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Copy pathformat.rs
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1224 lines (1138 loc) · 39.7 KB
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use itertools::{Itertools, PeekingNext};
use num_bigint::{BigInt, Sign};
use num_traits::{cast::ToPrimitive, Signed};
use rustpython_literal::float;
use rustpython_literal::format::Case;
use std::ops::Deref;
use std::{cmp, str::FromStr};
trait FormatParse {
fn parse(text: &str) -> (Option<Self>, &str)
where
Self: Sized;
}
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum FormatConversion {
Str,
Repr,
Ascii,
Bytes,
}
impl FormatParse for FormatConversion {
fn parse(text: &str) -> (Option<Self>, &str) {
let Some(conversion) = Self::from_string(text) else {
return (None, text);
};
let mut chars = text.chars();
chars.next(); // Consume the bang
chars.next(); // Consume one r,s,a char
(Some(conversion), chars.as_str())
}
}
impl FormatConversion {
pub fn from_char(c: char) -> Option<FormatConversion> {
match c {
's' => Some(FormatConversion::Str),
'r' => Some(FormatConversion::Repr),
'a' => Some(FormatConversion::Ascii),
'b' => Some(FormatConversion::Bytes),
_ => None,
}
}
fn from_string(text: &str) -> Option<FormatConversion> {
let mut chars = text.chars();
if chars.next() != Some('!') {
return None;
}
FormatConversion::from_char(chars.next()?)
}
}
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum FormatAlign {
Left,
Right,
AfterSign,
Center,
}
impl FormatAlign {
fn from_char(c: char) -> Option<FormatAlign> {
match c {
'<' => Some(FormatAlign::Left),
'>' => Some(FormatAlign::Right),
'=' => Some(FormatAlign::AfterSign),
'^' => Some(FormatAlign::Center),
_ => None,
}
}
}
impl FormatParse for FormatAlign {
fn parse(text: &str) -> (Option<Self>, &str) {
let mut chars = text.chars();
if let Some(maybe_align) = chars.next().and_then(Self::from_char) {
(Some(maybe_align), chars.as_str())
} else {
(None, text)
}
}
}
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum FormatSign {
Plus,
Minus,
MinusOrSpace,
}
impl FormatParse for FormatSign {
fn parse(text: &str) -> (Option<Self>, &str) {
let mut chars = text.chars();
match chars.next() {
Some('-') => (Some(Self::Minus), chars.as_str()),
Some('+') => (Some(Self::Plus), chars.as_str()),
Some(' ') => (Some(Self::MinusOrSpace), chars.as_str()),
_ => (None, text),
}
}
}
#[derive(Debug, PartialEq)]
pub enum FormatGrouping {
Comma,
Underscore,
}
impl FormatParse for FormatGrouping {
fn parse(text: &str) -> (Option<Self>, &str) {
let mut chars = text.chars();
match chars.next() {
Some('_') => (Some(Self::Underscore), chars.as_str()),
Some(',') => (Some(Self::Comma), chars.as_str()),
_ => (None, text),
}
}
}
#[derive(Debug, PartialEq)]
pub enum FormatType {
String,
Binary,
Character,
Decimal,
Octal,
Number(Case),
Hex(Case),
Exponent(Case),
GeneralFormat(Case),
FixedPoint(Case),
Percentage,
}
impl From<&FormatType> for char {
fn from(from: &FormatType) -> char {
match from {
FormatType::String => 's',
FormatType::Binary => 'b',
FormatType::Character => 'c',
FormatType::Decimal => 'd',
FormatType::Octal => 'o',
FormatType::Number(Case::Lower) => 'n',
FormatType::Number(Case::Upper) => 'N',
FormatType::Hex(Case::Lower) => 'x',
FormatType::Hex(Case::Upper) => 'X',
FormatType::Exponent(Case::Lower) => 'e',
FormatType::Exponent(Case::Upper) => 'E',
FormatType::GeneralFormat(Case::Lower) => 'g',
FormatType::GeneralFormat(Case::Upper) => 'G',
FormatType::FixedPoint(Case::Lower) => 'f',
FormatType::FixedPoint(Case::Upper) => 'F',
FormatType::Percentage => '%',
}
}
}
impl FormatParse for FormatType {
fn parse(text: &str) -> (Option<Self>, &str) {
let mut chars = text.chars();
match chars.next() {
Some('s') => (Some(Self::String), chars.as_str()),
Some('b') => (Some(Self::Binary), chars.as_str()),
