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Simplify function calling.

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This commit is contained in:
Stephen Chung 2020-07-31 12:11:16 +08:00
parent a7ff207636
commit cb005506e2
4 changed files with 130 additions and 99 deletions
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15
src/engine.rs
View File

@ -1179,7 +1179,6 @@ impl Engine {
#[cfg(not(feature = "no_index"))]
Dynamic(Union::Array(mut rhs_value)) => {
let op = "==";
let mut scope = Scope::new();
// Call the `==` operator to compare each value
for value in rhs_value.iter_mut() {
@ -1190,13 +1189,13 @@ impl Engine {
let hash =
calc_fn_hash(empty(), op, args.len(), args.iter().map(|a| a.type_id()));
let (r, _) = self
.call_fn_raw(
&mut scope, mods, state, lib, op, hash, args, false, false, false,
def_value, level,
)
.map_err(|err| err.new_position(rhs.position()))?;
if r.as_bool().unwrap_or(false) {
if self
.call_native_fn(state, lib, op, hash, args, false, false, def_value)
.map_err(|err| err.new_position(rhs.position()))?
.0
.as_bool()
.unwrap_or(false)
{
return Ok(true.into());
}
}

162
src/fn_call.rs
View File

@ -41,7 +41,7 @@ use crate::stdlib::{
format,
iter::{empty, once},
mem,
string::ToString,
string::{String, ToString},
vec::Vec,
};
@ -67,43 +67,69 @@ fn extract_prop_from_setter(_fn_name: &str) -> Option<&str> {
None
}
/// This function replaces the first argument of a method call with a clone copy.
/// This is to prevent a pure function unintentionally consuming the first argument.
fn normalize_first_arg<'a>(
normalize: bool,
this_copy: &mut Dynamic,
old_this_ptr: &mut Option<&'a mut Dynamic>,
args: &mut FnCallArgs<'a>,
) {
/// A type that temporarily stores a mutable reference to a `Dynamic`,
/// replacing it with a cloned copy.
#[derive(Debug, Default)]
struct ArgBackup<'a> {
orig_mut: Option<&'a mut Dynamic>,
value_copy: Dynamic,
}
impl<'a> ArgBackup<'a> {
/// This function replaces the first argument of a method call with a clone copy.
/// This is to prevent a pure function unintentionally consuming the first argument.
///
/// `restore_first_arg` must be called before the end of the scope to prevent the shorter lifetime from leaking.
///
/// # Safety
///
/// This method blindly casts a reference to another lifetime, which saves allocation and string cloning.
///
/// If `restore_first_arg` is called before the end of the scope, the shorter lifetime will not leak.
fn change_first_arg_to_copy(&mut self, normalize: bool, args: &mut FnCallArgs<'a>) {
// Only do it for method calls with arguments.
if !normalize || args.is_empty() {
return;
}
// Clone the original value.
*this_copy = args[0].clone();
self.value_copy = args[0].clone();
// Replace the first reference with a reference to the clone, force-casting the lifetime.
// Keep the original reference. Must remember to restore it later with `restore_first_arg_of_method_call`.
// Must remember to restore it later with `restore_first_arg`.
//
// # Safety
//
// Blindly casting a a reference to another lifetime saves on allocations and string cloning,
// Blindly casting a reference to another lifetime saves allocation and string cloning,
// but must be used with the utmost care.
//
// We can do this here because, at the end of this scope, we'd restore the original reference
// with `restore_first_arg_of_method_call`. Therefore this shorter lifetime does not get "out".
let this_pointer = mem::replace(args.get_mut(0).unwrap(), unsafe {
mem::transmute(this_copy)
});
// We can do this here because, before the end of this scope, we'd restore the original reference
// via `restore_first_arg`. Therefore this shorter lifetime does not leak.
