Added pl0.peg.

This commit is contained in:
yhirose 2015-07-29 20:15:09 -04:00
parent 9d5b5027e3
commit 0e70fc94f8

35
grammar/pl0.peg Normal file
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@ -0,0 +1,35 @@
program <- block '.' _
block <- const var procedure statement
const <- ('CONST' _ ident '=' _ number (',' _ ident '=' _ number)* ';' _)?
var <- ('VAR' _ ident (',' _ ident)* ';' _)?
procedure <- ('PROCEDURE' _ ident ';' _ block ';' _)*
statement <- (assignment / call / statements / if / while / write)?
assignment <- ident ':=' _ expression
call <- 'CALL' _ ident
statements <- 'BEGIN' _ statement (';' _ statement )* 'END' _
if <- 'IF' _ condition 'THEN' _ statement
while <- 'WHILE' _ condition 'DO' _ statement
out <- '!' _ expression
condition <- odd / compare
odd <- 'ODD' _ expression
compare <- expression compare_op expression
compare_op <- < '=' / '#' / '<=' / '<' / '>=' / '>' > _
expression <- sign term (term_op term)*
sign <- < [-+]? > _
term_op <- < [-+] > _
term <- factor (factor_op factor)*
factor_op <- < [*/] > _
factor <- ident / number / '(' _ expression ')' _
ident <- < [a-z] ([a-z] / [0-9])* > _
number <- < [0-9]+ > _
~_ <- [ \t\r\n]*