59 lines
1.1 KiB
Plaintext
59 lines
1.1 KiB
Plaintext
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Scanner = {
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src: String,
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i: int,
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hint: Callable,
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current: Callable,
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consume: Callable,
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consumeSpaces: Callable
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};
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fun hint(scan: Scanner, n: int = 1) {
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k = scan.i + n;
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if k < count(scan.src):
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return scan.src[k];
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return none;
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}
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fun current(scan: Scanner)
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return hint(scan, 0);
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fun consume(scan: Scanner, n: int = 1) {
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assert(n > 0);
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limit = count(scan.src);
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scan.i = min(scan.i + n, limit);
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return current(scan);
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}
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fun consumeSpaces(scan: Scanner) {
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char = current(scan);
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while isSpace(char):
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char = consume(scan);
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return char;
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}
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fun newScanner(src: String) {
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scan = {
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src: src,
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i: 0,
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hint: hint,
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consume: consume,
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current: current,
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consumeSpaces: consumeSpaces
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};
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assert(istypeof(Scanner, scan));
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return scan;
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}
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fun isDigit(char: ?String) {
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if char == none:
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return false;
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return string.ord(char) >= string.ord('0')
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and string.ord(char) <= string.ord('9');
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}
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fun isSpace(c: String)
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return c == ' '
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or c == '\t'
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or c == '\n';
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