rust/src/libcore/int.rs

/*
Module: int
*/

/*
Const: max_value

The maximum value of an integer
*/
// FIXME: Find another way to access the machine word size in a const expr
#[cfg(target_arch="x86")]
const max_value: int = (-1 << 31)-1;

#[cfg(target_arch="x86_64")]
const max_value: int = (-1 << 63)-1;

/*
Const: min_value

The minumum value of an integer
*/
#[cfg(target_arch="x86")]
const min_value: int = -1 << 31;

#[cfg(target_arch="x86_64")]
const min_value: int = -1 << 63;

/* Function: add */
pure fn add(x: int, y: int) -> int { ret x + y; }

/* Function: sub */
pure fn sub(x: int, y: int) -> int { ret x - y; }

/* Function: mul */
pure fn mul(x: int, y: int) -> int { ret x * y; }

/* Function: div */
pure fn div(x: int, y: int) -> int { ret x / y; }

/* Function: rem */
pure fn rem(x: int, y: int) -> int { ret x % y; }

/* Predicate: lt */
pure fn lt(x: int, y: int) -> bool { ret x < y; }

/* Predicate: le */
pure fn le(x: int, y: int) -> bool { ret x <= y; }

/* Predicate: eq */
pure fn eq(x: int, y: int) -> bool { ret x == y; }

/* Predicate: ne */
pure fn ne(x: int, y: int) -> bool { ret x != y; }

/* Predicate: ge */
pure fn ge(x: int, y: int) -> bool { ret x >= y; }

/* Predicate: gt */
pure fn gt(x: int, y: int) -> bool { ret x > y; }

/* Predicate: positive */
pure fn positive(x: int) -> bool { ret x > 0; }

/* Predicate: negative */
pure fn negative(x: int) -> bool { ret x < 0; }

/* Predicate: nonpositive */
pure fn nonpositive(x: int) -> bool { ret x <= 0; }

/* Predicate: nonnegative */
pure fn nonnegative(x: int) -> bool { ret x >= 0; }


// FIXME: Make sure this works with negative integers.
/*
Function: hash

Produce a uint suitable for use in a hash table
*/
fn hash(x: int) -> uint { ret x as uint; }

/*
Function: range

Iterate over the range [`lo`..`hi`)
*/
fn range(lo: int, hi: int, it: block(int)) {
    let i = lo;
    while i < hi { it(i); i += 1; }
}

/*
Function: parse_buf

Parse a buffer of bytes

Parameters:

buf - A byte buffer
radix - The base of the number

Failure:

buf must not be empty
*/
fn parse_buf(buf: [u8], radix: uint) -> int {
    if vec::len::<u8>(buf) == 0u {
        #error("parse_buf(): buf is empty");
        fail;
    }
    let i = vec::len::<u8>(buf) - 1u;
    let start = 0u;
    let power = 1;

    if buf[0] == ('-' as u8) {
        power = -1;
        start = 1u;
    }
    let n = 0;
    while true {
        let digit = char::to_digit(buf[i] as char);
        if (digit as uint) >= radix {
            fail;
        }
        n += (digit as int) * power;
        power *= radix as int;
        if i <= start { ret n; }
        i -= 1u;
    }
    fail;
}

/*
Function: from_str

Parse a string to an int

Failure:

s must not be empty
*/
fn from_str(s: str) -> int { parse_buf(str::bytes(s), 10u) }

/*
Function: to_str

Convert to a string in a given base
*/
fn to_str(n: int, radix: uint) -> str {
    assert (0u < radix && radix <= 16u);
    ret if n < 0 {
            "-" + uint::to_str(-n as uint, radix)
        } else { uint::to_str(n as uint, radix) };
}

/*
Function: str

Convert to a string
*/
fn str(i: int) -> str { ret to_str(i, 10u); }

/*
Function: pow

Returns `base` raised to the power of `exponent`
*/
fn pow(base: int, exponent: uint) -> int {
    if exponent == 0u { ret 1; } //Not mathemtically true if [base == 0]
    if base     == 0  { ret 0; }
    let my_pow  = exponent;
    let acc     = 1;
    let multiplier = base;
    while(my_pow > 0u) {
      if my_pow % 2u == 1u {
         acc *= multiplier;
      }
      my_pow     /= 2u;
      multiplier *= multiplier;
    }
    ret acc;
}
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