BNF Syntax of Ruby
Based on http://docs.huihoo.com/ruby/ruby-man-1.4/yacc.html with some edit-
ing. I have found other websites attesting that Ruby version 1.4.6 is the latest with a reference manual
in English, http://docs.huihoo.com/ruby/ruby-man-1.4/index.html, though Ruby
exists up to v1.9 in Japanese.
ALL-CAPS are used for nonterminals, and all-lowercase for literal keywords. Literal ( ) [ ]
{ } are quoted to distinguish them from BNF syntax.
PROGRAM : COMPSTMT
T : ";" | "\n" //a newline can terminate a statement
COMPSTMT : STMT {T EXPR} [T]
STMT : CALL do ["|" [BLOCK_VAR] "|"] COMPSTMT end
| undef FNAME
| alias FNAME FNAME
| STMT if EXPR
| STMT while EXPR
| STMT unless EXPR
| STMT until EXPR
| "BEGIN" "{" COMPSTMT "}" //object initializer
| "END" "{" COMPSTMT "}" //object finalizer
| LHS = COMMAND [do ["|" [BLOCK_VAR] "|"] COMPSTMT end]
| EXPR
EXPR : MLHS = MRHS
| return CALL_ARGS
| yield CALL_ARGS
| EXPR and EXPR
| EXPR or EXPR
| not EXPR
| COMMAND
| ! COMMAND
| ARG
CALL : FUNCTION
| COMMAND
COMMAND : OPERATION CALL_ARGS
| PRIMARY.OPERATION CALL_ARGS
| PRIMARY :: OPERATION CALL_ARGS
| super CALL_ARGS
FUNCTION : OPERATION ["(" [CALL_ARGS] ")"]
| PRIMARY.OPERATION "(" [CALL_ARGS] ")"
| PRIMARY :: OPERATION "(" [CALL_ARGS] ")"
| PRIMARY.OPERATION
| PRIMARY :: OPERATION
| super "(" [CALL_ARGS] ")"
| super
ARG : LHS = ARG
| LHS OP_ASGN ARG
| ARG .. ARG | ARG ... ARG
| ARG + ARG | ARG - ARG | ARG * ARG | ARG / ARG
| ARG % ARG | ARG ** ARG
| + ARG | - ARG
| ARG "|" ARG
| ARG ˆ ARG | ARG & ARG
| ARG <=> ARG
| ARG > ARG | ARG >= ARG | ARG < ARG | ARG <= ARG
| ARG == ARG | ARG === ARG | ARG != ARG
| ARG =˜ ARG | ARG !˜ ARG
| ! ARG | ˜ ARG
| ARG << ARG | ARG >> ARG
| ARG && ARG | ARG || ARG
| defined? ARG
| PRIMARY
PRIMARY: "(" COMPSTMT ")"
| LITERAL
| VARIABLE
| PRIMARY :: IDENTIFIER
| :: IDENTIFIER
| PRIMARY "[" [ARGS] "]"
| "[" [ARGS [,]] "]"
| "{" [ARGS | ASSOCS [,]] "}"
| return ["(" [CALL_ARGS] ")"]
| yield ["(" [CALL_ARGS] ")"]
| defined? "(" ARG ")"
| FUNCTION
| FUNCTION "{" ["|" [BLOCK_VAR] "|"] COMPSTMT "}"
| if EXPR THEN
COMPSTMT
{elsif EXPR THEN
COMPSTMT}
[else
COMPSTMT]
end
| unless EXPR THEN
COMPSTMT
[else
COMPSTMT]
end
| while EXPR DO COMPSTMT end
| until EXPR DO COMPSTMT end
| case COMPSTMT
when WHEN_ARGS THEN COMPSTMT
{when WHEN_ARGS THEN COMPSTMT}
[else
COMPSTMT]
end
