usecode-syntax.ebnf

(* Usecode C Grammar in EBNF Notation *)
(* Converted from Bison grammar (usecode-syntax.txt) *)

(* Whitespace and Comments *)
digit          = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
letter         = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m"
               | "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z"
               | "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M"
               | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z" ;
underscore     = "_" ;

(* Terminals *)
identifier             = letter { letter | digit | underscore } ;
int_literal            = digit { digit } ;
string_literal         = '"' { ? any character except '"' ? } '"' ;
string_prefix          = identifier string_literal ;

(* Keywords - represented as terminals *)
keyword = "if" | "else" | "return" | "do" | "while" | "for" | "with" | "to"
        | "extern" | "declare" | "break" | "goto" | "case" | "var" | "void"
        | "alias" | "struct" | "char" | "byte" | "int" | "long" | "const"
        | "string" | "enum" | "converse" | "nested" | "say" | "message" | "response"
        | "event" | "gflags" | "item" | "true" | "false" | "remove" | "add" | "hide"
        | "script" | "after" | "ticks" | "static" | "original" | "shape#" | "object#"
        | "id#" | "class" | "runscript" | "switch" | "default" | "fallthrough" | "always"
        | "user_choice" | "try" | "catch" | "abort" | "throw" | "attend" | "endconv"
        | "nobreak" | "continue" | "repeat" | "nop" | "nohalt" | "wait" | "rise"
        | "descend" | "frame" | "hatch" | "next" | "previous" | "cycle" | "step"
        | "music" | "call" | "speech" | "sfx" | "face" | "hit" | "hours" | "actor"
        | "attack" | "finish" | "resurrect" | "setegg" | "minutes" | "reset" | "weather"
        | "near" | "far" | "north" | "south" | "east" | "west" | "ne" | "nw" | "se"
        | "sw" | "nop2" | "raw" | "standing" | "step_right" | "step_left" | "ready"
        | "raise_1h" | "reach_1h" | "strike_1h" | "raise_2h" | "reach_2h" | "strike_2h"
        | "sitting" | "bowing" | "kneeling" | "sleeping" | "cast_up" | "cast_out"
        | "cached_in" | "party_near" | "avatar_near" | "avatar_far" | "avatar_footpad"
        | "party_footpad" | "something_on" | "external_criteria" | "normal_damage"
        | "fire_damage" | "magic_damage" | "lightning_damage" | "poison_damage"
        | "starvation_damage" | "freezing_damage" | "ethereal_damage" | "sonic_damage"
        | "forever" | "breakable" | "new" | "delete" ;

(* Operators *)
operator = "+" | "-" | "*" | "/" | "%" | "=" | "==" | "!=" | "<" | "<=" | ">" | ">="
         | "&&" | "||" | "!" | "&" | "->" | "::" | "<<" | "+=" | "-=" | "*=" | "/="
         | "%=" | "&=" | "in" ;

(* Top-level Design *)
design = global_decl { global_decl } ;

global_decl = function
            | function_decl
            | const_int_decl
            | enum_decl
            | static_decl
            | class_definition
            | struct_definition ;

(* Class Definitions *)
class_definition = "class" identifier [ ":" defined_class ] "{" [ class_item_list ] "}" ;

class_item_list = class_item { class_item } ;

class_item = "var" class_var_def
           | "var" alias_tok identifier "=" declared_var ";"
           | "struct" "<" defined_struct ">" class_struct_def
           | "struct" "<" defined_struct ">" alias_tok identifier "=" declared_var ";"
           | "class" "<" defined_class ">" method
           | [ opt_void ] method ;

class_var_def = var_decl_list ";"
              | method ;

class_struct_def = struct_decl_list ";"
                 | method ;

method = identifier "(" [ param_list ] ")" function_body ;

(* Struct Definitions *)
struct_definition = "struct" identifier "{" [ struct_item_list ] "}" ;

struct_item_list = struct_item { struct_item } ;

struct_item = "var" identifier ";"
            | "struct" "<" defined_struct ">" ";"
            | "struct" "<" defined_struct ">" identifier ";" ;

