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json-parser
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Add more error checking

This commit is contained in:
Timothy Warren 2020-02-12 11:22:02 -05:00
parent da888b743b
commit 9af3bd629c
1 changed files with 89 additions and 199 deletions
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288
src/lib.rs
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@ -61,18 +61,18 @@ impl From<JSONValue> for JSONMap {
fn from(val: JSONValue) -> JSONMap {
match val {
JSONValue::Object(o) => o,
_ => panic!("Invalid type conversion")
_ => unreachable!(),
}
}
}
impl From<JSONValue> for JSONArray{
impl From<JSONValue> for JSONArray {
/// Extracts the `Vec` in the `JSONValue` enum, if it exists.
/// Otherwise, panics.
fn from(val: JSONValue) -> JSONArray {
match val {
JSONValue::Array(a) => a,
_ => panic!("Invalid type conversion")
_ => unreachable!(),
}
}
}
@ -83,7 +83,7 @@ impl From<JSONValue> for f64 {
fn from(val: JSONValue) -> f64 {
match val {
JSONValue::Number(n) => n,
_ => panic!("Invalid type conversion")
_ => unreachable!(),
}
}
}
@ -94,7 +94,7 @@ impl From<JSONValue> for String {
fn from(val: JSONValue) -> String {
match val {
JSONValue::String(s) => s,
_ => panic!("Invalid type conversion")
_ => unreachable!(),
}
}
}
@ -106,14 +106,16 @@ impl From<JSONValue> for bool {
match val {
JSONValue::True => true,
JSONValue::False => false,
_ => panic!("Invalid type conversion")
_ => unreachable!(),
}
}
}
impl From<JSONValue> for () {
/// This will just swallow the enum value and return a unit tuple
fn from(_: JSONValue) -> () { () }
fn from(_: JSONValue) -> () {
()
}
}
impl From<JSONMap> for JSONValue {
@ -245,7 +247,9 @@ impl JSON {
);
// Every parser failed, so the syntax is probably incorrect
Err(ParseError::UnexpectedEndOfInput(format!("Doesn't seem to be valid JSON")))
Err(ParseError::UnexpectedEndOfInput(format!(
"Doesn't seem to be valid JSON"
)))
}
/// See if there's a `JSONValue::Object` next in the JSON
@ -270,20 +274,21 @@ impl JSON {
if initial == false {
self.eat(',')?;
self.skip_whitespace();
} else {
self.skip_whitespace();
}
let maybe_key = self.parse_string()?;
if maybe_key.is_none() {
return Err(ParseError::ExpectedObjectKey(format!(
"Expected an object key. Does the object have a trailing comma?"
)));
}
self.skip_whitespace();
let key = match self.parse_string()? {
Some(value) => match value {
JSONValue::String(s) => s,
_ => panic!("parse_string returned non-string value"),
},
None => String::new(),
};
self.skip_whitespace();
self.eat(':')?;
let key = maybe_key.unwrap().into();
let value = self.parse_value()?;
result.insert(key, value);
@ -293,6 +298,7 @@ impl JSON {
self.skip_whitespace();
}
self.expect_not_end('}')?;
// Move to the next character: '}'
self.increment(1);
@ -322,6 +328,7 @@ impl JSON {
initial = false;
}
self.expect_not_end(']')?;
// move to next character: ']'
self.increment(1);
@ -360,22 +367,31 @@ impl JSON {
};
result.push(ch);
self.increment(1);
} else if ch == 'u'
&& self.chars[self.i + 2].is_ascii_hexdigit()
&& self.chars[self.i + 3].is_ascii_hexdigit()
&& self.chars[self.i + 4].is_ascii_hexdigit()
&& self.chars[self.i + 5].is_ascii_hexdigit()
{
// Blech, parse out a JSON unicode (utf16) escape code. Handles surrogate pairs
// by giving you the replacement character...because...yeah
let char_str = String::from_iter(&self.chars[self.i + 2..=self.i + 5]);
let code = u16::from_str_radix(&char_str, 16)
.expect("Failed to parse unicode escape number");
let string = String::from_utf16_lossy(&[code]);
} else if ch == 'u' {
if self.chars[self.i + 2].is_ascii_hexdigit()
