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31 lines
608 B
Racket
31 lines
608 B
Racket
#lang brag
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program : line*
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line: NUMBER statement [":" statement]*
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statement : "END"
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| "GOSUB" NUMBER
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| "GOTO" expr
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| "IF" expr "THEN" (statement | expr) ["ELSE" (statement | expr)]
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| "INPUT" [print-list ";"] ID
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| ID "=" expr ; change: make "LET" opt
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| "PRINT" print-list
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| "RETURN"
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print-list : [expr [";" [print-list]]]
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expr : comp-expr [("AND" | "OR") expr]
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comp-expr : sum [("=" | ">" | ">=" | "<" | "<=" | "<>") comp-expr]
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sum : product [("+" | "-") sum]
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product : value [("*" | "/") product]
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@value : ID | id-expr
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| /"(" expr /")"
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| STRING
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| NUMBER
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/id-expr : ID [/"(" expr [/"," expr]* /")"] |