forked from xxq250/Nasal-Interpreter
116 lines
3.6 KiB
EBNF
116 lines
3.6 KiB
EBNF
(*
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<> must choose
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[] can choose
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{} can repeat 0 to infinite time(s)
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| or
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::= is defined as
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*)
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<var> = <token_var_reserve_word> ;
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<func> = <token_func_reserve_word> ;
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<and> = <token_and_operator> ;
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<or> = <token_or_operator> ;
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<number> = <token_number> ;
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<string> = <token_string> ;
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<nil> = <token_reserve_word_nil> ;
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<id> = <token_identifier> ;
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<dynamic_id> = <token_dynamic_id> ;
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<vector> = '[' { <calculation> ',' } ']' ;
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<hash> = '{' {(<id> | <string>) ':' <scalar> ','} '}' ;
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<scalar> =
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<number>
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| <nil>
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| <string>
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| <id>
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| <hash>
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| <vector>
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| <func> <id>
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| <function>
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| '(' <calculation> ')'
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| <scalar> { ('[' {<calculation> ','} ']') | ('[' <calculation> ':' [<calculation>] ']') | ('.' <id>) | ('(' {<calculation> ','} ')') | ('(' {<id> ':' <calculation> ','} ')') }
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;
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<function> =
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<func> ['(' ')'] <statement>
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| <func> ['(' ')'] '{' {<statement> ';'} '}'
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| <func> '(' {<id> ','} {<id> '=' <calculation> ','} {<dynamic_id>} ')' <statement>
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| <func> '(' {<id> ','} {<id> '=' <calculation> ','} {<dynamic_id>} ')' '{' {<statement> ';'} '}'
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;
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<calculation> =
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<and_calc>
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| <or_calc>
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| <additive_calc>
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| <multive_calc>
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| [('-' | '!')] <scalar>
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| <calculation> '?' <calculation> ':' <calculation>
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;
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<and_calc> = <or_calc> {<and> <or_calc>} ;
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<or_calc> = <additive_calc> {<or> <additive_calc>} ;
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<additive_calc> = <multive_calc> {('+' | '-' | '~') <multive_calc>} ;
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<multive_calc> = [('-' | '!')] <scalar> {('*' | '/') [('-' | '!')] <scalar>};
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(* this definition is also used in for loop*)
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<definition> =
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<var> <id> '=' <scalar>
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| <var> '(' {<id> ','} ')' '=' (<scalar> | '(' {<scalar> ','} ')')
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| '(' <var> {<id> ','} ')' '=' (<scalar> | '(' {<scalar> ','} ')')
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;
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<assignment> =
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<scalar> ('=' | '+=' | '-=' | '*=' | '/=' | '~=') <calculation>
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| '(' {<scalar> ','} ')' ('=' | '+=' | '-=' | '*=' | '/=' | '~=') (<calculation> | '(' {<calculation> ','} ')')
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;
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<loop_expr> =
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<for_loop>
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| <while_loop>
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| <forindex_loop>
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| <foreach_loop>
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;
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<for_loop> =
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<for> '(' [<statement>] ';' [<calculation>] ';' [<statement>] ')' <statement> [';']
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| <for> '(' [<statement>] ';' [<calculation>] ';' [<statement>] ')' '{' {<statement> ';'} '}'
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;
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<while_loop> =
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<while> '(' <calculation> ')' <statement> [';']
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| <while> '(' <calculation> ')' '{' {<statement> ';'} '}'
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;
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(* in forindex and foreach the scalar and definition cannot be lacked*)
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<forindex_loop> =
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<forindex> '(' (<var> <id>)|(<id>) ';' <scalar> ')' <statement> [';']
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| <forindex> '(' (<var> <id>)|(<id>) ';' <scalar> ')' '{' {<statement> ';'} '}'
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;
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<foreach_loop> =
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<foreach> '(' (<var> <id>)|(<id>) ';' <scalar> ')' <statement> [';']
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| <foreach> '(' (<var> <id>)|(<id>) ';' <scalar> ')' '{' {<statement> ';'} '}'
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;
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<choose_expr> = <choose_expr_if> {<choose_expr_elsif>} [<choose_expr_else>]
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;
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<choose_expr_if> =
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<if> '(' <calculation> ')' <statement> [';']
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| <if> '(' <calculation> ')' '{' {<statement> ';'} '}'
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;
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<choose_expr_elsif> =
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<elsif> '(' <calculation> ')' <statement> [';']
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| <elsif> '(' <calculation> ')' '{' {<statement> ';'} '}'
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| <else> <if> '(' <calculation> ')' <statement> [';']
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| <else> <if> '(' <calculation> ')' '{' {<statement> ';'} '}'
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;
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<choose_expr_else> =
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<else> <statement> [';']
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| <else> '{' {<statement> ';'} '}'
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;
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<continue_expr> = <continue> ;
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<break_expr> = <break> ;
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<return_expr> = <return> [<scalar>] ;
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<statement> =
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<definition>
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| <assignment>
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| <choose_expr>
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| <loop_expr>
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| <continue_expr>
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| <break_expr>
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| <return_expr>
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; |