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use kg_diag::{CharReader, MemCharReader, ParseDiag};
use super::*;
use super::Regex::*;
#[derive(Debug)]
pub enum Error {
Unspecified(u32),
IoError,
}
impl From<ParseDiag> for Error {
fn from(_: ParseDiag) -> Error {
Error::IoError
}
}
#[derive(Debug, Clone, Copy)]
struct Flags {
icase: bool,
}
impl Flags {
fn new() -> Flags {
Flags { icase: false }
}
}
#[derive(Debug)]
enum ParseExpr {
Regex(Regex),
Group {
flags: Flags,
},
}
pub struct Parser {
stack: Vec<ParseExpr>,
flags: Flags,
}
impl Parser {
pub fn parse(input: &str) -> Result<Regex, Error> {
if input.is_empty() {
Ok(Regex::Empty)
} else {
Parser {
stack: vec![],
flags: Flags::new(),
}.parse_regex(input)
}
}
fn parse_regex(mut self, input: &str) -> Result<Regex, Error> {
let mut r = MemCharReader::new(input.as_bytes());
while let Some(c) = r.next_char()? {
let expr = match c {
'|' => self.alternate()?,
'(' => self.group_open()?,
')' => self.group_close()?,
'[' => self.char_set(&mut r)?,
'?' | '*' | '+' | '{' => self.repeat(&mut r)?,
'.' => ParseExpr::Regex(Any),
'\\' => {
ParseExpr::Regex(Literal {
chars: vec![self.escape(&mut r)?],
icase: self.flags.icase,
})
}
_ => {
ParseExpr::Regex(Literal {
chars: vec![c],
icase: self.flags.icase,
})
}
};
self.stack.push(expr);
}
let mut nes = Vec::new();
while let Some(e) = self.stack.pop() {
match e {
ParseExpr::Regex(Alternate { mut es }) => {
if !nes.is_empty() {
es.push(Parser::concat(nes)?);
nes = Vec::new();
}
nes.push(Alternate { es: es });
}
ParseExpr::Regex(e @ _) => nes.push(e),
_ => return Err(Error::Unspecified(line!())),
}
}
Parser::concat(nes)?.simplify(1000)
}
fn escape(&mut self, r: &mut dyn CharReader) -> Result<char, Error> {
if let Some(c) = r.next_char()? {
match c {
'\\' | '.' | '-' | '+' | '*' | '?' | '[' | ']' | '{' | '}' | '(' | ')' | '^' => {
return Ok(c)
}
'a' => return Ok('\x07'),
'f' => return Ok('\x0C'),
't' => return Ok('\t'),
'n' => return Ok('\n'),
'r' => return Ok('\r'),
'v' => return Ok('\x0B'),
// '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7' => self.parse_octal(),
// 'x' => { self.bump(); self.parse_hex() }
// 'p'|'P' => {
// self.bump();
// self.parse_unicode_class(c == 'P')
// .map(|cls| Build::Expr(Expr::Class(cls)))
// }
// 'd'|'s'|'w'|'D'|'S'|'W' => {
// self.bump();
// Ok(Build::Expr(Expr::Class(self.parse_perl_class(c))))
// }
_ => return Err(Error::Unspecified(line!())),
}
}
return Err(Error::Unspecified(line!()));
}
fn alternate(&mut self) -> Result<ParseExpr, Error> {
let mut nes = Vec::new();
while let Some(e) = self.stack.pop() {
match e {
ParseExpr::Group { .. } => {
self.stack.push(e);
break;
}
ParseExpr::Regex(Alternate { mut es }) => {
if !nes.is_empty() {
es.push(Parser::concat(nes)?);
}
return Ok(ParseExpr::Regex(Alternate { es: es }));
}
ParseExpr::Regex(e @ _) => {
nes.push(e);
}
}
}
Ok(ParseExpr::Regex(Alternate { es: vec!(Parser::concat(nes)?) }))
}
fn group_open(&mut self) -> Result<ParseExpr, Error> {
Ok(ParseExpr::Group { flags: self.flags })
}
fn group_close(&mut self) -> Result<ParseExpr, Error> {
let mut nes = Vec::new();
while let Some(e) = self.stack.pop() {
match e {
ParseExpr::Group { flags } => {
self.flags = flags;
return Ok(ParseExpr::Regex(Concat { es: vec!(Parser::concat(nes)?) }));
}
ParseExpr::Regex(Alternate { mut es }) => {
if !nes.is_empty() {
es.push(Parser::concat(nes)?);
nes = Vec::new();
}
nes.push(Alternate { es: es });
}
ParseExpr::Regex(e @ _) => {
nes.push(e);
}
}
}
Err(Error::Unspecified(line!()))
}
fn repeat(&mut self, r: &mut dyn CharReader) -> Result<ParseExpr, Error> {
fn scan_repeat(r: &mut dyn CharReader) -> Result<(u32, u32), Error> {
let mut min = 0;
let mut max = 0;
let mut n = 0;
while let Some(c) = r.next_char()? {
if c >= '0' && c <= '9' {
if n < 2 {
n = 1;
min = min * 10 + (c as u32 - '0' as u32);
} else {
max = max * 10 + (c as u32 - '0' as u32);
}
} else if c == ',' {
if n == 1 {
n = 2;
} else {
return Err(Error::Unspecified(line!()));
}
} else if c == '}' {
if n == 0 {
return Err(Error::Unspecified(line!()));
} else if n == 1 {
max = min;
}
return Ok((min, max));
}
}
Err(Error::Unspecified(line!()))
}
if self.stack.is_empty() {
Err(Error::Unspecified(line!()))
} else {
let min: u32;
let max: u32;
let mut greedy = true;
match r.peek_char(0)?.unwrap() {
'?' => {
min = 0;
max = 1;
}
'+' => {
min = 1;
max = 0;
}
'*' => {
min = 0;
max = 0;
}
_ => {
let r = scan_repeat(r)?;
min = r.0;
max = r.1;
}
}
if let Some('?') = r.peek_char(1)? {
greedy = false;
r.skip_chars(1)?;
}
match self.stack.pop().unwrap() {
ParseExpr::Regex(r @ _) => {
Ok(ParseExpr::Regex(Repeat {
e: Box::new(r),
min: min,
max: max,
greedy: greedy,
}))
}
_ => {
Err(Error::Unspecified(line!()))
}
}
}
}
fn char_set(&mut self, r: &mut dyn CharReader) -> Result<ParseExpr, Error> {
let mut set = CharSet::new();
let mut p = '\0';
let mut range = false;
let mut found = false;
let mut exclude = false;
while let Some(mut c) = r.next_char()? {
match c {
'^' if !found => {
exclude = true;
continue;
}
']' => {
if range {
return Err(Error::Unspecified(line!()));
} else {
break;
}
}
'-' => {
if !found {
return Err(Error::Unspecified(line!()));
} else {
range = true;
continue;
}
}
'\\' => {
c = self.escape(r)?;
}
_ => {}
}
found = true;
if range {
if exclude {
set.remove_range(p, c);
} else {
set.add_range(p, c);
}
range = false;
} else {
if exclude {
set.remove_char(c);
} else {
set.add_char(c);
}
}
p = c;
}
if !set.is_empty() {
Ok(ParseExpr::Regex(Set { set: set }))
} else {
Err(Error::Unspecified(line!()))
}
}
fn concat(mut es: Vec<Regex>) -> Result<Regex, Error> {
match es.len() {
0 => Err(Error::Unspecified(line!())),
1 => Ok(es.pop().unwrap()),
_ => {
es.reverse();
Ok(Concat { es: es })
}
}
}
}