {
    path.each(
      function(decoratorPath) {
        parts.push(printPath(decoratorPath), line);
      },
      "decorators"
    );
  } else
    if (
      util.isExportDeclaration(node) && node.declaration &&
        node.declaration.decorators
    ) {
      // Export declarations are responsible for printing any decorators
      // that logically apply to node.declaration.
      path.each(
        function(decoratorPath) {
          parts.push(printPath(decoratorPath), line);
        },
        "declaration",
        "decorators"
      );
    } else {
      // Nodes with decorators can't have parentheses, so we can avoid
      // computing path.needsParens() except in this case.
      needsParens = path.needsParens();
    }

  if (needsParens) {
    parts.unshift("(");
  }

  parts.push(linesWithoutParens);

  if (needsParens) {
    parts.push(")");
  }

  return concat(parts);
}

function genericPrintNoParens(path, options, print) {
  var n = path.getValue();

  if (!n) {
    return fromString("");
  }

  if (typeof n === "string") {
    return fromString(n, options);
  }

  // TODO: For some reason NumericLiteralTypeAnnotation is not
  // printable so this throws, but I think that's a bug in ast-types.
  // This assert isn't very useful though.
  // namedTypes.Printable.assert(n);
  var parts = [];
  switch (n.type) {
  case "File":
    return path.call(print, "program");
  case "Program":

    // Babel 6
    if (n.directives) {
      path.each(
        function(childPath) {
          parts.push(print(childPath), ";", hardline);
        },
        "directives"
      );
    }

    parts.push(
      path.call(
        function(bodyPath) {
          return printStatementSequence(bodyPath, options, print);
        },
        "body"
      )
    );

    // Make sure the file always ends with a newline
    parts.push(hardline);

    return concat(parts);
  // Babel extension.
  case "Noop":
  case "EmptyStatement":
    return fromString("");
  case "ExpressionStatement":
    return concat([ path.call(print, "expression"), ";" ]);
  case // Babel extension.
  "ParenthesizedExpression":
    return concat([ "(", path.call(print, "expression"), ")" ]);
  case "AssignmentExpression":
    return group(
      concat(
        [
          path.call(print, "left"),
          " ",
          n.operator,
          " ",
          path.call(print, "right")
        ]
      )
    );
  case "BinaryExpression":
  case "LogicalExpression":
    return group(
      concat(
        [
          path.call(print, "left"),
          " ",
          n.operator,
          indent(options.tabWidth, concat([ line, path.call(print, "right") ]))
        ]
      )
    );
  case "AssignmentPattern":
    return concat(
      [ path.call(print, "left"), " = ", path.call(print, "right") ]
    );
  case "MemberExpression":

    parts.push(path.call(print, "object"));

    var property = path.call(print, "property");

    if (n.computed) {
      parts.push("[", property, "]");
    } else {
      parts.push(".", property);
    }

    return concat(parts);
  case "MetaProperty":
    return concat(
      [ path.call(print, "meta"), ".", path.call(print, "property") ]
    );
  case "BindExpression":

    if (n.object) {
      parts.push(path.call(print, "object"));
    }

    parts.push("::", path.call(print, "callee"));

    return concat(parts);
  case "Path":
    return fromString(".").join(n.body);
  case "Identifier":
    return concat(
      [ n.name, (n.optional ? "?" : ""), path.call(print, "typeAnnotation") ]
    );
  case "SpreadElement":
  case "SpreadElementPattern":
  // Babel 6 for ObjectPattern
  case "RestProperty":
  case "SpreadProperty":
  case "SpreadPropertyPattern":
  case "RestElement":
    return concat([ "...", path.call(print, "argument") ]);
  case "FunctionDeclaration":
  case "FunctionExpression":

    if (n.async)
      parts.push("async ");

    parts.push("function");

    if (n.generator)
      parts.push("*");

    if (n.id) {
      parts.push(" ", path.call(print, "id"));
    }

    parts.push(
      path.call(print, "typeParameters"),
      printFunctionParams(path, print, options),
      printReturnType(path, print),
      " ",
      path.call(print, "body")
    );

    return group(concat(parts));
  case "ArrowFunctionExpression":

    if (n.async)
      parts.push("async ");

    if (n.typeParameters) {
      parts.push(path.call(print, "typeParameters"));
    }

    if (
      !options.arrowParensAlways && n.params.length === 1 && !n.rest &&
        n.params[0].type === "Identifier" &&
        !n.params[0].typeAnnotation &&
        !n.predicate &&
        !n.returnType
    ) {
      parts.push(path.call(print, "params", 0));
    } else {
      parts.push(
        printFunctionParams(path, print, options),
        printReturnType(path, print)
      );
    }

    parts.push(" => ", path.call(print, "body"));

    return group(concat(parts));
  case "MethodDefinition":

    if (n.static) {
      parts.push("static ");
    }

    parts.push(printMethod(path, options, print));

    return concat(parts);
  case "YieldExpression":

    parts.push("yield");

    if (n.delegate)
      parts.push("*");

    if (n.argument)
      parts.push(" ", path.call(print, "argument"));

    return concat(parts);
  case "AwaitExpression":

    parts.push("await");

    if (n.all)
      parts.push("*");

    if (n.argument)
      parts.push(" ", path.call(print, "argument"));

    return concat(parts);
  case "ModuleDeclaration":

    parts.push("module", path.call(print, "id"));

    if (n.source) {
      assert.ok(!n.body);

      parts.push("from", path.call(print, "source"));
    } else {
      parts.push(path.call(print, "body"));
    }

