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36 lines
1.0 KiB
Plaintext
36 lines
1.0 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 / write)?
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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 <- '!' _ expression
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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-z] / [0-9])* > _
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number <- < [0-9]+ > _
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~_ <- [ \t\r\n]*
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