Some('c') => (Some(Self::Character), chars.as_str()),
Some('d') => (Some(Self::Decimal), chars.as_str()),
Some('o') => (Some(Self::Octal), chars.as_str()),
Some('n') => (Some(Self::Number(Case::Lower)), chars.as_str()),
Some('N') => (Some(Self::Number(Case::Upper)), chars.as_str()),
Some('x') => (Some(Self::Hex(Case::Lower)), chars.as_str()),
Some('X') => (Some(Self::Hex(Case::Upper)), chars.as_str()),
Some('e') => (Some(Self::Exponent(Case::Lower)), chars.as_str()),
Some('E') => (Some(Self::Exponent(Case::Upper)), chars.as_str()),
Some('f') => (Some(Self::FixedPoint(Case::Lower)), chars.as_str()),
Some('F') => (Some(Self::FixedPoint(Case::Upper)), chars.as_str()),
Some('g') => (Some(Self::GeneralFormat(Case::Lower)), chars.as_str()),
Some('G') => (Some(Self::GeneralFormat(Case::Upper)), chars.as_str()),
Some('%') => (Some(Self::Percentage), chars.as_str()),
_ => (None, text),
}
}
}
#[derive(Debug, PartialEq)]
pub struct FormatSpec {
conversion: Option<FormatConversion>,
fill: Option<char>,
align: Option<FormatAlign>,
sign: Option<FormatSign>,
alternate_form: bool,
width: Option<usize>,
grouping_option: Option<FormatGrouping>,
precision: Option<usize>,
format_type: Option<FormatType>,
}
fn get_num_digits(text: &str) -> usize {
for (index, character) in text.char_indices() {
if !character.is_ascii_digit() {
return index;
}
}
text.len()
}
fn parse_fill_and_align(text: &str) -> (Option<char>, Option<FormatAlign>, &str) {
let char_indices: Vec<(usize, char)> = text.char_indices().take(3).collect();
if char_indices.is_empty() {
(None, None, text)
} else if char_indices.len() == 1 {
let (maybe_align, remaining) = FormatAlign::parse(text);
(None, maybe_align, remaining)
} else {
let (maybe_align, remaining) = FormatAlign::parse(&text[char_indices[1].0..]);
if maybe_align.is_some() {
(Some(char_indices[0].1), maybe_align, remaining)
} else {
let (only_align, only_align_remaining) = FormatAlign::parse(text);
(None, only_align, only_align_remaining)
}
}
}
fn parse_number(text: &str) -> Result<(Option<usize>, &str), FormatSpecError> {
let num_digits: usize = get_num_digits(text);
if num_digits == 0 {
return Ok((None, text));
}
if let Ok(num) = text[..num_digits].parse::<usize>() {
Ok((Some(num), &text[num_digits..]))
} else {
// NOTE: this condition is different from CPython
Err(FormatSpecError::DecimalDigitsTooMany)
}
}
fn parse_alternate_form(text: &str) -> (bool, &str) {
let mut chars = text.chars();
match chars.next() {
Some('#') => (true, chars.as_str()),
_ => (false, text),
}
}
fn parse_zero(text: &str) -> (bool, &str) {
let mut chars = text.chars();
match chars.next() {
Some('0') => (true, chars.as_str()),
_ => (false, text),
}
}
fn parse_precision(text: &str) -> Result<(Option<usize>, &str), FormatSpecError> {
let mut chars = text.chars();
Ok(match chars.next() {
Some('.') => {
let (size, remaining) = parse_number(chars.as_str())?;
if let Some(size) = size {
if size > i32::MAX as usize {
return Err(FormatSpecError::PrecisionTooBig);
}
(Some(size), remaining)
} else {
(None, text)
}
}
_ => (None, text),
})
}
impl FormatSpec {
pub fn parse(text: &str) -> Result<Self, FormatSpecError> {
// get_integer in CPython
let (conversion, text) = FormatConversion::parse(text);
let (mut fill, mut align, text) = parse_fill_and_align(text);
let (sign, text) = FormatSign::parse(text);
let (alternate_form, text) = parse_alternate_form(text);
let (zero, text) = parse_zero(text);
let (width, text) = parse_number(text)?;
let (grouping_option, text) = FormatGrouping::parse(text);
let (precision, text) = parse_precision(text)?;
let (format_type, text) = FormatType::parse(text);
if !text.is_empty() {
return Err(FormatSpecError::InvalidFormatSpecifier);
}
if zero && fill.is_none() {
fill.replace('0');
align = align.or(Some(FormatAlign::AfterSign));