    return fromString(" ").join(parts);
  case "ImportSpecifier":

    if (n.imported) {
      parts.push(path.call(print, "imported"));

      if (n.local && n.local.name !== n.imported.name) {
        parts.push(" as ", path.call(print, "local"));
      }
    } else
      if (n.id) {
        parts.push(path.call(print, "id"));

        if (n.name) {
          parts.push(" as ", path.call(print, "name"));
        }
      }

    return concat(parts);
  case "ExportSpecifier":

    if (n.local) {
      parts.push(path.call(print, "local"));

      if (n.exported && n.exported.name !== n.local.name) {
        parts.push(" as ", path.call(print, "exported"));
      }
    } else
      if (n.id) {
        parts.push(path.call(print, "id"));

        if (n.name) {
          parts.push(" as ", path.call(print, "name"));
        }
      }

    return concat(parts);
  case "ExportBatchSpecifier":
    return fromString("*");
  case "ImportNamespaceSpecifier":

    parts.push("* as ");

    if (n.local) {
      parts.push(path.call(print, "local"));
    } else
      if (n.id) {
        parts.push(path.call(print, "id"));
      }

    return concat(parts);
  case "ImportDefaultSpecifier":

    if (n.local) {
      return path.call(print, "local");
    }

    return path.call(print, "id");
  case "ExportDeclaration":
  case "ExportDefaultDeclaration":
  case "ExportNamedDeclaration":
    return printExportDeclaration(path, options, print);
  case "ExportAllDeclaration":

    parts.push("export *");

    if (n.exported) {
      parts.push(" as ", path.call(print, "exported"));
    }

    parts.push(" from ", path.call(print, "source"));

    return concat(parts);
  case "ExportNamespaceSpecifier":
    return concat([ "* as ", path.call(print, "exported") ]);
  case "ExportDefaultSpecifier":
    return path.call(print, "exported");
  case "ImportDeclaration":

    parts.push("import ");

    if (n.importKind && n.importKind !== "value") {
      parts.push(n.importKind + " ");
    }

    if (n.specifiers && n.specifiers.length > 0) {
      var foundImportSpecifier = false;

      path.each(
        function(specifierPath) {
          var i = specifierPath.getName();

          if (i > 0) {
            parts.push(", ");
          }

          var value = specifierPath.getValue();

          if (
            namedTypes.ImportDefaultSpecifier.check(value) ||
              namedTypes.ImportNamespaceSpecifier.check(value)
          ) {
            assert.strictEqual(foundImportSpecifier, false);
          } else {
            namedTypes.ImportSpecifier.assert(value);

            if (!foundImportSpecifier) {
              foundImportSpecifier = true;

              parts.push((options.objectCurlySpacing ? "{ " : "{"));
            }
          }

          parts.push(print(specifierPath));
        },
        "specifiers"
      );

      if (foundImportSpecifier) {
        parts.push((options.objectCurlySpacing ? " }" : "}"));
      }

      parts.push(" from ");
    }

    parts.push(path.call(print, "source"), ";");

    return concat(parts);
  case "BlockStatement":
    var naked = path.call(
      function(bodyPath) {
        return printStatementSequence(bodyPath, options, print);
      },
      "body"
    );

    // If there are no contents, return a simple block
    if (!getFirstString(naked)) {
      return "{}";
    }

    parts.push("{");

    // Babel 6
    if (n.directives) {
      path.each(
        function(childPath) {
          parts.push(
            indent(
              options.tabWidth,
              concat([ line, print(childPath), ";", line ])
            )
          );
        },
        "directives"
      );
    }

    parts.push(indent(options.tabWidth, concat([ hardline, naked ])));

    parts.push(hardline, "}");

    return concat(parts);
  case "ReturnStatement":

    parts.push("return");

    var arg = path.call(print, "argument");

    if (n.argument) {
      if (
        namedTypes.JSXElement && namedTypes.JSXElement.check(n.argument) &&
          hasHardLine(arg)
      ) {
        parts.push(
          " (",
          indent(options.tabWidth, concat([ hardline, arg ])),
          hardline,
          ")"
        );
      } else {
        parts.push(" ", arg);
      }
    }

    parts.push(";");

    return concat(parts);
  case "CallExpression":
    return concat(
      [ path.call(print, "callee"), printArgumentsList(path, options, print) ]
    );
  case "ObjectExpression":
  case "ObjectPattern":
  case "ObjectTypeAnnotation":
    var allowBreak = false;
    var isTypeAnnotation = n.type === "ObjectTypeAnnotation";
    // Leave this here because we *might* want to make this
    // configurable later -- flow accepts ";" for type separators
    var separator = (isTypeAnnotation ? "," : ",");
    var fields = [];
    var leftBrace = (n.exact ? "{|" : "{");
    var rightBrace = (n.exact ? "|}" : "}");

    if (isTypeAnnotation) {
      fields.push("indexers", "callProperties");
    }

    fields.push("properties");

    var i = 0;
    var props = [];

    fields.forEach(
      function(field) {
        path.each(
          function(childPath) {
            props.push(group(print(childPath)));
          },
          field
        );
      }
    );

    if (props.length === 0) {
      return "{}";
    } else {
      return multilineGroup(
        concat(
          [
            leftBrace,
            indent(
              options.tabWidth,
              concat([
                options.bracketSpacing ? line : softline,
                join(concat([ separator, line ]), props)
              ])
            ),
            options.bracketSpacing ? line : softline,
            rightBrace,
            path.call(print, "typeAnnotation")
          ]
        )
      );
    }

