Mostly done, parse_number needs some more work

This commit is contained in:
Timothy Warren 2020-02-07 23:51:49 -05:00
parent 0993780c89
commit b0c2eb7e08

View File

@ -244,7 +244,62 @@ impl JSON {
/// See if there's a `JSONValue::Number` next in the JSON
fn parse_number(&mut self) -> Result<Option<JSONValue>, ParseError> {
todo!();
self.skip_whitespace();
// All this looping basically just counts the number of characters in the number
let start = self.i;
let max = self.chars.len() - 1;
let mut n = start;
if self.chars[n] == '-' && n < max {
n += 1;
}
if self.chars[n] == '0' && n < max {
n += 1;
} else if self.chars[n] >= '1' && self.chars[n] <= '9' && n < max {
n += 1;
while self.chars[n].is_ascii_digit() {
// && n < max {
n += 1;
}
}
if self.chars[n] == '.' && n < max {
n += 1;
while self.chars[n].is_ascii_digit() && n < max {
n += 1;
}
}
if self.chars[n] == 'e' || self.chars[n] == 'E' && n < max {
n += 1;
if self.chars[n] == '-' || self.chars[n] == '+' && n < max {
n += 1;
}
while self.chars[n].is_ascii_digit() && n < max {
n += 1;
}
}
if n > start {
let end = if n < self.chars.len() {
n
} else {
self.chars.len()
};
let str = String::from_iter(&self.chars[start..=end]);
match str.parse::<f64>() {
Ok(n) => Ok(Some(JSONValue::Number(n))),
Err(e) => Err(ParseError::ExpectedDigit(format!("{:#?}", (str, e)))),
}
} else {
Ok(None)
}
}
/// See if there's a `JSONValue::True`, `JSONValue::False`, or a `JSONValue::Null` next in the JSON
@ -284,7 +339,7 @@ impl JSON {
/// error is returned
fn eat(&mut self, ch: char) -> Result<(), ParseError> {
if self.chars[self.i] != ch {
let msg = format!(r#"Expected "{}"."#, ch);
let msg = format!("Expected '{}'.", ch);
return Err(ParseError::ExpectedToken(msg));
}
@ -339,6 +394,17 @@ mod tests {
assert_eq!(res, Ok(JSONValue::Array(vec![])));
}
#[test]
fn parse_number() {
let mut parser = JSON::new("3.14159");
let res = JSON::parse_number(&mut parser);
assert_eq!(res, Ok(Some(JSONValue::Number(3.14159f64))));
let mut parser = JSON::new("3e4");
let res = JSON::parse_number(&mut parser);
assert_eq!(res, Ok(Some(JSONValue::Number(3e4f64))));
}
#[test]
fn can_parse_array_of_keywords() {
let result = JSON::parse("[true,false,null]");
@ -352,4 +418,26 @@ mod tests {
]))
);
}
#[test]
fn can_parse_arbitrary_json() {
let result = JSON::parse(
r#"[{
"a": 9.38083151965,
"b": 4e3,
"c": [1, 2, 3],
"d": "foo",
"e": {
"f": {
"g": {
"h": null
}
}
},
"i": ["\"", "\\", "/", "\b", "\f", "\n", "\r", "\t", "\u0001", "\uface"]
}]"#,
);
// let msg = format!("{:#?}", result);
assert!(result.is_ok(), format!("{:#?}", result));
}
}