}
Ok(FormatSpec {
conversion,
fill,
align,
sign,
alternate_form,
width,
grouping_option,
precision,
format_type,
})
}
fn compute_fill_string(fill_char: char, fill_chars_needed: i32) -> String {
(0..fill_chars_needed)
.map(|_| fill_char)
.collect::<String>()
}
fn add_magnitude_separators_for_char(
magnitude_str: String,
inter: i32,
sep: char,
disp_digit_cnt: i32,
) -> String {
// Don't add separators to the floating decimal point of numbers
let mut parts = magnitude_str.splitn(2, '.');
let magnitude_int_str = parts.next().unwrap().to_string();
let dec_digit_cnt = magnitude_str.len() as i32 - magnitude_int_str.len() as i32;
let int_digit_cnt = disp_digit_cnt - dec_digit_cnt;
let mut result = FormatSpec::separate_integer(magnitude_int_str, inter, sep, int_digit_cnt);
if let Some(part) = parts.next() {
result.push_str(&format!(".{part}"))
}
result
}
fn separate_integer(
magnitude_str: String,
inter: i32,
sep: char,
disp_digit_cnt: i32,
) -> String {
let magnitude_len = magnitude_str.len() as i32;
let offset = (disp_digit_cnt % (inter + 1) == 0) as i32;
let disp_digit_cnt = disp_digit_cnt + offset;
let pad_cnt = disp_digit_cnt - magnitude_len;
let sep_cnt = disp_digit_cnt / (inter + 1);
let diff = pad_cnt - sep_cnt;
if pad_cnt > 0 && diff > 0 {
// separate with 0 padding
let padding = "0".repeat(diff as usize);
let padded_num = format!("{padding}{magnitude_str}");
FormatSpec::insert_separator(padded_num, inter, sep, sep_cnt)
} else {
// separate without padding
let sep_cnt = (magnitude_len - 1) / inter;
FormatSpec::insert_separator(magnitude_str, inter, sep, sep_cnt)
}
}
fn insert_separator(mut magnitude_str: String, inter: i32, sep: char, sep_cnt: i32) -> String {
let magnitude_len = magnitude_str.len() as i32;
for i in 1..sep_cnt + 1 {
magnitude_str.insert((magnitude_len - inter * i) as usize, sep);
}
magnitude_str
}
fn validate_format(&self, default_format_type: FormatType) -> Result<(), FormatSpecError> {
let format_type = self.format_type.as_ref().unwrap_or(&default_format_type);
match (&self.grouping_option, format_type) {
(
Some(FormatGrouping::Comma),
FormatType::String
| FormatType::Character
| FormatType::Binary
| FormatType::Octal
| FormatType::Hex(_)
| FormatType::Number(_),
) => {
let ch = char::from(format_type);
Err(FormatSpecError::UnspecifiedFormat(',', ch))
}
(
Some(FormatGrouping::Underscore),
FormatType::String | FormatType::Character | FormatType::Number(_),
) => {
let ch = char::from(format_type);
Err(FormatSpecError::UnspecifiedFormat('_', ch))
}
_ => Ok(()),
}
}
fn get_separator_interval(&self) -> usize {
match self.format_type {
Some(FormatType::Binary | FormatType::Octal | FormatType::Hex(_)) => 4,
Some(FormatType::Decimal | FormatType::Number(_) | FormatType::FixedPoint(_)) => 3,
None => 3,
_ => panic!("Separators only valid for numbers!"),
}
}
fn add_magnitude_separators(&self, magnitude_str: String, prefix: &str) -> String {
match &self.grouping_option {
Some(fg) => {
let sep = match fg {
FormatGrouping::Comma => ',',
FormatGrouping::Underscore => '_',
};
let inter = self.get_separator_interval().try_into().unwrap();
let magnitude_len = magnitude_str.len();
let width = self.width.unwrap_or(magnitude_len) as i32 - prefix.len() as i32;
let disp_digit_cnt = cmp::max(width, magnitude_len as i32);
FormatSpec::add_magnitude_separators_for_char(
magnitude_str,
inter,
sep,
disp_digit_cnt,
)
}
None => magnitude_str,
}
}
pub fn format_bool(&self, input: bool) -> Result<String, FormatSpecError> {
let x = u8::from(input);
let result: Result<String, FormatSpecError> = match &self.format_type {
Some(FormatType::Decimal) => Ok(x.to_string()),
None => {
let first_letter = (input.to_string().as_bytes()[0] as char).to_uppercase();
Ok(first_letter.collect::<String>() + &input.to_string()[1..])