  case "PropertyPattern":
    return concat(
      [ path.call(print, "key"), ": ", path.call(print, "pattern") ]
    );
  // Babel 6
  case "ObjectProperty":
  case // Non-standard AST node type.
  "Property":

    if (n.method || n.kind === "get" || n.kind === "set") {
      return printMethod(path, options, print);
    }

    if (n.computed) {
      parts.push("[", path.call(print, "key"), "]");
    } else {
      parts.push(path.call(print, (n.shorthand ? "value" : "key")));
    }

    if (!n.shorthand) {
      parts.push(": ", path.call(print, "value"));
    }

    return concat(parts);
  case // Babel 6
  "ClassMethod":

    if (n.static) {
      parts.push("static ");
    }

    parts = parts.concat(printObjectMethod(path, options, print));

    return concat(parts);
  case // Babel 6
  "ObjectMethod":
    return printObjectMethod(path, options, print);
  case "Decorator":
    return concat([ "@", path.call(print, "expression") ]);
  case "ArrayExpression":
  case "ArrayPattern":

    if (n.elements.length === 0) {
      parts.push("[]");
    } else {
      parts.push(
        multilineGroup(
          concat(
            [
              "[",
              indent(
                options.tabWidth,
                concat(
                  [
                    line,
                    join(concat([ ",", line ]), path.map(print, "elements"))
                  ]
                )
              ),
              line,
              "]"
            ]
          )
        )
      );
    }

    if (n.typeAnnotation)
      parts.push(path.call(print, "typeAnnotation"));

    return concat(parts);
  case "SequenceExpression":
    return join(", ", path.map(print, "expressions"));
  case "ThisExpression":
    return fromString("this");
  case "Super":
    return fromString("super");
  case // Babel 6 Literal split
  "NullLiteral":
    return fromString("null");
  case // Babel 6 Literal split
  "RegExpLiteral":
    return fromString(n.extra.raw);
  // Babel 6 Literal split
  case "BooleanLiteral":
  // Babel 6 Literal split
  case "NumericLiteral":
  // Babel 6 Literal split
  case "StringLiteral":
  case "Literal":

    if (typeof n.value !== "string")
      return fromString(n.value, options);

    return nodeStr(n.value, options);
  case // Babel 6
  "Directive":
    return path.call(print, "value");
  case // Babel 6
  "DirectiveLiteral":
    return fromString(nodeStr(n.value, options));
  case "ModuleSpecifier":

    if (n.local) {
      throw new Error("The ESTree ModuleSpecifier type should be abstract");
    }

    // The Esprima ModuleSpecifier type is just a string-valued
    // Literal identifying the imported-from module.
    return fromString(nodeStr(n.value, options), options);
  case "UnaryExpression":

    parts.push(n.operator);

    if (/[a-z]$/.test(n.operator))
      parts.push(" ");

    parts.push(path.call(print, "argument"));

    return concat(parts);
  case "UpdateExpression":

    parts.push(path.call(print, "argument"), n.operator);

    if (n.prefix)
      parts.reverse();

    return concat(parts);
  case "ConditionalExpression":
    return concat(
      [
        "(",
        path.call(print, "test"),
        " ? ",
        path.call(print, "consequent"),
        " : ",
        path.call(print, "alternate"),
        ")"
      ]
    );
  case "NewExpression":

    parts.push("new ", path.call(print, "callee"));

    var args = n.arguments;

    if (args) {
      parts.push(printArgumentsList(path, options, print));
    }

    return concat(parts);
  case "VariableDeclaration":
    var printed = path.map(
      function(childPath) {
        return print(childPath);
      },
      "declarations"
    );

    parts = [
      n.kind,
      " ",
      printed[0],
      indent(
        options.tabWidth,
        concat(printed.slice(1).map(p => concat([ ",", line, p ])))
      )
    ];

    // We generally want to terminate all variable declarations with a
    // semicolon, except when they are children of for loops.
    var parentNode = path.getParentNode();

    if (
      !namedTypes.ForStatement.check(parentNode) &&
        !namedTypes.ForInStatement.check(parentNode) &&
        !(namedTypes.ForOfStatement &&
          namedTypes.ForOfStatement.check(parentNode)) &&
        !(namedTypes.ForAwaitStatement &&
          namedTypes.ForAwaitStatement.check(parentNode))
    ) {
      parts.push(";");
    }

    return multilineGroup(concat(parts));
  case "VariableDeclarator":
    return (n.init ? concat(
      [ path.call(print, "id"), " = ", path.call(print, "init") ]
    ) : path.call(print, "id"));
  case "WithStatement":
    return concat(
      [ "with (", path.call(print, "object"), ") ", path.call(print, "body") ]
    );
  // var con = adjustClause(path.call(print, "consequent"), options),
  //     parts = ["if (", path.call(print, "test"), ")", con];
  // if (n.alternate)
  //     parts.push(
  //         endsWithBrace(con) ? " else" : "\nelse",
  //         adjustClause(path.call(print, "alternate"), options));
  // return concat(parts);
  case "IfStatement":
    const con = adjustClause(path.call(print, "consequent"), options);

    parts = [
      "if (",
      group(
        concat(
          [
            indent(
              options.tabWidth,
              concat([ softline, path.call(print, "test") ])
            ),
            softline
          ]
        )
      ),
      ")",
      con
    ];

    if (n.alternate) {
      const hasBraces = getFirstString(con) === "{";

      parts.push(
        (hasBraces ? " else" : "\nelse"),
        adjustClause(path.call(print, "alternate"), options)
      );
    }

