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Arithmetic evaluation: Difference between revisions
Added Dyalect
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=={{header|Delphi}}==
Adaptation of [[Arithmetic Evaluator/Pascal]] for run in Delphi. See [[Arithmetic_evaluation/Delphi]].
=={{header|Dyalect}}==
<lang swift>type Expr = Bin(op, Expr left, Expr right) or Literal(Float val)
type Token(val, Char kind)
func Token.toString() => this::val.toString()
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.len()
let tokens = []
func next() {
idx += 1
return '\0' when idx >= len
str[idx]
}
while true {
let c = next()
match c {
'\0' => { break },
'+' => tokens.add(Token(c, '+')),
'-' => tokens.add(Token(c, '-')),
'*' => tokens.add(Token(c, '*')),
'/' => tokens.add(Token(c, '/')),
'(' => tokens.add(Token(c, '(')),
')' => tokens.add(Token(c, ')')),
_ => {
let i = idx
while !isSep(next()) { }
idx -= 1
tokens.add(Token(Float.parse(str[i..idx]), 'F'))
}
}
}
tokens
}
func parse(tokens) {
var idx = -1
let len = tokens.len()
let eol = Token(val: nil, kind: 'E')
func pop() {
idx += 1
return eol when idx == len
tokens[idx]
}
func peek() {
let t = pop()
idx -=1
t
}
func expect(kind) {
peek()::kind == kind
}
var add_or_sub1
func literal() {
return false when !expect('F')
Expr.Literal(pop()::val)
}
func group() {
return false when !expect('(')
pop()
var ret = add_or_sub1()
throw "Invalid group" when !expect(')')
pop()
ret
}
func mul_or_div() {
var fst = group()
fst = literal() when !fst
return fst when !expect('*') && !expect('/')
let op = pop()::val
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()::val
let snd = mul_or_div()
Expr.Bin(op, fst, snd)
}
add_or_sub1 = add_or_sub
add_or_sub()
}
func exec(ast) {
match ast {
Bin(op, left, right) => {
return exec(left) + exec(right) when op == '+'
return exec(left) - exec(right) when op == '-'
return exec(left) * exec(right) when op == '*'
return exec(left) / exec(right) when op == '/'
},
Literal(value) => value
}
}
func eval(str) {
let tokens = tokenize(str)
let ast = parse(tokens)
exec(ast)
}
print( eval("(1+33.23)*7") )
print( eval("1+33.23*7") )</lang>
{{out}}
<pre>239.60999999999999
233.60999999999999</pre>
=={{header|E}}==
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