}
_ => Err(FormatSpecError::InvalidFormatSpecifier),
};
result
}
pub fn format_float(&self, num: f64) -> Result<String, FormatSpecError> {
self.validate_format(FormatType::FixedPoint(Case::Lower))?;
let precision = self.precision.unwrap_or(6);
let magnitude = num.abs();
let raw_magnitude_str: Result<String, FormatSpecError> = match &self.format_type {
Some(FormatType::FixedPoint(case)) => Ok(float::format_fixed(
precision,
magnitude,
*case,
self.alternate_form,
)),
Some(FormatType::Decimal)
| Some(FormatType::Binary)
| Some(FormatType::Octal)
| Some(FormatType::Hex(_))
| Some(FormatType::String)
| Some(FormatType::Character)
| Some(FormatType::Number(Case::Upper)) => {
let ch = char::from(self.format_type.as_ref().unwrap());
Err(FormatSpecError::UnknownFormatCode(ch, "float"))
}
Some(FormatType::GeneralFormat(case)) | Some(FormatType::Number(case)) => {
let precision = if precision == 0 { 1 } else { precision };
Ok(float::format_general(
precision,
magnitude,
*case,
self.alternate_form,
false,
))
}
Some(FormatType::Exponent(case)) => Ok(float::format_exponent(
precision,
magnitude,
*case,
self.alternate_form,
)),
Some(FormatType::Percentage) => match magnitude {
magnitude if magnitude.is_nan() => Ok("nan%".to_owned()),
magnitude if magnitude.is_infinite() => Ok("inf%".to_owned()),
_ => {
let result = format!("{:.*}", precision, magnitude * 100.0);
let point = float::decimal_point_or_empty(precision, self.alternate_form);
Ok(format!("{result}{point}%"))
}
},
None => match magnitude {
magnitude if magnitude.is_nan() => Ok("nan".to_owned()),
magnitude if magnitude.is_infinite() => Ok("inf".to_owned()),
_ => match self.precision {
Some(precision) => Ok(float::format_general(
precision,
magnitude,
Case::Lower,
self.alternate_form,
true,
)),
None => Ok(float::to_string(magnitude)),
},
},
};
let format_sign = self.sign.unwrap_or(FormatSign::Minus);
let sign_str = if num.is_sign_negative() && !num.is_nan() {
"-"
} else {
match format_sign {
FormatSign::Plus => "+",
FormatSign::Minus => "",
FormatSign::MinusOrSpace => " ",
}
};
let magnitude_str = self.add_magnitude_separators(raw_magnitude_str?, sign_str);
self.format_sign_and_align(&AsciiStr::new(&magnitude_str), sign_str, FormatAlign::Right)
}
#[inline]
fn format_int_radix(&self, magnitude: BigInt, radix: u32) -> Result<String, FormatSpecError> {
match self.precision {
Some(_) => Err(FormatSpecError::PrecisionNotAllowed),
None => Ok(magnitude.to_str_radix(radix)),
}
}
pub fn format_int(&self, num: &BigInt) -> Result<String, FormatSpecError> {
self.validate_format(FormatType::Decimal)?;
let magnitude = num.abs();
let prefix = if self.alternate_form {
match self.format_type {
Some(FormatType::Binary) => "0b",
Some(FormatType::Octal) => "0o",
Some(FormatType::Hex(Case::Lower)) => "0x",
Some(FormatType::Hex(Case::Upper)) => "0X",
_ => "",
}
} else {
""
};
let raw_magnitude_str = match self.format_type {
Some(FormatType::Binary) => self.format_int_radix(magnitude, 2),
Some(FormatType::Decimal) => self.format_int_radix(magnitude, 10),
Some(FormatType::Octal) => self.format_int_radix(magnitude, 8),
Some(FormatType::Hex(Case::Lower)) => self.format_int_radix(magnitude, 16),
Some(FormatType::Hex(Case::Upper)) => match self.precision {
Some(_) => Err(FormatSpecError::PrecisionNotAllowed),
None => {
