FlatBuffers
An open source project by FPL.
Grammar of the schema language

schema = include* ( namespace_decl | type_decl | enum_decl | root_decl | file_extension_decl | file_identifier_decl | attribute_decl | rpc_decl | object )*

include = include string_constant ;

namespace_decl = namespace ident ( . ident )* ;

attribute_decl = attribute ident | "</tt>ident<tt>" ;

type_decl = ( table | struct ) ident metadata { field_decl+ }

enum_decl = ( enum ident : type | union ident ) metadata { commasep( enumval_decl ) }

root_decl = root_type ident ;

field_decl = ident : type [ = scalar ] metadata ;

rpc_decl = rpc_service ident { rpc_method+ }

rpc_method = ident ( ident ) : ident metadata ;

type = bool | byte | ubyte | short | ushort | int | uint | float | long | ulong | double | int8 | uint8 | int16 | uint16 | int32 | uint32| int64 | uint64 | float32 | float64 | string | [ type ] | ident

enumval_decl = ident [ = integer_constant ]

metadata = [ ( commasep( ident [ : single_value ] ) ) ]

scalar = integer_constant | float_constant

object = { commasep( ident : value ) }

single_value = scalar | string_constant

value = single_value | object | [ commasep( value ) ]

commasep(x) = [ x ( , x )* ]

file_extension_decl = file_extension string_constant ;

file_identifier_decl = file_identifier string_constant ;

string_constant = \".*?\\"

ident = [a-zA-Z_][a-zA-Z0-9_]*

[:digit:] = [0-9]

[:xdigit:] = [0-9a-fA-F]

dec_integer_constant = [-+]?[:digit:]+

hex_integer_constant = [-+]?0[xX][:xdigit:]+

integer_constant = dec_integer_constant | hex_integer_constant

dec_float_constant = [-+]?(([.][:digit:]+)|([:digit:]+[.][:digit:]*)|([:digit:]+))([eE][-+]?[:digit:]+)?

hex_float_constant = [-+]?0[xX](([.][:xdigit:]+)|([:xdigit:]+[.][:xdigit:]*)|([:xdigit:]+))([pP][-+]?[:digit:]+)

special_float_constant = [-+]?(nan|inf|infinity)

float_constant = decimal_float_constant | hexadecimal_float_constant | special_float_constant

boolean_constant = (true|false) | (integer_constant ? true : false)