Allows for arbitrary spacing between operands when parsing Complex
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Alan Liddell
parent
e5e8266009
commit
ac746c2a5d
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@ -750,42 +750,64 @@ impl<T> FromStr for Complex<T> where
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/// Parses `a +/- bi`; `ai +/- b`; `a`; or `bi` where `a` and `b` are of type `T`
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fn from_str(s: &str) -> Result<Complex<T>, ParseComplexError>
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{
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// first try to split on " + "
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let mut split_p = s.splitn(2, " + ");
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let imag = 'i';
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let mut a = match split_p.next() {
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None => return Err(ParseComplexError { kind: ComplexErrorKind::ParseError }),
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Some(s) => s.trim_right().to_string()
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};
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let mut a = String::with_capacity(s.len());
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let mut b = String::with_capacity(s.len());
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let mut b = match split_p.next() {
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// no second item could mean we need to split on " - " instead
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None => {
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let mut split_m = s.splitn(2, " - ");
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let mut first = true;
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let mut char_indices = s.char_indices();
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let mut pc = ' ';
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a = match split_m.next() {
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None => return Err(ParseComplexError { kind: ComplexErrorKind::ParseError }),
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Some(s) => s.trim_right().to_string()
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};
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loop {
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match char_indices.next() {
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Some(t) => {
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let i = t.0;
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let cc = t.1;
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if cc == '+' {
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// handle exponents
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if pc != 'e' && pc != 'E' {
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first = false;
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// don't carry '+' over into b
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pc = ' ';
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continue;
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}
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} else if cc == '-' {
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// handle exponents and negative numbers
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if i > 0 && pc != 'e' && pc != 'E' {
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first = false;
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// DO carry '-' over into b
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}
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}
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let c = match split_m.next() {
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None => {
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// if `a` is imaginary, let `b` be real (and vice versa)
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match a.rfind('i') {
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if !first && cc == ' ' && pc == '-' {
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// ignore whitespace between minus sign and next number
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continue;
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}
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if first {
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a.push(cc);
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} else {
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b.push(cc);
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}
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pc = cc;
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},
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None => break,
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}
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}
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a = a.trim_right().to_string();
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b = b.trim_left().to_string();
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if b.is_empty() {
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b = match a.rfind(imag) {
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None => "0i".to_string(),
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_ => "0".to_string()
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}
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}
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Some(s) => {
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"-".to_string() + s.trim_left()
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}
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};
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c
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},
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Some(s) => s.trim_left().to_string()
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};
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}
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let re = match a.rfind('i') {
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let re = match a.rfind(imag) {
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None => {
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try!(T::from_str(&a)
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.map_err(|_| ParseComplexError { kind: ComplexErrorKind::ParseError }))
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@ -796,20 +818,20 @@ impl<T> FromStr for Complex<T> where
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}
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};
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let im = match a.rfind('i') {
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let im = match a.rfind(imag) {
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None => {
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// a is real
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match b.pop() {
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// b was empty
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None => return Err(ParseComplexError { kind: ComplexErrorKind::ParseError }),
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Some(c) => {
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if c == 'i' {
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if c == imag {
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// b is imaginary
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if b.is_empty() {
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// b was just 'i'
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// b was just 'imag'
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b = "1".to_string();
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} else if b == "-" {
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// b was just '-i'
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// b was just '-imag'
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b = "-1".to_string();
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}
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} else {
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@ -823,17 +845,17 @@ impl<T> FromStr for Complex<T> where
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.map_err(|_| ParseComplexError { kind: ComplexErrorKind::ParseError }))
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},
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_ => {
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// a contains an 'i'
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// a contains imag
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match a.pop() {
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None => return Err(ParseComplexError { kind: ComplexErrorKind::ParseError }),
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Some(c) => {
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if c == 'i' {
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if c == imag {
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// a is imaginary
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if a.is_empty() {
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// a was just 'i'
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// a was just 'imag'
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a = "1".to_string();
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} else if a == "-" {
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// a was just '-i'
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// a was just '-imag'
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a = "-1".to_string();
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}
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} else {
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@ -1553,25 +1575,38 @@ mod test {
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test(_0_0i, "-0".to_string());
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test(_0_0i, "-0i".to_string());
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test(_0_0i, "0 + 0i".to_string());
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test(_0_0i, "0+0i".to_string());
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test(_0_0i, "0 - 0i".to_string());
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test(_0_0i, "0-0i".to_string());
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test(_1_0i, "1".to_string());
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test(_1_0i, "1 + 0i".to_string());
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test(_1_0i, "1+0i".to_string());
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test(_1_0i, "1 - 0i".to_string());
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test(_1_0i, "1-0i".to_string());
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test(_1_1i, "1 + i".to_string());
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test(_1_1i, "1+i".to_string());
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test(_1_1i, "1 + 1i".to_string());
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test(_1_1i, "1+1i".to_string());
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test(_0_1i, "i".to_string());
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test(_0_1i, "1i".to_string());
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test(_0_1i, "0 + i".to_string());
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test(_0_1i, "0+i".to_string());
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test(_0_1i, "-0 + i".to_string());
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test(_0_1i, "-0+i".to_string());
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test(_0_1i, "0 + 1i".to_string());
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test(_0_1i, "0+1i".to_string());
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test(_0_1i, "-0 + 1i".to_string());
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test(_0_1i, "-0+1i".to_string());
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test(_neg1_1i, "-1 + i".to_string());
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test(_neg1_1i, "-1+i".to_string());
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test(_neg1_1i, "-1 + 1i".to_string());
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test(_neg1_1i, "-1+1i".to_string());
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test(_05_05i, "0.5 + 0.5i".to_string());
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test(_05_05i, "0.5+0.5i".to_string());
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}
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}
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