import type { Maybe } from '../jsutils/Maybe.js';
import type { ASTNode } from './ast.js';
import { printBlockString } from './blockString.js';
import { printString } from './printString.js';
import type { ASTReducer } from './visitor.js';
import { visit } from './visitor.js';
export function print(ast: ASTNode): string {
return visit(ast, printDocASTReducer);
}
const MAX_LINE_LENGTH = 80;
const printDocASTReducer: ASTReducer<string> = {
Name: { leave: (node) => node.value },
Variable: { leave: (node) => '$' + node.name },
Document: {
leave: (node) => join(node.definitions, '\n\n'),
},
OperationDefinition: {
leave(node) {
const varDefs = wrap('(', join(node.variableDefinitions, ', '), ')');
const prefix = join(
[
node.operation,
join([node.name, varDefs]),
join(node.directives, ' '),
],
' ',
);
return (prefix === 'query' ? '' : prefix + ' ') + node.selectionSet;
},
},
VariableDefinition: {
leave: ({ variable, type, defaultValue, directives }) =>
variable +
': ' +
type +
wrap(' = ', defaultValue) +
wrap(' ', join(directives, ' ')),
},
SelectionSet: { leave: ({ selections }) => block(selections) },
Field: {
leave({
alias,
name,
arguments: args,
nullabilityAssertion,
directives,
selectionSet,
}) {
const prefix = join([wrap('', alias, ': '), name], '');
let argsLine = prefix + wrap('(', join(args, ', '), ')');
if (argsLine.length > MAX_LINE_LENGTH) {
argsLine = prefix + wrap('(\n', indent(join(args, '\n')), '\n)');
}
return join([
argsLine,
nullabilityAssertion,
wrap(' ', join(directives, ' ')),
wrap(' ', selectionSet),
]);
},
},
Argument: { leave: ({ name, value }) => name + ': ' + value },
ListNullabilityOperator: {
leave({ nullabilityAssertion }) {
return join(['[', nullabilityAssertion, ']']);
},
},
NonNullAssertion: {
leave({ nullabilityAssertion }) {
return join([nullabilityAssertion, '!']);
},
},
ErrorBoundary: {
leave({ nullabilityAssertion }) {
return join([nullabilityAssertion, '?']);
},
},
FragmentSpread: {
leave: ({ name, directives }) =>
'...' + name + wrap(' ', join(directives, ' ')),
},
InlineFragment: {
leave: ({ typeCondition, directives, selectionSet }) =>
join(
[
'...',
wrap('on ', typeCondition),
join(directives, ' '),
selectionSet,
],
' ',
),
},
FragmentDefinition: {
leave: ({
name,
typeCondition,
variableDefinitions,
directives,
selectionSet,
}) =>
`fragment ${name}${wrap('(', join(variableDefinitions, ', '), ')')} ` +
`on ${typeCondition} ${wrap('', join(directives, ' '), ' ')}` +
selectionSet,
},
IntValue: { leave: ({ value }) => value },
FloatValue: { leave: ({ value }) => value },
StringValue: {
leave: ({ value, block: isBlockString }) =>
isBlockString ? printBlockString(value) : printString(value),
},
BooleanValue: { leave: ({ value }) => (value ? 'true' : 'false') },
NullValue: { leave: () => 'null' },
EnumValue: { leave: ({ value }) => value },
ListValue: { leave: ({ values }) => '[' + join(values, ', ') + ']' },
ObjectValue: { leave: ({ fields }) => '{ ' + join(fields, ', ') + ' }' },
ObjectField: { leave: ({ name, value }) => name + ': ' + value },
Directive: {
leave: ({ name, arguments: args }) =>
'@' + name + wrap('(', join(args, ', '), ')'),
},
NamedType: { leave: ({ name }) => name },
ListType: { leave: ({ type }) => '[' + type + ']' },
NonNullType: { leave: ({ type }) => type + '!' },
SchemaDefinition: {
leave: ({ description, directives, operationTypes }) =>
wrap('', description, '\n') +
join(['schema', join(directives, ' '), block(operationTypes)], ' '),
},
OperationTypeDefinition: {
leave: ({ operation, type }) => operation + ': ' + type,
},
ScalarTypeDefinition: {
leave: ({ description, name, directives }) =>
wrap('', description, '\n') +
join(['scalar', name, join(directives, ' ')], ' '),
},
ObjectTypeDefinition: {
leave: ({ description, name, interfaces, directives, fields }) =>
