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const NUMS: &[char] = &['零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖']; const POS_001: char = '分'; const POS_01: char = '角'; const POS_0: char = '圆'; const POS_10: char = '拾'; const POS_100: char = '佰'; const POS_1000: char = '仟'; const POS_10K: char = '万'; const POS_1M: char = '亿'; const NUM_EXACTLY: char = '整'; const MINUS: char = '负'; pub trait ChineseCurrency { fn to_chinese_currency(self) -> String; } impl ChineseCurrency for isize { fn to_chinese_currency(self) -> String { let (value, is_minus) = if self < 0 { (-self as usize, true) } else { (self as usize, false) }; Builder::new(value, is_minus).build() } } struct Builder { position_groups: PositionGroups, pos_01: usize, pos_001: usize, is_minus: bool, } struct PositionGroups { position_groups: Vec<PositionGroup>, } struct PositionGroup { pos_1: usize, pos_10: usize, pos_100: usize, pos_1000: usize, rank: Rank, } struct Rank { rank: u8, } impl Builder { fn new(mut i: usize, is_minus: bool) -> Builder { let pos_001 = i % 10; i /= 10; let pos_01 = i % 10; i /= 10; let position_groups = PositionGroups::new(i); Builder { position_groups, pos_01, pos_001, is_minus, } } fn build(self) -> String { let mut buf = String::default(); if self.is_minus { buf.push(MINUS); } let is_empty = self.position_groups.build(&mut buf); let mut exactly = if self.pos_01 > 0 { buf.push(NUMS[self.pos_01]); buf.push(POS_01); false } else { true }; if self.pos_001 > 0 { if exactly { buf.push(NUMS[self.pos_01]); } buf.push(NUMS[self.pos_001]); buf.push(POS_001); exactly = false; } if exactly { if is_empty { buf.push(NUMS[0]); buf.push(POS_0); } buf.push(NUM_EXACTLY); } buf } } impl PositionGroups { fn new(mut i: usize) -> PositionGroups { let mut position_groups = Vec::new(); let mut rank = 0; while i > 0 { let pos_1 = i % 10; i /= 10; let pos_10 = i % 10; i /= 10; let pos_100 = i % 10; i /= 10; let pos_1000 = i % 10; i /= 10; position_groups.push(PositionGroup { pos_1, pos_10, pos_100, pos_1000, rank: Rank { rank }, }); rank += 1; } PositionGroups { position_groups } } fn build(&self, buf: &mut String) -> bool { if self.position_groups.is_empty() { true } else { let mut group_iter = self.position_groups.iter().rev(); if let Some(position_group) = group_iter.next() { position_group.build(buf, false); } for position_group in group_iter { position_group.build(buf, true); } buf.push(POS_0); false } } } impl PositionGroup { fn build(&self, buf: &mut String, show_zero: bool) { let mut is_rendered = false; if self.pos_1000 > 0 { buf.push(NUMS[self.pos_1000]); buf.push(POS_1000); is_rendered = true; } else if show_zero { buf.push(NUMS[self.pos_1000]); } if self.pos_100 > 0 { buf.push(NUMS[self.pos_100]); buf.push(POS_100); is_rendered = true; } if self.pos_10 > 0 { if is_rendered && self.pos_100 == 0 { buf.push(NUMS[self.pos_100]); } buf.push(NUMS[self.pos_10]); buf.push(POS_10); is_rendered = true; } if self.pos_1 > 0 { if is_rendered && self.pos_10 == 0 { buf.push(NUMS[self.pos_10]); } buf.push(NUMS[self.pos_1]); is_rendered = true; } if is_rendered { buf.push_str(&self.rank.to_string()); } else { buf.pop(); } } } impl Rank { fn to_string(&self) -> String { Rank::rank_to_string(self.rank) } fn rank_to_string(rank: u8) -> String { match rank { 0 => "".into(), 1 => POS_10K.to_string(), _ => { let m = rank % 2; let d = rank / 2; let mut s = String::with_capacity(d as usize + 1); if m == 1 { s.push(POS_10K); } for _ in 0..d { s.push(POS_1M); } s } } } } #[cfg(test)] mod tests { use super::{ChineseCurrency, Rank}; #[test] fn smoke_rank() { assert_eq!(Rank::rank_to_string(0), ""); assert_eq!(Rank::rank_to_string(1), "万"); assert_eq!(Rank::rank_to_string(2), "亿"); assert_eq!(Rank::rank_to_string(3), "万亿"); assert_eq!(Rank::rank_to_string(4), "亿亿"); assert_eq!(Rank::rank_to_string(5), "万亿亿"); assert_eq!(Rank::rank_to_string(6), "亿亿亿"); } #[test] fn smoke_to_chinese_currency() { assert_eq!(0.to_chinese_currency(), "零圆整"); assert_eq!(1.to_chinese_currency(), "零壹分"); assert_eq!(21.to_chinese_currency(), "贰角壹分"); assert_eq!(20.to_chinese_currency(), "贰角"); assert_eq!(321.to_chinese_currency(), "叁圆贰角壹分"); assert_eq!(300.to_chinese_currency(), "叁圆整"); assert_eq!(4321.to_chinese_currency(), "肆拾叁圆贰角壹分"); assert_eq!(54321.to_chinese_currency(), "伍佰肆拾叁圆贰角壹分"); assert_eq!(654321.to_chinese_currency(), "陆仟伍佰肆拾叁圆贰角壹分"); assert_eq!( 7654321.to_chinese_currency(), "柒万陆仟伍佰肆拾叁圆贰角壹分" ); assert_eq!( 87654321.to_chinese_currency(), "捌拾柒万陆仟伍佰肆拾叁圆贰角壹分" ); assert_eq!( 987654321.to_chinese_currency(), "玖佰捌拾柒万陆仟伍佰肆拾叁圆贰角壹分" ); assert_eq!( 8987654321.to_chinese_currency(), "捌仟玖佰捌拾柒万陆仟伍佰肆拾叁圆贰角壹分" ); assert_eq!( 78987654321.to_chinese_currency(), "柒亿捌仟玖佰捌拾柒万陆仟伍佰肆拾叁圆贰角壹分" ); assert_eq!( 70987654321.to_chinese_currency(), "柒亿零玖佰捌拾柒万陆仟伍佰肆拾叁圆贰角壹分" ); assert_eq!( (-70987654321).to_chinese_currency(), "负柒亿零玖佰捌拾柒万陆仟伍佰肆拾叁圆贰角壹分" ); } }