let mut result = magnitude.to_str_radix(16);
result.make_ascii_uppercase();
Ok(result)
}
},
Some(FormatType::Number(Case::Lower)) => self.format_int_radix(magnitude, 10),
Some(FormatType::Number(Case::Upper)) => {
Err(FormatSpecError::UnknownFormatCode('N', "int"))
}
Some(FormatType::String) => Err(FormatSpecError::UnknownFormatCode('s', "int")),
Some(FormatType::Character) => match (self.sign, self.alternate_form) {
(Some(_), _) => Err(FormatSpecError::NotAllowed("Sign")),
(_, true) => Err(FormatSpecError::NotAllowed("Alternate form (#)")),
(_, _) => match num.to_u32() {
Some(n) if n <= 0x10ffff => Ok(std::char::from_u32(n).unwrap().to_string()),
Some(_) | None => Err(FormatSpecError::CodeNotInRange),
},
},
Some(FormatType::GeneralFormat(_))
| Some(FormatType::FixedPoint(_))
| Some(FormatType::Exponent(_))
| Some(FormatType::Percentage) => match num.to_f64() {
Some(float) => return self.format_float(float),
_ => Err(FormatSpecError::UnableToConvert),
},
None => self.format_int_radix(magnitude, 10),
}?;
let format_sign = self.sign.unwrap_or(FormatSign::Minus);
let sign_str = match num.sign() {
Sign::Minus => "-",
_ => match format_sign {
FormatSign::Plus => "+",
FormatSign::Minus => "",
FormatSign::MinusOrSpace => " ",
},
};
let sign_prefix = format!("{sign_str}{prefix}");
let magnitude_str = self.add_magnitude_separators(raw_magnitude_str, &sign_prefix);
self.format_sign_and_align(
&AsciiStr::new(&magnitude_str),
&sign_prefix,
FormatAlign::Right,
)
}
pub fn format_string<T>(&self, s: &T) -> Result<String, FormatSpecError>
where
T: CharLen + Deref<Target = str>,
{
self.validate_format(FormatType::String)?;
match self.format_type {
Some(FormatType::String) | None => self
.format_sign_and_align(s, "", FormatAlign::Left)
.map(|mut value| {
if let Some(precision) = self.precision {
value.truncate(precision);
}
value
}),
_ => {
let ch = char::from(self.format_type.as_ref().unwrap());
Err(FormatSpecError::UnknownFormatCode(ch, "str"))
}
}
}
fn format_sign_and_align<T>(
&self,
magnitude_str: &T,
sign_str: &str,
default_align: FormatAlign,
) -> Result<String, FormatSpecError>
where
T: CharLen + Deref<Target = str>,
{
let align = self.align.unwrap_or(default_align);
let num_chars = magnitude_str.char_len();
let fill_char = self.fill.unwrap_or(' ');
let fill_chars_needed: i32 = self.width.map_or(0, |w| {
cmp::max(0, (w as i32) - (num_chars as i32) - (sign_str.len() as i32))
});
let magnitude_str = magnitude_str.deref();
Ok(match align {
FormatAlign::Left => format!(
"{}{}{}",
sign_str,
magnitude_str,
FormatSpec::compute_fill_string(fill_char, fill_chars_needed)
),
FormatAlign::Right => format!(
"{}{}{}",
FormatSpec::compute_fill_string(fill_char, fill_chars_needed),
sign_str,
magnitude_str
),
FormatAlign::AfterSign => format!(
"{}{}{}",
sign_str,
FormatSpec::compute_fill_string(fill_char, fill_chars_needed),
magnitude_str
),
FormatAlign::Center => {
let left_fill_chars_needed = fill_chars_needed / 2;
let right_fill_chars_needed = fill_chars_needed - left_fill_chars_needed;
let left_fill_string =
FormatSpec::compute_fill_string(fill_char, left_fill_chars_needed);
let right_fill_string =
FormatSpec::compute_fill_string(fill_char, right_fill_chars_needed);
format!("{left_fill_string}{sign_str}{magnitude_str}{right_fill_string}")
}
})
}
}
pub trait CharLen {