wrap('', description, '\n') +
join(
[
'type',
name,
wrap('implements ', join(interfaces, ' & ')),
join(directives, ' '),
block(fields),
],
' ',
),
},
FieldDefinition: {
leave: ({ description, name, arguments: args, type, directives }) =>
wrap('', description, '\n') +
name +
(hasMultilineItems(args)
? wrap('(\n', indent(join(args, '\n')), '\n)')
: wrap('(', join(args, ', '), ')')) +
': ' +
type +
wrap(' ', join(directives, ' ')),
},
InputValueDefinition: {
leave: ({ description, name, type, defaultValue, directives }) =>
wrap('', description, '\n') +
join(
[name + ': ' + type, wrap('= ', defaultValue), join(directives, ' ')],
' ',
),
},
InterfaceTypeDefinition: {
leave: ({ description, name, interfaces, directives, fields }) =>
wrap('', description, '\n') +
join(
[
'interface',
name,
wrap('implements ', join(interfaces, ' & ')),
join(directives, ' '),
block(fields),
],
' ',
),
},
UnionTypeDefinition: {
leave: ({ description, name, directives, types }) =>
wrap('', description, '\n') +
join(
['union', name, join(directives, ' '), wrap('= ', join(types, ' | '))],
' ',
),
},
EnumTypeDefinition: {
leave: ({ description, name, directives, values }) =>
wrap('', description, '\n') +
join(['enum', name, join(directives, ' '), block(values)], ' '),
},
EnumValueDefinition: {
leave: ({ description, name, directives }) =>
wrap('', description, '\n') + join([name, join(directives, ' ')], ' '),
},
InputObjectTypeDefinition: {
leave: ({ description, name, directives, fields }) =>
wrap('', description, '\n') +
join(['input', name, join(directives, ' '), block(fields)], ' '),
},
DirectiveDefinition: {
leave: ({ description, name, arguments: args, repeatable, locations }) =>
wrap('', description, '\n') +
'directive @' +
name +
(hasMultilineItems(args)
? wrap('(\n', indent(join(args, '\n')), '\n)')
: wrap('(', join(args, ', '), ')')) +
(repeatable ? ' repeatable' : '') +
' on ' +
join(locations, ' | '),
},
SchemaExtension: {
leave: ({ directives, operationTypes }) =>
join(
['extend schema', join(directives, ' '), block(operationTypes)],
' ',
),
},
ScalarTypeExtension: {
leave: ({ name, directives }) =>
join(['extend scalar', name, join(directives, ' ')], ' '),
},
ObjectTypeExtension: {
leave: ({ name, interfaces, directives, fields }) =>
join(
[
'extend type',
name,
wrap('implements ', join(interfaces, ' & ')),
join(directives, ' '),
block(fields),
],
' ',
),
},
InterfaceTypeExtension: {
leave: ({ name, interfaces, directives, fields }) =>
join(
[
'extend interface',
name,
wrap('implements ', join(interfaces, ' & ')),
join(directives, ' '),
block(fields),
],
' ',
),
},
UnionTypeExtension: {
leave: ({ name, directives, types }) =>
join(
[
'extend union',
name,
join(directives, ' '),
wrap('= ', join(types, ' | ')),
],
' ',
),
},
EnumTypeExtension: {
leave: ({ name, directives, values }) =>
join(['extend enum', name, join(directives, ' '), block(values)], ' '),
},
InputObjectTypeExtension: {
leave: ({ name, directives, fields }) =>
join(['extend input', name, join(directives, ' '), block(fields)], ' '),
},
};
function join(
maybeArray: Maybe<ReadonlyArray<string | undefined>>,
separator = '',
): string {
return maybeArray?.filter((x) => x).join(separator) ?? '';
}
function block(array: Maybe<ReadonlyArray<string | undefined>>): string {
return wrap('{\n', indent(join(array, '\n')), '\n}');
}
function wrap(
start: string,
maybeString: Maybe<string>,
end: string = '',
): string {
return maybeString != null && maybeString !== ''
? start + maybeString + end
: '';
}
function indent(str: string): string {
return wrap(' ', str.replaceAll('\n', '\n '));
}
function hasMultilineItems(maybeArray: Maybe<ReadonlyArray<string>>): boolean {
return maybeArray?.some((str) => str.includes('\n')) ?? false;
}