self.orig_mut = Some(mem::replace(args.get_mut(0).unwrap(), unsafe {
mem::transmute(&mut self.value_copy)
}));
}
*old_this_ptr = Some(this_pointer);
/// This function restores the first argument that was replaced by `change_first_arg_to_copy`.
///
/// # Safety
///
/// If `change_first_arg_to_copy` has been called, this function **MUST** be called _BEFORE_ exiting
/// the current scope. Otherwise it is undefined behavior as the shorter lifetime will leak.
fn restore_first_arg(&mut self, args: &mut FnCallArgs<'a>) {
if let Some(this_pointer) = self.orig_mut.take() {
args[0] = this_pointer;
}
}
}
/// This function restores the first argument that was replaced by `normalize_first_arg_of_method_call`.
fn restore_first_arg<'a>(old_this_ptr: Option<&'a mut Dynamic>, args: &mut FnCallArgs<'a>) {
if let Some(this_pointer) = old_this_ptr {
args[0] = this_pointer;
impl Drop for ArgBackup<'_> {
fn drop(&mut self) {
// Panic if the shorter lifetime leaks.
assert!(
self.orig_mut.is_none(),
"MutBackup::restore has not been called prior to existing this scope"
);
}
}
@ -138,34 +164,21 @@ impl Engine {
/// Function call arguments be _consumed_ when the function requires them to be passed by value.
/// All function arguments not in the first position are always passed by value and thus consumed.
/// **DO NOT** reuse the argument values unless for the first `&mut` argument - all others are silently replaced by `()`!
pub(crate) fn call_fn_raw(
pub(crate) fn call_native_fn(
&self,
_scope: &mut Scope,
_mods: &mut Imports,
state: &mut State,
lib: &Module,
fn_name: &str,
hash_fn: u64,
args: &mut FnCallArgs,
is_ref: bool,
_is_method: bool,
pub_only: bool,
def_val: Option<bool>,
_level: usize,
) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
self.inc_operations(state)?;
// Check for stack overflow
#[cfg(not(feature = "no_function"))]
#[cfg(not(feature = "unchecked"))]
if _level > self.limits.max_call_stack_depth {
return Err(Box::new(
EvalAltResult::ErrorStackOverflow(Position::none()),
));
}
// Search for the function
// First search registered native functions (can override packages)
// Search for the native function
// First search registered functions (can override packages)
// Then search packages
let func = self
.global_module
@ -173,22 +186,19 @@ impl Engine {
.or_else(|| self.packages.get_fn(hash_fn, pub_only));
if let Some(func) = func {
#[cfg(not(feature = "no_function"))]
let need_normalize = is_ref && (func.is_pure() || (func.is_script() && !_is_method));
#[cfg(feature = "no_function")]
let need_normalize = is_ref && func.is_pure();
let mut this_copy: Dynamic = Default::default();
let mut old_this_ptr: Option<&mut Dynamic> = None;
assert!(func.is_native());
// Calling pure function but the first argument is a reference?
normalize_first_arg(need_normalize, &mut this_copy, &mut old_this_ptr, args);
let mut backup: ArgBackup = Default::default();
backup.change_first_arg_to_copy(is_ref && func.is_pure(), args);
// Run external function
let result = func.get_native_fn()(self, lib, args)?;
let result = func.get_native_fn()(self, lib, args);
// Restore the original reference
restore_first_arg(old_this_ptr, args);
backup.restore_first_arg(args);
let result = result?;
// See if the function match print/debug (which requires special processing)
return Ok(match fn_name {
@ -320,6 +330,17 @@ impl Engine {
args: &mut FnCallArgs,
level: usize,
) -> Result<Dynamic, Box<EvalAltResult>> {
self.inc_operations(state)?;
// Check for stack overflow
#[cfg(not(feature = "no_function"))]
#[cfg(not(feature = "unchecked"))]
if level > self.limits.max_call_stack_depth {
return Err(Box::new(
EvalAltResult::ErrorStackOverflow(Position::none()),
));
}
