From 87a7e44fcfaf2056dfa1191477e02ed225063286 Mon Sep 17 00:00:00 2001
From: Yaroslav Bolyukin <iam@lach.pw>
Date: Wed, 09 Nov 2022 23:33:37 +0000
Subject: [PATCH] perf: destruct capacity hints


---
--- a/crates/jrsonnet-evaluator/src/function/parse.rs
+++ b/crates/jrsonnet-evaluator/src/function/parse.rs
@@ -44,7 +44,8 @@
 	args: &dyn ArgsLike,
 	tailstrict: bool,
 ) -> Result<Context> {
-	let mut passed_args = GcHashMap::with_capacity(params.len());
+	let mut passed_args =
+		GcHashMap::with_capacity(params.iter().map(|p| p.0.capacity_hint()).sum());
 	if args.unnamed_len() > params.len() {
 		throw!(TooManyArgsFunctionHas(
 			params.len(),
@@ -83,8 +84,10 @@
 		// Some args are unset, but maybe we have defaults for them
 		// Default values should be created in newly created context
 		let fctx = Context::new_future();
-		let mut defaults =
-			GcHashMap::with_capacity(params.len() - filled_named - filled_positionals);
+		let mut defaults = GcHashMap::with_capacity(
+			params.iter().map(|p| p.0.capacity_hint()).sum::<usize>()
+				- filled_named - filled_positionals,
+		);
 
 		for (idx, param) in params.iter().enumerate().filter(|p| p.1 .1.is_some()) {
 			if let Some(name) = param.0.name() {
@@ -241,7 +244,7 @@
 
 	let fctx = Context::new_future();
 
-	let mut bindings = GcHashMap::new();
+	let mut bindings = GcHashMap::with_capacity(params.iter().map(|p| p.0.capacity_hint()).sum());
 
 	for param in params.iter() {
 		if let Some(v) = &param.1 {
--- a/crates/jrsonnet-parser/src/expr.rs
+++ b/crates/jrsonnet-parser/src/expr.rs
@@ -228,6 +228,39 @@
 			_ => None,
 		}
 	}
+	pub fn capacity_hint(&self) -> usize {
+		#[cfg(feature = "exp-destruct")]
+		fn cap_rest(rest: &Option<DestructRest>) -> usize {
+			match rest {
+				Some(DestructRest::Keep(_)) => 1,
+				Some(DestructRest::Drop) => 0,
+				None => 0,
+			}
+		}
+		match self {
+			Self::Full(_) => 1,
+			#[cfg(feature = "exp-destruct")]
+			Self::Skip => 0,
+			#[cfg(feature = "exp-destruct")]
+			Self::Array { start, rest, end } => {
+				start.iter().map(Destruct::capacity_hint).sum::<usize>()
+					+ end.iter().map(Destruct::capacity_hint).sum::<usize>()
+					+ cap_rest(rest)
+			}
+			#[cfg(feature = "exp-destruct")]
+			Self::Object { fields, rest } => {
+				let mut out = 0;
+				for (_, into, _) in fields {
+					match into {
+						Some(v) => out += v.capacity_hint(),
+						// Field is destructured to default name
+						None => out += 1,
+					}
+				}
+				out + cap_rest(rest)
+			}
+		}
+	}
 }
 
 #[cfg_attr(feature = "structdump", derive(Codegen))]
@@ -244,6 +277,14 @@
 		value: LocExpr,
 	},
 }
+impl BindSpec {
+	pub fn capacity_hint(&self) -> usize {
+		match self {
+			BindSpec::Field { into, .. } => into.capacity_hint(),
+			BindSpec::Function { .. } => 1,
+		}
+	}
+}
 
 #[cfg_attr(feature = "structdump", derive(Codegen))]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]

-- 
gitstuff