method

unscan

v1_8_7_330 - Show latest stable - 0 notes - Class: StringScanner

unscan() public

Set the scan pointer to the previous position. Only one previous position is remembered, and it changes with each scanning operation.

s = StringScanner.new('test string')
s.scan(/\w+/)        # => "test"
s.unscan
s.scan(/../)         # => "te"
s.scan(/\d/)         # => nil
s.unscan             # ScanError: unscan failed: previous match had failed

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/*
 * Set the scan pointer to the previous position.  Only one previous position is
 * remembered, and it changes with each scanning operation.
 *
 *   s = StringScanner.new('test string')
 *   s.scan(/\w+/)        # => "test"
 *   s.unscan
 *   s.scan(/../)         # => "te"
 *   s.scan(/\d/)         # => nil
 *   s.unscan             # ScanError: unscan failed: previous match had failed
 */
static VALUE
strscan_unscan(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p)) {
        rb_raise(ScanError, "unscan failed: previous match had failed");
    }
    p->curr = p->prev;
    CLEAR_MATCH_STATUS(p);
    return self;
}

unscan

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