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Refactor JSON.parse #1535

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Sep 15, 2021
Merged

Refactor JSON.parse #1535

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b070f5d
Refactor `JSON.parse`
raskad Aug 29, 2021
53e4f04
Change while loop to for loop
raskad Aug 30, 2021
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146 changes: 109 additions & 37 deletions boa/src/builtins/json/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ use crate::{
BuiltIn,
},
object::{JsObject, ObjectInitializer, RecursionLimiter},
property::{Attribute, PropertyKey, PropertyNameKind},
property::{Attribute, PropertyNameKind},
symbol::WellKnownSymbols,
value::IntegerOrInfinity,
BoaProfiler, Context, JsResult, JsString, JsValue,
Expand Down Expand Up @@ -72,59 +72,131 @@ impl Json {
/// [spec]: https://tc39.es/ecma262/#sec-json.parse
/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse
pub(crate) fn parse(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
let arg = args
// 1. Let jsonString be ? ToString(text).
let json_string = args
.get(0)
.cloned()
.unwrap_or_else(JsValue::undefined)
.unwrap_or_default()
.to_string(context)?;

match serde_json::from_str::<JSONValue>(&arg) {
Ok(json) => {
let j = JsValue::from_json(json, context);
match args.get(1) {
Some(reviver) if reviver.is_function() => {
let mut holder: JsValue = context.construct_object().into();
holder.set_field("", j, true, context)?;
Self::walk(reviver, context, &mut holder, &PropertyKey::from(""))
}
_ => Ok(j),
}
// 2. Parse ! StringToCodePoints(jsonString) as a JSON text as specified in ECMA-404.
// Throw a SyntaxError exception if it is not a valid JSON text as defined in that specification.
if let Err(e) = serde_json::from_str::<JSONValue>(&json_string) {
return context.throw_syntax_error(e.to_string());
}

// 3. Let scriptString be the string-concatenation of "(", jsonString, and ");".
let script_string = JsString::concat_array(&["(", json_string.as_str(), ");"]);

// 4. Let script be ParseText(! StringToCodePoints(scriptString), Script).
// 5. NOTE: The early error rules defined in 13.2.5.1 have special handling for the above invocation of ParseText.
// 6. Assert: script is a Parse Node.
// 7. Let completion be the result of evaluating script.
// 8. NOTE: The PropertyDefinitionEvaluation semantics defined in 13.2.5.5 have special handling for the above evaluation.
// 9. Let unfiltered be completion.[[Value]].
// 10. Assert: unfiltered is either a String, Number, Boolean, Null, or an Object that is defined by either an ArrayLiteral or an ObjectLiteral.
let unfiltered = context.eval(script_string.as_bytes())?;

match args.get(1).cloned().unwrap_or_default().as_object() {
// 11. If IsCallable(reviver) is true, then
Some(obj) if obj.is_callable() => {
// a. Let root be ! OrdinaryObjectCreate(%Object.prototype%).
let root = context.construct_object();

// b. Let rootName be the empty String.
// c. Perform ! CreateDataPropertyOrThrow(root, rootName, unfiltered).
root.create_data_property_or_throw("", unfiltered, context)
.expect("CreateDataPropertyOrThrow should never throw here");

// d. Return ? InternalizeJSONProperty(root, rootName, reviver).
Self::internalize_json_property(root, "".into(), obj, context)
}
Err(err) => context.throw_syntax_error(err.to_string()),
// 12. Else,
// a. Return unfiltered.
_ => Ok(unfiltered),
}
}

/// This is a translation of the [Polyfill implementation][polyfill]
/// `25.5.1.1 InternalizeJSONProperty ( holder, name, reviver )`
///
/// This function recursively walks the structure, passing each key-value pair to the reviver function
/// for possible transformation.
/// More information:
/// - [ECMAScript reference][spec]
///
/// [polyfill]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse
fn walk(
reviver: &JsValue,
/// [spec]: https://tc39.es/ecma262/#sec-internalizejsonproperty
fn internalize_json_property(
holder: JsObject,
name: JsString,
reviver: JsObject,
context: &mut Context,
holder: &mut JsValue,
key: &PropertyKey,
) -> JsResult<JsValue> {
let value = holder.get_field(key.clone(), context)?;

if let JsValue::Object(ref object) = value {
let keys: Vec<_> = object.borrow().properties().keys().collect();

for key in keys {
let v = Self::walk(reviver, context, &mut value.clone(), &key);
match v {
Ok(v) if !v.is_undefined() => {
value.set_field(key, v, false, context)?;
// 1. Let val be ? Get(holder, name).
let val = holder.get(name.clone(), context)?;