&& self.chars[self.i + 3].is_ascii_hexdigit()
&& self.chars[self.i + 4].is_ascii_hexdigit()
&& self.chars[self.i + 5].is_ascii_hexdigit()
{
// Blech, parse out a JSON unicode (utf16) escape code. Handles surrogate pairs
// by giving you the replacement character...because...yeah
let char_str = String::from_iter(&self.chars[self.i + 2..=self.i + 5]);
let code = u16::from_str_radix(&char_str, 16)
.expect("Failed to parse unicode escape number");
let string = String::from_utf16_lossy(&[code]);
result.push_str(&string);
result.push_str(&string);
self.increment(5);
self.increment(5);
} else {
return Err(ParseError::ExpectedUnicodeEscape(format!(
"Expected a unicode escape sequence"
)));
}
} else {
return Err(ParseError::ExpectedEscapeChar(format!(
"Expected an escape sequence"
)));
}
} else {
result.push(self.chars[self.i]);
@ -383,7 +399,8 @@ impl JSON {
self.increment(1);
}
self.eat('"')?;
self.expect_not_end('"')?;
self.increment(1);
Ok(Some(JSONValue::from(result)))
}
@ -404,6 +421,7 @@ impl JSON {
// Minus sign
if self.chars[n] == '-' && n < max {
n += 1;
self.expect_digit(start, n)?;
}
// Integer Part
@ -414,6 +432,7 @@ impl JSON {
// Decimal Part
if self.chars[n] == '.' && n < max {
n += 1;
self.expect_digit(start, n)?;
while self.chars[n].is_ascii_digit() && n < max {
n += 1;
}
@ -428,6 +447,7 @@ impl JSON {
}
// Exponent base
self.expect_digit(start, n)?;
while self.chars[n].is_ascii_digit() && n < max {
n += 1;
}
@ -512,6 +532,31 @@ impl JSON {
}
}
/// Check that the next character is a digit. If not, return ParseError.
fn expect_digit(&mut self, start: usize, end: usize) -> Result<(), ParseError> {
let current = String::from_iter(&self.chars[start..end]);
if !self.chars[end].is_ascii_digit() {
Err(ParseError::ExpectedDigit(format!(
"Expected a digit, received '{}' after numeric '{}'",
self.chars[end], current
)))
} else {
Ok(())
}
}
/// Verify that we are not at the end of the input string
fn expect_not_end(&mut self, ch: char) -> Result<(), ParseError> {
if self.i == self.chars.len() {
Err(ParseError::UnexpectedEndOfInput(format!(
"Unexpected end of input. Expected '{}'",
ch
)))
} else {
Ok(())
}
}
/// Convert a `&str` containing JSON into a `Result<JSONValue, ParseError>`
pub fn parse(json: &str) -> JSONResult {
JSON::new(json).parse_value()
@ -520,7 +565,7 @@ impl JSON {
#[cfg(test)]
mod tests {
use super::JSONValue::{Array, False, Null, Number, Object, True};
use super::JSONValue::{Array, Number, True};
use super::*;
#[test]
@ -528,7 +573,11 @@ mod tests {
let map: JSONMap = HashMap::new();
let num = 9.380831539;
let str = "applesauce";
let arr: JSONArray = vec![JSONValue::from(map.clone()), JSONValue::from(num), JSONValue::from(str)];
let arr: JSONArray = vec![
JSONValue::from(map.clone()),
JSONValue::from(num),
JSONValue::from(str),
];
assert_eq!(map.clone(), JSONMap::from(JSONValue::from(map.clone())));
assert_eq!(num, f64::from(JSONValue::from(num)));
@ -544,7 +593,11 @@ mod tests {
let map: JSONMap = HashMap::new();
let num = 9.380831539;
let str = "applesauce";
let arr: JSONArray = vec![JSONValue::from(map.clone()), JSONValue::from(num), JSONValue::from(str)];
let arr: JSONArray = vec![
JSONValue::from(map.clone()),
JSONValue::from(num),
JSONValue::from(str),
];
let s: String = JSONValue::from(str).unwrap();
let a: JSONArray = JSONValue::from(arr.clone()).unwrap();
@ -597,9 +650,6 @@ mod tests {
let res = JSON::new(r#""foo""#).parse_number();
assert_eq!(res, Ok(None));
let res = JSON::new("3.14159").parse_number();
assert_eq!(res, Ok(Some(Number(3.14159f64))));
let res = JSON::new("3e4").parse_number();