    return concat(parts);
  case "ForStatement":
    // TODO Get the for (;;) case right.
    return concat(
      [
        "for (",
        group(
          concat(
            [
              indent(
                options.tabWidth,
                concat(
                  [
                    softline,
                    path.call(print, "init"),
                    ";",
                    line,
                    path.call(print, "test"),
                    ";",
                    line,
                    path.call(print, "update")
                  ]
                )
              ),
              softline
            ]
          )
        ),
        ")",
        adjustClause(path.call(print, "body"), options)
      ]
    );
  case "WhileStatement":
    return concat(
      [
        "while (",
        path.call(print, "test"),
        ")",
        adjustClause(path.call(print, "body"), options)
      ]
    );
  case "ForInStatement":
    // Note: esprima can't actually parse "for each (".
    return concat(
      [
        (n.each ? "for each (" : "for ("),
        path.call(print, "left"),
        " in ",
        path.call(print, "right"),
        ")",
        adjustClause(path.call(print, "body"), options)
      ]
    );
  case "ForOfStatement":
    return concat(
      [
        "for (",
        path.call(print, "left"),
        " of ",
        path.call(print, "right"),
        ")",
        adjustClause(path.call(print, "body"), options)
      ]
    );
  case "ForAwaitStatement":
    return concat(
      [
        "for await (",
        path.call(print, "left"),
        " of ",
        path.call(print, "right"),
        ")",
        adjustClause(path.call(print, "body"), options)
      ]
    );
  case "DoWhileStatement":
    var clause = adjustClause(path.call(print, "body"), options);
    var doBody = concat([ "do", clause ]);
    var parts = [ doBody ];
    const hasBraces = getFirstString(clause) === "{";

    if (hasBraces)
      parts.push(" while");
else
      parts.push(concat([ line, "while" ]));

    parts.push(" (", path.call(print, "test"), ");");

    return concat(parts);
  case "DoExpression":
    var statements = path.call(
      function(bodyPath) {
        return printStatementSequence(bodyPath, options, print);
      },
      "body"
    );
    return concat([ "do {\n", statements.indent(options.tabWidth), "\n}" ]);
  case "BreakStatement":

    parts.push("break");

    if (n.label)
      parts.push(" ", path.call(print, "label"));

    parts.push(";");

    return concat(parts);
  case "ContinueStatement":

    parts.push("continue");

    if (n.label)
      parts.push(" ", path.call(print, "label"));

    parts.push(";");

    return concat(parts);
  case "LabeledStatement":
    return concat(
      [ path.call(print, "label"), ":", hardline, path.call(print, "body") ]
    );
  case "TryStatement":

    parts.push("try ", path.call(print, "block"));

    if (n.handler) {
      parts.push(" ", path.call(print, "handler"));
    } else
      if (n.handlers) {
        path.each(
          function(handlerPath) {
            parts.push(" ", print(handlerPath));
          },
          "handlers"
        );
      }

    if (n.finalizer) {
      parts.push(" finally ", path.call(print, "finalizer"));
    }

    return concat(parts);
  case "CatchClause":

    parts.push("catch (", path.call(print, "param"));

    if (n.guard)
      // Note: esprima does not recognize conditional catch clauses.
      parts.push(" if ", path.call(print, "guard"));

    parts.push(") ", path.call(print, "body"));

    return concat(parts);
  case "ThrowStatement":
    return concat([ "throw ", path.call(print, "argument"), ";" ]);
  // Note: ignoring n.lexical because it has no printing consequences.
  case "SwitchStatement":
    return concat(
      [
        "switch (",
        path.call(print, "discriminant"),
        ") {",
        hardline,
        join(hardline, path.map(print, "cases")),
        hardline,
        "}"
      ]
    );
  case "SwitchCase":

    if (n.test)
      parts.push("case ", path.call(print, "test"), ":");
else
      parts.push("default:");

    if (n.consequent.length > 0) {
      parts.push(
        indent(
          options.tabWidth,
          concat(
            [
              hardline,
              path.call(
                function(consequentPath) {
                  return printStatementSequence(consequentPath, options, print);
                },
                "consequent"
              )
            ]
          )
        )
      );
    }

    return concat(parts);
  // JSX extensions below.
  case "DebuggerStatement":
    return fromString("debugger;");
  case "JSXAttribute":

    parts.push(path.call(print, "name"));

    if (n.value)
      parts.push("=", path.call(print, "value"));

    return concat(parts);
  case "JSXIdentifier":
    return fromString(n.name, options);
  case "JSXNamespacedName":
    return fromString(":").join(
      [ path.call(print, "namespace"), path.call(print, "name") ]
    );
  case "JSXMemberExpression":
    return fromString(".").join(
      [ path.call(print, "object"), path.call(print, "property") ]
    );
  case "JSXSpreadAttribute":
    return concat([ "{...", path.call(print, "argument"), "}" ]);
  case "JSXExpressionContainer":
    return concat([ "{", path.call(print, "expression"), "}" ]);
  case "JSXElement":
    var openingLines = path.call(print, "openingElement");

    if (n.openingElement.selfClosing) {
      assert.ok(!n.closingElement);

      return openingLines;
    }

    var children = [];

    path.map(
      function(childPath) {
        var child = childPath.getValue();

        if (
          namedTypes.Literal.check(child) && typeof child.value === "string"
        ) {
          if (/\S/.test(child.value)) {
            const beginBreak = child.value.match(/^\s*\n/);
            const endBreak = child.value.match(/\n\s*$/);