let orig_scope_level = state.scope_level;
state.scope_level += 1;
@ -382,7 +403,7 @@ impl Engine {
|| self.packages.contains_fn(hash_fn, pub_only)
}
/// Perform an actual function call, taking care of special functions
/// Perform an actual function call, native Rust or scripted, taking care of special functions.
/// Position in `EvalAltResult` is `None` and must be set afterwards.
///
/// ## WARNING
@ -470,33 +491,26 @@ impl Engine {
)?
} else {
// Normal call of script function - map first argument to `this`
let mut first_copy: Dynamic = Default::default();
let mut old_first: Option<&mut Dynamic> = None;
// The first argument is a reference?
normalize_first_arg(is_ref, &mut first_copy, &mut old_first, args);
let mut backup: ArgBackup = Default::default();
backup.change_first_arg_to_copy(is_ref, args);
let result = self.call_script_fn(
scope, mods, state, lib, &mut None, fn_name, func, args, level,
)?;
);
// Restore the original reference
restore_first_arg(old_first, args);
backup.restore_first_arg(args);
result
result?
};
Ok((result, false))
}
// Normal native function call
_ => {
let mut scope = Scope::new();
let mut mods = Imports::new();
self.call_fn_raw(
&mut scope, &mut mods, state, lib, fn_name, hash_fn, args, is_ref, is_method,
pub_only, def_val, level,
)
}
_ => self.call_native_fn(
state, lib, fn_name, hash_fn, args, is_ref, pub_only, def_val,
),
}
}
@ -508,9 +522,21 @@ impl Engine {
mods: &mut Imports,
state: &mut State,
lib: &Module,
script: &Dynamic,
script_expr: &Dynamic,
level: usize,
) -> Result<Dynamic, Box<EvalAltResult>> {
let script = script.as_str().map_err(|typ| {
self.inc_operations(state)?;
// Check for stack overflow
#[cfg(not(feature = "no_function"))]
#[cfg(not(feature = "unchecked"))]
if level > self.limits.max_call_stack_depth {
return Err(Box::new(
EvalAltResult::ErrorStackOverflow(Position::none()),
));
}
let script = script_expr.as_str().map_err(|typ| {
EvalAltResult::ErrorMismatchOutputType(
self.map_type_name(type_name::<ImmutableString>()).into(),
typ.into(),
@ -782,12 +808,12 @@ impl Engine {
let expr = args_expr.get(0).unwrap();
let script = self.eval_expr(scope, mods, state, lib, this_ptr, expr, level)?;
let result = self
.eval_script_expr(scope, mods, state, lib, &script)
.eval_script_expr(scope, mods, state, lib, &script, level + 1)
.map_err(|err| err.new_position(expr.position()));
if scope.len() != prev_len {
// IMPORTANT! If the eval defines new variables in the current scope,
// all variable offsets from this point on will be mis-aligned.
if scope.len() != prev_len {
state.always_search = true;
}

10
src/fn_native.rs
View File

@ -280,6 +280,16 @@ impl CallableFunction {
Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => false,
}
}
/// Is this a native Rust function?
pub fn is_native(&self) -> bool {
match self {
Self::Pure(_) | Self::Method(_) => true,
Self::Iterator(_) => true,
#[cfg(not(feature = "no_function"))]
Self::Script(_) => false,
}
}
/// Get the access mode.
pub fn access(&self) -> FnAccess {
match self {

12
src/optimize.rs
View File

@ -3,7 +3,7 @@
use crate::any::Dynamic;
use crate::calc_fn_hash;
use crate::engine::{
Engine, Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
Engine, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
};
use crate::fn_native::FnPtr;
use crate::module::Module;
@ -132,22 +132,18 @@ fn call_fn_with_constant_arguments(
state
.engine
.call_fn_raw(
&mut Scope::new(),
&mut Imports::new(),
.call_native_fn(
&mut Default::default(),
state.lib,
fn_name,
hash_fn,
arg_values.iter_mut().collect::<StaticVec<_>>().as_mut(),
false,
false,
true,
None,
0,
)
.map(|(v, _)| Some(v))
.unwrap_or_else(|_| None)
.ok()
.map(|(v, _)| v)
}
/// Optimize a statement.