graphql/lib/language/printer.js

A Query Language and Runtime which can target any service.

/**
 *  Copyright (c) 2015, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 */

'use strict';

var _Object$defineProperty = require('babel-runtime/core-js/object/define-property')['default'];

_Object$defineProperty(exports, '__esModule', {
  value: true
});

exports.print = print;

var _visitor = require('./visitor');

/**
 * Converts an AST into a string, using one set of reasonable
 * formatting rules.
 */

function print(ast) {
  return (0, _visitor.visit)(ast, {
    leave: {
      Name: function Name(node) {
        return node.value;
      },
      Variable: function Variable(node) {
        return '$' + node.name;
      },

      // Document

      Document: function Document(node) {
        return join(node.definitions, '\n\n') + '\n';
      },
      OperationDefinition: function OperationDefinition(node) {
        var op = node.operation;
        var name = node.name;
        var defs = manyList('(', node.variableDefinitions, ', ', ')');
        var directives = join(node.directives, ' ');
        var selectionSet = node.selectionSet;
        return !name ? selectionSet : join([op, join([name, defs]), directives, selectionSet], ' ');
      },
      VariableDefinition: function VariableDefinition(node) {
        return join([node.variable + ': ' + node.type, node.defaultValue], ' = ');
      },
      SelectionSet: function SelectionSet(node) {
        return blockList(node.selections, ',\n');
      },
      Field: function Field(node) {
        return join([join([join([node.alias, node.name], ': '), manyList('(', node.arguments, ', ', ')')]), join(node.directives, ' '), node.selectionSet], ' ');
      },
      Argument: function Argument(node) {
        return node.name + ': ' + node.value;
      },

      // Fragments

      FragmentSpread: function FragmentSpread(node) {
        return join(['...' + node.name, join(node.directives, ' ')], ' ');
      },
      InlineFragment: function InlineFragment(node) {
        return join(['... on', node.typeCondition, join(node.directives, ' '), node.selectionSet], ' ');
      },
      FragmentDefinition: function FragmentDefinition(node) {
        return join(['fragment', node.name, 'on', node.typeCondition, join(node.directives, ' '), node.selectionSet], ' ');
      },

      // Value

      IntValue: function IntValue(node) {
        return node.value;
      },
      FloatValue: function FloatValue(node) {
        return node.value;
      },
      StringValue: function StringValue(node) {
        return JSON.stringify(node.value);
      },
      BooleanValue: function BooleanValue(node) {
        return node.value ? 'true' : 'false';
      },
      EnumValue: function EnumValue(node) {
        return node.value;
      },
      ArrayValue: function ArrayValue(node) {
        return '[' + join(node.values, ', ') + ']';
      },
      ObjectValue: function ObjectValue(node) {
        return '{' + join(node.fields, ', ') + '}';
      },
      ObjectField: function ObjectField(node) {
        return node.name + ': ' + node.value;
      },

      // Directive

      Directive: function Directive(node) {
        return join(['@' + node.name, node.value], ': ');
      },

      // Type

      ListType: function ListType(node) {
        return '[' + node.type + ']';
      },
      NonNullType: function NonNullType(node) {
        return node.type + '!';
      }
    }
  });
}

function blockList(list, separator) {
  return length(list) === 0 ? null : indent('{\n' + join(list, separator)) + '\n}';
}

function indent(maybeString) {
  return maybeString && maybeString.replace(/\n/g, '\n  ');
}

function manyList(start, list, separator, end) {
  return length(list) === 0 ? null : start + join(list, separator) + end;
}

function length(maybeArray) {
  return maybeArray ? maybeArray.length : 0;
}

function join(maybeArray, separator) {
  return maybeArray ? maybeArray.filter(function (x) {
    return !!x;
  }).join(separator || '') : '';
}