            children.push(
              (beginBreak ? hardline : ""),
              child.value.replace(/^\s+|\s+$/g, ""),
              (endBreak ? hardline : "")
            );
          } else
            if (/\n/.test(child.value)) {
              children.push(hardline);
            }
        } else {
          children.push(print(childPath));
        }
      },
      "children"
    );

    var mostChildren = children.slice(0, -1);
    var closingLines = path.call(print, "closingElement");
    return concat(
      [
        openingLines,
        indent(options.tabWidth, concat(mostChildren)),
        util.getLast(children) || "",
        closingLines
      ]
    );
  case "JSXOpeningElement":
    return group(
      concat(
        [
          "<",
          path.call(print, "name"),
          concat(path.map(attr => concat([ " ", print(attr) ]), "attributes")),
          (n.selfClosing ? "/>" : ">")
        ]
      )
    );
  case "JSXClosingElement":
    return concat([ "</", path.call(print, "name"), ">" ]);
  case "JSXText":
    throw new Error("JSXTest should be handled by JSXElement");
  case "JSXEmptyExpression":
    return "";
  case "TypeAnnotatedIdentifier":
    return concat(
      [ path.call(print, "annotation"), " ", path.call(print, "identifier") ]
    );
  case "ClassBody":

    if (n.body.length === 0) {
      return fromString("{}");
    }

    return concat(
      [
        "{",
        indent(
          options.tabWidth,
          concat(
            [
              hardline,
              path.call(
                function(bodyPath) {
                  return printStatementSequence(bodyPath, options, print);
                },
                "body"
              )
            ]
          )
        ),
        hardline,
        "}"
      ]
    );
  case "ClassPropertyDefinition":

    parts.push("static ", path.call(print, "definition"));

    if (!namedTypes.MethodDefinition.check(n.definition))
      parts.push(";");

    return concat(parts);
  case "ClassProperty":

    if (n.static)
      parts.push("static ");

    var key = path.call(print, "key");

    if (n.computed) {
      key = concat([ "[", key, "]" ]);
    } else
      if (n.variance === "plus") {
        key = concat([ "+", key ]);
      } else
        if (n.variance === "minus") {
          key = concat([ "-", key ]);
        }

    parts.push(key);

    if (n.typeAnnotation)
      parts.push(path.call(print, "typeAnnotation"));

    if (n.value)
      parts.push(" = ", path.call(print, "value"));

    parts.push(";");

    return concat(parts);
  case "ClassDeclaration":
  case "ClassExpression":
    return concat(printClass(path, print));
  case "TemplateElement":
    return join(literalline, n.value.raw.split("\n"));
  case "TemplateLiteral":
    var expressions = path.map(print, "expressions");

    parts.push("`");

    path.each(
      function(childPath) {
        var i = childPath.getName();

        parts.push(print(childPath));

        if (i < expressions.length) {
          parts.push("${", expressions[i], "}");
        }
      },
      "quasis"
    );

    parts.push("`");

    return concat(parts);
  // These types are unprintable because they serve as abstract
  // supertypes for other (printable) types.
  case "TaggedTemplateExpression":
    return concat([ path.call(print, "tag"), path.call(print, "quasi") ]);
  case "Node":
  case "Printable":
  case "SourceLocation":
  case "Position":
  case "Statement":
  case "Function":
  case "Pattern":
  case "Expression":
  case "Declaration":
  case "Specifier":
  case "NamedSpecifier":
  // Supertype of Block and Line.
  case "Comment":
  // Flow
  case "MemberTypeAnnotation":
  case // Flow
  "Type":
    throw new Error("unprintable type: " + JSON.stringify(n.type));
  // Babel block comment.
  case "CommentBlock":
  case // Esprima block comment.
  "Block":
    return concat([ "/*", fromString(n.value, options), "*/" ]);
  // Babel line comment.
  case "CommentLine":
  case // Esprima line comment.
  "Line":
    return concat([ "//", fromString(n.value, options) ]);
  // Type Annotations for Facebook Flow, typically stripped out or
  // transformed away before printing.
  case "TypeAnnotation":

    if (n.typeAnnotation) {
      if (n.typeAnnotation.type !== "FunctionTypeAnnotation") {
        parts.push(": ");
      }

      parts.push(path.call(print, "typeAnnotation"));

      return concat(parts);
    }

    return "";
  case "TupleTypeAnnotation":
    return concat([ "[", join(", ", path.map(print, "types")), "]" ]);
  case "ExistentialTypeParam":
  case "ExistsTypeAnnotation":
    return fromString("*", options);
  case "EmptyTypeAnnotation":
    return fromString("empty", options);
  case "AnyTypeAnnotation":
    return fromString("any", options);
  case "MixedTypeAnnotation":
    return fromString("mixed", options);
  case "ArrayTypeAnnotation":
    return concat([ path.call(print, "elementType"), "[]" ]);
  case "BooleanTypeAnnotation":
    return fromString("boolean", options);
  case "NumericLiteralTypeAnnotation":
  case "BooleanLiteralTypeAnnotation":
    return "" + n.value;
  case "DeclareClass":
    return printFlowDeclaration(path, printClass(path, print));
  case "DeclareFunction":
    return printFlowDeclaration(
      path,
      [
        "function ",
        path.call(print, "id"),
        (n.predicate ? " " : ""),
        path.call(print, "predicate"),
        ";"
      ]
    );
  case "DeclareModule":
    return printFlowDeclaration(
      path,
      [ "module ", path.call(print, "id"), " ", path.call(print, "body") ]
    );
  case "DeclareModuleExports":
    return printFlowDeclaration(
      path,
      [ "module.exports", path.call(print, "typeAnnotation"), ";" ]
    );
  case "DeclareVariable":
    return printFlowDeclaration(path, [ "var ", path.call(print, "id"), ";" ]);
  case "DeclareExportAllDeclaration":
    return concat([ "declare export * from ", path.call(print, "source") ]);
  case "DeclareExportDeclaration":
    return concat([ "declare ", printExportDeclaration(path, options, print) ]);
  case "FunctionTypeAnnotation":
    // FunctionTypeAnnotation is ambiguous:
    // declare function foo(a: B): void; OR
    // var A: (a: B) => void;
    var parent = path.getParentNode(0);
    var isArrowFunctionTypeAnnotation = !(!parent.variance &&
      !parent.optional &&
      namedTypes.ObjectTypeProperty.check(parent) ||
      namedTypes.ObjectTypeCallProperty.check(parent) ||
      namedTypes.DeclareFunction.check(path.getParentNode(2)));
    var needsColon = isArrowFunctionTypeAnnotation &&
      namedTypes.TypeAnnotation.check(parent);