(* Functions *)
function = function_proto function_body ;

function_body = "{" [ statement_list ] [ label_statement ] "}" ;

function_proto = ret_type identifier [ opt_funid ] "(" [ param_list ] ")"
               | "class" "<" defined_class ">" identifier [ const_int_val ] "(" [ param_list ] ")" ;

opt_funid = "shape#" "(" const_int_expr ")"
          | "object#" "(" [ const_int_expr ] ")"
          | [ const_int_val ]
          | "id#" "(" const_int_expr ")" ;

opt_const_int_expr = [ const_int_expr ] ;

const_int_expr = const_int_val
               | const_int_expr "+" const_int_expr
               | const_int_expr "-" const_int_expr
               | const_int_expr "*" const_int_expr
               | const_int_expr "/" const_int_expr
               | const_int_expr "%" const_int_expr
               | const_int_expr "==" const_int_expr
               | const_int_expr "!=" const_int_expr
               | const_int_expr "<" const_int_expr
               | const_int_expr "<=" const_int_expr
               | const_int_expr ">" const_int_expr
               | const_int_expr ">=" const_int_expr
               | const_int_expr "&&" const_int_expr
               | const_int_expr "||" const_int_expr
               | "!" const_int_expr
               | "(" const_int_expr ")"
               | addressof ;

const_int_val = sign_int_literal | identifier ;

(* Statements *)
statement_list = { statement } ;

statement = simple_or_if_statement
          | statement_block
          | converse_case_attend ;

simple_or_if_statement = simple_statement | if_statement ;

simple_statement = stmt_declaration
                 | assignment_statement
                 | trycatch_statement
                 | while_statement
                 | array_loop_statement
                 | array_enum_statement
                 | function_call_statement
                 | special_method_call_statement
                 | return_statement
                 | converse_statement
                 | switch_statement
                 | script_statement
                 | break_statement
                 | continue_statement
                 | fallthrough_statement
                 | goto_statement
                 | delete_statement
                 | "say" "(" [ nonclass_expr_list ] ")" ";"
                 | "message" "(" [ nonclass_expr_list ] ")" ";"
                 | answer_statement
                 | "endconv" ";"
                 | throwabort_statement [ expression ] ";"
                 | ";" ;

statement_block = "{" [ statement_list ] [ label_statement ] "}" ;

throwabort_statement = "abort" | "throw" ;

alias_tok = "alias" | "&" ;

stmt_declaration = "declare" "var" identifier ";"
                 | "declare" "struct" "<" defined_struct ">" identifier ";"
                 | "declare" "class" "<" defined_class ">" identifier ";"
                 | "var" var_decl_list ";"
                 | "var" alias_tok identifier "=" declared_var ";"
                 | "struct" "<" defined_struct ">" struct_decl_list ";"
                 | "struct" "<" defined_struct ">" alias_tok identifier "=" declared_var ";"
                 | "class" "<" defined_class ">" class_decl_list ";"
                 | "class" "<" defined_class ">" alias_tok identifier "=" declared_var ";"
                 | "string" string_decl_list [ "," ] ";"
                 | const_int_decl
                 | enum_decl
                 | function_decl
                 | static_decl ;

var_decl_list = var_decl { "," var_decl } ;

var_decl = identifier
         | identifier "=" nonclass_expr
         | identifier "=" script_expr ;

(* Enumerations *)
enum_decl = "enum" identifier [ ":" const_int_type ] "{" enum_item_list [ "," ] "}" ";" ;

const_int_type = "int" | "char" | "byte" | "long" | "long" "int" ;

enum_item_list = enum_item { "," enum_item } ;

enum_item = const_int | identifier ;

const_int_decl = "const" const_int_type const_int_decl_list [ "," ] ";" ;

const_int_decl_list = const_int { "," const_int } ;

const_int = identifier "=" [ int_cast ] const_int_expr ;