/// Returns the number of characters in the text
fn char_len(&self) -> usize;
}
struct AsciiStr<'a> {
inner: &'a str,
}
impl<'a> AsciiStr<'a> {
fn new(inner: &'a str) -> Self {
Self { inner }
}
}
impl CharLen for AsciiStr<'_> {
fn char_len(&self) -> usize {
self.inner.len()
}
}
impl Deref for AsciiStr<'_> {
type Target = str;
fn deref(&self) -> &Self::Target {
self.inner
}
}
#[derive(Debug, PartialEq)]
pub enum FormatSpecError {
DecimalDigitsTooMany,
PrecisionTooBig,
InvalidFormatSpecifier,
UnspecifiedFormat(char, char),
UnknownFormatCode(char, &'static str),
PrecisionNotAllowed,
NotAllowed(&'static str),
UnableToConvert,
CodeNotInRange,
NotImplemented(char, &'static str),
}
#[derive(Debug, PartialEq)]
pub enum FormatParseError {
UnmatchedBracket,
MissingStartBracket,
UnescapedStartBracketInLiteral,
InvalidFormatSpecifier,
UnknownConversion,
EmptyAttribute,
MissingRightBracket,
InvalidCharacterAfterRightBracket,
}
impl FromStr for FormatSpec {
type Err = FormatSpecError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
FormatSpec::parse(s)
}
}
#[derive(Debug, PartialEq)]
pub enum FieldNamePart {
Attribute(String),
Index(usize),
StringIndex(String),
}
impl FieldNamePart {
fn parse_part(
chars: &mut impl PeekingNext<Item = char>,
) -> Result<Option<FieldNamePart>, FormatParseError> {
chars
.next()
.map(|ch| match ch {
'.' => {
let mut attribute = String::new();
for ch in chars.peeking_take_while(|ch| *ch != '.' && *ch != '[') {
attribute.push(ch);
}
if attribute.is_empty() {
Err(FormatParseError::EmptyAttribute)
} else {
Ok(FieldNamePart::Attribute(attribute))
}
}
'[' => {
let mut index = String::new();
for ch in chars {
if ch == ']' {
return if index.is_empty() {
Err(FormatParseError::EmptyAttribute)
} else if let Ok(index) = index.parse::<usize>() {
Ok(FieldNamePart::Index(index))
} else {
Ok(FieldNamePart::StringIndex(index))
};
}
index.push(ch);
}
Err(FormatParseError::MissingRightBracket)
}
_ => Err(FormatParseError::InvalidCharacterAfterRightBracket),
})
.transpose()
}
}
#[derive(Debug, PartialEq)]
pub enum FieldType {
Auto,
Index(usize),
Keyword(String),
}
#[derive(Debug, PartialEq)]
pub struct FieldName {
pub field_type: FieldType,
pub parts: Vec<FieldNamePart>,
}
impl FieldName {
pub fn parse(text: &str) -> Result<FieldName, FormatParseError> {
let mut chars = text.chars().peekable();
let mut first = String::new();
for ch in chars.peeking_take_while(|ch| *ch != '.' && *ch != '[') {
first.push(ch);
}
let field_type = if first.is_empty() {
FieldType::Auto
} else if let Ok(index) = first.parse::<usize>() {
FieldType::Index(index)
} else {
FieldType::Keyword(first)
};
let mut parts = Vec::new();
while let Some(part) = FieldNamePart::parse_part(&mut chars)? {
parts.push(part)
}
Ok(FieldName { field_type, parts })
}
}
#[derive(Debug, PartialEq)]
pub enum FormatPart {
Field {
field_name: String,
conversion_spec: Option<char>,
format_spec: String,
},
Literal(String),
}
#[derive(Debug, PartialEq)]
pub struct FormatString {
pub format_parts: Vec<FormatPart>,
}
impl FormatString {
fn parse_literal_single(text: &str) -> Result<(char, &str), FormatParseError> {
let mut chars = text.chars();
// This should never be called with an empty str
let first_char = chars.next().unwrap();
// isn't this detectable only with bytes operation?
