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changing preview_next() to return Option and next_is to bool (#26)

pull/27/head
Jason Williams 6 years ago committed by GitHub
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2 changed files with 54 additions and 41 deletions
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  1. 86
      src/lib/syntax/lexer.rs
  2. 1
      tests/js/test.js

86
src/lib/syntax/lexer.rs
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@ -14,7 +14,7 @@ use std::str::FromStr;
#[allow(unused)]
macro_rules! vop {
($this:ident, $assign_op:expr, $op:expr) => ({
let preview = $this.preview_next()?;
let preview = $this.preview_next().unwrap();
match preview {
'=' => {
$this.next()?;
@ -24,7 +24,7 @@ macro_rules! vop {
}
});
($this:ident, $assign_op:expr, $op:expr, {$($case:pat => $block:expr), +}) => ({
let preview = $this.preview_next()?;
let preview = $this.preview_next().unwrap();
match preview {
'=' => {
$this.next()?;
@ -35,7 +35,7 @@ macro_rules! vop {
}
});
($this:ident, $op:expr, {$($case:pat => $block:expr),+}) => {
let preview = $this.preview_next()?;
let preview = $this.preview_next().unwrap();
match preview {
$($case => $block) +,
_ => $op
@ -161,11 +161,11 @@ impl<'a> Lexer<'a> {
}
/// Preview the next character but don't actually increment
fn preview_next(&mut self) -> Result<char, LexerError> {
fn preview_next(&mut self) -> Option<char> {
// No need to return a reference, we can return a copy
match self.buffer.peek() {
Some(v) => Ok(*v),
None => Err(LexerError::new("finished")),
Some(v) => Some(*v),
None => None,
}
}
@ -176,7 +176,7 @@ impl<'a> Lexer<'a> {
F: FnMut(char) -> bool,
{
let mut s = String::new();
while self.buffer.peek().is_some() && f(self.preview_next()?) {
while self.buffer.peek().is_some() && f(self.preview_next().unwrap()) {
s.push(self.next()?);
}
@ -184,26 +184,24 @@ impl<'a> Lexer<'a> {
}
/// next_is compares the character passed in to the next character, if they match true is returned and the buffer is incremented
fn next_is(&mut self, peek: char) -> Result<bool, LexerError> {
let result = self.preview_next()? == peek;
fn next_is(&mut self, peek: char) -> bool {
let result = match self.preview_next() {
Some(v) => v == peek,
None => false,
};
if result {
self.buffer.next();
}
Ok(result)
result
}
pub fn lex(&mut self) -> Result<(), LexerError> {
loop {
// Check if we've reached the end
match self.preview_next() {
Ok(_) => (), // If there are still characters, carry on
Err(e) => {
if e.details == "finished" {
// If there are no more characters left in the Chars iterator, we should just return
Some(_) => (), // If there are still characters, carry on
None => {
return Ok(());
} else {
return Err(e);
}
}
}
self.column_number += 1;
@ -254,7 +252,7 @@ impl<'a> Lexer<'a> {
// Example Test: https://github.com/tc39/test262/blob/ee3715ee56744ccc8aeb22a921f442e98090b3c1/implementation-contributed/v8/mjsunit/es6/unicode-escapes.js#L39-L44
// Support \u{X..X} (Unicode Codepoint)
if self.next_is('{')? {
if self.next_is('{') {
let s = self
.take_char_while(|c| c.is_alphanumeric())
.unwrap();
@ -288,7 +286,7 @@ impl<'a> Lexer<'a> {
self.column_number += s.len() as u64 + 2;
// Check for another UTF-16 codepoint
if self.next_is('\\')? && self.next_is('u')? {
if self.next_is('\\') && self.next_is('u') {
continue;
}
break;
@ -325,32 +323,38 @@ impl<'a> Lexer<'a> {
}
'0' => {
let mut buf = String::new();
let num = if self.next_is('x')? {
let num = if self.next_is('x') {
loop {
let ch = self.preview_next()?;
match ch {
ch if ch.is_digit(16) => {
match self.preview_next() {
Some(ch) => {
if ch.is_digit(16) {
buf.push(self.next()?);
} else {
break;
}
_ => break,
}
None => break,
};
}
u64::from_str_radix(&buf, 16).unwrap()
} else if self.next_is('b')? {
} else if self.next_is('b') {
loop {
let ch = self.preview_next()?;
match ch {
ch if ch.is_digit(2) => {
match self.preview_next() {
Some(ch) => {
if ch.is_digit(2) {
buf.push(self.next()?);
} else {
break;
}
_ => break,
}
None => break,
}
}
u64::from_str_radix(&buf, 2).unwrap()
} else {
let mut gone_decimal = false;
loop {
let ch = self.preview_next()?;
let ch = self.preview_next().unwrap_or('_');
match ch {
ch if ch.is_digit(8) => {
buf.push(ch);
@ -384,8 +388,8 @@ impl<'a> Lexer<'a> {
loop {
// There might not be a next character
let ch = match self.preview_next() {
Ok(c) => c,
Err(_) => break,
Some(c) => c,
None => break,
};
match ch {
'.' | 'e' | '+' | '-' => {
@ -403,7 +407,10 @@ impl<'a> Lexer<'a> {
_ if ch.is_alphabetic() || ch == '$' || ch == '_' => {
let mut buf = ch.to_string();
loop {
let ch = self.preview_next()?;
let ch = match self.preview_next() {
Some(ch) => ch,
None => break,
};
match ch {
_ if ch.is_alphabetic() || ch.is_digit(10) || ch == '_' => {
buf.push(self.next()?);
@ -440,7 +447,12 @@ impl<'a> Lexer<'a> {
'?' => self.push_punc(Punctuator::Question),
// Comments
'/' => {
let token = match self.preview_next()? {
let ch = match self.preview_next() {
Some(ch) => ch,
None => return Err(LexerError::new("Expecting Token /,*,=")),
};
let token = match ch {
// Matched comment
'/' => {
let comment = self.read_line()?;
@ -451,7 +463,7 @@ impl<'a> Lexer<'a> {
loop {
match self.next()? {
'*' => {
if self.next_is('/')? {
if self.next_is('/') {
break;
} else {
buf.push('*')
@ -485,7 +497,7 @@ impl<'a> Lexer<'a> {
'&' => Punctuator::BoolAnd
}),
'^' => op!(self, Punctuator::AssignXor, Punctuator::Xor),
'=' => op!(self, if self.next_is('=')? {
'=' => op!(self, if self.next_is('=') {
Punctuator::StrictEq
} else {
Punctuator::Eq
@ -595,7 +607,7 @@ mod tests {
#[test]
fn numbers() {
let mut lexer = Lexer::new("1 2 0x34 056 7.89 5e3 5e+3 5e-3 0b10 0O123 0999;");
let mut lexer = Lexer::new("1 2 0x34 056 7.89 5e3 5e+3 5e-3 0b10 0O123 0999");
lexer.lex().expect("finished");
assert_eq!(lexer.tokens[0].data, TokenData::NumericLiteral(1.0));
assert_eq!(lexer.tokens[1].data, TokenData::NumericLiteral(2.0));

1
tests/js/test.js
Unescape View File

@ -1 +1,2 @@
let a = "hello world";
a;

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