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# Copyright 2010 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
package main
type Calculator Peg {
Expression
}
e <- sp e1 !.
e1 <- e2 ( add e2 { p.AddOperator(TypeAdd) }
/ minus e2 { p.AddOperator(TypeSubtract) }
)*
e2 <- e3 ( multiply e3 { p.AddOperator(TypeMultiply) }
/ divide e3 { p.AddOperator(TypeDivide) }
/ modulus e3 { p.AddOperator(TypeModulus) }
)*
e3 <- e4 ( exponentiation e4 { p.AddOperator(TypeExponentiation) }
)*
e4 <- minus value { p.AddOperator(TypeNegation) }
/ value
value <- < [0-9]+ > sp { p.AddValue(buffer[begin:end]) }
/ open e1 close
add <- '+' sp
minus <- '-' sp
multiply <- '*' sp
divide <- '/' sp
modulus <- '%' sp
exponentiation <- '^' sp
open <- '(' sp
close <- ')' sp
sp <- ( ' ' / '\t' )*
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