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22 lines
712 B
Racket
22 lines
712 B
Racket
#lang brag
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b-program : [b-line] (/NEWLINE [b-line])*
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b-line : b-line-number [b-statement] (/":" [b-statement])*
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@b-line-number : INTEGER
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@b-statement : b-rem | b-end | b-print | b-let
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| b-goto | b-gosub | b-return | b-for | b-next
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b-rem : REM
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b-end : /"end"
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b-print : /"print" [STRING | b-num-expr]
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b-goto : /"goto" b-num-expr
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b-gosub : /"gosub" b-num-expr
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b-return : /"return"
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b-let : [/"let"] b-id /"=" b-num-expr
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b-for : /"for" b-id /"=" b-num-expr /"to" b-num-expr [/"step" b-num-expr]
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b-next : /"next" [b-id]
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@b-id : ID
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b-num-expr : b-sum
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b-sum : (b-value /"+" b-value)*
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@b-value : b-id | b-number
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@b-number : b-positive | b-negative
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@b-positive : INTEGER | DECIMAL
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b-negative : /"-" b-positive |