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38 lines
1.2 KiB
Plaintext
38 lines
1.2 KiB
Plaintext
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program <- _ block '.' _
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block <- const var procedure statement
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const <- ('CONST' __ ident '=' _ number (',' _ ident '=' _ number)* ';' _)?
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var <- ('VAR' __ ident (',' _ ident)* ';' _)?
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procedure <- ('PROCEDURE' __ ident ';' _ block ';' _)*
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statement <- (assignment / call / statements / if / while / out / in)?
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assignment <- ident ':=' _ expression
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call <- 'CALL' __ ident
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statements <- 'BEGIN' __ statement (';' _ statement )* 'END' __
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if <- 'IF' __ condition 'THEN' __ statement
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while <- 'WHILE' __ condition 'DO' __ statement
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out <- ('out' __ / 'write' __ / '!' _) expression
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in <- ('in' __ / 'read' __ / '?' _) ident
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condition <- odd / compare
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odd <- 'ODD' __ expression
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compare <- expression compare_op expression
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compare_op <- < '=' / '#' / '<=' / '<' / '>=' / '>' > _
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expression <- sign term (term_op term)*
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sign <- < [-+]? > _
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term_op <- < [-+] > _
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term <- factor (factor_op factor)*
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factor_op <- < [*/] > _
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factor <- ident / number / '(' _ expression ')' _
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ident <- < [a-z] [a-z0-9]* > _
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number <- < [0-9]+ > _
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~_ <- [ \t\r\n]*
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~__ <- ![a-z0-9_] _
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