assert_eq!(res, Ok(Some(Number(3e4f64))));
@ -607,13 +657,6 @@ mod tests {
assert_eq!(res, Ok(Some(Number(1.234f64))));
}
#[test]
fn can_parse_array_of_keywords() {
let result = JSON::parse("[true,false,null]");
assert_eq!(result, Ok(Array(vec![True, False, Null])));
}
#[test]
fn parse_object() {
let result = JSON::new(r#"{"foo": "bar"}"#).parse_object();
@ -623,157 +666,4 @@ mod tests {
assert_eq!(result, Ok(Some(JSONValue::Object(hash_map))));
}
#[test]
fn parse_json_types() {
// Boolean / Null
let res = JSON::parse("true");
assert_eq!(res, Ok(True));
let res = JSON::parse("false");
assert_eq!(res, Ok(False));
let res = JSON::parse("null");
assert_eq!(res, Ok(Null));
// Number
let res = JSON::parse("9.38083151965");
assert_eq!(res, Ok(Number(9.38083151965)), "Failed to parse number");
// String
let res = JSON::parse(r#""/^$/""#);
assert_eq!(
res,
Ok(JSONValue::from("/^$/")),
"Failed to parse string"
);
// Number array
let res = JSON::parse("[1, 2, 3]");
assert_eq!(
res,
Ok(Array(vec![Number(1f64), Number(2f64), Number(3f64)]))
);
// Object array
let result = JSON::parse("[{}]");
assert_eq!(result, Ok(JSONValue::Array(vec![Object(HashMap::new())])));
}
#[test]
fn parse_nested_object() {
let res = JSON::parse(r#"{"a": {"b": []}}"#);
let mut outermap: JSONMap = HashMap::new();
let mut innermap: JSONMap = HashMap::new();
innermap.insert(String::from("b"), Array(vec![]));
outermap.insert(String::from("a"), Object(innermap));
let expected = Ok(Object(outermap));
assert_eq!(res, expected);
}
#[test]
fn parse_object_with_number_values() {
let result = JSON::parse(r#"[{ "a": 9.38083151965, "b": 4e3 }]"#);
let mut map: JSONMap = HashMap::new();
map.insert(String::from("a"), Number(9.38083151965f64));
map.insert(String::from("b"), Number(4e3f64));
let expected = Ok(Array(vec![Object(map)]));
assert_eq!(
result, expected,
"Failed on just number values: {:#?}",
result
);
}
#[test]
fn parse_weird_character_array() {
let result =
JSON::parse(r#"["\"", "\\", "/", "\b", "\f", "\n", "\r", "\t", "\u0001", "\uface"]"#);
let expected = Ok(Array(vec![
JSONValue::from("\""),
JSONValue::from("\\"),
JSONValue::from("/"),
JSONValue::from("\u{8}"),
JSONValue::from("\x0C"),
JSONValue::from("\n"),
JSONValue::from("\r"),
JSONValue::from("\t"),
JSONValue::from("\u{1}"),
JSONValue::from("\u{face}"),
]));
assert_eq!(result, expected);
}
#[test]
fn parse_full_json_example() {
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 mut map: JSONMap = HashMap::new();
let mut emap: JSONMap = HashMap::new();
let mut fmap: JSONMap = HashMap::new();
let mut gmap: JSONMap = HashMap::new();
gmap.insert(String::from("h"), Null);
fmap.insert(String::from("g"), Object(gmap));
emap.insert(String::from("f"), Object(fmap));
map.insert(String::from("a"), Number(9.38083151965f64));
map.insert(String::from("b"), Number(4e3f64));
map.insert(
String::from("c"),
Array(vec![Number(1f64), Number(2f64), Number(3f64)]),
);
map.insert(String::from("d"), JSONValue::from("foo"));
map.insert(String::from("e"), Object(emap));
map.insert(
String::from("i"),
Array(vec![
JSONValue::from("\""),
JSONValue::from("\\"),
JSONValue::from("/"),
JSONValue::from("\u{8}"),
JSONValue::from("\x0C"),
JSONValue::from("\n"),
JSONValue::from("\r"),
JSONValue::from("\t"),
JSONValue::from("\u{1}"),
JSONValue::from("\u{face}"),
]),
);
assert!(result.is_ok(), format!("{:#?}", result));
let outer_array: Vec<JSONValue> = result.unwrap().unwrap();
let result_map: JSONMap = outer_array[0].clone().unwrap();
for (k, v) in &map {
assert_eq!(
result_map.get(k).unwrap(),
v,
"HashMap Entry Differs: {:#?}, {:#?}",
result_map.get(k).unwrap(),
v
);
}
}
}