if first_char == '{' || first_char == '}' {
let maybe_next_char = chars.next();
// if we see a bracket, it has to be escaped by doubling up to be in a literal
return if maybe_next_char.is_none() || maybe_next_char.unwrap() != first_char {
Err(FormatParseError::UnescapedStartBracketInLiteral)
} else {
Ok((first_char, chars.as_str()))
};
}
Ok((first_char, chars.as_str()))
}
fn parse_literal(text: &str) -> Result<(FormatPart, &str), FormatParseError> {
let mut cur_text = text;
let mut result_string = String::new();
while !cur_text.is_empty() {
match FormatString::parse_literal_single(cur_text) {
Ok((next_char, remaining)) => {
result_string.push(next_char);
cur_text = remaining;
}
Err(err) => {
return if !result_string.is_empty() {
Ok((FormatPart::Literal(result_string), cur_text))
} else {
Err(err)
};
}
}
}
Ok((FormatPart::Literal(result_string), ""))
}
fn parse_part_in_brackets(text: &str) -> Result<FormatPart, FormatParseError> {
let parts: Vec<&str> = text.splitn(2, ':').collect();
// before the comma is a keyword or arg index, after the comma is maybe a spec.
let arg_part = parts[0];
let format_spec = if parts.len() > 1 {
parts[1].to_owned()
} else {
String::new()
};
// On parts[0] can still be the conversion (!r, !s, !a)
let parts: Vec<&str> = arg_part.splitn(2, '!').collect();
// before the bang is a keyword or arg index, after the comma is maybe a conversion spec.
let arg_part = parts[0];
let conversion_spec = parts
.get(1)
.map(|conversion| {
// conversions are only every one character
conversion
.chars()
.exactly_one()
.map_err(|_| FormatParseError::UnknownConversion)
})
.transpose()?;
Ok(FormatPart::Field {
field_name: arg_part.to_owned(),
conversion_spec,
format_spec,
})
}
fn parse_spec(text: &str) -> Result<(FormatPart, &str), FormatParseError> {
let mut nested = false;
let mut end_bracket_pos = None;
let mut left = String::new();
// There may be one layer nesting brackets in spec
for (idx, c) in text.char_indices() {
if idx == 0 {
if c != '{' {
return Err(FormatParseError::MissingStartBracket);
}
} else if c == '{' {
if nested {
return Err(FormatParseError::InvalidFormatSpecifier);
} else {
nested = true;
left.push(c);
continue;
}
} else if c == '}' {
if nested {
nested = false;
left.push(c);
continue;
} else {
end_bracket_pos = Some(idx);
break;
}
} else {
left.push(c);
}
}
if let Some(pos) = end_bracket_pos {
let (_, right) = text.split_at(pos);
let format_part = FormatString::parse_part_in_brackets(&left)?;
Ok((format_part, &right[1..]))
} else {
Err(FormatParseError::UnmatchedBracket)
}
}
}
pub trait FromTemplate<'a>: Sized {
type Err;
fn from_str(s: &'a str) -> Result<Self, Self::Err>;
}
impl<'a> FromTemplate<'a> for FormatString {
type Err = FormatParseError;
fn from_str(text: &'a str) -> Result<Self, Self::Err> {
let mut cur_text: &str = text;
let mut parts: Vec<FormatPart> = Vec::new();
while !cur_text.is_empty() {
// Try to parse both literals and bracketed format parts until we
// run out of text
cur_text = FormatString::parse_literal(cur_text)
.or_else(|_| FormatString::parse_spec(cur_text))
.map(|(part, new_text)| {
parts.push(part);
new_text
})?;
}
Ok(FormatString {
format_parts: parts,
})
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_fill_and_align() {
assert_eq!(
parse_fill_and_align(" <"),
(Some(' '), Some(FormatAlign::Left), "")
);
assert_eq!(
parse_fill_and_align(" <22"),
(Some(' '), Some(FormatAlign::Left), "22")
);
assert_eq!(
parse_fill_and_align("<22"),
(None, Some(FormatAlign::Left), "22")
);
assert_eq!(
parse_fill_and_align(" ^^"),
(Some(' '), Some(FormatAlign::Center), "^")
);
assert_eq!(
parse_fill_and_align("==="),
(Some('='), Some(FormatAlign::AfterSign), "=")
);
}
#[test]
fn test_width_only() {
let expected = Ok(FormatSpec {
conversion: None,
fill: None,
align: None,
sign: None,
alternate_form: false,
width: Some(33),
grouping_option: None,
precision: None,
format_type: None,
});
assert_eq!(FormatSpec::parse("33"), expected);
}