(* Classes and Structs *)
class_decl_list = class_decl { "," class_decl } ;

class_decl = identifier
           | identifier "=" class_expr ;

class_expr = new_expr | identifier | function_call ;

struct_decl_list = struct_decl { "," struct_decl } ;

struct_decl = identifier
            | identifier "=" nonclass_expr ;

static_decl = "static" "var" static_var_decl_list ";"
            | "static" "struct" "<" defined_struct ">" static_struct_var_decl_list ";"
            | "static" "class" "<" defined_class ">" static_cls_decl_list ";" ;

static_var_decl_list = static_var { "," static_var } ;

static_var = identifier ;

static_struct_var_decl_list = static_struct_var { "," static_struct_var } ;

static_struct_var = identifier ;

static_cls_decl_list = static_cls { "," static_cls } ;

static_cls = identifier ;

string_literal_rule = string_literal { string_literal } ;

string_prefix_rule = string_literal_rule string_prefix ;

string_decl_list = string_decl { "," string_decl } ;

string_decl = identifier "=" string_literal_rule ;

function_decl = "extern" function_proto ";" ;

(* Assignment *)
assignment_statement = expression "=" expression ";"
                     | expression "=" script_expr ";"
                     | nonclass_expr assignment_operator nonclass_expr ";"
                     | nonclass_expr "<<" appended_element_list ";" ;

assignment_operator = "+=" | "-=" | "*=" | "/=" | "%=" | "&=" ;

appended_element_list = appended_element { "<<" appended_element } ;

appended_element = nonclass_expr | "{" script_command_list "}" ;

(* Control Flow *)
scoped_statement = "{" [ statement_list ] [ label_statement ] "}"
                 | simple_statement
                 | if_statement ;

if_statement = "if" "(" expression ")" scoped_statement [ "else" scoped_statement ] ;

trycatch_statement = "try" "{" [ statement_list ] [ label_statement ] "}" "catch" "(" [ identifier ] ")" "{" [ statement_list ] [ label_statement ] "}" ;

while_statement = "while" "(" nonclass_expr ")" scoped_statement [ opt_nobreak ]
               | "forever" scoped_statement [ opt_nobreak ]
               | "do" scoped_statement "while" "(" nonclass_expr ")" [ opt_nobreak_do ]
               | "breakable" scoped_statement [ opt_nobreak ] ;

opt_nobreak = "nobreak" "{" [ statement_list ] [ label_statement ] "}" ;

opt_nobreak_do = "nobreak" "{" [ statement_list ] [ label_statement ] "}" | ";" ;

opt_nobreak_conv = [ "nobreak" "{" [ statement_list ] [ label_statement ] "}" ] ;

array_enum_statement = "enum" "(" ")" ";" ;

array_loop_statement = start_array_variables scoped_statement [ opt_nobreak ]
                     | start_array_variables "attend" identifier ";" ;

start_array_variables = start_array_loop ")"
                      | start_array_loop "with" identifier ")"
                      | start_array_loop "with" identifier "to" identifier ")" ;

start_array_loop = "for" "(" identifier "in" declared_var ;

(* Function Calls *)
function_call_statement = function_call ";" ;

special_method_call_statement = primary hierarchy_tok "say" "(" [ nonclass_expr_list ] ")" ";"
                              | primary hierarchy_tok "hide" "(" ")" ";"
                              | run_script_expression ";" ;

run_script_expression = [ opt_primary_expression ] "runscript" "(" nonclass_expr [ opt_delay ] ")" ;

opt_delay = "," nonclass_expr ;

return_statement = "return" [ expression ] ";" ;

(* Conversation *)
opt_nest = [ ":" "nested" ] ;

converse_statement = "converse" "{" [ noncase_statement_list ] response_case_list "}" [ opt_nobreak_conv ]
                   | "converse" [ opt_nest ] conv_expression "{" [ noncase_statement_list ] converse_case_list "}" [ opt_nobreak_conv ]
                   | "converse" "attend" identifier ";" ;

conv_expression = "(" expression ")" ;

converse_case_list = { converse_case } ;

converse_case = "case" declared_var_value [ converse_options ] ":" [ noncase_statement_list ]
              | "case" string_list [ converse_options ] ":" [ noncase_statement_list ]
              | "always" ":" [ noncase_statement_list ]
              | "default" ":" [ noncase_statement_list ] ;

