ruffle/core/src/property_map.rs

//! The map of property names to values used by the ActionScript VM.
//! This allows for dynamically choosing case-sensitivty at runtime,
//! because SWFv6 and below is case-insensitive. This also maintains
//! the insertion order of properties, which is necessary for accurate
//! enumeration order.

use crate::string_utils;
use gc_arena::Collect;
use indexmap::{Equivalent, IndexMap};
use std::hash::{Hash, Hasher};

/// A map from property names to values.
#[derive(Debug)]
pub struct PropertyMap<V>(IndexMap<PropertyName, V>);

impl<V> PropertyMap<V> {
    pub fn new() -> Self {
        Self(IndexMap::new())
    }

    pub fn contains_key(&self, key: &str, case_sensitive: bool) -> bool {
        if case_sensitive {
            self.0.contains_key(&CaseSensitiveStr(key))
        } else {
            self.0.contains_key(&CaseInsensitiveStr(key))
        }
    }

    pub fn entry<'a>(&'a mut self, key: &'a str, case_sensitive: bool) -> Entry<'a, V> {
        if case_sensitive {
            match self.0.get_full_mut(&CaseSensitiveStr(&key)) {
                Some((index, _, _)) => Entry::Occupied(OccupiedEntry {
                    map: &mut self.0,
                    index,
                }),
                None => Entry::Vacant(VacantEntry {
                    map: &mut self.0,
                    key,
                }),
            }
        } else {
            match self.0.get_full_mut(&CaseInsensitiveStr(&key)) {
                Some((index, _, _)) => Entry::Occupied(OccupiedEntry {
                    map: &mut self.0,
                    index,
                }),
                None => Entry::Vacant(VacantEntry {
                    map: &mut self.0,
                    key,
                }),
            }
        }
    }

    /// Gets the value for the specified property.
    pub fn get(&self, key: &str, case_sensitive: bool) -> Option<&V> {
        if case_sensitive {
            self.0.get(&CaseSensitiveStr(key))
        } else {
            self.0.get(&CaseInsensitiveStr(key))
        }
    }

    /// Gets a mutable reference to the value for the specified property.
    #[allow(dead_code)]
    pub fn get_mut(&mut self, key: &str, case_sensitive: bool) -> Option<&mut V> {
        if case_sensitive {
            self.0.get_mut(&CaseSensitiveStr(key))
        } else {
            self.0.get_mut(&CaseInsensitiveStr(key))
        }
    }

    /// Gets a value by index, based on insertion order.
    pub fn get_index(&self, index: usize) -> Option<&V> {
        self.0.get_index(index).map(|(_, v)| v)
    }

    pub fn insert(&mut self, key: &str, value: V, case_sensitive: bool) -> Option<V> {
        match self.entry(key, case_sensitive) {
            Entry::Occupied(entry) => Some(entry.insert(value)),
            Entry::Vacant(entry) => {
                entry.insert(value);
                None
            }
        }
    }

    /// Returns the value tuples in Flash's iteration order (most recently added first).
    pub fn iter(&self) -> impl Iterator<Item = (&String, &V)> {
        self.0.iter().rev().map(|(k, v)| (&k.0, v))
    }

    /// Returns the key-value tuples in Flash's iteration order (most recently added first).
    pub fn iter_mut(&mut self) -> impl Iterator<Item = (&String, &mut V)> {
        self.0.iter_mut().rev().map(|(k, v)| (&k.0, v))
    }

    pub fn remove(&mut self, key: &str, case_sensitive: bool) -> Option<V> {
        // Note that we must use shift_remove to maintain order in case this object is enumerated.
        if case_sensitive {
            self.0.shift_remove(&CaseSensitiveStr(key))
        } else {
            self.0.shift_remove(&CaseInsensitiveStr(key))
        }
    }
}

unsafe impl<V: Collect> Collect for PropertyMap<V> {
    fn trace(&self, cc: gc_arena::CollectionContext) {
        for value in self.0.values() {
            value.trace(cc);
        }
    }
}

pub enum Entry<'a, V> {
    Occupied(OccupiedEntry<'a, V>),
    Vacant(VacantEntry<'a, V>),
}

pub struct OccupiedEntry<'a, V> {
    map: &'a mut IndexMap<PropertyName, V>,
    index: usize,
}

impl<'a, V> OccupiedEntry<'a, V> {
    pub fn remove_entry(&mut self) -> (String, V) {
        let (k, v) = self.map.shift_remove_index(self.index).unwrap();
        (k.0, v)
    }

    pub fn get_mut(&mut self) -> &mut V {
        self.map.get_index_mut(self.index).unwrap().1
    }

    pub fn insert(self, value: V) -> V {
        std::mem::replace(self.map.get_index_mut(self.index).unwrap().1, value)
    }
}

pub struct VacantEntry<'a, V> {
    map: &'a mut IndexMap<PropertyName, V>,
    key: &'a str,
}

impl<'a, V> VacantEntry<'a, V> {
    pub fn insert(self, value: V) {
        self.map.insert(PropertyName(self.key.to_string()), value);
    }
}

/// Wraps a str, causing the hash map to use a case insensitive hash and equality.
struct CaseInsensitiveStr<'a>(&'a str);

impl<'a> Hash for CaseInsensitiveStr<'a> {
    fn hash<H: Hasher>(&self, state: &mut H) {
        swf_hash_string_ignore_case(&self.0, state);
    }
}

impl<'a> Equivalent<PropertyName> for CaseInsensitiveStr<'a> {
    fn equivalent(&self, key: &PropertyName) -> bool {
        string_utils::swf_string_eq_ignore_case(&key.0, self.0)
    }
}

/// Wraps a str, causing the property map to use a case insensitive hash lookup,
/// but case sensitive equality.
struct CaseSensitiveStr<'a>(&'a str);

impl<'a> Hash for CaseSensitiveStr<'a> {
    fn hash<H: Hasher>(&self, state: &mut H) {
        swf_hash_string_ignore_case(&self.0, state);
    }
}

impl<'a> Equivalent<PropertyName> for CaseSensitiveStr<'a> {
    fn equivalent(&self, key: &PropertyName) -> bool {
        key.0 == self.0
    }
}

/// The property keys stored in the property map.
/// This uses a case insensitive hash to ensure that properties can be found in
/// SWFv6, which is case insensitve. The equality check is handled by the `Equivalent`
/// impls above, which allow it to be either case-sensitive or insensitive.
/// Note that the property of if key1 == key2 -> hash(key1) == hash(key2) still holds.
#[derive(Debug, Clone, PartialEq, Eq, Collect)]
#[collect(require_static)]
struct PropertyName(String);

#[allow(clippy::derive_hash_xor_eq)]
impl Hash for PropertyName {
    fn hash<H: Hasher>(&self, state: &mut H) {
        swf_hash_string_ignore_case(&self.0, state);
    }
}

fn swf_hash_string_ignore_case<H: Hasher>(s: &str, state: &mut H) {
    s.chars()
        .for_each(|c| string_utils::swf_char_to_lowercase(c).hash(state));
    state.write_u8(0xff);
}