    if (needsColon) {
      parts.push(": ");
    }

    parts.push(path.call(print, "typeParameters"));

    parts.push(printFunctionParams(path, print, options));

    // The returnType is not wrapped in a TypeAnnotation, so the colon
    // needs to be added separately.
    if (n.returnType || n.predicate) {
      parts.push(
        (isArrowFunctionTypeAnnotation ? " => " : ": "),
        path.call(print, "returnType"),
        path.call(print, "predicate")
      );
    }

    return group(concat(parts));
  case "FunctionTypeParam":
    return concat(
      [
        path.call(print, "name"),
        (n.optional ? "?" : ""),
        ": ",
        path.call(print, "typeAnnotation")
      ]
    );
  case "GenericTypeAnnotation":
    return concat(
      [ path.call(print, "id"), path.call(print, "typeParameters") ]
    );
  case "DeclareInterface":

    parts.push("declare ");

  case "InterfaceDeclaration":

    parts.push(
      fromString("interface ", options),
      path.call(print, "id"),
      path.call(print, "typeParameters"),
      " "
    );

    if (n["extends"].length > 0) {
      parts.push("extends ", join(", ", path.map(print, "extends")));
    }

    parts.push(" ", path.call(print, "body"));

    return concat(parts);
  case "ClassImplements":
  case "InterfaceExtends":
    return concat(
      [ path.call(print, "id"), path.call(print, "typeParameters") ]
    );
  case "IntersectionTypeAnnotation":
    return join(" & ", path.map(print, "types"));
  case "NullableTypeAnnotation":
    return concat([ "?", path.call(print, "typeAnnotation") ]);
  case "NullLiteralTypeAnnotation":
    return fromString("null", options);
  case "ThisTypeAnnotation":
    return fromString("this", options);
  case "NumberTypeAnnotation":
    return fromString("number", options);
  case "ObjectTypeCallProperty":

    if (n.static) {
      parts.push("static ");
    }

    parts.push(path.call(print, "value"));

    return concat(parts);
  case "ObjectTypeIndexer":
    var variance = (n.variance === "plus" ? "+" : (n.variance ===
      "minus" ? "-" : ""));
    return concat(
      [
        variance,
        "[",
        path.call(print, "id"),
        ": ",
        path.call(print, "key"),
        "]: ",
        path.call(print, "value")
      ]
    );
  case "ObjectTypeProperty":
    var variance = (n.variance === "plus" ? "+" : (n.variance ===
      "minus" ? "-" : ""));
    // TODO: This is a bad hack and we need a better way to know
    // when to emit an arrow function or not.
    var isFunction = !n.variance && !n.optional &&
      n.value.type === "FunctionTypeAnnotation";
    return concat(
      [
        (n.static ? "static " : ""),
        variance,
        path.call(print, "key"),
        (n.optional ? "?" : ""),
        (isFunction ? "" : ": "),
        path.call(print, "value")
      ]
    );
  case "QualifiedTypeIdentifier":
    return concat(
      [ path.call(print, "qualification"), ".", path.call(print, "id") ]
    );
  case "StringLiteralTypeAnnotation":
    return fromString(nodeStr(n.value, options), options);
  case "NumberLiteralTypeAnnotation":

    assert.strictEqual(typeof n.value, "number");

    return fromString("" + n.value, options);
  case "StringTypeAnnotation":
    return fromString("string", options);
  case "DeclareTypeAlias":
  case "TypeAlias":
    {
      const parent = path.getParentNode(1);

      if (
        n.type === "DeclareTypeAlias" ||
          parent && parent.type === "DeclareModule"
      ) {
        parts.push("declare ");
      }

      parts.push(
        "type ",
        path.call(print, "id"),
        path.call(print, "typeParameters"),
        " = ",
        path.call(print, "right"),
        ";"
      );

      return concat(parts);
    }
  case "TypeCastExpression":
    return concat(
      [
        "(",
        path.call(print, "expression"),
        path.call(print, "typeAnnotation"),
        ")"
      ]
    );
  case "TypeParameterDeclaration":
  case "TypeParameterInstantiation":
    return concat([ "<", join(", ", path.map(print, "params")), ">" ]);
  case "TypeParameter":
    switch (n.variance) {
    case "plus":

      parts.push("+");

      break;
    case "minus":

      parts.push("-");

      break;
    default:
    }

    parts.push(path.call(print, "name"));

