From 3ccbcbc1c228fd3ad3287ad85326c341549078e1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emmanuel=20Beno=C3=AEt?= <tseeker@nocternity.net>
Date: Fri, 30 Dec 2022 19:10:14 +0100
Subject: [PATCH] Scanner - Numbers
---
src/scanner.rs | 52 ++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 48 insertions(+), 4 deletions(-)
diff --git a/src/scanner.rs b/src/scanner.rs
index af5db1c..1e9df17 100644
--- a/src/scanner.rs
+++ b/src/scanner.rs
@@ -54,7 +54,7 @@ impl Scanner {
'/' => {
if self.is_match('/') {
while self.peek() != '\n' && !self.is_at_end() {
- self.advance();
+ self.current += 1;
}
} else {
self.add_token(TokenType::Slash)
@@ -91,14 +91,19 @@ impl Scanner {
}
// String litterals
'"' => self.string_litteral(err_hdl),
+ // Numbers
+ '0'..='9' => self.number(err_hdl),
// Handle whitespace
' ' | '\r' | '\t' => (),
'\n' => self.line += 1,
// Anything else is an error
- ch => err_hdl.error(self.line, &format!("unexpected character {:#?}", ch)),
+ ch => {
+ err_hdl.error(self.line, &format!("unexpected character {:#?}", ch));
+ }
}
}
+ /// Read the rest of a string litteral
fn string_litteral(&mut self, err_hdl: &mut ErrorHandler) {
loop {
let p = self.peek();
@@ -108,18 +113,47 @@ impl Scanner {
if p == '\n' {
self.line += 1;
}
- self.advance();
+ self.current += 1;
}
if self.is_at_end() {
err_hdl.error(self.line, "unterminated string");
} else {
- self.advance(); // Last '"'
+ self.current += 1; // Last '"'
let value = self.get_substring(self.start + 1, self.current - 1);
self.add_token(TokenType::String(value));
}
}
+ /// Read the rest of a number.
+ fn number(&mut self, err_hdl: &mut ErrorHandler) {
+ while self.peek().is_digit(10) {
+ self.current += 1;
+ }
+ if self.peek() == '.' && self.peek_next().is_digit(10) {
+ self.current += 1;
+ while self.peek().is_digit(10) {
+ self.current += 1;
+ }
+ }
+
+ let tok_string = self.get_substring(self.start, self.current);
+ match tok_string.parse::<f64>() {
+ Err(e) => {
+ err_hdl.error(
+ self.line,
+ &format!(
+ "Could not parse {} as a floating point number: {:?}",
+ tok_string, e
+ ),
+ );
+ }
+ Ok(value) => {
+ self.add_token(TokenType::Number(value));
+ }
+ };
+ }
+
/// Check whether the end of the input has been reached.
fn is_at_end(&self) -> bool {
self.current >= self.len
@@ -154,6 +188,16 @@ impl Scanner {
}
}
+ /// Returns the next character, or a NULL character if the end has been
+ /// reached.
+ fn peek_next(&self) -> char {
+ if self.current + 1 >= self.source.chars().count() {
+ '\0'
+ } else {
+ self.source.chars().nth(self.current + 1).unwrap()
+ }
+ }
+
/// Read the current character.
fn cur_char(&self) -> char {
self.source.chars().nth(self.current).unwrap()