Anonymous user
Arithmetic evaluation: Difference between revisions
m
→{{header|Dyalect}}
m (→{{header|J}}) |
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=={{header|Dyalect}}==
<lang
type Token(val, Char kind)
func Token.
func tokenize(str) {
func isSep(c) =>
c is '+' or '-' or '*' or '/' or ' ' or '\t' or '\n' or '\r' or '(' or ')' or '\0'
var idx = -1
let len = str.
let tokens = []
func next() {
idx += 1
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str[idx]
}
while true {
let c = next()
match c {
'\0' => { break },
'+' => tokens.
'-' => tokens.
'*' => tokens.
'/' => tokens.
'(' => tokens.
')' => tokens.
_ => {
let i = idx
while !isSep(next()) { }
idx -= 1
tokens.
}
}
}
tokens
}
func parse(tokens) {
var idx = -1
let len = tokens.
let eol = Token(val: nil, kind: 'E')
func pop() {
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}
func expect(kind) {
peek()
}
var add_or_sub1
func literal() {
return false when !expect('F')
Expr.Literal(pop()
}
func group() {
return false when !expect('(')
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ret
}
func mul_or_div() {
var fst = group()
fst = literal() when !fst
return fst when !expect('*') && !expect('/')
let op = pop()
var snd = group()
snd = literal() when !snd
Expr.Bin(op, fst, snd)
}
func add_or_sub() {
let fst = mul_or_div()
return fst when !expect('+') && !expect('-')
let op = pop()
let snd = mul_or_div()
Expr.Bin(op, fst, snd)
}
add_or_sub1 = add_or_sub
add_or_sub()
}
func exec(ast) {
match ast {
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}
}
func eval(str) {
let tokens = tokenize(str)
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exec(ast)
}
print( eval("(1+33.23)*7") )
print( eval("1+33.23*7") )</lang>
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