45 lines
1.4 KiB
Text
45 lines
1.4 KiB
Text
# str.ludic — the string handling a compiler lives on: comparison, copying,
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# slicing out substrings, and integer<->text. All over raw NUL-terminated
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# byte buffers reached with peek8/poke8.
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function char_is_digit(c: int) -> bool { return c >= '0' and c <= '9' }
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function char_is_alpha(c: int) -> bool {
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if c >= 'A' and c <= 'Z' { return true }
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if c >= 'a' and c <= 'z' { return true }
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return c == '_'
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}
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function char_is_alnum(c: int) -> bool { return char_is_alpha(c) or char_is_digit(c) }
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# does `s` begin with `prefix`? (byte-wise; both NUL-terminated)
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function str_starts(s: pointer, prefix: pointer) -> bool {
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var i = 0
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while prefix[i] != 0 { if s[i] != prefix[i] { return false }; i += 1 }
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return true
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}
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# integer -> fresh decimal string
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function itoa(v: int) -> pointer {
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if v == 0 { let z = bytes(2); z[0] = '0'; z[1] = 0; return z }
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# digits are taken off v as it is, never off -v: the most negative int has no positive twin, and
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# -v overflowed back to itself, so a 0x80000000 in an i32 was emitted as a bare "-"
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let neg = v < 0
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var x = v
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let tmp = bytes(24)
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var n = 0
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while x != 0 {
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var d = x % 10
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if d < 0 { d = -d }
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tmp[n] = 48 + d
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x /= 10
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n += 1
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}
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var total = n
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if neg { total += 1 }
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let out = bytes(total + 1)
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var k = 0
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if neg { out[0] = '-'; k = 1 }
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var i = 0
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while i < n { out[k + i] = tmp[n - 1 - i]; i += 1 }
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out[total] = 0
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return out
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}
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