opt_int_value = [ "(" int_literal ")" ] ;

converse_case_attend = "case" declared_var_value [ converse_options ] "attend" identifier ":"
                     | "case" string_list [ converse_options ] "attend" identifier ":"
                     | "default" [ opt_int_value ] "attend" identifier ":" ;

response_case_list = response_case { "else" response_case } ;

response_case = response_expression [ statement_list ] ;

response_expression = "if" "(" "response" "==" string_literal_rule ")"
                    | "if" "(" "response" "in" "[" string_list "]" ")" ;

string_list = string_literal_rule { "," string_literal_rule } ;

converse_options = [ "(" "remove" ")" ] ;

(* Switch Statements *)
switch_statement = "switch" "(" expression ")" "{" switch_case_list "}" ;

switch_case_list = switch_case { switch_case } ;

switch_case = "case" int_literal ":" [ noncase_statement_list ]
            | "case" string_literal ":" [ noncase_statement_list ]
            | "default" ":" [ noncase_statement_list ] ;

(* Scripts *)
script_expr = "script" item [ opt_script_delay ] script_command ;

script_statement = script_expr ;

item = nonclass_expr ;

script_command_list = script_command { script_command } ;

script_command = "finish" ";"
               | "resurrect" ";"
               | "continue" ";"
               | "reset" ";"
               | "repeat" repeat_count script_command ";"
               | "repeat" nonclass_expr "," nonclass_expr script_command ";"
               | "raw" "(" int_literal ")" ";"
               | "nop" ";"
               | "nop2" ";"
               | "nohalt" ";"
               | "wait" nonclass_expr [ "minutes" | "hours" ] ";"
               | "wait" "while" [ "near" | "far" ] nonclass_expr ";"
               | "remove" ";"
               | "rise" ";"
               | "descend" ";"
               | "frame" nonclass_expr ";"
               | "actor" "frame" [ nonclass_expr | actor_frames ] ";"
               | "hatch" ";"
               | "setegg" nonclass_expr "," nonclass_expr ";"
               | "setegg" egg_criteria "," nonclass_expr ";"
               | "next" "frame" [ "cycle" ] ";"
               | "previous" "frame" [ "cycle" ] ";"
               | "say" nonclass_expr ";"
               | "step" nonclass_expr [ "," nonclass_expr ] ";"
               | "step" direction ";"
               | "music" nonclass_expr [ "," nonclass_expr ] ";"
               | start_call [ "," nonclass_expr ] ";"
               | "speech" nonclass_expr ";"
               | "sfx" nonclass_expr ";"
               | "face" [ nonclass_expr | direction ] ";"
               | "weather" nonclass_expr ";"
               | "hit" nonclass_expr "," [ nonclass_expr | dam_type ] ";"
               | "attack" ";"
               | declared_var_value ";"
               | "{" script_command_list "}" ;

start_call = "call" nonclass_expr ;

repeat_count = nonclass_expr | "forever" ;

dam_type = "normal_damage" | "fire_damage" | "magic_damage" | "lightning_damage"
         | "poison_damage" | "starvation_damage" | "freezing_damage" | "ethereal_damage"
         | "sonic_damage" ;

direction = "north" | "ne" | "east" | "se" | "south" | "sw" | "west" | "nw" ;

actor_frames = "standing" | "step_right" | "step_left" | "ready" | "raise_1h" | "reach_1h"
             | "strike_1h" | "raise_2h" | "reach_2h" | "strike_2h" | "sitting" | "bowing"
             | "kneeling" | "sleeping" | "cast_up" | "cast_out" ;

egg_criteria = "cached_in" | "party_near" | "avatar_near" | "avatar_far" | "avatar_footpad"
             | "party_footpad" | "something_on" | "external_criteria" ;

opt_script_delay = [ "after" nonclass_expr "ticks" ] ;

