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Refactor number scanners

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This commit is contained in:
Araozu 2022-11-29 20:30:56 -05:00
parent 53fd824e8d
commit c46291ed8a
1 changed files with 48 additions and 72 deletions
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122
src/lexic/scanner/number.rs
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@ -5,52 +5,37 @@ use crate::lexic::{token::{Token, self}, utils};
/// This function assumes that the character at `start_pos` is a number [0-9],
/// if not it will panic
pub fn scan(chars: &Vec<char>, start_pos: usize) -> Result<(Token, usize), String> {
let next_char = chars.get(start_pos);
let next_char_1 = chars.get(start_pos);
let next_char_2 = chars.get(start_pos + 1);
// Try to scan a HEX value
if let Some(c) = next_char {
if *c == '0' {
// May be an 'x' or 'X'
let next_next_char = chars.get(start_pos + 1);
if let Some(c2) = next_next_char {
if *c2 == 'x' || *c2 == 'X' {
return scan_hex(chars, start_pos + 2, String::from("0x"));
match (next_char_1, next_char_2) {
// Test if the input contains a hex number
(Some(c1), Some(c2)) if *c1 == '0' && (*c2 == 'x' || *c2 == 'X') => {
scan_hex(chars, start_pos + 2, String::from("0x"))
},
// Scan decimal/double/scientific otherwise
_ => scan_decimal(chars, start_pos, String::from(""))
}
}
}
}
scan_decimal(chars, start_pos, String::from(""))
}
/// Recursively scans an integer. If a dot `.` is found, scans a double,
/// if a `e` is found, scans a number in scientific notation
fn scan_decimal(chars: &Vec<char>, start_pos: usize, current: String) -> Result<(Token, usize), String> {
let next_char = chars.get(start_pos);
// If a char is found
if let Some(c) = next_char {
let c = *c;
// If a dot is found scan a double
if c == '.' {
return scan_double(chars, start_pos + 1, utils::str_append(current, c))
}
// If a `e` is found scan a double with exponent
else if c == 'e' {
return scan_scientific(chars, start_pos + 1, utils::str_append(current, c))
}
// Scan a decimal number
else if utils::is_digit(c) {
return scan_decimal(chars, start_pos + 1, utils::str_append(current, c))
}
}
// Return the current value
match chars.get(start_pos) {
Some(c) if *c == '.' => {
scan_double(chars, start_pos + 1, utils::str_append(current, *c))
},
Some(c) if *c == 'e' => {
scan_scientific(chars, start_pos + 1, utils::str_append(current, *c))
},
Some(c) if utils::is_digit(*c) => {
scan_decimal(chars, start_pos + 1, utils::str_append(current, *c))
},
_ => {
Ok((token::new_number(current, start_pos as i32), start_pos))
}
}
}
@ -60,26 +45,14 @@ fn scan_decimal(chars: &Vec<char>, start_pos: usize, current: String) -> Result<
/// - The char at `start_pos` is a value between [0-9a-fA-F]. If not, will return an error.
/// - `current == "0x"`. If not will return an incorrect value, or panic.
fn scan_hex(chars: &Vec<char>, start_pos: usize, current: String) -> Result<(Token, usize), String> {
let next_char = chars.get(start_pos);
if let Some(c) = next_char {
let c = *c;
if utils::is_hex_digit(c) {
return scan_hex(chars, start_pos + 1, utils::str_append(current, c))
}
}
// If the current value is "0x" that means that there wasn't any hex number thereafter
if current.len() == 2 {
Err(String::from("Tried to scan an incomplete hex value"))
}
else {
Ok((token::new_number(current, start_pos as i32), start_pos))
match chars.get(start_pos) {
Some(c) if utils::is_hex_digit(*c) => {
Ok(scan_hex_digits(chars, start_pos + 1, utils::str_append(current, *c)))
},
_ => Err(String::from("Tried to scan an incomplete hex value"))
}
}
/// Scans a floating point number
///
/// This function expects the following:
@ -87,15 +60,14 @@ fn scan_hex(chars: &Vec<char>, start_pos: usize, current: String) -> Result<(Tok
///
/// Returns a syntax error if the char at `start_pos` is not a value between [0-9]
fn scan_double(chars: &Vec<char>, start_pos: usize, current: String) -> Result<(Token, usize), String> {
let next_char = chars.get(start_pos);
// Check that the first characters exists and is a number
if let Some(c) = next_char {
if utils::is_digit(*c) { Ok(scan_digits(chars, start_pos, current)) }
else {Err(String::from("The character after the dot when scanning a double is not a number."))}
}
else {
Err(String::from("EOF when scanning a double number."))
match chars.get(start_pos) {
Some(c) if utils::is_digit(*c) => {
Ok(scan_digits(chars, start_pos, current))
},
Some(_) => {
Err(String::from("The character after the dot when scanning a double is not a number."))
},
_ => Err(String::from("EOF when scanning a double number."))
}
}
@ -124,18 +96,22 @@ fn scan_scientific(chars: &Vec<char>, start_pos: usize, current: String) -> Resu
/// Scans chars between [0-9], returns when none is found
fn scan_digits(chars: &Vec<char>, start_pos: usize, current: String) -> (Token, usize) {
let next_char = chars.get(start_pos);
if let Some(c) = next_char {
let c = *c;
if utils::is_digit(c) {
return scan_digits(chars, start_pos + 1, utils::str_append(current, c))
}
match chars.get(start_pos) {
Some(c) if utils::is_digit(*c) => {
scan_digits(chars, start_pos + 1, utils::str_append(current, *c))
},
_ => (token::new_number(current, start_pos as i32), start_pos)
}
}
// Return current value
(token::new_number(current, start_pos as i32), start_pos)
/// Scans chars between [0-9a-fA-F], returns when none is found
fn scan_hex_digits(chars: &Vec<char>, start_pos: usize, current: String) -> (Token, usize) {
match chars.get(start_pos) {
Some(c) if utils::is_hex_digit(*c) => {
scan_hex_digits(chars, start_pos + 1, utils::str_append(current, *c))
},
_ => (token::new_number(current, start_pos as i32), start_pos)
}
}