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|
class Calculator
prechigh
left '*' '/'
left '+' '-'
preclow
convert
NUMBER 'Number'
end
rule
target : exp
| /* none */ { result = 0 }
exp : exp '+' exp { result += val[2]; a = 'plus' }
| exp '-' exp { result -= val[2]; a = "string test" }
| exp '*' exp { result *= val[2] }
| exp '/' exp { result /= val[2] }
| '(' { $emb = true } exp ')'
{
raise 'must not happen' unless $emb
result = val[2]
}
| '-' NUMBER { result = -val[1] }
| NUMBER
----header
class Number
end
----inner
def initialize
@racc_debug_out = $stdout
@yydebug = false
end
def validate(expected, src)
result = parse(src)
unless result == expected
raise "test #{@test_number} fail"
end
@test_number += 1
end
def parse(src)
@src = src
@test_number = 1
yyparse self, :scan
end
def scan(&block)
@src.each(&block)
end
----footer
calc = Calculator.new
calc.validate(9, [[Number, 9], nil])
calc.validate(-3,
[[Number, 5],
['*', '*'],
[Number, 1],
['-', '*'],
[Number, 1],
['*', '*'],
[Number, 8],
nil])
calc.validate(-1,
[[Number, 5],
['+', '+'],
[Number, 2],
['-', '-'],
[Number, 5],
['+', '+'],
[Number, 2],
['-', '-'],
[Number, 5],
nil])
calc.validate(-4,
[['-', 'UMINUS'],
[Number, 4],
nil])
calc.validate(40,
[[Number, 7],
['*', '*'],
['(', '('],
[Number, 4],
['+', '+'],
[Number, 3],
[')', ')'],
['-', '-'],
[Number, 9],
nil])
|