(* Break, Continue, and Labels *)
break_statement = "break" ";"
                | "break" identifier ;

continue_statement = "continue" ";"
                   | "continue" identifier ;

fallthrough_statement = "fallthrough" ";" ;

label_statement = identifier ":" ;

goto_statement = "goto" identifier ";" ;

delete_statement = "delete" declared_var ";" ;

answer_statement = "add" "(" nonclass_expr_list ")" ";"
                 | "remove" "(" nonclass_expr_list ")" ";" ;

(* Expressions *)
noncase_statement_list = { noncase_statement } ;

noncase_statement = simple_or_if_statement | statement_block ;

opt_nonclass_expr_list = [ nonclass_expr_list ] ;

nonclass_expr_list = nonclass_expr { "," nonclass_expr } ;

nonclass_expr = expression ;

expression = primary
           | nonclass_expr "+" nonclass_expr
           | nonclass_expr "-" nonclass_expr
           | nonclass_expr "*" nonclass_expr
           | nonclass_expr "/" nonclass_expr
           | nonclass_expr "%" nonclass_expr
           | nonclass_expr "==" nonclass_expr
           | "new" "script" script_command
           | "user_choice"
           | nonclass_expr "!=" nonclass_expr
           | nonclass_expr "<" nonclass_expr
           | nonclass_expr "<=" nonclass_expr
           | nonclass_expr ">" nonclass_expr
           | nonclass_expr ">=" nonclass_expr
           | nonclass_expr "&&" nonclass_expr
           | nonclass_expr "||" nonclass_expr
           | nonclass_expr "in" nonclass_expr
           | nonclass_expr "&" nonclass_expr
           | "+" primary
           | "-" primary
           | addressof
           | "!" primary
           | "[" [ expression_list ] "]"
           | string_literal_rule
           | string_prefix_rule
           | new_expr
           | run_script_expression ;

addressof = "&" identifier
          | "&" "struct" "<" defined_struct ">" "::" identifier ;

opt_expression_list = [ expression_list [ "," ] ] ;

expression_list = expression { "," expression } ;

int_cast = "(" const_int_type ")" ;

primary = int_literal
        | [ int_cast ] int_literal
        | member_selector
        | declared_var_value
        | declared_var "[" expression "]"
        | "gflags" "[" nonclass_expr "]"
        | function_call
        | "true"
        | "false"
        | "event"
        | "item"
        | "(" expression ")" ;

new_expr = "new" defined_class "(" [ nonclass_expr_list ] ")" ;

hierarchy_tok = "->" | "." ;

member_selector = primary hierarchy_tok identifier ;

opt_primary_expression = [ primary hierarchy_tok ] ;

function_call = member_selector [ "original" ] "(" [ expression_list ] ")"
              | identifier [ "original" ] "(" [ expression_list ] ")"
              | primary hierarchy_tok defined_class "::" identifier "(" [ expression_list ] ")"
              | defined_class "::" identifier "(" [ expression_list ] ")"
              | primary hierarchy_tok "(" "*" primary ")" "(" [ expression_list ] ")"
              | "(" "*" primary ")" "(" [ expression_list ] ")"
              | primary hierarchy_tok "(" "@" int_literal ")" "(" [ expression_list ] ")"
              | "(" "@" int_literal ")" "(" [ expression_list ] ")" ;

(* Parameters *)
opt_param_list = [ param_list ] ;

param_list = param { "," param } ;

param = identifier
      | "var" identifier
      | "struct" "<" defined_struct ">" identifier
      | "class" "<" defined_class ">" identifier ;

(* Integer Literals *)
sign_int_literal = int_literal
                 | "-" int_literal
                 | "+" int_literal ;

int_literal = sign_int_literal
            | [ int_cast ] sign_int_literal
            | declared_sym
            | "true"
            | "false" ;

(* Types *)
opt_void = [ "void" ] ;

ret_type = "var"
         | "struct" "<" defined_struct ">"
         | [ "void" ] ;

(* Declared Identifiers *)
declared_var_value = declared_sym ;

declared_var = declared_sym ;

declared_sym = identifier ;

defined_class = identifier ;

defined_struct = identifier ;