    if (n.bound) {
      parts.push(path.call(print, "bound"));
    }

    if (n["default"]) {
      parts.push("=", path.call(print, "default"));
    }

    return concat(parts);
  case "TypeofTypeAnnotation":
    return concat(
      [ fromString("typeof ", options), path.call(print, "argument") ]
    );
  case "UnionTypeAnnotation":
    return join(" | ", path.map(print, "types"));
  case "VoidTypeAnnotation":
    return "void";
  case "NullTypeAnnotation":
    return "null";
  case "InferredPredicate":
    return "%checks";
  // Unhandled types below. If encountered, nodes of these types should
  // be either left alone or desugared into AST types that are fully
  // supported by the pretty-printer.
  case "DeclaredPredicate":
    return concat([ "%checks(", path.call(print, "value"), ")" ]);
  // TODO
  case "ClassHeritage":
  // TODO
  case "ComprehensionBlock":
  // TODO
  case "ComprehensionExpression":
  // TODO
  case "Glob":
  // TODO
  case "GeneratorExpression":
  // TODO
  case "LetStatement":
  // TODO
  case "LetExpression":
  // TODO
  case "GraphExpression":
  // TODO
  // XML types that nobody cares about or needs to print.
  case "GraphIndexExpression":
  case "XMLDefaultDeclaration":
  case "XMLAnyName":
  case "XMLQualifiedIdentifier":
  case "XMLFunctionQualifiedIdentifier":
  case "XMLAttributeSelector":
  case "XMLFilterExpression":
  case "XML":
  case "XMLElement":
  case "XMLList":
  case "XMLEscape":
  case "XMLText":
  case "XMLStartTag":
  case "XMLEndTag":
  case "XMLPointTag":
  case "XMLName":
  case "XMLAttribute":
  case "XMLCdata":
  case "XMLComment":
  case "XMLProcessingInstruction":
  default:
    debugger;
    throw new Error("unknown type: " + JSON.stringify(n.type));
  }
  return p;
}

function printStatementSequence(path, options, print) {
  let inClassBody = namedTypes.ClassBody &&
    namedTypes.ClassBody.check(path.getParentNode());
  let printed = [];
  let prevAddSpacing = false;

  path.map(
    function(stmtPath, i) {
      var stmt = stmtPath.getValue();

      // Just in case the AST has been modified to contain falsy
      // "statements," it's safer simply to skip them.
      if (!stmt) {
        return;
      }

      // Skip printing EmptyStatement nodes to avoid leaving stray
      // semicolons lying around.
      if (stmt.type === "EmptyStatement") {
        return;
      }

      const addSpacing = shouldAddSpacing(stmt);
      const stmtPrinted = print(stmtPath);
      const parts = [];

      if (!prevAddSpacing && addSpacing && !isFirstStatement(stmtPath)) {
        parts.push(hardline);
      }

      parts.push(stmtPrinted);

      if (addSpacing && !isLastStatement(stmtPath)) {
        parts.push(hardline);
      }

      printed.push(concat(parts));

      prevAddSpacing = addSpacing;
    }
  );

  return join(hardline, printed);
}

function printMethod(path, options, print) {
  var node = path.getNode();
  var kind = node.kind;
  var parts = [];

  if (node.type === "ObjectMethod" || node.type === "ClassMethod") {
    node.value = node;
  } else {
    namedTypes.FunctionExpression.assert(node.value);
  }

  if (node.value.async) {
    parts.push("async ");
  }

  if (!kind || kind === "init" || kind === "method" || kind === "constructor") {
    if (node.value.generator) {
      parts.push("*");
    }
  } else {
    assert.ok(kind === "get" || kind === "set");

    parts.push(kind, " ");
  }

  var key = path.call(print, "key");

  if (node.computed) {
    key = concat([ "[", key, "]" ]);
  }

  parts.push(
    key,
    path.call(print, "value", "typeParameters"),
    path.call(
      function(valuePath) {
        return printFunctionParams(valuePath, print, options);
      },
      "value"
    ),
    path.call(p => printReturnType(p, print), "value"),
    " ",
    path.call(print, "value", "body")
  );

  return group(concat(parts));
}

function printArgumentsList(path, options, print) {
  var printed = path.map(print, "arguments");
  var trailingComma = util.isTrailingCommaEnabled(options, "parameters");
  var args;

  if (printed.length === 0) {
    return "()";
  }

  const shouldBreak = printed.slice(0, -1).some(hasHardLine);
  const lastArg = util.getLast(path.getValue().arguments);
  // This is just an optimization; I think we could return the
  // conditional group for all function calls, but it's more expensive
  // so only do it for specific forms.
  const groupLastArg = lastArg.type === "ObjectExpression" ||
        lastArg.type === "ArrayExpression" ||
        lastArg.type === "FunctionExpression" ||
        lastArg.type === "ArrowFunctionExpression";

  if (groupLastArg) {
    return conditionalGroup(
      [
        concat([
          "(",
          join(concat([ ", " ]), printed),
          ")"
        ]),

        concat([
          "(",
          join(concat([ ",", line ]), printed.slice(0, -1)),
          printed.length > 1 ? ", " : "",
          group(util.getLast(printed), { shouldBreak: true }),
          ")"
        ]),

        group(
          concat([
            "(",
            indent(
              options.tabWidth,
              concat([ line, join(concat([ ",", line ]), printed) ])
            ),
            line,
            ")"
          ]),
          { shouldBreak: true }
        ),
      ],
      { shouldBreak }
    );
  }