// 2. If Type(val) is Object, then
if let Some(obj) = val.as_object() {
// a. Let isArray be ? IsArray(val).
// b. If isArray is true, then
if obj.is_array() {
// i. Let I be 0.
// ii. Let len be ? LengthOfArrayLike(val).
// iii. Repeat, while I < len,
let len = obj.length_of_array_like(context)? as i64;
for i in 0..len {
// 1. Let prop be ! ToString(𝔽(I)).
// 2. Let newElement be ? InternalizeJSONProperty(val, prop, reviver).
let new_element = Self::internalize_json_property(
obj.clone(),
i.to_string().into(),
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reviver.clone(),
context,
)?;

// 3. If newElement is undefined, then
if new_element.is_undefined() {
// a. Perform ? val.[[Delete]](prop).
obj.__delete__(&i.into(), context)?;
}
Ok(_) => {
value.remove_property(key);
// 4. Else,
else {
// a. Perform ? CreateDataProperty(val, prop, newElement).
obj.create_data_property(i, new_element, context)?;
}
}
}
// c. Else,
else {
// i. Let keys be ? EnumerableOwnPropertyNames(val, key).
let keys = obj.enumerable_own_property_names(PropertyNameKind::Key, context)?;

// ii. For each String P of keys, do
for p in keys {
// This is safe, because EnumerableOwnPropertyNames with 'key' type only returns strings.
let p = p.as_string().unwrap();

// 1. Let newElement be ? InternalizeJSONProperty(val, P, reviver).
let new_element = Self::internalize_json_property(
obj.clone(),
p.clone(),
reviver.clone(),
context,
)?;

// 2. If newElement is undefined, then
if new_element.is_undefined() {
// a. Perform ? val.[[Delete]](P).
obj.__delete__(&p.clone().into(), context)?;
}
// 3. Else,
else {
// a. Perform ? CreateDataProperty(val, P, newElement).
obj.create_data_property(p.as_str(), new_element, context)?;
}
Err(_v) => {}
}
}
}
context.call(reviver, holder, &[key.into(), value])

// 3. Return ? Call(reviver, holder, « name, val »).
reviver.call(&holder.into(), &[name.into(), val], context)
}

/// `JSON.stringify( value[, replacer[, space]] )`
Expand Down
7 changes: 0 additions & 7 deletions boa/src/object/gcobject.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -846,13 +846,6 @@ impl JsObject {
self.borrow_mut().insert(key, property)
}

/// Helper function for property removal.
#[inline]
#[track_caller]
pub(crate) fn remove(&self, key: &PropertyKey) -> Option<PropertyDescriptor> {
self.borrow_mut().remove(key)
}

/// Inserts a field in the object `properties` without checking if it's writable.
///
/// If a field was already in the object with the same name that a `Some` is returned
Expand Down
52 changes: 1 addition & 51 deletions boa/src/value/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,15 +8,14 @@ mod tests;
use crate::{
builtins::{
number::{f64_to_int32, f64_to_uint32},
Array, Number,
Number,
},
object::{JsObject, Object, ObjectData},
property::{PropertyDescriptor, PropertyKey},
symbol::{JsSymbol, WellKnownSymbols},
BoaProfiler, Context, JsBigInt, JsResult, JsString,
};
use gc::{Finalize, Trace};
use serde_json::Value as JSONValue;
use std::{
collections::HashSet,
convert::TryFrom,
Expand Down Expand Up @@ -115,45 +114,6 @@ impl JsValue {
context.construct_object().into()
}

/// Convert from a JSON value to a JS value
pub fn from_json(json: JSONValue, context: &mut Context) -> Self {
match json {
JSONValue::Number(v) => {
if let Some(Ok(integer_32)) = v.as_i64().map(i32::try_from) {
Self::new(integer_32)
} else {
Self::new(v.as_f64().expect("Could not convert value to f64"))
}
}
JSONValue::String(v) => Self::new(v),
JSONValue::Bool(v) => Self::new(v),
JSONValue::Array(vs) => {
let vs: Vec<_> = vs
.into_iter()
.map(|json| Self::from_json(json, context))
.collect();

Array::create_array_from_list(vs, context).into()
}
JSONValue::Object(obj) => {
let new_obj = JsValue::new_object(context);
for (key, json) in obj.into_iter() {
let value = Self::from_json(json, context);
new_obj.set_property(
key,
PropertyDescriptor::builder()
.value(value)
.writable(true)
.enumerable(true)
.configurable(true),
);
}
new_obj
}
JSONValue::Null => Self::null(),
}
}

/// Returns true if the value is an object
#[inline]
pub fn is_object(&self) -> bool {
Expand Down Expand Up @@ -304,16 +264,6 @@ impl JsValue {
}
}

/// Removes a property from a [`JsValue`] object.
///
/// It will return a boolean based on if the value was removed, if there was no value to remove false is returned.
pub(crate) fn remove_property<Key>(&self, key: Key) -> bool
where
Key: Into<PropertyKey>,
{
self.as_object().map(|x| x.remove(&key.into())).is_some()
}

/// Resolve the property in the object.
///
/// A copy of the Property is returned.
Expand Down