loop_macro.rs

macro_rules! custom_loop {
    (for $i:ident in $e:expr; $for_block:block between $between_block:block) => {
        {
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {
                            $between_block
                            x
                        }
                        None => {
                            break
                        }
                    }
                }
            }
        }
    };
    (for $i:ident in $e:expr; $for_block:block between $between_block:block then $then_block:block else $else_block:block) => {
        {
            let mut _normal = true;
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                _normal = false;
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {
                            $between_block
                            x
                        }
                        None => {
                            _normal = true;
                            break
                        }
                    }
                }
            }
            if _normal {
                $then_block
            } else {
                $else_block
            }
        }
    };
    (for $i:ident in $e:expr; $for_block:block between $between_block:block then $then_block:block) => {
        {
            let mut _normal = true;
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                _normal = false;
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {
                            $between_block
                            x
                        }
                        None => {
                            _normal = true;
                            break
                        }
                    }
                }
            }
            if _normal {
                $then_block
            }
        }
    };
    (for $i:ident in $e:expr; $for_block:block between $between_block:block else $else_block:block) => {
        {
            let mut _normal = true;
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                _normal = false;
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {
                            $between_block
                            x
                        }
                        None => {
                            _normal = true;
                            break
                        }
                    }
                }
            }
            if !_normal {
                $else_block
            }
        }
    };
    (for $i:ident in $e:expr; $for_block:block then $then_block:block else $else_block:block) => {
        {
            let mut _normal = true;
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                _normal = false;
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {x}
                        None => {
                            _normal = true;
                            break
                        }
                    }
                }
            }
            if _normal {
                $then_block
            } else {
                $else_block
            }
        }
    };
    (for $i:ident in $e:expr; $for_block:block then $then_block:block) => {
        {
            let mut _normal = true;
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                _normal = false;
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {x}
                        None => {
                            _normal = true;
                            break
                        }
                    }
                }
            }
            if _normal {
                $then_block
            }
        }
    };
    (for $i:ident in $e:expr; $for_block:block else $else_block:block) => {
        {
            let mut _normal = true;
            let mut iter = IntoIterator::into_iter($e);
            let a = iter.next();
            if a.is_some() {
                _normal = false;
                let mut $i = a.unwrap();
                loop {
                    $for_block
                    $i = match iter.next() {
                        Some(x) => {x}
                        None => {
                            _normal = true;
                            break
                        }
                    }
                }
            }
            if !_normal {
                $else_block
            }
        }
    };
}