  return group(
    concat([
      "(",
      indent(
        options.tabWidth,
        concat([ softline, join(concat([ ",", line ]), printed) ])
      ),
      softline,
      ")"
    ]),
    { shouldBreak }
  );
}

function printFunctionParams(path, print, options) {
  var fun = path.getValue();
  // namedTypes.Function.assert(fun);
  var printed = path.map(print, "params");

  if (fun.defaults) {
    path.each(
      function(defExprPath) {
        var i = defExprPath.getName();
        var p = printed[i];

        if (p && defExprPath.getValue()) {
          printed[i] = concat([ p, " = ", print(defExprPath) ]);
        }
      },
      "defaults"
    );
  }

  if (fun.rest) {
    printed.push(concat([ "...", path.call(print, "rest") ]));
  }

  return concat([
    "(",
    indent(
      options.tabWidth,
      concat([ softline, join(concat([ ",", line ]), printed) ])
    ),
    softline,
    ")"
  ]);
}

function printObjectMethod(path, options, print) {
  var objMethod = path.getValue();
  var parts = [];

  if (objMethod.async)
    parts.push("async ");

  if (objMethod.generator)
    parts.push("*");

  if (
    objMethod.method || objMethod.kind === "get" || objMethod.kind === "set"
  ) {
    return printMethod(path, options, print);
  }

  var key = path.call(print, "key");

  if (objMethod.computed) {
    parts.push("[", key, "]");
  } else {
    parts.push(key);
  }

  parts.push(
    printFunctionParams(path, print),
    printReturnType(path, print),
    " ",
    path.call(print, "body")
  );

  return group(concat(parts));
}

function printReturnType(path, print) {
  const n = path.getValue();
  const parts = [ path.call(print, "returnType") ];

  if (n.predicate) {
    // The return type will already add the colon, but otherwise we
    // need to do it ourselves
    parts.push((n.returnType ? " " : ": "), path.call(print, "predicate"));
  }

  return concat(parts);
}

function printExportDeclaration(path, options, print) {
  var decl = path.getValue();
  var parts = [ "export " ];
  var shouldPrintSpaces = options.objectCurlySpacing;

  namedTypes.Declaration.assert(decl);

  if (decl["default"] || decl.type === "ExportDefaultDeclaration") {
    parts.push("default ");
  }

  if (decl.declaration) {
    parts.push(path.call(print, "declaration"));
  } else
    if (decl.specifiers && decl.specifiers.length > 0) {
      if (
        decl.specifiers.length === 1 &&
          decl.specifiers[0].type === "ExportBatchSpecifier"
      ) {
        parts.push("*");
      } else {
        parts.push(
          (decl.exportKind === "type" ? "type " : ""),
          (shouldPrintSpaces ? "{ " : "{"),
          join(", ", path.map(print, "specifiers")),
          (shouldPrintSpaces ? " }" : "}")
        );
      }

      if (decl.source) {
        parts.push(" from ", path.call(print, "source"));
      }
    }

  return concat(parts);
}

function printFlowDeclaration(path, parts) {
  var parentExportDecl = util.getParentExportDeclaration(path);

  if (parentExportDecl) {
    assert.strictEqual(parentExportDecl.type, "DeclareExportDeclaration");
  } else {
    // If the parent node has type DeclareExportDeclaration, then it
    // will be responsible for printing the "declare" token. Otherwise
    // it needs to be printed with this non-exported declaration node.
    parts.unshift("declare ");
  }

  return concat(parts);
}

function printClass(path, print) {
  const n = path.getValue();
  const parts = [ "class" ];

  if (n.id) {
    parts.push(" ", path.call(print, "id"), path.call(print, "typeParameters"));
  }

  if (n.superClass) {
    parts.push(
      " extends ",
      path.call(print, "superClass"),
      path.call(print, "superTypeParameters")
    );
  } else
    if (n.extends && n.extends.length > 0) {
      parts.push(" extends ", join(", ", path.map(print, "extends")));
    }

  if (n["implements"] && n["implements"].length > 0) {
    parts.push(
      " implements ",
      fromString(", ").join(path.map(print, "implements"))
    );
  }

  parts.push(" ", path.call(print, "body"));

  return parts;
}

function adjustClause(clause, options) {
  if (getFirstString(clause) === "{") {
    return concat([ " ", clause ]);
  }

  return indent(options.tabWidth, concat([ hardline, clause ]));
}

function lastNonSpaceCharacter(lines) {
  var pos = lines.lastPos();
  do {
    var ch = lines.charAt(pos);

    if (/\S/.test(ch))
      return ch;
  } while (lines.prevPos(pos));
}

function swapQuotes(str) {
  return str.replace(
    /['"]/g,
    function(m) {
      return (m === "\"" ? "'" : "\"");
    }
  );
}

function nodeStr(str, options) {
  isString.assert(str);

  switch (options.quote) {
  case "single":
    return swapQuotes(JSON.stringify(swapQuotes(str)));
  case "double":
  default:
    return JSON.stringify(str);
  }
}

function shouldAddSpacing(node) {
  return node.type === "IfStatement" || node.type === "ForStatement" ||
    node.type === "ForInStatement" ||
    node.type === "ForOfStatement" ||
    node.type === "ExpressionStatement" ||
    node.type === "FunctionDeclaration";
}

function isFirstStatement(path) {
  const parent = path.getParentNode();
  const node = path.getValue();
  const body = parent.body;
  return body && body[0] === node;
}

function isLastStatement(path) {
  const parent = path.getParentNode();
  const node = path.getValue();
  const body = parent.body;
  return body && body[body.length - 1] === node;
}